Stable sediment retention and rapid economic growth occurred together from the end of the 1970s to 2015 in the Three Gorges Reservoir area

Studies of land use/cover change (LUCC) and its impact on sediment retention services (SRS) can provide references for governments to aid them in identifying priorities for conservation or development. We analysed the LUCC characteristics of the Three Gorges Reservoir area (TGRA) and their impact on SRS for the period from the end of the 1970s to 2015 using the Sediment Delivery Ratio model of the Integrated Valuation of Ecosystem Services and Tradeoffs, and we further explored the relationship between SRS and economic growth. Our major findings were as follows. (a) Expansion of construction land and waterbodies with gross rates of 9.245% and 0.950%, respectively, and conversion from cropland to forestland/grassland with an area of 41,379 ha constitute the three main LUCC characteristics in the TGRA. (b) The amount of sediment retention was stable at about 1.42 x 10(6) t ha(-1)yr(-1) from the end of the 1970s to 2015, with a decrease of <1%. Spatially, ecological programmes resulted in an increase in SRS in the central areas of the TGRA, and urbanization undermined the capacity of SRS supply in the Chongqing urban centres. (c) SRS was concentrated in regions with an altitude of 500-2,200 m. As the slope increased, the percentage of grids with high SRS increased dramatically. (d) Stable SRS and rapid economic growth co-occurred in TGRA from the end of the 1970s to 2015, which offers a positive reference for achieving sustainable development.

Automated summary

This study analyzed the land use/cover change and its impact on sediment retention services in the Three Gorges Reservoir area, finding that expansion of construction land and waterbodies, as well as conversion from cropland to forestland/grassland, were the main characteristics. While sediment retention remained stable, ecological projects increased SRS in central areas but urbanization decreased it in urban centers. SRS was concentrated at altitudes of 500-2,200 meters, with higher slopes leading to a dramatic increase in SRS.