Eco-environmental changes due to human activities in the Erhai Lake Basin from 1990 to 2020

Abstract

Human activities have increased with urbanisation in the Erhai Lake Basin, considerably impacting its eco-environmental quality (EEQ). This study aims to reveal the evolution and driving forces of the EEQ using water benefit–based ecological index (WBEI) in response to human activities and policy variations in the Erhai Lake Basin from 1990 to 2020. Results show that (1) the EEQ exhibited a pattern of initial degradation, subsequent improvement, further degradation and a rebound from 1990 to 2020, and the areas with poor and fair EEQ levels mainly concentrated around the Erhai Lake Basin with a high level of urbanisation and relatively flat terrain; (2) the EEQ levels were not optimistic in 1990, 1995 and 2015, and areas with poor and fair EEQ levels accounted for 43.41%, 47.01% and 40.05% of the total area, respectively; and (3) an overall improvement in the EEQ was observed in 1995–2000, 2000–2005, 2005–2009 and 2015–2020, and the improvement was most significant in 1995–2000, covering an area of 823.95 km2 and accounting for 31.79% of the total area. Results also confirmed that the EEQ changes in the Erhai Lake Basin were primarily influenced by human activities and policy variations. Moreover, these results can provide a scientific basis for the formulation and planning of sustainable development policy in the Erhai Lake Basin.

Effects of Vegetation Cover Varying along the Hydrological Gradient on Microbial Community and N-Cycling Gene Abundance in a Plateau Lake Littoral Zone

“…The lake experiences a low-latitude subtropical monsoon climate, with a latitude ranging from 25°36′ N to 25°38′ N and a water level ranging from 1966.0 m to 1964.3 m. The annual mean temperature of the basin is 15 °C, and the temperature of the lake water varies from 10 °C to 20 °C. [13]. In 2022, the water level varied by 0.55 m, ranging from 1965.5 m to 1964.9 m. Ten typical sampling areas were selected surrounding Lake Erhai based on the hydrographic and topographic features of the lake, as shown in Figure 1b.…”

“…Lake Erhai is the second largest plateau freshwater lake in China. Rapid urbanization in the lakeside area over the past few decades has increased the pollution load into the lake [13]. Due to the narrow width of the catchment area and the short surface-inflow path, the purification effectiveness of the lake littoral zone is crucial for controlling eutrophication.…”