Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 429 | 03391C030301 | 29.26920 | 96.15700 | Jairu Chu | 3991 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 103 | 104 | 1 |
| 430 | 03282D160026 | 28.11590 | 92.95130 | | 4648 | Brahmaputra | Kurung Kumey | Arunachal Pradesh | 56 | 56 | 1 |
| 431 | 03082L052049 | 28.98550 | 94.27010 | Neyul pu chu | 3478 | Brahmaputra | West Siang | Arunachal Pradesh | 51 | 51 | 1 |
| 432 | 03391C030269 | 29.30910 | 96.13550 | Jairu Chu | 4204 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 27 | 27 | 1 |
| 433 | 03591H081919 | 28.07990 | 97.30390 | | 4304 | Brahmaputra | Anjaw | Arunachal Pradesh | 24 | 24 | 1 |
| 434 | 03592A142141 | 27.72560 | 96.84840 | | 3669 | Brahmaputra | Anjaw | Arunachal Pradesh | 19 | 19 | 1 |
| 435 | 03382P050216 | 28.83120 | 95.34960 | Emra River | 4046 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 18 | 18 | 1 |
| 436 | 03382O160158 | 29.17340 | 95.82600 | Aison Chu | 3790 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 15 | 15 | 1 |
| 437 | 03382O160174 | 29.07400 | 95.94640 | Matuni | 4165 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 13 | 13 | 1 |
| 438 | 03592E012219 | 27.94950 | 97.10750 | | 3874 | Brahmaputra | Anjaw | Arunachal Pradesh | 13 | 13 | 1 |
| 439 | 03282D160031 | 28.10610 | 92.97010 | | 4340 | Brahmaputra | Kurung Kumey | Arunachal Pradesh | 13 | 13 | 1 |
| 440 | 03592A142147 | 27.71210 | 96.93840 | | 3751 | Brahmaputra | Anjaw | Arunachal Pradesh | 13 | 13 | 1 |
| 441 | 03382P050201 | 28.87500 | 95.37730 | Emra River | 3504 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 12 | 12 | 1 |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 442 | 03391C030259 | 29.32130 | 96.11750 | Jairu Chu | 3975 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | 11 | 1 |
| 443 | 03391C040395 | 29.07940 | 96.14480 | Dri Chu | 3945 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 86 | 86 | 0 |
| 444 | 03591D160698 | 28.20220 | 96.89800 | Dzayul chu | 3731 | Brahmaputra | Anjaw | Arunachal Pradesh | 67 | 67 | 0 |
| 445 | 03082O080107 | 29.06180 | 95.26310 | Dihang | 3668 | Brahmaputra | Upper Siang | Arunachal Pradesh | 48 | 48 | 0 |
| 446 | 03682L010077 | 28.75260 | 94.00100 | Siyom | 4019 | Brahmaputra | West Siang | Arunachal Pradesh | 23 | 23 | 0 |
| 447 | 03382P050214 | 28.84810 | 95.32010 | Emra River | 3913 | Brahmaputra | Upper Siang | Arunachal Pradesh | 22 | 22 | 0 |
| 448 | 03391D090733 | 28.83790 | 96.49740 | Thangkung Chu | 3388 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 21 | 21 | 0 |
| 449 | 03382O120071 | 29.16580 | 95.67410 | Andra Chu | 3771 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 19 | 19 | 0 |
| 450 | 03082O120228 | 29.23330 | 95.65410 | Rirung Chu | 3915 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 17 | 17 | 0 |
| 451 | 03383A100182 | 27.74150 | 92.51540 | Pachuk | 3863 | Brahmaputra | East Kameng | Arunachal Pradesh | 13 | 13 | 0 |
| 452 | 03591H041404 | 28.02050 | 97.19390 | | 4040 | Brahmaputra | Anjaw | Arunachal Pradesh | 11 | 11 | 0 |
| 453 | 03082O040061 | 29.05800 | 95.23680 | Dihang | 3743 | Brahmaputra | Upper Siang | Arunachal Pradesh | 10 | 10 | 0 |
| 454 | 03382P050213 | 28.85160 | 95.36850 | Emra River | 3192 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 10 | 10 | 0 |

Sl. No.
Lake ID
Latitude
Longitude
River
Elevation
Basin
District
State
Inventory Area (Ha) 2021
Lake Area August 2025 (Ha)
Change in Area w.r.t. Inventory Area


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 455 | 03082O120243 | 29.19520 | 95.59170 | Rirung Chu | 3708 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 43 | 43 | -1 |
| 456 | 03182H100356 | 28.59450 | 93.72570 | Subansiri | 4208 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 25 | 25 | -1 |
| 457 | 03391D060637 | 28.72910 | 96.44640 | Thangkung Chu | 4086 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 21 | 21 | -1 |
| 458 | 03383A090169 | 27.83470 | 92.68540 | Kameng | 3951 | Brahmaputra | East Kameng | Arunachal Pradesh | 18 | 18 | -1 |
| 459 | 03182H100371 | 28.56770 | 93.56270 | Subansiri | 4074 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 16 | 16 | -1 |
| 460 | 03592A142177 | 27.64640 | 96.87790 | | 3263 | Brahmaputra | Changlang | Arunachal Pradesh | 15 | 15 | -1 |
| 461 | 03391D060681 | 28.56520 | 96.40780 | Thangkung Chu | 4124 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 14 | 14 | -1 |
| 462 | 03391D010517 | 28.81980 | 96.14460 | Thangkung Chu | 3723 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 14 | 14 | -1 |
| 463 | 03683A020714 | 27.58850 | 92.22210 | Mago Chu | 4455 | Brahmaputra | West Kameng | Arunachal Pradesh | 13 | 13 | -1 |
| 464 | 03082K160032 | 29.22580 | 94.78320 | Nugong Chu | 3683 | Brahmaputra | Upper Siang | Arunachal Pradesh | 13 | 13 | -1 |
| 465 | 03678M140443 | 27.69720 | 91.87320 | Towang Chu | 4467 | Brahmaputra | Tawang | Arunachal Pradesh | 13 | 13 | -1 |
| 466 | 03382P050195 | 28.91120 | 95.33350 | Emra River | 3789 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 12 | 12 | -1 |
| 467 | 03382O120067 | 29.17230 | 95.73640 | Yonggyap Chu | 3652 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 10 | 10 | -1 |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 494 | 03391D060639 | 28.72730 | 96.48540 | Thangkung Chu | 4084 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 29 | 27 | -6 |
| 495 | 03082K120012 | 29.17670 | 94.52570 | Rigong Chu | 4258 | Brahmaputra | Upper Siang | Arunachal Pradesh | 15 | 14 | -6 |
| 496 | 03391C030294 | 29.28330 | 96.09110 | Jairu Chu | 4204 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 13 | 12 | -6 |
| 497 | 03682L050088 | 28.95330 | 94.38290 | Siyom | 3858 | Brahmaputra | Upper Siang | Arunachal Pradesh | 19 | 18 | -7 |
| 498 | 03082K112004 | 29.30770 | 94.63690 | Lushar pu chu | 4142 | Brahmaputra | Upper Siang | Arunachal Pradesh | 15 | 14 | -7 |
| 499 | 03382P050193 | 28.91680 | 95.33970 | Emra River | 3901 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | 10 | -7 |
| 500 | 03678M140517 | 27.62470 | 91.80340 | Towang Chu | 4329 | Brahmaputra | Tawang | Arunachal Pradesh | 11 | 10 | -7 |
| 501 | 03591H041374 | 28.05830 | 97.22590 | | 4113 | Brahmaputra | Anjaw | Arunachal Pradesh | 18 | 17 | -8 |
| 502 | 03182H060310 | 28.54110 | 93.37990 | Subansiri | 4307 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 16 | 15 | -8 |
| 503 | 03082P050299 | 28.92240 | 95.32290 | Yang Sang Chu | 3841 | Brahmaputra | Upper Siang | Arunachal Pradesh | 16 | 15 | -9 |
| 504 | 03391D060633 | 28.73990 | 96.41340 | Thangkung Chu | 4105 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 12 | 11 | -9 |
| 505 | 03383A130216 | 27.90420 | 92.80980 | Kameng | 4306 | Brahmaputra | East Kameng | Arunachal Pradesh | 12 | 11 | -10 |
| 506 | 03592E012220 | 27.94750 | 97.13110 | | 3819 | Brahmaputra | Anjaw | Arunachal Pradesh | 11 | 10 | -10 |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 507 | 03382P060219 | 28.74640 | 95.39840 | Chichi River | 3787 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | 10 | -10 |
| 508 | 03182H140401 | 28.61620 | 93.81990 | Subansiri | 3590 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 46 | 41 | -11 |
| 509 | 03682H130005 | 28.76280 | 93.98650 | | 3957 | Brahmaputra | West Siang | Arunachal Pradesh | 20 | 18 | -11 |
| 510 | 03182H140408 | 28.58270 | 93.81160 | Subansiri | 3799 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 11 | 10 | -12 |
| 511 | 03391D050598 | 28.86240 | 96.44010 | Thangkung Chu | 2979 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | 10 | -12 |
| 512 | 03391D010492 | 28.88670 | 96.19690 | Dri Chu | 3255 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 44 | 38 | -13 |
| 513 | 03391D050623 | 28.80180 | 96.44020 | Thangkung Chu | 4114 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 31 | 27 | -13 |
| 514 | 03382O160153 | 29.20220 | 95.79670 | Aison Chu | 4054 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 15 | 13 | -13 |
| 515 | 03591H041399 | 28.02540 | 97.18630 | | 4227 | Brahmaputra | Anjaw | Arunachal Pradesh | 15 | 13 | -13 |
| 516 | 03382O120059 | 29.20770 | 95.74160 | Aison Chu | 3913 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 10 | 9 | -14 |
| 517 | 03382O160130 | 29.25130 | 95.95710 | Aison Chu | 3738 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 10 | 9 | -14 |
| 518 | 03682L050087 | 28.96320 | 94.37220 | Siyom | 4145 | Brahmaputra | Upper Siang | Arunachal Pradesh | 19 | 16 | -16 |
| 519 | 03082H101688 | 28.67210 | 93.72350 | Nelung phu chu | 4361 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 12 | 10 | -17 |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 520 | 03682L010076 | 28.75390 | 94.13350 | Siyom | 4057 | Brahmaputra | West Siang | Arunachal Pradesh | 11 | 9 | -18 |
| 521 | 03391C040367 | 29.14530 | 96.06630 | Dri Chu | 3949 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 31 | 25 | -19 |
| 522 | 03391D060711 | 28.52130 | 96.24980 | Thangkung Chu | 3636 | Brahmaputra | Lower Dibang Valley | Arunachal Pradesh | 16 | 13 | -19 |
| 523 | 03391D010469 | 28.98940 | 96.18810 | Dri Chu | 4316 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | 9 | -20 |
| 524 | 03182H110392 | 28.45770 | 93.57910 | Subansiri | 3922 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 48 | 37 | -22 |
| 525 | 03382P050202 | 28.87460 | 95.33410 | Emra River | 3756 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 21 | 16 | -22 |
| 526 | 03391D050617 | 28.82330 | 96.35900 | Thangkung Chu | 3941 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 19 | 15 | -22 |
| 527 | 03591H081932 | 28.05280 | 97.28130 | | 4499 | Brahmaputra | Anjaw | Arunachal Pradesh | 11 | 8 | -24 |
| 528 | 03391D060669 | 28.61730 | 96.43940 | Thangkung Chu | 3914 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | 8 | -25 |
| 529 | 03591H041413 | 28.00820 | 97.17630 | | 4240 | Brahmaputra | Anjaw | Arunachal Pradesh | 15 | 11 | -29 |
| 530 | 03391C040319 | 29.24140 | 96.07370 | Jairu Chu | 4199 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 13 | 9 | -30 |
| 531 | 03591H081936 | 28.04450 | 97.29260 | | 4472 | Brahmaputra | Anjaw | Arunachal Pradesh | 10 | 7 | -33 |
| 532 | 03182H070344 | 28.30470 | 93.43720 | Yu me chu | 3952 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 35 | 20 | -43 |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 533 | 03082O150278 | 29.35240 | 95.91530 | Chendruk Chu | 4357 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 46 | 25 | -46 |
| 534 | 03391C040435 | 29.00930 | 96.08370 | Dri Chu | 4018 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 15 | # | # |
| 535 | 03391D020537 | 28.54180 | 96.12500 | Thangkung Chu | 4031 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | # | # |
| 536 | 03391D050624 | 28.80140 | 96.48430 | Thangkung Chu | 3819 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 35 | # | # |
| 537 | 03391D090727 | 28.87230 | 96.51030 | Thangkung Chu | 3926 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 19 | # | # |
| 538 | 03391D090741 | 28.80060 | 96.51250 | Thangkung Chu | 4344 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 26 | # | # |
| 539 | 03182H110391 | 28.45860 | 93.60540 | Subansiri | 3957 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 12 | # | # |
| 540 | 03182H140406 | 28.58680 | 93.83940 | Subansiri | 4296 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 11 | # | # |
| 541 | 03591D150678 | 28.31460 | 96.81730 | Dzayul chu | 3879 | Brahmaputra | Anjaw | Arunachal Pradesh | 20 | # | # |
| 542 | 03591D150686 | 28.25300 | 96.81940 | Dzayul chu | 4030 | Brahmaputra | Anjaw | Arunachal Pradesh | 16 | # | # |
| 543 | 03591D160702 | 28.16450 | 96.83050 | Gediu chu | 3890 | Brahmaputra | Anjaw | Arunachal Pradesh | 21 | # | # |
| 544 | 03592E012191 | 27.98990 | 97.09780 | | 3687 | Brahmaputra | Anjaw | Arunachal Pradesh | 12 | # | # |
| 545 | 03082K081990 | 29.06890 | 94.30030 | Neyul pu chu | 4435 | Brahmaputra | Upper Siang | Arunachal Pradesh | 13 | # | # |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 546 | 03391C040346 | 29.19740 | 96.19240 | Dri Chu | 4321 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 16 | # | # |
| 547 | 03391C030291 | 29.28790 | 96.13440 | Jairu Chu | 4045 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 10 | # | # |
| 548 | 03182H110385 | 28.48300 | 93.60300 | Subansiri | 3987 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 12 | # | # |
| 549 | 03382O160146 | 29.22890 | 95.96160 | Aison Chu | 4328 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 14 | # | # |
| 550 | 03391C040355 | 29.18290 | 96.08690 | Dri Chu | 4263 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 24 | # | # |
| 551 | 03182H070342 | 28.31310 | 93.39150 | Yu me chu | 4066 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 20 | # | # |
| 552 | 03282H070072 | 28.29400 | 93.35480 | | 3597 | Brahmaputra | Kurung Kumey | Arunachal Pradesh | 10 | # | # |
| 553 | 03391C040369 | 29.14140 | 96.03630 | Dri Chu | 4139 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 30 | # | # |
| 554 | 03678M090241 | 27.80160 | 91.64290 | Dangme Chu | 4504 | Brahmaputra | Tawang | Arunachal Pradesh | 12 | # | # |
| 555 | 03391C030262 | 29.31530 | 96.12530 | Jairu Chu | 3996 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 12 | # | # |
| 556 | 03391D050585 | 28.89040 | 96.49440 | Thangkung Chu | 3366 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 17 | # | # |
| 557 | 03391C040313 | 29.24930 | 96.02800 | Aison Chu | 4133 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 12 | # | # |
| 558 | 03182H060321 | 28.52390 | 93.39400 | Yu me chu | 4249 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 12 | # | # |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 559 | 03592E052239 | 27.99360 | 97.31550 | | 4270 | Brahmaputra | Anjaw | Arunachal Pradesh | 14 | # | # |
| 560 | 03082P050307 | 28.87560 | 95.31600 | Yang Sang Chu | 3847 | Brahmaputra | Upper Siang | Arunachal Pradesh | 15 | # | # |
| 561 | 03592A092125 | 27.81640 | 96.70680 | | 3488 | Brahmaputra | Anjaw | Arunachal Pradesh | 11 | # | # |
| 562 | 03592E052276 | 27.89270 | 97.35850 | | 3931 | Brahmaputra | Anjaw | Arunachal Pradesh | 22 | # | # |
| 563 | 03592A142140 | 27.73240 | 96.87060 | | 4012 | Brahmaputra | Anjaw | Arunachal Pradesh | 12 | # | # |
| 564 | 03391D050593 | 28.87540 | 96.39450 | Thangkung Chu | 3119 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 41 | # | # |
| 565 | 03391D050594 | 28.87410 | 96.43580 | Thangkung Chu | 3220 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 17 | # | # |
| 566 | 03082P020293 | 28.72040 | 95.16010 | Dihang | 3640 | Brahmaputra | Upper Siang | Arunachal Pradesh | 22 | # | # |
| 567 | 03391D060629 | 28.74900 | 96.37490 | Thangkung Chu | 3784 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 26 | # | # |
| 568 | 03182H100359 | 28.58530 | 93.74300 | Subansiri | 3758 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 11 | # | # |
| 569 | 03182H100368 | 28.57570 | 93.57830 | Subansiri | 3842 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 37 | # | # |
| 570 | 03678M090251 | 27.75720 | 91.65040 | Dangme Chu | 4152 | Brahmaputra | Tawang | Arunachal Pradesh | 17 | # | # |
| 571 | 03682H140058 | 28.56230 | 93.88680 | | 3938 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 13 | # | # |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
Type: table
Table

