Integrated Assessment of Climate Change and Land Use Change Impacts on Hydrology in the Kathmandu Valley Watershed, Central Nepal

Abstract

The population growth and urbanization are rapidly increasing in both central and peripheral areas of the Kathmandu Valley (KV) watershed. Land use/cover (LULC) change and climate variability/change are exacerbating the hydrological cycle in the KV. This study aims to evaluate the extent of changes in hydrology due to changes in climate, LULC and integrated change considering both factors, with KV watershed in central Nepal as a case study. Historical LULC data were extracted from satellite image and future LULC are projected in decadal scale (2020 to 2050) using CLUE-S (the Conversion of Land Use and its Effects at Small regional contest) model. Future climate is projected based on three regional climate models (RCMs) and two representative concentration pathways (RCPs) scenarios, namely, RCP4.5 and RCP8.5. A hydrological model in soil and water assessment tool (SWAT) was developed to simulate hydrology and analyze impacts in hydrology under various scenarios. The modeling results show that the river runoff for RCP4.5 scenarios is projected to increase by 37%, 21%, and 12%, respectively, for climate change only, LULC only, and integrated changes of both. LULC change resulted in an increase in average annual flow, however, a decrease in base-flow. Furthermore, the impacts of integrated changes in both LULC and climate is not a simple superposition of individual changes.

Application of SWAT in Hydrological Simulation of Complex Mountainous River Basin (Part I: Model Development)

“…SWAT model has successfully been used in other Nepalese catchments too; Koshi [27,41] Narayani [42], West Rapti [43] and Karnali [25,[44][45][46]. There are a number of similar studies that used SWAT model in other river basins of Nepal to assess the river hydrology and the impact of climate change [47] in Kaligandaki basin; [48,49] in Bagmati basin; [50] in Karnali basin; [51] in Tamor basin, and [52] in Koshi basin. SWAT being a freely available public domain hydrological model capable of simulating complex hydrological processes might have made it popular for hydrological simulation around the world.…”

Relationships between Hydropower Generation and Rainfall-Gauged and Ungauged Catchments from Sri Lanka

“…e prediction model can be handy in feeding the climate data from various models. Regional climate models such as ACCESS1 [42], CNRM-CM5-CSIRO-CCAM [43], MPI-ESM-LR [44], and REMO2009 [45,46] can be used to obtain the future rainfall to the catchment. ese rainfall values have to be corrected for the biases.…”

Hydrological Modeling: A Better Alternative to Empirical Methods for Monthly Flow Estimation in Ungauged Basins

“…HEC-HMS, SWAT, MIKE SHE, MIKE NAM and VIC, among others, are some popular hydrological models used globally for assessing flows [29]. SWAT (Soil and Water Assessment Tool) model capable of simulating the hydrological process satisfactorily in Nepalese catchments [23] [26] [27] [33] was used for simulating the flows of the BRB in this study.…”