Integrated characterization of ephemeral streambed alluvium for sustainable management of groundwater recharge and flash floods

Ephemeral stream beds in arid and semi-arid regions are crucial for groundwater recharge and flood control, making their study vital for water management. This study examined surface soil properties of ephemeral stream beds in Jazan Province, Saudi Arabia. Grain size analysis revealed that over 80% of the samples are uniformly graded sands with high permeability. Effective grain sizes (D10 and D60) show that the upper 0–60 cm layer favours infiltration, supporting managed aquifer recharge (MAR) potential. Porosity ranged from 0.272 to 0.44, indicating substantial water storage. Together, these factors enhance recharge, limit runoff, and help mitigate flash floods. A weak correlation (r = 0.2) between measured and predicted saturated hydraulic conductivity, often resulting in underestimation of infiltration, underscores the need for field measurements. GIS maps have been developed for the best locations for MAR. Overall, ephemeral stream beds are promising sites for MAR and flood resilience.