| Sl. No. | Lake ID | Latitude | Longitude | River | Elevation | Basin | District | State | Inventory Area (Ha) 2021 | Lake Area August 2025 (Ha) | Change in Area w.r.t. Inventory Area |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 572 | 03182H100349 | 28.66780 | 93.73410 | Subansiri | 4016 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 20 | # | # |
| 573 | 03182H100360 | 28.58470 | 93.71210 | Subansiri | 3873 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 14 | # | # |
| 574 | 03082L050034 | 28.97820 | 94.39780 | Pite | 3111 | Brahmaputra | Upper Siang | Arunachal Pradesh | 25 | # | # |
| 575 | 03682H140047 | 28.60610 | 93.84530 | | 4022 | Brahmaputra | Upper Subansiri | Arunachal Pradesh | 12 | # | # |
| 576 | 03682L010072 | 28.75690 | 94.15250 | Siyom | 3875 | Brahmaputra | West Siang | Arunachal Pradesh | 13 | # | # |
| 577 | 03282D160025 | 28.11710 | 92.96890 | | 4214 | Brahmaputra | Kurung Kumey | Arunachal Pradesh | 18 | # | # |
| 578 | 03391C040381 | 29.10000 | 96.17310 | Dri Chu | 3949 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 22 | # | # |
| 579 | 03391D050578 | 28.92400 | 96.36800 | Thangkung Chu | 4109 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 10 | # | # |
| 580 | 03591D160688 | 28.24510 | 96.83170 | Dzayul chu | 3900 | Brahmaputra | Anjaw | Arunachal Pradesh | 43 | # | # |
| 581 | 03391C030257 | 29.32490 | 96.11400 | Jairu Chu | 3962 | Brahmaputra | Dibang Valley | Arunachal Pradesh | 11 | # | # |


Document: Monitoring Report Aug 2025
Section: 1. Introduction > 1.3 Inventory of Glacial Lakes & Water Bodies 2011 > 5.2 Conclusion on Monitoring of 1941 Glacial lakes being monitored from 2025 (as per Glacial Lake Atlas, 2023)
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*Note: “#” indicates frozen/ dried/cloud covered lakes. Inventory Area (in Ha) has been rounded off.*

- GLs displaying increase in area

**6. References**

1. NRSC, July 2011. *Final Report of "Inventory and Monitoring of Glacial Lakes / Water Bodies in the Himalayan Region of Indian River Basins"*, Technical Report Published by National Remote Sensing Centre, Hyderabad.

2. NRSC, April 2012. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins during 2011"*, Technical Report Published by National Remote Sensing Centre, Hyderabad.

3. NRSC, March 2013. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins during 2012"*, Technical Report Published by National Remote Sensing Centre, Hyderabad.

4. NRSC, December 2013. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins during 2013"*, Technical Report Published by National Remote Sensing Centre, Hyderabad.

5. NRSC, December 2014. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins during 2014"*, Technical Report Published by National Remote Sensing Centre, Hyderabad.

6. NRSC, December 2015. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins during 2015"*, Technical Report Published by National Remote Sensing Centre, Hyderabad.

7. CWC, February 2017. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins for 2016"*, Technical Report Published by Climate Change & IAD Directorate, CWC, New Delhi.

8. CWC, March 2018. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins for 2017"*, Technical Report Published by Morphology & Climate Change Directorate, CWC, New Delhi.

9. CWC, January 2019. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins for 2018"*, Technical Report Published by Morphology & Climate Change Directorate, CWC, New Delhi.

10. CWC, February 2020. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins for 2019"*, Technical Report Published by Morphology & Climate Change Directorate, CWC, New Delhi.

11. CWC, December 2020. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins for 2020"*, Technical Report Published by Morphology & Climate Change Directorate, CWC, New Delhi.

12. CWC, December 2021. *Report on "Monitoring of Glacial Lakes/Water Bodies in the Himalayan Region of Indian River Basins for 2021"*, Technical Report Published by Morphology & Climate Change Directorate, CWC, New Delhi.

13. Gorelick, N. a. (2017). Google Earth Engine: Planetary-scale geospatial analysis for everyone. Remote Sensing of Environment. doi: 10.1016/j.rse.2017.06.031

14. NRSC, March 2023. *Final Report of "Glacial Lake Atlas of Indian Himalayan River Basins"*, Technical Report Published by National Remote Sensing Centre, Hyderabad.


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National Remote Sensing Centre (NRSC), Indian Space Research Organisation (ISRO), Hyderabad as one of the Implementing Agency under the National Hydrology Project (NHP), is carrying out hydrological studies using satellite data and geospatial techniques. As part of this, detailed glacial lake inventory, prioritization for Glacial Lake Outburst Flood (GLOF) risk, and simulation of GLOF for selected lakes are taken up for entire catchment of Indian Himalayan Rivers covering Indus, Ganga, and Brahmaputra River Basins. Under this activity, an updated inventory of glacial lakes using high resolution satellite data was prepared for the Indus and Ganga River basins and published in December 2020 (NRSC-RSAA-WRG-WRAD-Nov2020-TR-0001702-V1.0) and June 2021 (NRSC-RSAA-WRG-WRAD-Mar2021-TR-0001818-V1.0) respectively, and currently an updated inventory of glacial lakes has been prepared for the Brahmaputra River basin. The present glacial lake atlas is based on the inventoried glacial lakes in part of Brahmaputra River basin from its origin to foothills of Himalayas covering a catchment area of 3,99,833 Km².

