Flood modelling and its impacts on groundwater vulnerability in sub-Himalayan region of Pakistan: integration between HEC-RAS and geophysical techniques

Hydropower projects play a pivot role in the development of a country. Constructions of reservoirs create job opportunities and provide cheap energy but at the same time cause several environmental issues. The current study utilizes geoelectric and flood modelling data to develop a relationship between flood scenarios and their effect on river flows in association with the vulnerability of groundwater due to hydroelectric projects on Neelum River, Pakistan. The resistivity data delineated local aquifer systems that comprised both confined and unconfined aquifers ranging from 05 to 48 m depth, having poor to weak protective capacity with good groundwater development potential. The flood zonation models indicate a decline in the flow rate of the Neelum River from 317 to 39 m3/s with a drop in stage and flow velocity that contributes to a high risk of leachate penetration in the poorly protected shallow aquifer. The aquifer systems that mostly lie near the banks of the river face a serious threat of contamination due to low river flow. The flood modelling revealed that in case of dam burst, maximum probable flood will affect the land cover of 30,43,250 m2 and 33,64,433 m2 in Muzaffarabad and Patikka areas, respectively, affecting major population.