Effects of reservoir system historical evolution on water system landscape patterns: the case of Changshou, China.

Abstract

Reservoirs are a crucial form of water ecological infrastructure that offers a wide range of ecosystem services. The impact of reservoir construction on land use and landscape patterns is a matter of considerable importance. However, the specific effects of local-scale reservoir development on water system landscape patterns have not been comprehensively investigated. The Changshou district of Chongqing, located in southwest China and having an artificial lake system primarily composed of reservoirs, is an excellent example of examining the effects of human activities on the landscape patterns of water systems. This research reconstructed the historical evolution of reservoirs and rivers in Changshou District by historical maps and remote sensing data over seven decades from 1950 to 2020. On this basis, the landscape pattern metrics and graph-theoretical metrics of water systems in four crucial years, 1950, 1960, 1990, and 2020, were analyzed. The results indicate that from 1950 to 2020, the reservoir area in Changshou District increased by 64.195 km2, while the river area decreased by 7.297 km2; the two periods with the highest reservoir construction intensity were the 1950s and the 1970s to 1980s, when the reservoir area increased by 58.456 km2 and 3.089 km2, respectively; the construction of reservoirs diminished the connectivity of water systems and increased their fragmentation, dispersion, and edge complexity, but had little effect on their concentration and shape complexity. The findings can be applied to the optimization of water system patterns at the local level, the management of reservoir groups, the decision-making of water ecological infrastructure, and ecological effect studies of artificial lakes.