The study portion of Brahmaputra River basin covers part of India and transboundary region. Brahmaputra River basin has been divided into 12 subbasins on the basis of confluence of major rivers contributing into the system viz., Amo chu, Dibang, Dihang, Jia Bharali, Lhasa Tsangpo, Lohit, Lower Yarlung Tsangpo, Manas, Puna Tsang Chu, Subansiri, Teesta and Upper Yarlung Tsangpo. Elevation in the river basin varies from the minimum 450 m to the maximum 8,352 m above mean sea level (amsl). In India, Brahmaputra River basin extends in two states viz., Arunachal Pradesh and Sikkim.

In the present study, glacial lakes with water spread area ≥ 0.25 ha have been mapped using Resourcesat-2 (RS-2) Linear Imaging Self Scanning Sensor-IV (LISS-IV) satellite data using visual interpretation techniques. Based on its process of lake formation, location, and type of damming material, glacial lakes are identified in all ten different types, majorly grouped into four categories viz., Moraine-dammed, Ice-dammed, Glacier Erosion, and Other glacial lakes.

Amo chu
Dibang
Dihang
Jia Bharali
Lhasa Tsangpo
Lohit
Lower Yarlung Tsangpo
Manas
Puna Tsang Chu
Subansiri
Teesta
Upper Yarlung Tsangpo


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level ( amsl ) . In India , Brahmaputra River basin extends in two states viz . , Arunachal Pradesh and Sikkim . In the present study , glacial lakes with water spread area ≥ 0 . 25 ha have been mapped using Resourcesat - 2 ( RS - 2 ) Linear Imaging Self Scanning Sensor - IV ( LISS - IV ) satellite data using visual interpretation techniques . Based on its process of lake formation , location , and type of damming material , glacial lakes are identified in all ten different types , majorly grouped into four categories viz . , Moraine - dammed , Ice - dammed , Glacier Erosion , and Other glacial lakes .

A total of 18,001 glacial lakes have been mapped in the Brahmaputra River basin using a total of 187 high resolution multispectral RS-2 LISS-IV images, with a total lake water spread area of 92,990.74 ha. Each glacial lake has been given a 12 alpha-numeric unique glacial lake ID, along with several attributes that include hydrological, geometrical, geographical, and topographical characteristics. About 14,499 (80.55%) lakes are with < 5 ha lake area contributing to 21.92% of total lake area. The remaining lakes with > 5 ha in size are 3,502 (19.45%) contributing to 78.08% of total lake area in the basin. There are only 207 glacial lakes in the Brahmaputra River basin having an area of greater than 50 ha. Other Glacial Erosion lake type are found to be the maximum with 11,846 (65.81%) occupying a total lake extent of 48,368.91 ha at 52.01% in the basin. Majority (i.e. 93.34%) of the lakes are situated above the high altitude range of greater than 4,000 m amsl and dominated by Other Glacial Erosion lake type i.e., 65.31%.

Glacial lakes are predominantly distributed in Lower Yarlung Tsangpo subbasin (27.66%) followed by Upper Yarlung Tsangpo subbasin (16.11%), with a total lake extent of 26,371.81 ha and 16,088.67 ha at 28.36% and 17.30% respectively in the entire basin. In terms of very large size lakes i.e. >50 ha Lower Yarlung Tsangpo subbasin has majority i.e. 54 out of 207 large lakes within it. Very large size glacial lakes of one each are present in Amo chu and Dibang subbasins. Other Glacial Erosion lakes, which are dominant lake type in Brahmaputra

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

River basin distributed in all subbasins, and found maximum in count in Lower Yarlung Tsangpo subbasin. However, two Lateral Moraine Dammed lakes with Ice are present in the entire Brahmaputra River basin and one each is located in Lower Yarlung Tsangpo and Upper Yarlung Tsangpo subbasins. Teesta subbasin consists of higher number of Supra-glacial Lakes in the entire Brahmaputra River basin, whereas UpperYarlung Tsangpo subbasin contains higher number of Other Moraine Dammed lakes.

A total of 2,921 (i.e. 16.23%) glacial lakes lies within Indian region covering 16.95% of the total lake area, whereas remaining 83.77% of lakes are located in transboundary region with a 83.05% of the total lake area.

Amo chu
Dibang
Lower Yarlung Tsangpo
Teesta
Upper Yarlung Tsangpo


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, two Lateral Moraine Dammed lakes with Ice are present in the entire Brahmaputra River basin and one each is located in Lower Yarlung Tsangpo and Upper Yarlung Tsangpo subbasins . Teesta subbasin consists of higher number of Supra - glacial Lakes in the entire Brahmaputra River basin , whereas UpperYarlung Tsangpo subbasin contains higher number of Other Moraine Dammed lakes . A total of 2 , 921 ( i . e . 16 . 23 % ) glacial lakes lies within Indian region covering 16 . 95 % of the total lake area , whereas remaining 83 . 77 % of lakes are located in transboundary region with a 83 . 05 % of the total lake area .

In Indian region, majority of glacial lakes are of Other Glacial Erosion Lake type (73.60%), followed by Cirque Erosion lakes (11.23%) and Other Moraine Dammed lakes (7.91%). Arunachal Pradesh and Sikkim States share 74.91% and 25.09% of lake count with a total lake area of 79.27% and 20.73% respectively. Majority of lakes in Arunachal Pradesh and Sikkim are predominantly of lake area < 5 ha, but lying in high (4,001 - 5,000 m) and very high altitude range (> 5,000 m) respectively. Lakes in Sikkim are only situated above 3,000 m elevation.

In this atlas, map sheets (plates) are prepared on the basis of the Survey of India (SOI) toposheet index (1: 250,000 scale) which are 65 in number covering the entire Brahmaputra River basin. Out of 65 plates, only 54 plates have glacial lakes and corresponding plates are incorporated in atlas. The map sheets are arranged in such a way that glacial lake map is on the right page and its corresponding satellite image is on the left page. At the end of the atlas, an annexure is provided containing list of glacial lakes of size ≥ 5 ha inventoried in the Brahmaputra River basin with their unique glacial lake ID, latitude, longitude, subbasin, glacial lake type, area (ha), and elevation (m). Glacial Lake ID number of 12 alpha-numeric character has 3 characters bold with dark red colour depicting the corresponding toposheet number of the SOI of 1:250,000 scale.

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

Lower Yarlung Tsangpo
Teesta
Upper Yarlung Tsangpo


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The National Hydrology Project (NHP) sponsored by Department of Water Resources, River Development and Ganga Rejuvenation (DoWR, RD&GR), Ministry of Jal Shakti, Government of India (GOI) with financial aid from the World Bank. The objective of the project is to improve the extent and accessibility of water resources information and strengthen institutional capacity to enable improved water resources planning and management across India. The mission is to establish an effective and sound hydrologic database and Hydrological Information System (HIS), together with the development of consistent and scientifically based tools and design aids, to assist in the effective water resources planning and management of the implementing agencies.

NHP is intended for setting up of a system for timely and reliable water resources data acquisition, storage, collation and management. It will also provide tools/systems for informed decision making through Decision Support Systems (DSS) for water resources assessment, flood management, reservoir operations, drought management, etc. NHP also seeks to build capacity of the State and Central sector organisations in water resources management through the use of Information Systems and adoption of State-of-the-art technologies like Remote Sensing. NHP will improve and expand hydrology data and information systems, strengthen water resources operation and planning systems, and enhance institutional capacity for water resources management. NHP will contribute to the GOI Digital India initiative by integrating water resources information across State and Central agencies.

National Remote Sensing Centre (NRSC), as one of the Implementing Agency under NHP, is engaged with generation of geo-spatial products & services pertaining to water resources sector, generation of high resolution Digital Elevation Models (DEM), development of flood early warning systems, decision support system development for irrigation water management, modelling & dissemination of hydrological products to support water resources management and capacity building to NHP stakeholders. The satellite data based geo-spatial products & services, mainly encompassing the following:

* Satellite Data/Geo-Spatial Data Hosting & Services through Bhuvan Web Portal
* Water Resources Information Products & Services (Satellite/Model derived – Bhuvan/India- Water Resources Information System (India-WRIS)/National Water Informatics Centre (NWIC))
* Customized Applications Development (Flood Forecasting, Irrigation Water Management)
* Hydro-conditioned Digital Elevation Model (Satellite & Aerial)
* Capacity Building (Customized Training & Hand Holding)

As part of various NHP technical studies carried out, NRSC has taken up “Glacial Lake Outburst Flood (GLOF) Risk Assessment of Glacial Lakes in the Himalayan Region of Indian River Basins”. In this activity, it was proposed to prepare an updated inventory of glacial lakes, prioritization and selection of critical glacial lakes based on certain characteristics (such as glacial lake, glacier, topography and others), GLOF modelling and flood inundation simulation for selected few lakes using high resolution Digital Elevation Model (DEM) for downstream of the lakes along their river reach, and to assess GLOF risk.

As a result of initial outcome of this activity, an updated inventory of glacial lakes in Indus and Ganga River basins was generated using multispectral (MX) high resolution satellite data of Resourcesat-2 (RS-2) Linear Imaging

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of critical glacial lakes based on certain characteristics ( such as glacial lake , glacier , topography and others ) , GLOF modelling and flood inundation simulation for selected few lakes using high resolution Digital Elevation Model ( DEM ) for downstream of the lakes along their river reach , and to assess GLOF risk . As a result of initial outcome of this activity , an updated inventory of glacial lakes in Indus and Ganga River basins was generated using multispectral ( MX ) high resolution satellite data of Resourcesat - 2 ( RS - 2 ) Linear Imaging * * * National Remote Sensing Centre , ISRO , Hyderabad | 3 GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

Self Scanning Sensor-IV (LISS-IV) for mapping lakes with size ≥ 0.25 ha. The geo-spatial database of glacial lakes has been used to publish “Glacial Lake Atlas of Indus River Basin” (NRSC-RSAA-WRG-WRAD-Nov2020-TR-0001702-V1.0), “Glacial Lake Atlas of Ganga River Basin” (NRSC-RSAA-WRG-WRAD-Mar2021-TR-0001818-V1.0) and presently the atlas of “Glacial Lake Atlas of Brahmaputra River Basin”.


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Indian Himalayan Region (IHR) contains the world’s largest number of glaciers and snow outside the Polar Regions and are aptly called third pole of the world. Many studies undertaken globally showed that glaciers around the world have been retreating since the industrial revolution, which began around eighteenth century. As the glaciers are thinning and retreating, resulting in associated glacier melt water lakes are expanding in size and new lakes continue to form. The lakes receiving melt water from glaciers are generally known as glacial lakes. A glacial lake is defined as water mass existing in a sufficient amount and extending with a free surface in, under, beside, and/or in front of a glacier and originating from glacier activities and/or retreating processes of a glacier. As glaciers retreat, the formation of glacial lakes takes place behind moraine or ice ‘dam’. These damming materials are generally weak and can breach suddenly due to various triggering factors, leading to catastrophic floods. Such outburst floods are known as GLOF.

