Enhancing Groundwater Recharge with Sand Ditches

Localized and artificial groundwater recharge is an important water management strategy in arid regions. However, artificial recharge is limited by the hydraulic characteristics of surface soil which control downward water percolation to the aquifers. In heavy soils with low infiltration and hydraulic conductivity rate, water percolation can be enhanced by constructing deep ditches filled with highly permeable materials, such as sand. Laboratory experiments were conducted to examine the effect of constructing a deep sand ditch across the slope of a soil box (50 × 20 × 25 cm3) on runoff and deep percolation to the drainage outlet of the soil box. A sandy loam soil packed in two bulk densities (1200 and 1500 kg/m3) was used for the experiments. The experiments were carried out using simulated steady runoff of about 300 mL/min for a duration of 60 min. Experimental results showed that sand ditches greatly enhanced water deep percolation in soils but their relative effect was more profound in compacted high-density soil compared to soil having low-density. The drainage water collected from compacted soil boxes in the presence of sand ditches increased by 10 times compared to control soil without sand ditches. In the case of low-density soil, the presence of sand ditches eliminated the runoff but the increase in drainage water was about 18% compared to control. The experimental results clearly revealed that creating high infiltration zones within the soil matrix, such as sand ditches, significantly increased water deep percolation and herewith groundwater recharge in drylands, especially in heavy soils. Keywords: Arid regions, Groundwater recharge, Percolation, Rapid infiltration.