Interferometric radar satellite and in-situ well time-series reveal groundwater extraction rate changes in urban and rural Afghanistan

Population growth, climate change, and a lack of infrastructure have increased water demand and groundwater exploitation in urban and rural Afghanistan, resulting in significant ground subsidence in various regions. 

Using Sentinel-1 radar-interferometric time-series data based on over 7-years (2015-2022), we assess country-wide Afghan subsidence rates for groundwater levels, precipitation, and changes in irrigation practices. Urban Kabul city and the growing agricultural sector of rural Ghazni provinces are of particular focus. In Kabul city, we compare spatiotemporal subsidence patterns to water table heights and precipitation amounts. In Ghazni, we monitored the transition from ancient to modern irrigation techniques by mapping solar-panel arrays as a proxy for electrical water pumping and evaluating the vegetation index as a proxy for agricultural activity.

Several provinces in Afghanistan such as Kabul, Ghazni, Helmand, Farah, Baghlan, and Kunduz exhibit significant subsidence of more than ~5 ± 0.1 cm/yr. In Kabul, ground subsidence is most pronounced in the city center with a 6-yr total of 31.2 ± 0.5 cm, but it’s the peripheral wells of the Kabul basin that exhibit the highest water-table drops, where aquifers are also thinner and wells are deeper. In Ghazni, a 7-yr total of 77.8 ± 0.5 cm ground subsidence was recorded. Before 2018 barren lands were transformed into farmland throughout the province, and traditional irrigation such as Kariz networks were replaced by electrical water pumps to tap groundwater, which enabled the conversion of barren land into farmland and marked the acceleration of ground subsidence after 2018. In addition severe droughts in 2020 and 2021 further exacerbated groundwater depletion, leading to m-wide and km-long desiccation cracks that appeared in the area with the highest irrigation volume and ground subsidence.