Lateral flow assessment in laterite terrain under simulated rainfall conditions

Abstract

The subsurface flow of water in laterite terrain can play a vital role in regulating the groundwater. The state of Kerala experiences an average annual rainfall of about 3000 mm. Conversely, it experiences severe dry spells during the post−monsoon season leading to an unusual decline in the groundwater levels resulting in water scarcity. The study highlights the analysis of lateral flow in a laterite terrain and its variation with varying soil profile depths. The possible contribution of lateral flow in groundwater recharge has been analyzed and emphasized in the study. The experiment was carried out in Tavanur, a village located in the Malappuram district of Kerala. Lateral movement of water was assessed through a soil profile under simulated rainfall conditions. It was done by using the conventional gravimetric method of moisture measurement. A trench of dimensions (6 m × 0.5 m × 2 m) was installed to monitor the lateral movement of water. Moisture measurements were carried out for three soil profile depths of 0−40 cm, 40−80 cm, and 80−120 cm over a period of 12 hrs. Simulation of rainfall was carried out throughout a week for 12 hrs continuously in a day using a butterfly sprinkler. The study revealed that the lateral flow in the site accounted for 28.3% of the total simulated rainfall. It was inferred from the study that a major portion of applied water was lost in the form of rapid lateral flow even when there was no considerable surface runoff. Thus, the study signified the adoption of effective interventions for rainwater harvesting and its conservation in laterite terrain irrespective of abundant annual rainfall for effective groundwater replenishment.