Hydro-climatic stress, shallow groundwater wells and coping in Ghana's White Volta basin

Highlights: • Data paucity is undermining climate change - groundwater recharge nexus for management. • Combined hydro and social models are key to frame human dimensions of groundwater issues. • Vulnerable populations are adopting shallow groundwater to supplement surface water. • Ghana's White Volta basin's discharge could support seasonal shallow wells (SSWs). • Science of shallow groundwater wells is crucial for climate resilience building. Debates of the nexus between water-related stresses and water availability for groundwater-dependent irrigation which comprises of non-conventional groundwater abstraction schemes is only recently emerging. The interaction between Seasonal Shallow Wells (SSWs), one of such indigenous abstractions scheme and groundwater recharge remains new to groundwater science and development. The SSWs supplement formal irrigation (e.g. reservoirs) and surface water for dry season agriculture in Ghana's White Volta Basin, yet links with the overall gradient of groundwater is unknown. Therefore, using the Water Evaluation And Planning (WEAP) model and qualitative techniques, the implications of groundwater recharge and surface runoff in their orientation to shallow wells is explored. Standardized precipitation index (SPI) from a regional downscale model for droughts and floods showed increased drought and flood influence on groundwater recharge and irrigation. Enhanced surface runoff water and climate change continuously reduced groundwater recharge by 2030, with decreased stream and water inflows. Irrigation water requirements of reservoirs were computed to be between 173% and 327% of normal reservoir water requirements, yet majority of dams did not meet these requirements especially during the dry season. The basin has history of dryness and exhibited uneven distribution of groundwater, yet recharged water of unsaturated soil moisture zones made water available to the SSWs. The SSWs were patronised mostly by women and farming households based on perceptions of limited cost, less sophistication and no formal regulatory measures. The paper therefore provides framework for establishing links between the mechanics of SSWs, and existing climatic and hydrologic conditions for informed groundwater development.