Identifying the effects of land use change on sediment export: Integrating sediment source and sediment delivery in the Qiantang River Basin, China

Mengmeng Zhou; Jinsong Deng; Yi Lin; Marye Belete; Ke Wang; Alexis Comber; Lingyan Huang; Muye Gan

doi:10.1016/j.scitotenv.2019.05.336

Identifying the effects of land use change on sediment export: Integrating sediment source and sediment delivery in the Qiantang River Basin, China

Sci Total Environ. 2019 Oct 10:686:38-49. doi: 10.1016/j.scitotenv.2019.05.336. Epub 2019 Jun 2.

Authors

Mengmeng Zhou¹, Jinsong Deng², Yi Lin³, Marye Belete¹, Ke Wang¹, Alexis Comber⁴, Lingyan Huang¹, Muye Gan¹

Affiliations

¹ College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
² College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: jsong_deng@zju.edu.cn.
³ Department of Geography, University of Hong Kong, Pokfulam Road, Hong Kong SAR, China.
⁴ School of Geography, University of Leeds, Leeds LS2 9JT, UK.

PMID: 31176141
DOI: 10.1016/j.scitotenv.2019.05.336

Abstract

Dramatic land use change caused by the rapid economic development in China has impacted the sediment export dynamics in the large basin. However, how land use change affects sediment export is still poorly understood. This study provided an integrated analysis of the relationships in a "three-level" chain linked as follows: "land use change → changes in sediment source and sediment delivery → sediment export change" for a better understanding. It used the InVEST sediment delivery ratio (SDR) model to analyze the Qiantang River Basin (4.27 ∗ 10⁴ km²), China. Sediment export change was examined from the two perspectives: the effects of land use change on sediment source and on sediment delivery. Correlations between changes in individual land use types and changes in sediment source and sediment delivery were identified. The results indicated that sediment export reduced from 1.69 t ha^-1 yr^-1 in 1990 to 1.22 t ha^-1 yr^-1 in 2015 because of the decreased sediment source and a weakened sediment delivery function. In the study area, the conversions of cropland to urban land (urbanization) and bare land to forestland (afforestation) were found to make the major contributions to reductions in soil loss and SDR, respectively. Furthermore, soil loss change resulted in the decreases in total value of sediment export and SDR change caused a large-scale spatial change in sediment export. Our hotspot analysis revealed that the Wuxi River watershed should be targeted for priority conservation to optimize land use/cover for reducing sediment export. This study demonstrates the benefits of taking a comprehensive approach to analyze the processes associated with sediment export change. These allow to improve sediment management and promote aquatic ecosystem health by providing specific future land use recommendations, aimed at source treatment and delivery interception.

Keywords: InVEST model; Land use change; Sediment delivery ratio; Sediment export; Soil loss.