IWMIHQ/volta_water_accounting

Volta Water Accounting

Water accounting for the Volta basin at ~248 m: rainfall, total ET, green and blue ET, water yield and runoff, each as a yearly average and split into dry and wet seasons, averaged over 2010-2019. Water Accounting Plus output rebuilt from IWMI's Africa GeoPortal tile services, which serve no downloadable raster.

• Region Volta
• Period 2010-2019
• Theme Water accounting
• Grid EPSG:4326, 3412 x 4066 at 0.002232143 deg (~248 m)
• Bands 18
• Files 18 Cloud-Optimised GeoTIFFs under data/, named <band>.tif, one per band

Bands

Band	Type	Units	Nodata
yearly_rainfall	float32	mm	-9999.0
yearly_et	float32	mm	-9999.0
yearly_rainfall_et	float32	mm	-9999.0
yearly_incremental_et	float32	mm	-9999.0
yearly_water_yield	float32	mm	-9999.0
yearly_runoff	float32	mm	-9999.0
dry_rainfall	float32	mm	-9999.0
dry_et	float32	mm	-9999.0
dry_rainfall_et	float32	mm	-9999.0
dry_incremental_et	float32	mm	-9999.0
dry_water_yield	float32	mm	-9999.0
dry_runoff	float32	mm	-9999.0
wet_rainfall	float32	mm	-9999.0
wet_et	float32	mm	-9999.0
wet_rainfall_et	float32	mm	-9999.0
wet_incremental_et	float32	mm	-9999.0
wet_water_yield	float32	mm	-9999.0
wet_runoff	float32	mm	-9999.0

Read it

These are COGs, so GDAL reads them in place over HTTP -- no full download, and a windowed read fetches only the bytes it needs:

from huggingface_hub import hf_hub_url
import rasterio

url = hf_hub_url("IWMIHQ/volta_water_accounting", "data/dry_et.tif", repo_type="dataset")
with rasterio.open(url) as src:
    print(src.width, src.height, src.crs, src.nodata)
    patch = src.read(1, window=((0, 256), (0, 256)))

Or pull the whole repo:

from huggingface_hub import snapshot_download
path = snapshot_download("IWMIHQ/volta_water_accounting", repo_type="dataset")

Read this before using it

A 2010-2019 AVERAGE, not a time series. The period is the publisher's own: its sibling "Seasonal Maps" and "Yearly Maps" items for Volta both carry 2010-2019 in their titles. Every cell is a multi-year mean, so no individual year is described and no trend can be read from it. Season months are undeclared. Nothing in the service metadata or the item records says where the dry season ends and the wet begins, so these bands cannot be aligned to a calendar or compared with another dataset's seasons. What is known is measured: the wet season averages 788 mm of rainfall against the dry season's 115 mm. The seasonal and yearly bands DO NOT agree, and this geography is unusual in that. dry + wet differs from yearly by up to 38 mm (99.9th percentile 26.9 mm) across 1843507 cells of 6764119 -- not a few bad pixels but a systematic offset, so the yearly layers are evidently a different processing run from the seasonal ones rather than their sum. Do not mix the two: pick the yearly bands or the seasonal pair and stay within it. Dry-season water yield averages -106 mm, i.e. negative: ET exceeds rainfall and draws on stored moisture. Ordinary for a dry season, but it means that band is not "water available". Only 48.8% of the frame carries data -- the rest lies outside the mapped area -- so any whole-frame statistic is meaningless. Rebuilt from a tile cache rather than downloaded, so these values are whatever was published into the LERC pyramid, read at the pyramid level that matches the services' native resolution. The ArcGIS service named in each file's source tag remains the authority.

Provenance

Rebuilt from IWMI Africa GeoPortal ArcGIS image services, which serve no downloadable raster: they answer exportImage with HTTP 400 because their capabilities are Image,TilesOnly. The full-resolution grid was recovered by fetching every LERC tile at the pyramid level matching the service's own native resolution, decoding, and mosaicking. Each GeoTIFF carries the originating service in its source tag, and that service -- not this copy -- is the authority for its values.

The same product is indexed in IWMI's Open Data Cube, which is the route to its footprint, time extent and band metadata as STAC:

https://explorer-production-0070.up.railway.app/stac/collections/volta_water_accounting

Citation

International Water Management Institute (IWMI), Volta Water Accounting. Published via the IWMI Open Data Cube. Licence CC-BY-4.0.

@misc{iwmi_volta_water_accounting,
  title        = {Volta Water Accounting},
  author       = {International Water Management Institute},
  howpublished = {Hugging Face Hub, IWMIHQ/volta_water_accounting},
  note         = {Derived from IWMI Africa GeoPortal services; see Provenance},
  year         = {2026}
}