Impact of urbanization on hydrological balance in urban lakes: a case study of Dianchi Lake

Urbanization can significantly transform land-cover patterns and modify lacustrine landscapes within urban lake watersheds over relatively short periods. These transformations are characterized by the expansion of urban areas into previously natural cover types, potentially leading to adverse outcomes such as lake shrinkage. Taking Dianchi Lake as an example, we applied the entropy method to determine the weights of 8 land-use types in a fuzzy synthetic evaluation, thereby the Comprehensive Index of City Urbanization (CICU) from 1988 to 2013. Comparing the comprehensive evaluation values with changes in the Dianchi Lake area revealed distinct correlations before and after 2000. Results indicated that moderate urban expansion in Kunming between 1988 and 2000 may have positively influenced the water levels of Dianchi Lake. Conversely, accelerated urbanization post-2000 led to substantial alterations in land-cover patterns and hydrological models, contributing to the shrinkage of Dianchi Lake. The CICU can be used for the analysis of human impacts on lake shrinkage and can thus provide a mathematical model for better understanding the water quantity balance of urban lakes.