Impact of sedimentation on groundwater recharge at Sahalanowt Dam, Salalah, Oman

Abstract

Recharge dams in Oman detain floods to recharge groundwater. The impact of sedimentation on recharge at Wadi Sahalanowt Recharge Dam, in Salalah, Oman, was evaluated using field data and numerical modelling. Analysis of the thickness of sediments after flood events shows that maximum depositions were at the same locations after each event, coinciding with the lowest positions in the wadi. Numerical modelling suggests that the current practice of periodic removal of sediments will restore the storage capacity of the reservoir, but that ploughing or raking of the underlying native sedimentary rocks could be required to significantly improve infiltration rates.

Keywords:

• recharge dams
• groundwater recharge
• sedimentation
• Oman

Notes

1. The upper boundary condition being set with 34 time variable-boundary records implies that the depth of standing water was continuously changing due to infiltration, and during infiltration, depth was recorded 34 times. The assumption of free drainage conditions for the bottom boundary implies water may drain freely at the bottom due to gravity. The assumption of no flow boundary conditions for the two vertical boundaries implies that water may not enter the model domain from the sides (vertical boundaries).