GLOFs are characterized by extreme peak discharges, with an exceptional erosion/transport potential; therefore, they can turn into flow-type movements (Emmer, 2017). Failure of such lake happens due to many factors which include erosion process, increase in water pressure, merging of an avalanche/rock into lake, nature of the damming materials etc., and this may lead to a GLOF event which could be highly disastrous in nature and create long-term degradation in the valleys, both physically and socio-economically (Mool et al., 2001b). Accordingly, Emmer et al., (2016) showed an annual nonlinear increase in the number of scientific publications focusing on GLOFs recently. Hence, monitoring of glacier associated lakes is very useful in the IHR to identify critical glacial lakes, for which a detailed inventory of glacial lakes and its type is required. According to their position relative to the glacier and damming mechanism, these glacial lakes can be classified into several types (Panda et al., 2014).

Inventorying glacial lakes located in these remote mountain areas with rugged terrain and inclement weather by traditional means is very tedious and difficult, hence Remote Sensing (RS) data plays a greater role in generating information on glacial lakes (Kulkarni, 1991; Berither et al., 2007; Wagnon et al., 2007; Raj, 2010; Cogley et al., 2011; Pratap et al., 2016; Gupta et al., 2019, Guru et al., 2019). Satellites with high spatial, spectral and temporal resolution sensors are useful in deriving lake information with better accuracy and repeatedly.


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Several studies have been taken up in the past to assess the glacial lake distribution in the Hindu Kush Himalayas (HKH), covering parts of eight countries viz., Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan, and lies within five river basins of Amu Darya, Indus, Ganga, Brahmaputra, and Irrawaddy (Komori, 2007; Gardelle et al., 2011; Wang et al., 2011; Wang et al., 2012; Nie et al., 2013; Raj et al., 2013; Wang et al., 2013; Worni et al., 2013; Che et al., 2014; Bambari et al., 2015; Zhang et al., 2015; Nie et al., 2017; Rounce et al., 2017; Nagai et al., 2017; Gupta et al., 2019; Guru et al., 2019; Shugar et al., 2020). But only few glacial lake inventories are available in public domain, amongst which the first inventory was prepared by the International Centre for Integrated Mountain Development (ICIMOD), Nepal, for the entire HKH region (covering

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

the entire IHR within it), using satellite data of the Land Observation Satellite (Landsat) Thematic Mapper (TM) of the United States Geological Survey (USGS) and the Indian Remote Sensing satellite (IRS-1D) Linear Imaging and Self-scanning Sensor-III (LISS-III) during 1999-2005, along with topographic maps published between the 1950s and 1982 (Mool et al., 2001a; Mool et al., 2001b; Mool et al., 2003; Bhagat et al., 2004; Roohi et al., 2005; Sah et al., 2005; Wu et al., 2005, Ives et al., 2010). This inventory has been revised in 2018 using Landsat TM and Enhanced Thematic Mapper Plus (ETM+) data of years 2004-07 ± 3 (Maharjan et al., 2018). Both glacial lake inventories prepared by the ICIMOD, have mapped lakes with size > 0.3 ha. Second inventory of glacial lakes and water bodies in the IHR (within India only) was carried out by the NRSC, Hyderabad in collaboration with the Central Water Commission (CWC), New Delhi (NRSC-RS&GISAA-WRG-CWC-Lakes-May2011-TR255). Glacial lakes and water bodies located in all three major basins of Indus, Ganga, and Brahmaputra, of size > 10 ha were mapped using Indian Remote Sensing (IRS) Advanced Wide Field Sensor (AWiFS) data for the year 2009 (Hakeem et al., 2011). Subsequently, monthly monitoring of these lakes (> 50 ha) was carried out using satellite data for the months of June to October during the years 2011 to 2015.

Third latest glacial lake inventory is prepared by the Space Application Centre (SAC), Ahmedabad i.e. “National Wetland Atlas: High Altitude Lakes of India”, using IRS-P6 LISS-III, comprising high altitude lake information of the IHR, within Indian administrative region only (Panigrahy et al., 2012). In this atlas, wetlands of size > 2.25 ha were mapped as a polygons and less than that were mapped as a points, using satellite data for the period of 2006-08.


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**The highlights of the present atlas:**
* The present atlas is first of its kind depicting spatial distribution of glacial lakes of size ≥ 0.25 ha in Brahmaputra River basin mapped using high resolution satellite data
* The atlas provides the details of all the glacial lakes in entire catchment of Brahmaputra River basin, both within Indian and transboundary region
* The atlas contain details of area range-wise glacial lakes along with 10 categories of types. Further, the atlas present the distribution of glacial lakes in terms of area vs. type, elevation, area vs. elevation and type vs. elevation, at basin, subbasin, administrative and transboundary regions
* The atlas also provides comprehensive list of all glacial lakes with unique ID considering hydrological, geometrical, geographical, topographical attribute information

**The expected utility of the atlas:**
* The atlas provides a comprehensive & systematic glacial lake database for Brahmaputra River basin with size ≥ 0.25 ha
* In the context of climate change impact analysis, the atlas can be used as reference data for carrying out change analysis, both with respect to historical and future time periods
* The atlas also provides authentic database for regular or periodic monitoring changes in spatial extent (expansion/shrinkage), and formation of new lakes
* The atlas can also be used in conjunction with glacier information for their retreat and climate impact studies
* The information on glacial lakes like their type, hydrological, topographical, and associated glaciers are useful in identifying the potential critical glacial lakes and consequent GLOF risk
* Central and State Disaster Management Authorities can make use of the atlas for disaster mitigation planning and related programs
* This glacial lake atlas can be used in Detailed Project Report (DPR) preparation for new hydropower/multi purpose projects

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

Luggye Tsho & Raphstreng Tsho at the snout of Glacier in Puna Tsang Chu Subbasin, Located in Bhutan as seen in FCC Satellite image

Satellite: Resourcesat – 2
Sensor: LISS-IV MX
Date of Image: 16.12.2016

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

1. INTRODUCTION
1.4 Highlights of the Atlas


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The IHR consists of three major river systems of Indus, Ganga, and Brahmaputra stretches over four countries viz., India, China, Nepal and Bhutan, and on the basis of physiography it has been divided into four mountain regions viz., Eastern Himalayas, Central Himalayas, Western Himalayas, and the Karakoram Mountain range. The Brahmaputra basin spreads over countries of Tibet (China), India, Bhutan and Bangladesh covering drainage area of 5,80,000 Sq.Km. In India it has a share of about 33.52% which is 1,94,413 Sq.Km cutting across the states Arunachal Pradesh, Assam, West Bengal, Meghalaya, Nagaland and Sikkim.

Topographically River Brahmaputra is unique in terms of its diverse environment as it has cold plateau in Tibet, rainy Himalayan region, alluvial lands of Assam and the large deltaic plains of Bangladesh (Figure 1). The Brahmaputra River also known as Yarlung Tsangpo (in Tibet) originates in the glacier mass from the Kailash ranges of Himalayas at an altitude of 5,150 m south of the lake ’Konggyu Tsho’. The higher elevation zones in the basin causes snow fall mostly over the northern region. The river flows through a length of 2,900 Km out of which 916 Km in the Indian Territory and joins finally in the Bay of Bengal. The catchment area receives number of tributaries at its north and south banks especially in Indian region. The catchment receives heavy rainfall with significant spatial variability. The land use/cover of the basin consist extensive forest cover, plantations, crop fields and swampy water lands, the northern part of the basin (outside India) covers mostly snow. There are number of hydraulic structures constructed across the tributaries in terms of weirs, barrages for the purpose of Irrigation and Dams for the hydro power utilization.

The Brahmaputra River basin from its origin to foothills of Himalayas with a catchment area of 3,99,833 Sq.Km is considered in the present study, which extends from latitude 26.70 N to 3.270 N and from longitude 820 E to 97.770 E (Figure 2).


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The entire Brahmaputra River basin is sub divided into three reaches namely upper, middle and lower. In the upper reach the river is fed by glaciers. In the lower and middle reaches it is joined by number of tributaries. The

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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

principal tributaries of the Brahmaputra River joining from right are the Lohit, the Dibang, the Subansiri, the Jia bharali, the Dhansiri, the Manas, the Torsa, the Sankosh and the Teesta whereas the Burhidihing, the Desang, the Dikhow, the Dhansiri and the Kopili joins it from left. Considering hydrological settings of the above said reaches and the present study reach, Brahmaputra River basin is divided in 12 subbasins viz., Upper Yarlung Tsangpo, Lhasa Tsangpo, Lower Yarlung Tsangpo, Dihang, Dibang, Lohit, Subansiri, Jia Bharali, Manas, Amo Chu, Puna Tsang Chu, and Teesta. Figure 2 shows the location of the study area with Resourcesat-2 (RS-2) Linear Imaging Self Scanner (LISS-IV) satellite images. Table 1 shows the catchment area of each of the above subbasins.

Amo Chu
Dibang
Dihang
Jia Bharali
Jia bharali
Lhasa Tsangpo
Lohit
Lower Yarlung Tsangpo
Manas
Puna Tsang Chu
Subansiri
Teesta
Upper Yarlung Tsangpo


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Figure: Figure 2: Location of Brahmaputra River basin showing RS-2 LISS-IV images

**Figure 2: Location of Brahmaputra River basin showing RS-2 LISS-IV images**


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Table: Table 1: Details of subbasins of Brahmaputra River basin

| S. No. | Subbasin | Area (Km²) | Area (%) |
|---|---|---|---|
| 1 | Amo Chu | 9,829 | 2.46 |
| 2 | Dibang | 12,238 | 3.06 |
| 3 | Dihang | 22,158 | 5.54 |
| 4 | Jia Bharali | 13,084 | 3.27 |
| 5 | Lhasa Tsangpo | 32,896 | 8.23 |
| 6 | Lohit | 25,799 | 6.45 |
| 7 | Lower Yarlung Tsangpo | 74,334 | 18.59 |
| 8 | Manas | 32,166 | 8.04 |
| 9 | Puna Tsang Chu | 10,204 | 2.55 |
| 10 | Subansiri | 30,644 | 7.66 |
| 11 | Teesta | 8,555 | 2.14 |
| 12 | Upper Yarlung Tsangpo | 1,27,926 | 31.99 |
| | **Total** | **3,99,833** | **100.00** |

Amo Chu
Dibang
Dihang
Jia Bharali
Lhasa Tsangpo
Lohit
Lower Yarlung Tsangpo
Manas
Puna Tsang Chu
Subansiri
Teesta
Upper Yarlung Tsangpo


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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The Upper reach of the River Brahmaputra flows through 1,625 Km from the source of origination point to the Indo-China border through Tibetan plateau and enters India at Kobo, Arunachal Pradesh, Upper reach of the River is mostly fed by snow and glaciers. In the middle reach between India and Bangladesh border it flows through a length of 916 Km where it has numerous riverine islands because of its low gradient. The entire lower reach falls within the Bangladesh flows about a length of 337 Km and drains into Bay of Bengal. The river flows are at low in winter season, gradually increases in summer season (due to melting of snow and glaciers in upper reaches) and reaches peak in monsoon season. The average water resources potential (In India) of the basin is 537.24 BCM out of which utilizable surface water resource is 24 BCM (Brahmaputra Basin Report, 2014).


