Geophysical Investigation using 2D-ERT Method to revive depleted source of springs on hard rock area after Gorkha Earthquake 2015 in Lesser Himalyan region, Dolkha District Nepal.
Abstract
The massive Gorkha earthquake that hit Nepal on 25 April has left unprecedented damage in life and property as well as on surface and subsurface condition of the area. The underground land deformation has impact on the groundwater flow movement which has been observed at several places after earthquake. Present study focuses on Geophysical approaches to revive depleted source of springs after Gorkha Earthquake 2015 in Dolakha District, Nepal.
The study was carried out for Water Resources Research and Development Centre, Government of Nepal. Geologically study area lies on Lesser Himalyan Zone of Nepal Himalaya. Geophysical Investigation was carried out in area using (WDJD-4 Multi-function Digital DC Resistivity/IP) equipment. Study area was mapped by six 2D ERT profiles to map vertical as well as horizontal variations of electrical resistivity for the detection of thickness of overburden, depth and extension of the water bearing zones / fractured rock, hard rock and rock mass condition up to the depth of investigation. Data inversion was carried out using RES2DINV software. Geological / hydrogeological mapping was carried out in the area. The results of ERT show that the subsurface is classified into distinct geo-electric layers representing dry unconsolidated overburden, saturated fractured rock and fresh bedrock of schist and gneiss with different resistivity values. Initial water flow path of the area was blocked due to land deformation in the area. Water bearing fracture zone is found to be trapped by hard rock. Horizontal drilling was recommended to drill up to the fracture zone at recommended locations. Horizontal drilling was successfully conducted with discharge rate of 1500 liter/min. from two horizontal tube well.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNS41B0822G
- Keywords:
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- 0933 Remote sensing;
- EXPLORATION GEOPHYSICS;
- 1829 Groundwater hydrology;
- HYDROLOGY;
- 1835 Hydrogeophysics;
- HYDROLOGY;
- 1880 Water management;
- HYDROLOGY