The Groundwater Natural Background Quality indicators stands for the percentage of the transboundary aquifer (TBA) area where groundwater natural quality satisfies local drinking water standards.In north-eastern Africa, parts of the Middle East and Northern India and Pakistan, low recharge values in TBAs are combined with high population densities. In these areas, return flows from irrigation and other human induced recharge appear to play a major role in the sustainability of groundwater resource utilization. Very low natural quality (< 20 per cent of the aquifer area) coincides with TBAs highly impacted by irrigation return flows in densely populated areas with low to medium natural recharge, like the Nubian, Indus, Pre Caspian TBAs.For more information, visit: https://ggis.un-igrac.org/ggis-viewer/viewer/twap/public/default