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The study area mainly resides in the middle and eastern Himalayan region, which is also known as one of the main topographic division of the Indian subcontinent. The Himalayas comprises the Himalayan ranges including their numerous snow peaks and each of these peaks is surrounded by snow fields and glaciers. The elevation of the study area ranges between 450 m and 8,352 m amsl, where glaciers and glacial lakes are mostly distributed in the higher altitude region. The mean elevation of the study area is about 4,048 m amsl. Hypsometric curve is a graph which shows the proportion of land area that exists at various elevations by plotting relative area against relative height, as shown in Figure 3 for the study area.

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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The climate of the Brahmaputra river basin varies from the harsh cold, and dry conditions found in Tibet to the generally hot and humid conditions prevailing in Assam state. Tibetan winters are severely cold, with average temperatures below 0°C, while summers are mild and sunny. The upper river valley lies in the rain shadow of the Himalayas, and precipitation there is relatively light (Lhasa receives about 400 mm annually). Climate over the Brahmaputra River basin is mainly experiences four seasons in a year namely winter, summer, and monsoon and post monsoon. The winter season begins in December and continues to the end of February. From March onwards, the hot weather starts and continues up to the last week of May. The monsoon begins in the last week of May or in early June and the basin receives heavy rainfall spatially distributed over the basin.

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Section: 3. DATA USED
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Earth observation satellites capture the data repeatedly in various spectral ranges and at different spatial and radiometric resolutions. For inventorying glacial lakes, high to medium resolution datasets are proved to be useful by many research studies (Bolch et al., 2010; Mergili et al., 2013; Wang et al., 2013; Zhang et al., 2015; Gupta et al., 2019, Guru et al., 2019). Data captured between September and December were mostly used because the presence of snow or cloud cover during this period is minimum. USGS satellite data of Landsat 5 and 7 (TM and ETM+) has been used widely for mapping glacial lakes due to free accessibility. Whereas, IRS satellite data from sensors of AWiFS, LISS-III and LISS-IV has also been used for such inventory.

In the present study, high resolution Resourcesat-2 LISS-IV satellite images with spatial resolution of 5.8 m covering a swath of 70 × 70 Km have been used for inventorying glacial lakes. Maximum of the images used for inventorying were of 2016-2021 (74%) and remaining images procured were of previous years due to non-availability of cloud-free and snow-free images for the recent years. Majority of images were of September and December months (73%) due to less snow and cloud cover, and rest 27% images of other months. Figure 4 shows the layout of the RS-2 LISS-IV scenes (path-wise) procured for the Brahmaputra River basin along with its details in Table 2. The layout of satellite scenes is divided into paths (shown in separate colours) and rows (row numbers shown in the layout).

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Section: 3. DATA USED
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Table: Table 2: Details of satellite scenes used for inventory

| | Other Months | Sep - Dec | Total |
| :--- | :---: | :---: | :---: |
| Prior to 2016 | 16 | 33 | 49 |
| 2016-21 | 34 | 104 | 138 |
| **Total** | **50** | **137** | **187** |


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Section: 3. DATA USED
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Digital Elevation Model (DEM) of Cartosat satellite with 10 m spatial resolution has been used for topographic information and watershed boundary generation. Figure 5 shows elevation range map of the study area i.e. Brahmaputra River basin. Other information like names of lakes and rivers has been gathered from digital toposheets available from University of Texas - Toposheet Library at 1:250,000 scale and Tibet Map Institute at 1:100,000 scale (U.S. Army Map Service 1955; Andre 2017).

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Section: 4. METHODOLOGY > 4.1 Satellite Data Interpretation
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The spectral reflectance curve of water in the visible spectrum starts with a low in Blue region (0.4 to 0.5 μm), reaches peak in Green region (0.5 to 0.6 μm), decreases in Red region (0.6 to 0.7 μm) and probably the most distinctive characteristic is the energy absorption at Near InfraRed (NIR) wavelengths. Identifying and delineating water bodies with remote sensing data are carried out easily in near infrared wavelengths because of this absorption property in IR region. However, various physical conditions of water bodies (water depth, turbidity, chlorophyll content, etc.) manifest spectral changes. As a result of various conditions of lakes, the water in satellite images in False Colour Composite (FCC) ranges in appearance from light to dark blue to black. In the case of frozen lakes, it appears white.

Glacial lake sizes are generally small, having circular, semi-circular, or elongated shapes with very fine texture and are generally associated with glaciers in high altitude areas. Certain types of glacial lakes, like erosion and cirque lakes are not necessarily associated with glaciers. Knowledge of the physical characteristics of the glacial lakes, and their associated features is always essential for the interpretation of the images.

Satellite data interpretation can be done using visual image interpretation keys such as colour, size, tone, texture, pattern, association, shape, shadow, and orientation. A number of remote sensing methods had been developed for glacial lake detection and mapping or development of inventory (Kääb 2000; Mool et al., 2001a; Huggel et al., 2002; Huggel et al., 2006; Ives et al., 2010). Manual or automated lake mapping methods have certain difficulties in identifying the lakes, which are described in the following section. An attempt was made to study the accuracy of mapping of glacial lakes using multiple automated methods along with visual interpretation, the details of which are given in Annexure-1. From this study, it was concluded that visual interpretation method was best accurate method. Hence, in the present study glacial lakes and their different types are identified and mapped using RS-2 LISS-IV multispectral images using visual interpretation method.

4. METHODOLOGY
4.1 Satellite Data Interpretation


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Glacial lake identification can be done either using visual interpretation or automatic mapping methods. The automatic mapping procedures have limitations due to varying terrain conditions like lakes situated in the shadow portions of mountains, presence of snow cover, cloud cover, and partly frozen lakes, etc. In the presence of snow cover on the glacier tongue or glacier’s ablation area where many Supra-glacial lakes may present, both methods have limitations and difficulties.

As lake water absorbs the incident radiation making it appear in darker tone and colour in the standard FCC of satellite data, similar response also prevails over shadow region of clouds or mountains on surface, which may lead to incorrect mapping. In fact, a mountain shadow covering a lake partly/completely within its vicinity, making it difficult to accurately map the lake boundary.

Many lakes due to inclement terrain condition, can be under shadow of high peaks and will get missed in both ways of mapping. On the contrary, a lake can also present in white colour while it is in frozen form due to cold

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

weather conditions over the area, then definitely it will not get classified while automatic mapping. Whereas, frozen lakes can be identified and mapped using visual interpretation to some extent.

4. METHODOLOGY
4.1 Satellite Data Interpretation
Difficulties in Lake Identification:


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In the IHR, due to high and inclement terrain surface and due to near vertical acquisition of satellite images, some lakes get covered with shadows of mountains, which create problems in identifying glacial lakes. Also identification of lakes with high turbidity, partial ice covered lakes and the lakes in shadow areas are misclassified by automatic methods. Glacial lake mapping is always a semi-automatic approach because even after applying any of that method, it should always be followed by the post processing i.e. correcting the errors using visual interpretation. Even in all cases, automatic mapping will never give the exact and accurate boundary of the lake, leading to necessary manual corrections.

4. METHODOLOGY
4.1 Satellite Data Interpretation
Challenges in Automatic Mapping:


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Although automatic mapping methods can speed up the detection of glacial lakes, but these methods could not be applied to the entire Himalayan region due to lot of variations in satellite scenes (seasons/years) and problems mentioned above. For example, if lakes are frozen or covered with snow or cloud and lies in a shadow area, they cannot be detected using these automatic methods. In such cases, the manual interpretation method will be helpful to map these lakes. Thus, any mapping of glacial lakes can be automated up to a certain extent only. So, visual image interpretation keys and technique will give accurate results and avoids misclassification. Therefore, in this present study, glacial lakes and its type identification, and its mapping for the entire Brahmaputra River basin (within IHR) has been done manually using visual interpretation. High resolution satellite data available on Bhuvan/Google Earth has been used on need basis in finalizing various features of glacial lake database.

4. METHODOLOGY
4.1 Satellite Data Interpretation
Reasoning for Visual Interpretation:


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The RS-2 LISS-IV MX data used for glacial lake database preparation sporadically covered with cloud and seasonal/permanent snow. Also, the Himalayan region being highly varying topography with steep slopes, the satellite data has hill shadows. Thus few glacial lakes would not have been mapped owing to the following constraints:
* Presence of snow or cloud over the glacial lakes
* Glacial lakes under frozen condition
* Glacial lakes under mountain shadow

4. METHODOLOGY
4.1 Satellite Data Interpretation
Limitations:


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Section: 4. METHODOLOGY > 4.2 Types of Glacial Lake
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Various researchers have proposed glacial lakes classification schemes based on dam type, process of lake formation, topographic feature, and geographical position (Hewitt 1982; Liu and Sharma 1988; Clague and Evans 2000; Mool et al., 2001a, 2001b). Lakes located on the glacier surface can be mapped using satellite data, but there are englacial and subglacial lakes that may also exist, but cannot be mapped from aerial/optical satellite images, requires ground based instrument (Yao et al., 2018). Majorly surface glacial lakes are classified in 4 classes and 10 subclasses, i.e. Moraine-dammed lake, Ice-dammed lake, Glacier Erosion lake (also known as Bed-rock lake), and Other Glacial lake. Two character symbol has been used for glacial lake classification, in

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

which first letter (uppercase) represents lake type and second letter (lowercase) within brackets represents lake subtype, for example, M(e) for End-moraine dammed lake. Details of types of lakes are given in Table 3 and their appearance in satellite images are shown in Figure 6.

4. METHODOLOGY
4.2 Types of Glacial Lake


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Table: Table 3: Glacial lake types and their identification keys

| S.No. | Lake Type | Lake Subtype | Code | Identification Keys |
|---|---|---|---|---|
| 1 | Moraine-dammed Lake | End-moraine Dammed Lake | M(e) | Lake dammed by end (terminal) moraines |
| 2 | Moraine-dammed Lake | Lateral Moraine Dammed Lake | M(l) | Lake dammed by lateral moraine(s) not in contact with glacial ice |
| 3 | Moraine-dammed Lake | Lateral Moraine Dammed Lake (with Ice) | M(lg) | Lake dammed by lateral moraine(s) in contact with glacial ice |
| 4 | Moraine-dammed Lake | Other Moraine Dammed Lake | M(o) | Lake dammed by other moraines |
| 5 | Ice-dammed Lake | Supra-glacial Lake | I(s) | Pond or lake on the surface of a glacier |
| 6 | Ice-dammed Lake | Glacier Ice-dammed Lake | I(d) | Lake dammed by glacier ice with no lateral moraines |
| 7 | Glacier Erosion Lake | Cirque Erosion Lake | E(c) | A small pond occupying a cirque |
| 8 | Glacier Erosion Lake | Glacier Trough Valley Erosion Lake | E(v) | Lakes formed in the glacier trough as a result of the glacier erosion process |
| 9 | Glacier Erosion Lake | Other Glacial Erosion Lake | E(o) | Bodies of water occupying depressions formed by the glacial erosion process |
| 10 | Other Glacial Lake | Other Glacial Lake | O | Lakes formed in a glaciated valley, and fed by glacial melt, but damming material not directly part of the glacial process |

S.No.
Lake Type
Lake Subtype
Code
Identification Keys


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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A total of 22 attributes has been given to all mapped lake features in the geodatabase, which are broadly consisting information grouped in five different categories as shows in Table 4.

