Evidence of rising groundwater and potential for sustainable management amid multi-year droughts in the pastoral regions of northern Kenya

Denis Macharia Muthike, Styvers Kathuni , Christian Muragijimana , Taylor Sharpe , Gabriel Senay, Evan Thomas

Groundwater underpins water security in the drylands of East Africa, where climate extremes and increasing groundwater use pose growing water management challenges. This study examines groundwater dynamics in arid northern Kenya using multi-source data that combine in-situ electronic sensor measurements with satellite-based rainfall observations, terrestrial water storage anomalies, and model simulations of groundwater storage. Analysis of long-term rainfall records reveals pronounced hydroclimatic variability over the past four decades. The analysis revealed a clear climate signal in regional water storage, characterized by pronounced interannual variability driven by alternating drought and wet extremes during the long rains (March--May; MAM) and the short rains (October--December; OND) seasons. The OND season showed a progressive tendency toward wetter conditions over the study period, while MAM rains experienced episodic wet anomalies. Groundwater storage increased gradually from 2004 to 2024, with notable declines during multi-year droughts and strong rebounds during wet periods. Annual mean groundwater storage across the study domain over the same period increased by approximately 21.7%, rising from 109.68 km^3 to 133.49 km^3. At the well scale, monitored sites exhibited distinct drawdown–recovery behavior and delayed responses to cumulative rainfall, with lags ranging from approximately one to four months. Differences among sites highlight the heterogeneous nature of groundwater responses across the region and are likely influenced by local hydrogeologic controls. Recovery ratios suggest that, during the monitoring period, short-term abstraction was generally offset by recovery, findings that could support evidence of potential groundwater sustainability. Overall, these findings demonstrate the value of high-frequency groundwater monitoring and satellite observations for diagnosing groundwater dynamics in data-scarce drylands and emphasize the need for sustained monitoring and improved hydrogeological characterization to support groundwater management under intensifying climate variability and rising water demand.