Impacts of floods in land use land cover change: A case study of Indrawati and Melamchi River, Melamchi and Indrawati municipality, Nepal

Abstract

Every year, flood affects millions of people worldwide causing an imbalance in social, economic, and natural harmony as it is one of the most destructive natural hazards. Floods occur when the river channel overflows and extends across the surrounding topography. Nepal is highly vulnerable to floods. We studied the impacts of flood that occurred on 15 June, 2021 in the Melamchi- Indrawati river basin which is the second highest flood prone area zone in Sidhupalchowk district. We used a pre, post-event, and present land use and cover (LULC) map of the study area to quantify the impacts in the study area. We used Sentinel 2 imagery from 2019-02-01 to 2019-03-01, 2021-07-01 to 2021-08-01, 2022-02-01 to 2022-03-01 and the google earth engine to study the LULC change. We used a random forest classifier to run supervised classification and build 5 classes: built-up, cropland, barren land, water bodies, and forest in our LULC map. We found overall accuracy of 94.26% for the LULC 2019 map, 92.18% for the 2021 LULC map, and 92.72% for the 2022 LULC map. We found the highest impact of floods on agriculture/crops in the study area as the agriculture area reduced by 90.48 % following the flood event. Similarly, the barren areas grew by 78.58%. The built-up area was reduced by 70.61 %. The forest area was reduced by 93.06% in the flooded zone. Government should introduce effective policies like mandatory insurance on the risk-prone land to cover the losses after natural hazards.