4. METHODOLOGY
4.3 Lake Attribute Information


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Table: Table 4: Details of glacial lake attributes

| S.No. | Category | Attribute |
| :--- | :--- | :--- |
| 1 | Hydrological | Basin, subbasin, river, lake name |
| 2 | Geometrical | Maximum length, mean width, surface area |
| 3 | Geographical | Latitude, longitude, region, state, district, toposheet 250k, toposheet 50k |
| 4 | Topographical | Elevation, aspect |
| 5 | Lake Information | Feature types, glacial lake type, lake ID |
| 6 | Data Source Information | Source of database, source of elevation, date of pass |


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Typically, lake ID is given in 12 alpha-numeric character format like “0378A0115656”, where first two digits ‘03’ refers to Basin code which is Brahmaputra (01-Indus and 02-Ganga), next five characters ‘78A01’ refers to the 1:250,000 (78A) and 1:50,000 (78A01) scale SOI Toposheet number, and the last five digits refers to the sequential number of each lake sorted from top left to bottom right. A typical example of the glacial lake database generated is given below in Table 5 along with fields and format.


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Table: Table 5: Typical example of glacial lake attribute database

| S.No. | Database Fields | Type | Format / Unit | Lake Attribute |
| :--- | :--- | :--- | :--- | :--- |
| 1 | ID No | String | Text | 0378A0115656 |
| 2 | Toposheet 250K | String | Text | 78A |
| 3 | Toposheet 50K | String | Text | 78A01 |
| 4 | Latitude* | Float | Decimal Degree | 27.913 |
| 5 | Longitude* | Float | Decimal Degree | 88.195 |
| 6 | Basin | String | Text | Brahmaputra |
| 7 | Subbasin | String | Text | Teesta |
| 8 | River | String | Text | Teesta River |
| 9 | Type (GL/WB) | String | Text | Glacial Lake |
| 10 | Name | String | Text | South Lhonak |
| 11 | Glacial Lake Type | String | Text | M(e): End-moraine Dammed Lake |
| 12 | Surface Area | Float | ha | 128.13 |
| 13 | Length | Float | Km | 2.45 |
| 14 | Mean Width | Float | Km | 0.66 |
| 15 | Elevation | Integer | m (amsl) | 5,194 |
| 16 | Aspect | String | Text | NE |
| 17 | Source of Database | String | Text | RS-2 LISS-IV |
| 18 | Date of Pass | Date | DDMMYYYY | 30122016 |
| 19 | Source of Elevation | String | Text | Cartosat DEM |
| 20 | Region | String | Text | India |
| 21 | State | String | Text | Sikkim |
| 22 | District | String | Text | North Sikkim |

S.No.
Database Fields
Type
Format / Unit
Lake Attribute


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\* Latitude, longitude, and elevation has been taken at the centroid of the lake

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Section: 5. RESULTS
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The mapped glacial lakes are analyzed for their distribution in terms of area, type, and elevation, at basin, subbasin, administrative and transboundary level. Area of mapped glacial lakes is ranging from a minimum of 0.25 ha to a maximum of 2,658.49 ha. Details of glacial lakes of size ≥ 5 ha inventoried for the Brahmaputra River basin is given in Annexure-II. The results are discussed in subsequent sections:


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**Area range-wise Distribution**

A total of 18,001 glacial lakes (≥ 0.25 ha) were identified and mapped using RS-2 LISS-IV images for the entire Brahmaputra River basin, with a total lake water spread area of 92,990.74 ha. Table 6 and Figure 7 shows the area range-wise distribution of glacial lakes for the entire basin. About 14,499 (80.55%) lakes are with < 5 ha lake area contributing to 21.92% of total lake area. The remaining lakes with > 5 ha in size are 3,502 (19.45%) contributing to 78.08% of total lake area in the basin. Details of lakes > 50 ha is given in Annexure-III.

5. RESULTS
5.1 Brahmaputra Basin Level Statistics


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Table: Table 6: Area range-wise distribution of Glacial Lakes (GL) in Brahmaputra River basin

| S. No. | Lake Area Range (ha) | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :--- | :--- | :--- | :--- | :--- |
| 1 | 0.25 - 0.5 | 3,627 | 1,294.83 | 1.39 |
| 2 | 0.5 - 1 | 3,856 | 2,771.84 | 2.98 |
| 3 | 1 - 5 | 7,016 | 16,315.71 | 17.55 |
| 4 | 5 - 10 | 1,749 | 12,348.79 | 13.28 |
| 5 | 10 - 50 | 1,546 | 30,040.25 | 32.31 |
| 6 | > 50 | 207 | 30,219.32 | 32.50 |
| | **Total** | **18,001** | **92,990.74** | **100.00** |

S. No.
Lake Area Range (ha)
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Distribution of different types of glacial lakes in the entire Brahmaputra River basin is given in Table 7 and Figure 8. Out of 10 types of lakes described above, all types of lakes are present in the basin. Out of 10 types of glacial lakes, Other Glacial Erosion lakes are found to be the maximum with 11,846 (65.81%) occupying a total lake extent of 48,368.91 ha at 52.01% in the basin. Two other types of lake, namely, Other Moraine Dammed and Other Glacial lakes are 3,019 (16.77%) and 1,481 (8.23%), extend over an area of 9,457.52 ha (10.17%) and 12,049.76 ha (12.96%) respectively.

5. RESULTS
5.1 Brahmaputra Basin Level Statistics
Type-wise Distribution


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Table: Table 7: Type-wise distribution of GL in Brahmaputra River basin

| S. No. | Code | Types of Glacial Lake | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | M(e) | End-moraine Dammed Lake | 391 | 10,620.51 | 11.42 |
| 2 | M(l) | Lateral Moraine Dammed Lake | 38 | 259.67 | 0.28 |
| 3 | M(lg) | Lateral Moraine Dammed Lake with Ice | 2 | 0.93 | 0.00 |
| 4 | M(o) | Other Moraine Dammed Lake | 3,019 | 9,457.52 | 10.17 |
| 5 | I(s) | Supra-glacial Lake | 272 | 263.13 | 0.28 |
| 6 | I(d) | Glacier Ice-dammed Lake | 2 | 2.50 | 0.00 |
| 7 | E(c) | Cirque Erosion Lake | 943 | 8,521.90 | 9.16 |
| 8 | E(v) | Glacier Trough Valley Erosion Lake | 7 | 3,445.91 | 3.71 |
| 9 | E(o) | Other Glacial Erosion Lake | 11,846 | 48,368.91 | 52.01 |
| 10 | O | Other Glacial Lake | 1,481 | 12,049.76 | 12.96 |
| | | **Total** | **18,001** | **92,990.74** | **100.00** |

S. No.
Code
Types of Glacial Lake
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)


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Figure: Figure 8: Type-wise distribution of GL in Brahmaputra River basin

**Figure 8: Type-wise distribution of GL in Brahmaputra River basin**


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Area range-Type-wise Distribution**

Glacial lake distribution by area range vs. type-wise is given in Table 8 and Figure 9. The lakes with < 5 ha in size (80.55%) are dominant with Other Glacial Erosion lake type (67.58%) followed by Other Moraine Dammed (18.02%) and Other Glacial lake (8.66%). The lakes with > 5 ha (19.45%) are dominated by Other Glacial Erosion lakes (58.45%) followed by Cirque Erosion lake (14.85%) and Other Moraine Dammed lake (11.62%). All types of Moraine-dammed glacial lakes, which constitute about 18.99% are predominantly with < 5 ha in water spread.


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Table: Table 8: Area range-wise vs. Type-wise distribution of GL in Brahmaputra River basin

| S. No. | Lake Area Range (ha) | Types of Glacial Lake | | | | | | | | | | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| | | **M(e)** | **M(l)** | **M(lg)** | **M(o)** | **I(s)** | **I(d)** | **E(c)** | **E(v)** | **E(o)** | **O** | |
| 1 | 0.25 - 0.5 | 6 | 6 | 1 | 718 | 153 | 0 | 13 | 0 | 2,324 | 406 | 3,627 |
| 2 | 0.5 - 1 | 12 | 6 | 1 | 743 | 75 | 1 | 46 | 0 | 2,636 | 336 | 3,856 |
| 3 | 1 - 5 | 93 | 17 | 0 | 1,151 | 38 | 1 | 364 | 0 | 4,839 | 513 | 7,016 |
| 4 | 5 - 10 | 78 | 3 | 0 | 236 | 4 | 0 | 250 | 0 | 1,092 | 86 | 1,749 |
| 5 | 10 - 50 | 152 | 5 | 0 | 156 | 2 | 0 | 262 | 0 | 868 | 101 | 1,546 |
| 6 | > 50 | 50 | 1 | 0 | 15 | 0 | 0 | 8 | 7 | 87 | 39 | 207 |
| | **Total** | **391** | **38** | **2** | **3,019** | **272** | **2** | **943** | **7** | **11,846** | **1,481** | **18,001** |

S. No.
Lake Area Range (ha)
Types of Glacial Lake
Total


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Elevation ranges over the entire study area has been classified into four different categories viz., low altitude (up to 3,000 m), medium altitude (3,001 - 4,000 m), high altitude (4,001 - 5,000 m), and very high altitude (> 5,000 m). Table 9 and Figure 10 shows the distribution of the glacial lakes in the Brahmaputra basin as per elevation range-wise. Majority of glacial lakes are situated above 4,000 m elevation i.e. 16,802 (93.34%) with total lake area of 81,290.89 ha (87.41%) and remaining 6.66% glacial lakes are below 4,000 m elevation.

5. RESULTS
5.1 Brahmaputra Basin Level Statistics
Elevation range-wise Distribution


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Table: Table 9: Elevation range-wise distribution of GL in Brahmaputra River basin

| S. No. | Elevation Range (m) | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :---: | :--- | :---: | :---: | :---: |
| 1 | up to 3,000 | 11 | 152.21 | 0.16 |
| 2 | 3,001 - 4,000 | 1,188 | 11,547.28 | 12.42 |
| 3 | 4,001 - 5,000 | 9,670 | 52,525.25 | 56.48 |
| 4 | > 5,000 | 7,132 | 28,765.99 | 30.93 |
| | **Total** | **18,001** | **92,990.74** | **100.00** |

S. No.
Elevation Range (m)
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)


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20 | National Remote Sensing Centre, ISRO, Hyderabad

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Area-Elevation range-wise Distribution**

Glacial lake distribution has been analyzed as per area range vs. elevation range-wise, given in Table 10 and Figure 11. It is noted that, about 39.62% of glacial lakes (7,132) are situated in very high altitude range i.e. > 5,000 m amsl, which also constitutes total lake area within that range i.e. 30.93%. However, very few glacial lakes (11) lies below 3,000 m amsl, has maximum of its lakes with 10 - 50 ha lake area range. Figure 11 shows that maximum of lakes lying in very high altitude range is of size ranging 1 - 5 ha (i.e. 2,728), followed by lakes in high altitude range within in 1 - 5 ha (i.e. 3,772).


