Functions of traditional ponds in altering sediment budgets in the hilly area of the Three Gorges Reservoir, China

Mingquan Lü; Maohua Ma; Yu Wang; Chundi Chen; Jilong Chen; Shengjun Wu

doi:10.1016/j.scitotenv.2018.12.017

Functions of traditional ponds in altering sediment budgets in the hilly area of the Three Gorges Reservoir, China

Sci Total Environ. 2019 Mar 25:658:537-549. doi: 10.1016/j.scitotenv.2018.12.017. Epub 2018 Dec 4.

Authors

Mingquan Lü¹, Maohua Ma¹, Yu Wang¹, Chundi Chen¹, Jilong Chen¹, Shengjun Wu²

Affiliations

¹ Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122, China.
² Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122, China. Electronic address: wsj@cigit.ac.cn.

PMID: 30580209
DOI: 10.1016/j.scitotenv.2018.12.017

Abstract

The landscape pattern will affect the sediment transport process. The cluster of ponds is a common landscape, which has traditionally been used for irrigation in the hilly area of the Three Gorges Reservoir (TGR). However, little is known about how the landscape elements temporally changed over the past decades and if the ponds can be applied to function in balancing watershed sediments against soil erosion. The Jinglingxi watershed, covering 20.5 km², was selected as the study area. The changes in pond number, surface area, and drainage catchment were analyzed with aid of high-resolution typographical map and unmanned aerial vehicles imagery. The spatial WaTEM/SEDEM model was developed to simulate watershed soil erosion and sediment deposition under the absence and presence of water bodies scenarios. Results from different simulation scenarios were compared and revealed the trapping effects of the multi-pond system. From 1983 to 2016, the number and total area of ponds roughly doubled. The density reached 30 ponds/km². From 1983 to 2016, the total drainage area of ponds increased from 13.22% to 35.4% of the whole watershed. The sediments deposited at the bottom of ponds can indicate the past specific sediment yield (SSY) in drainage catchments. Our results suggest that the multi-pond system not only reduce watershed sediment export but also alter the sediment deposition in different land uses. The reduced sediments export is expected to prolong the service life of downstream reservoirs at the expectancy of ponds' storage capacities. The ecological compensation from downstream reservoirs' revenues to upstream regions should be established to drive dredging actions for the upstream ponds.

Keywords: Multi-pond system; Sediment yield; Three Gorges reservoir area; Unmanned aerial vehicles imagery; WaTEM/SEDEM.