Recent climatic variations have had a great impact on the availability of water resources in arid and semi-arid regions of the world. It is crucial to understand the integrated relationship between surface runoff and the aquifers. The present study aims to invistigate and evaluate the climatic factors, especially rainfall storms and their influence on water resources in Wadi El Dif, as well as an assessment the relationship of runoff to the replenishment of the groundwater aquifer. In addition, we use morphometric parameters of the investigated basin to elucidate their impact on the surface runoff within the main channel during rain storms.
Two storms of different rainfall depths (51.8 and 34 mm) having return periods of 20 and 8 years, respectively, were selected based on meteorological data of the Shalateen weather for the period (1979–2019). The SAMADA6.3 programme was applied to generate hydrographs for the two storms to calculate the peak runoff. The obtained volume of runoff varies from 0.884 million m3to 0.276 million m3.
Wadi El Dif is consideredone of the main subbasins of Wadi Hodein and covers about 518 km2. The catchment area of the Wadi El Dif is characterised by the mature hazards of flash floods. The obtained values for the infiltration rate in the study area range from 6 to 8 m/day, indicating that the soil of the Wadi El Dif is characterised by a very rapid rate of infiltration that directly impacts and replenishes the groundwater aquifer.
On the other hand, the relationship between the return period and the annual rainfall depth was inversely proportional. The groundwater of the Wadi El Dif is available from the Nubian Sandstone Aquifer. The water depth didn't signiticantly change from 23.66 to 23.7m in the period from 2007 to 2020, which means a balance between the amount of discharge and the amount of recharge to the aquifer. Groundwater replenishment amounts reached 2.69 million m3 in 2018 and 1.41 million m3 in 2019.The hydraulic parameters of the study aquifer revealed low potential and capability to transmit water through it due to partially penetration inthe studied aquifer.