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Table: Table 10: Area range-wise vs. Elevation range-wise distribution of GL in Brahmaputra River basin

| S. No. | Lake Area Range (ha) | Elevation Range (m) up to 3,000 - No. of lakes | Elevation Range (m) up to 3,000 - Total Lake Area (ha) | Elevation Range (m) 3,001 - 4,000 - No. of lakes | Elevation Range (m) 3,001 - 4,000 - Total Lake Area (ha) | Elevation Range (m) 4,001 - 5,000 - No. of lakes | Elevation Range (m) 4,001 - 5,000 - Total Lake Area (ha) | Elevation Range (m) > 5,000 - No. of lakes | Elevation Range (m) > 5,000 - Total Lake Area (ha) | Total - No. of lakes | Total - Lake Area (ha) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 0.25 - 0.5 | 0 | 0.00 | 98 | 36.60 | 1,824 | 655.23 | 1,705 | 603.00 | 3,627 | 1,294.83 |
| 2 | 0.5 - 1 | 1 | 0.64 | 124 | 90.74 | 1,966 | 1,417.19 | 1,765 | 1,263.30 | 3,856 | 2,771.84 |
| 3 | 1 - 5 | 3 | 10.07 | 513 | 1,299.91 | 3,772 | 8,855.14 | 2,728 | 6,150.52 | 7,016 | 16,315.71 |
| 4 | 5 - 10 | 1 | 5.77 | 219 | 1,576.08 | 1,035 | 7,306.45 | 494 | 3,460.51 | 1,749 | 12,348.79 |
| 5 | 10 - 50 | 6 | 135.75 | 209 | 4,288.89 | 952 | 18,351.30 | 379 | 7,264.24 | 1,546 | 30,040.25 |
| 6 | > 50 | 0 | 0.00 | 25 | 4,255.00 | 121 | 15,939.70 | 61 | 10,024.36 | 207 | 30,219.32 |
| Total | | 11 | 152.21 | 1,188 | 11,547.28 | 9,670 | 52,525.25 | 7,132 | 28,765.99 | 18,001 | 92,990.74 |


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Figure: Figure 11: Area range-wise vs. Elevation range-wise distribution of GL in Brahmaputra River basin

**Figure 11: Area range-wise vs. Elevation range-wise distribution of GL in Brahmaputra River basin**


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Glacial lake distribution has been analyzed as per type-wise vs. elevation range-wise, given in Table 11 and Figure 12. The dominant lake type in the basin i.e., Other Glacial Erosion lakes (65.81%) are predominantly located in the elevation range of 4,001 - 5,000 m (60.20%). The two other dominant lake types, namely, Other Moraine Dammed and Other Glacial lakes are mostly distributed in both 4,001 - 5,000 m and > 5,000 m elevation ranges. 72.98% of Moraine-dammed glacial lakes, which constitute 13.98% of the total lakes, lies in the very high altitude range of > 5,000 m amsl. Elevation range-type-wise distribution of glacial lakes has been represented in Figure 13.

5. RESULTS
5.1 Brahmaputra Basin Level Statistics
Type-Elevation range-wise Distribution


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Table: Table 11: Type-wise vs. Elevation range-wise distribution of GL in Brahmaputra River basin

| S.No. | Elevation Range (m) | Types of Glacial Lake   M(e) | Types of Glacial Lake   M(l) | Types of Glacial Lake   M(lg) | Types of Glacial Lake   M(o) | Types of Glacial Lake   I(s) | Types of Glacial Lake   I(d) | Types of Glacial Lake   E(c) | Types of Glacial Lake   E(v) | Types of Glacial Lake   E(o) | Types of Glacial Lake   O | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | up to 3,000 | 0 | 0 | 0 | 4 | 0 | 0 | 0 | 0 | 4 | 3 | 11 |
| 2 | 3,001 - 4,000 | 11 | 0 | 0 | 26 | 16 | 0 | 158 | 2 | 869 | 106 | 1,188 |
| 3 | 4,001 - 5,000 | 147 | 25 | 1 | 718 | 159 | 0 | 687 | 4 | 7,131 | 798 | 9,670 |
| 4 | > 5,000 | 233 | 13 | 1 | 2,271 | 97 | 2 | 98 | 1 | 3,842 | 574 | 7,132 |
| | **Total** | **391** | **38** | **2** | **3,019** | **272** | **2** | **943** | **7** | **11,846** | **1,481** | **18,001** |

S.No.
Elevation Range (m)
Types of Glacial Lake M(e)
Types of Glacial Lake M(l)
Types of Glacial Lake M(lg)
Types of Glacial Lake M(o)
Types of Glacial Lake I(s)
Types of Glacial Lake I(d)
Types of Glacial Lake E(c)
Types of Glacial Lake E(v)
Types of Glacial Lake E(o)
Types of Glacial Lake O
Total


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Figure: Figure 13: Elevation range-Type-wise spatial distribution of GL in Brahmaputra River basin

Figure 13: Elevation range-Type-wise spatial distribution of GL in Brahmaputra River basin


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The Amo Chu subbasin of the Brahmaputra River basin is the eleventh largest subbasin amongst all, covering a total area of 9,829 Km² i.e. 2.46% of the total basin area (Figure 14). The Amo Chu as known as Torsa River originates in Tibet with two main tributaries, the Torsa river, and the Wong Chu, all flowing south. It drains about 16,000 sq.km of Tibetan territory before entering Bhutan, where it flows southeast for about 170 km and then enters the Indian flood plains of West Bengal near Phuntsholing (a border town of Bhutan). A total of 513 glacial lakes has been mapped, covering a total area of 1,565.46 ha i.e. 0.15% of the total area of the subbasin.

5. RESULTS
5.2 Subbasin-Wise Statistics
5.2.1 Amo Chu Subbasin


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Figure: Figure 14: Location map of the Amo Chu subbasin

**Figure 14: Location map of the Amo Chu subbasin**


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Area range-wise Distribution**

In Amo Chu subbasin, glacial lakes has been distributed in all 6 different classes of area ranges viz., 0.25 - 0.5 ha, 0.5 - 1 ha, 1 - 5 ha, 5 - 10 ha, 10 - 50 ha and > 50 ha. Table 12 and Figure 15 shows the area-wise distribution of glacial lakes for the Amo Chu subbasin. About 437 (85.19%) lakes are with < 5 ha lake area contributing to 36.78% of total lake area. The remaining lakes with > 5 ha in size are only 76 (14.81%) but contributing to 63.22% of total lake area in the subbasin.


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Table: Table 12: Area range-wise distribution of GL in Amo Chu subbasin

| S.No. | Lake Area Range (ha) | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :--- | :--- | :--- | :--- | :--- |
| 1 | 0.25 - 0.5 | 111 | 37.82 | 2.42 |
| 2 | 0.5 - 1 | 130 | 94.31 | 6.02 |
| 3 | 1 - 5 | 196 | 443.69 | 28.34 |
| 4 | 5 - 10 | 43 | 297.44 | 19.00 |
| 5 | 10 - 50 | 32 | 639.52 | 40.85 |
| 6 | > 50 | 1 | 52.68 | 3.37 |
| | **Total** | **513** | **1,565.46** | **100.00** |

S.No.
Lake Area Range (ha)
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Type-wise Distribution**

Distribution of different types of glacial lakes in the Amo Chu subbasin is given in Table 13 and Figure 16. Out of 10, 7 types of glacial lakes are present in the Amo Chu subbasin, where Other Glacial Erosion lakes are found to be the maximum with 412 (80.31%) occupying a total lake extent of 943.57 ha at 60.27% in the subbasin. Cirque Erosion Lake are second majority of lakes i.e. 61 (11.89%) and extend over an area of 467.50 ha (29.86%).


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Table: Table 13: Type-wise distribution of GL in Amo Chu subbasin

| S.No. | Code | Types of Glacial Lake | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :---: | :---: | :--- | :---: | :---: | :---: |
| 1 | M(e) | End-moraine Dammed Lake | 2 | 65.08 | 4.16 |
| 2 | M(l) | Lateral Moraine Dammed Lake | 4 | 8.37 | 0.53 |
| 3 | M(lg) | Lateral Moraine Dammed Lake with Ice | 0 | 0.00 | 0.00 |
| 4 | M(o) | Other Moraine Dammed Lake | 27 | 75.33 | 4.81 |
| 5 | I(s) | Supra-glacial Lake | 5 | 3.31 | 0.21 |
| 6 | I(d) | Glacier Ice-dammed Lake | 0 | 0.00 | 0.00 |
| 7 | E(c) | Cirque Erosion Lake | 61 | 467.50 | 29.86 |
| 8 | E(v) | Glacier Trough Valley Erosion Lake | 0 | 0.00 | 0.00 |
| 9 | E(o) | Other Glacial Erosion Lake | 412 | 943.57 | 60.27 |
| 10 | O | Other Glacial Lake | 2 | 2.30 | 0.15 |
| | | **Total** | **513** | **1,565.46** | **100.00** |

S.No.
Code
Types of Glacial Lake
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Area range-Type-wise Distribution**

Glacial lake distribution by area range vs. type-wise is given in Table 14 and Figure 17. The lakes with < 5 ha in size (85.19%) are dominated by Other Glacial Erosion lake (80.31%) followed by Cirque Erosion lake type (11.89%). Lakes with > 5 ha (14.81%) are dominated by Other Glacial Erosion lake (48.68%) followed by Cirque Erosion lake type (44.74%). All types of Moraine-dammed lakes, which constitute about 6.43%, are predominantly with < 5 ha in water spread.


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Table: Table 14: Area range-wise vs. Type-wise distribution of GL in Amo Chu subbasin

| S. No. | Lake Area Range (ha) | M(e) | M(l) | M(lg) | M(o) | I(s) | I(d) | E(c) | E(v) | E(o) | O | Total |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | 0.25 - 0.5 | 0 | 0 | 0 | 3 | 2 | 0 | 0 | 0 | 106 | 0 | 111 |
| 2 | 0.5 - 1 | 0 | 1 | 0 | 6 | 2 | 0 | 5 | 0 | 116 | 0 | 130 |
| 3 | 1 - 5 | 0 | 3 | 0 | 15 | 1 | 0 | 22 | 0 | 153 | 2 | 196 |
| 4 | 5 - 10 | 0 | 0 | 0 | 1 | 0 | 0 | 19 | 0 | 23 | 0 | 43 |
| 5 | 10 - 50 | 1 | 0 | 0 | 2 | 0 | 0 | 15 | 0 | 14 | 0 | 32 |
| 6 | > 50 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| **Total** | | **2** | **4** | **0** | **27** | **5** | **0** | **61** | **0** | **412** | **2** | **513** |

S. No.
Lake Area Range (ha)
M(e)
M(l)
M(lg)
M(o)
I(s)
I(d)
E(c)
E(v)
E(o)
O
Total


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Elevation range-wise Distribution**

Elevation range-wise distribution of the glacial lakes in the Amo Chu subbasin has been shown in Table 15 and Figure 18. Majority of glacial lakes are situated above 4,000 m elevation i.e. 496 (96.69%) with total lake area of 1,460.94 ha (93.31%) and remaining 3.31% glacial lakes are below 4,000 m elevation.


