Towards the hydrological effects of land use change in karst area, a case study in Lijiang River Basin, China

Abstract

With economic and social development, the inevitable conflict between growing populations and land use change has become increasingly prominent. In karst areas, such as the Lijiang River Basin (LRB) in South China, land use has undergone rapid and intense changes over the past few decades due to urbanization and agricultural development. Assessing the hydrological effects of future land use change scenarios in karst areas is essential for estimating potential flood risks. In this study, we constructed hydrological models for the LRB based on a widely used hydrological model (SWAT, Soil and Water Assessment Tool), analyzed the runoff coefficient (Rc) at event scale, and evaluated the hydrological effects under future land use scenarios in 2100 based on five shared socio-economic pathways (SSPs). The results indicate that the simulated streamflow effectively replicated the hydrographs of the LRB. The model exhibited good performance, as evidenced by daily streamflow simulation with NSE greater than 0.65 and PBIAS within the range of ± 15 %. This demonstrates the applicability of SWAT in karst areas. The analysis of storm events revealed that severe storms in the LRB mainly took place between April and July and in November, with relatively long durations and high Rc values. Under all five SSP-based future land use scenarios, it is predicted that flood risk will increase in the LRB. Notably, the severity of flood events during the dry season is expected to escalate, with Rc potentially increasing by up to 16 %. To address environmental degradation and achieve sustainable development, it is imperative to adopt appropriate environment-friendly land use practices and implement effective land management strategies.