Use of electrical resistivity method to quantify accumulated sediments in Wellington reservoir, India.

Accumulated Sediment layer thickness is an important parameter to assess the capacity lost in any reservoir. The study focuses on assessing the quantity and depth of sediment layers at various points of Wellington reservoir using geophysical survey method. This electrical resistivity survey was done in fifteen locations in Wellington reservoir using ABEM Terrameter SAS 1000 with Schlumberger electrode arrangement. The data interpretation was carried out using IX1D v2 software. The results revealed that the resistivity of deposited sediments carried by inflow water ranges from, 0.8 Ωm to 58 Ωm and Sampling of sediments was done in those vertical electrical sounding points to validate the results and to characterize the type of soil. The thickness of sediments is around 4m near embankments and around 0.5 m thickness in the far ends of the reservoir. This study also revealed the native bed level of the reservoir and also the total volume of sediments of about 30.51 × 106 m3 which is responsible for the capacity loss of reservoir. Reservoir management practices against sedimentation like dredging needs information about the depth and distribution of sediment deposition. This method can only be adopted when the reservoir is dry and will give optimum results of sediment deposition by giving their depths. [ABSTRACT FROM AUTHOR]