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Table: Table 15: Elevation range-wise distribution of GL in Amo Chu subbasin

| S. No. | Elevation Range (m) | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :---: | :--- | :---: | :---: | :---: |
| 1 | up to 3,000 | 0 | 0.00 | 0.00 |
| 2 | 3,001 - 4,000 | 17 | 104.52 | 6.68 |
| 3 | 4,001 - 5,000 | 462 | 1,350.92 | 86.28 |
| 4 | > 5,000 | 34 | 110.02 | 7.03 |
| | **Total** | **513** | **1,565.46** | **100.00** |


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Area-Elevation range-wise Distribution**

Glacial lake distribution has been analyzed as per area range vs. elevation range-wise, given in Table 16 and Figure 19. It is noted that, 96.69% of glacial lakes (496) are situated above high altitude range i.e. > 4,000 m amsl, which constitutes 93.32% of total lake area. However, few glacial lakes (17) lies below 4,001 m, which are within 0.25 - 50 ha lake area range. Maximum of lakes lying in very high altitude range is of size ranging 1 - 5 ha (i.e. 196), followed by lakes of size 0.5 - 1 ha (i.e. 130).


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Table: Table 16: Area range-wise vs. Elevation range-wise distribution of GL in Amo Chu subbasin

| S. No. | Lake Area Range (ha) | Elevation Range (m) up to 3,000 - No. of lakes | Elevation Range (m) up to 3,000 - Total Lake Area (ha) | Elevation Range (m) 3,001 - 4,000 - No. of lakes | Elevation Range (m) 3,001 - 4,000 - Total Lake Area (ha) | Elevation Range (m) 4,001 - 5,000 - No. of lakes | Elevation Range (m) 4,001 - 5,000 - Total Lake Area (ha) | Elevation Range (m) > 5,000 - No. of lakes | Elevation Range (m) > 5,000 - Total Lake Area (ha) | Total - No. of lakes | Total - Lake Area (ha) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 0.25 - 0.5 | 0 | 0.00 | 1 | 0.35 | 99 | 33.84 | 11 | 3.63 | 111 | 37.82 |
| 2 | 0.5 - 1 | 0 | 0.00 | 0 | 0.00 | 122 | 88.40 | 8 | 5.91 | 130 | 94.31 |
| 3 | 1 - 5 | 0 | 0.00 | 9 | 25.18 | 175 | 393.48 | 12 | 25.04 | 196 | 443.69 |
| 4 | 5 - 10 | 0 | 0.00 | 5 | 35.39 | 37 | 255.69 | 1 | 6.36 | 43 | 297.44 |
| 5 | 10 - 50 | 0 | 0.00 | 2 | 43.60 | 29 | 579.51 | 1 | 16.40 | 32 | 639.52 |
| 6 | > 50 | 0 | 0.00 | 0 | 0.00 | 0 | 0.00 | 1 | 52.68 | 1 | 52.68 |
| Total | | 0 | 0.00 | 17 | 104.52 | 462 | 1,350.92 | 34 | 110.02 | 513 | 1,565.46 |


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Figure: Figure 19: Area range-wise vs. Elevation range-wise distribution of GL in Amo Chu subbasin

**Figure 19: Area range-wise vs. Elevation range-wise distribution of GL in Amo Chu subbasin**


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Type-Elevation range-wise Distribution**

Glacial lake distribution has also been analyzed as per type-wise vs. elevation range-wise, given in Table 17 and Figure 20. The dominant lake types in the basin i.e., Other Glacial Erosion lakes (80.31%) are predominantly located in the elevation range of > 4,000 m (96.69%). The other dominant lake type, namely, Cirque Erosion lakes are also distributed in > 4,000 m elevation range which constitutes 11.89% of the total lakes. Elevation range-type-wise distribution of glacial lakes has been represented in Figure 21.


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Table: Table 17: Type-wise vs. Elevation range-wise distribution of GL in Amo Chu subbasin

| S. No. | Elevation Range (m) | M(e) | M(l) | M(lg) | M(o) | I(s) | I(d) | E(c) | E(v) | E(o) | O | Total |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | up to 3,000 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 2 | 3,001 - 4,000 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 0 | 14 | 0 | 17 |
| 3 | 4,001 - 5,000 | 1 | 4 | 0 | 17 | 3 | 0 | 55 | 0 | 380 | 2 | 462 |
| 4 | > 5,000 | 1 | 0 | 0 | 10 | 2 | 0 | 3 | 0 | 18 | 0 | 34 |
| | **Total** | **2** | **4** | **0** | **27** | **5** | **0** | **61** | **0** | **412** | **2** | **513** |

S. No.
Elevation Range (m)
M(e)
M(l)
M(lg)
M(o)
I(s)
I(d)
E(c)
E(v)
E(o)
O
Total


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Figure: Figure 20: Type-wise vs. Elevation range-wise distribution of GL in Amo Chu subbasin

**Figure 20: Type-wise vs. Elevation range-wise distribution of GL in Amo Chu subbasin**


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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The Dibang subbasin is the Ninth Smallest subbasin of the Brahmaputra basin covering a total area of 12,238 Km² i.e. 3.06% of the total basin area (Figure 22). The Sisar, Mathun, Tangon, Dri, Ithun and Emra are the major tributaries of the Dibang. It is an upstream tributary river of the Brahmaputra that originates and flows through the Mishmi Hills from the state of Arunachal Pradesh and Nyingchi Prefecture in the Tibet Autonomous Region. A total of 772 glacial lakes has been mapped, covering a total area of 6,566.10 ha i.e. 0.53% of the total area of the subbasin.

GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Area range-wise Distribution**

In Dibang subbasin, glacial lakes have been distributed in all 6 classes of area ranges. Table 18 and Figure 23 shows the area range-wise distribution of glacial lakes for the Dibang subbasin. About 440 (56.99%) lakes are with < 5 ha lake area contributing to 14.78% of total lake area. The remaining lakes with > 5 ha in size are only 332 (43.01%) contributing to 85.22% of total lake area in the subbasin.

5. RESULTS
5.2 Subbasin-Wise Statistics
5.2.2 Dibang Subbasin


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Table: Table 18: Area range-wise distribution of GL in Dibang subbasin

| S. No. | Lake Area Range (ha) | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :---: | :--- | :---: | :---: | :---: |
| 1 | 0.25 - 0.5 | 24 | 9.90 | 0.15 |
| 2 | 0.5 - 1 | 82 | 60.95 | 0.93 |
| 3 | 1 - 5 | 334 | 899.70 | 13.70 |
| 4 | 5 - 10 | 144 | 1,030.44 | 15.69 |
| 5 | 10 - 50 | 175 | 3,532.30 | 53.80 |
| 6 | > 50 | 13 | 1,032.81 | 15.73 |
| | **Total** | **772** | **6,566.10** | **100.00** |

S. No.
Lake Area Range (ha)
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)


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**GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN**

**Type-wise Distribution**

Distribution of different types of glacial lakes in the Dibang subbasin is given in Table 19 and Figure 24. Out of 10 types of glacial lakes, 5 types of lake are present in the Dibang subbasin, where Other Glacial Erosion lakes are found to be the maximum with 601 (77.85%) occupying a total lake extent of 4,319.31 ha at 65.78% in the subbasin. After that, Other Cirque Erosion lakes are in majority with 141 (18.26%) and extend over a total area of 1,750.15 ha (26.65%). All Moraine Dammed lakes covers about 0.49% of entire area in the subbasin.


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Table: Table 19: Type-wise distribution of GL in Dibang subbasin

| S. No. | Code | Types of Glacial Lake | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
| :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | M(e) | End-moraine Dammed Lake | 1 | 4.29 | 0.07 |
| 2 | M(l) | Lateral Moraine Dammed Lake | 0 | 0.00 | 0.00 |
| 3 | M(lg) | Lateral Moraine Dammed Lake with Ice | 0 | 0.00 | 0.00 |
| 4 | M(o) | Other Moraine Dammed Lake | 1 | 27.72 | 0.42 |
| 5 | I(s) | Supra-glacial Lake | 0 | 0.00 | 0.00 |
| 6 | I(d) | Glacier Ice-dammed Lake | 0 | 0.00 | 0.00 |
| 7 | E(c) | Cirque Erosion Lake | 141 | 1,750.15 | 26.65 |
| 8 | E(v) | Glacier Trough Valley Erosion Lake | 0 | 0.00 | 0.00 |
| 9 | E(o) | Other Glacial Erosion Lake | 601 | 4,319.31 | 65.78 |
| 10 | O | Other Glacial Lake | 28 | 464.63 | 7.08 |
| | | **Total** | **772** | **6,566.10** | **100.00** |

S. No.
Code
Types of Glacial Lake
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN


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Glacial lake distribution by area range vs. type-wise is given in Table 20 and Figure 25. The lakes with < 5 ha in size (56.99%) are dominant with Other Glacial Erosion Lakes (87.50%) and Cirque Erosion lakes (8.86%). Lakes with > 5 ha (43.01%) are dominated by Other Glacial Erosion Lakes (65.06%). Out of 772, 742 are all types of Glacier Erosion lakes contributes to about 96.11%.

5. RESULTS
5.2 Subbasin-Wise Statistics
Area range-Type-wise Distribution


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Table: Table 20: Area range-wise vs. Type-wise distribution of GL in Dibang subbasin

| S. No. | Lake Area Range (ha) | M(e) | M(l) | M(lg) | M(o) | I(s) | I(d) | E(c) | E(c) | E(o) | O | Total |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | 0.25 - 0.5 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 20 | 3 | 24 |
| 2 | 0.5 - 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 80 | 1 | 82 |
| 3 | 1 - 5 | 1 | 0 | 0 | 0 | 0 | 0 | 37 | 0 | 285 | 11 | 334 |
| 4 | 5 - 10 | 0 | 0 | 0 | 0 | 0 | 0 | 39 | 0 | 103 | 2 | 144 |
| 5 | 10 - 50 | 0 | 0 | 0 | 1 | 0 | 0 | 62 | 0 | 103 | 9 | 175 |
| 6 | > 50 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 10 | 2 | 13 |
| | **Total** | **1** | **0** | **0** | **1** | **0** | **0** | **141** | **0** | **601** | **28** | **772** |

S. No.
Lake Area Range (ha)
M(e)
M(l)
M(lg)
M(o)
I(s)
I(d)
E(c)
E(c)
E(o)
O
Total


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Figure: Figure 25: Area range-wise vs. Type-wise distribution of GL in Dibang subbasin

**Figure 25: Area range-wise vs. Type-wise distribution of GL in Dibang subbasin**


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GLACIAL LAKE ATLAS OF BRAHMAPUTRA RIVER BASIN

**Elevation range-wise Distribution**

Elevation range-wise distribution of the glacial lakes in the Dibang subbasin has been shown in Table 21 and Figure 26. Majority of glacial lakes are situated above 3,000 m elevation range i.e. 770 (99.74%) with total lake area of 6,538.64 ha (99.58%) and remaining only 0.26% glacial lakes are below 3,000 m elevation.


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Table: Table 21: Elevation range-wise distribution of GL in Dibang subbasin

| S. No. | Elevation Range (m) | No. of Lakes | Total Lake Area (ha) | Total Lake Area (%) |
|---|---|---|---|---|
| 1 | up to 3,000 | 2 | 27.46 | 0.42 |
| 2 | 3,001 - 4,000 | 405 | 3,586.02 | 54.61 |
| 3 | 4,001 - 5,000 | 365 | 2,952.62 | 44.97 |
| 4 | > 5,000 | 0 | 0.00 | 0.00 |
| | **Total** | **772** | **6,566.10** | **100.00** |

S. No.
Elevation Range (m)
No. of Lakes
Total Lake Area (ha)
Total Lake Area (%)