Ecological Indicators (Aug 2024)
Prediction and impact of Location-Weighted landscape Index on water quality in a typical karst region in southwest China: A case study of the Huanghou basin
Abstract
The karst region serves as a crucial drinking water source. With the rise in water quality pollution, there is a substantial increase in pressure on water resources. Real-time monitoring and assessment of water quality pollution in the karst region are imperative. The Location-Weighted Landscape Index (LWLI) is a dynamic indicator that focuses on changes in ecological processes, synthesizing landscape composition and topographic features, has found widespread application in diverse water quality studies. In this study, the Huanghou Basin, a typical karst basin, was selected as the study area and based on the theory of source-sink landscapes, the LWLI was computed to efficiently and rapidly predict water quality changes in the watershed and the abrupt change point of LWLI on water quality were calculated using the nonparametric change-point analysis (nCPA). The Redundancy Analysis (RDA) comparing the impacts of LWLI and landscape indicators on water quality. The study results revealed that exceedingly low-risk areas (64.7%) and low-risk areas (18.4%) cover a much larger area than medium-risk areas (6.9%), high-risk areas (4.9%) and exceedingly high-risk areas (5.1%). Water quality is better in the lower reaches of the Huanghou Basin than in the upper reaches of the basin, and the risk to water quality and safety is generally low. The RDA results showed that LWLI explained up to 62.2% of water quality, while landscape indicators explained between 1% and 15.2% of water quality. It is evident that the LWLI provides a better explanation of water quality in karst regions than do landscape indicators. LWLI elevation, LWLI slope and LWLI distance explained water quality with magnitude 62.5%, 43.2%, 34.9% in the dry season and 54.4%, 41.3%, 29.1% in the wet season, respectively. Therefore, the relationship between LWLI‘elevation, LWLI slope and LWLI distance on the magnitude of the water quality explanatory rate is LWLI elevation＞LWLI slope＞LWLI distance. It can be seen that among the topographic features, the elevation factor has the greatest influence on water quality in karst areas, and the explanation rate is higher in the dry season than in the rainy season. In this study, when LWLI reaches 0.55, water quality experiences a sudden deterioration. Enhancing water quality in karst areas is attainable through prevention and control of desertification, increased vegetation planting on slopes, reduced fertilizer use, and enhanced vegetation richness.
