Assessment of the Impacts of Land Use Change on Non-Point Source Loading under Future Climate Scenarios Using the SWAT Model

Mao Feng,Zhenyao Shen

doi:10.3390/w13060874

Abstract

The Miyun Reservoir is an important source of surface drinking water in Beijing. Due to climate change and human activities, the inflow of Miyun Reservoir watershed (MRW) has been continuously reduced in the past 30 years, which has seriously affected the safety of Beijing’s water supply. Therefore, this study aimed to assess the mitigation measures based on the quantification of the integrated impacts of climate and land use change in MRW. The non-point source (NPS) model (soil and water assessment tool, SWAT) was used for the development of future climate scenarios which were derived from two regional climate models (RCMs) under two representative concentration pathways (RCPs). Three land use scenarios were generated by the land use model (conversion of land-use and its effects (CLUE-S)): (1) historical trend scenario, (2) ecological protection without consideration of spatial configuration scenario and (3) ecological protection scenario. Moreover, the reduction of sediment and nutrients under three future land use patterns in future climate scenarios was evaluated. The results showed that an appropriate land use change project led to the desired reduction effect on sediment and nutrients output under future climate scenarios. The average reduction rates of sediment, total nitrogen and total phosphorus were 11.4%, 6.3% and 7.4%, respectively. The ecological protection scenario considering spatial configuration showed the best reduction effect on sediment, total nitrogen and total phosphorus. Therefore, the addition of region-specific preference variables as part of land use change provides better pollutant control effects. Overall, this research provides technical support to protect the safety of Beijing’s drinking water and future management of non-point source pollution in MRW.

Highlights

Introduction published maps and institutional affilThe non-point source (NPS) pollution has become the main source of pollution in most of China’s rivers and lakes, causing the deterioration of water quality [1]
Climate change affects the hydrological cycle of the watershed by changing the physical and chemical processes, migration and transformation capacity of pollutants as well as the ability of water bodies to dilute pollutants [3,4], resulting in deteriorating surface water quality and bringing new challenges for the environmental management of watershed [5]
It was found that future changes in the spatial distribution of watershed runoff, sediment, total nitrogen and total phosphorus load in the watershed will differ greatly depending on the evaluation period, emission scenarios and global climate models

Summary

Introduction

Introduction published maps and institutional affilThe non-point source (NPS) pollution has become the main source of pollution in most of China’s rivers and lakes, causing the deterioration of water quality [1]. It is well known that land use and climate change are two essential factors affecting water quality through NPS progress. Climate change affects the hydrological cycle of the watershed by changing the physical and chemical processes, migration and transformation capacity of pollutants as well as the ability of water bodies to dilute pollutants [3,4], resulting in deteriorating surface water quality and bringing new challenges for the environmental management of watershed [5]. Land use as a key factor affecting the properties of the underlying surface which determines the basic parameters of the watershed runoff generation and soil erosion processes [6], has a significant impact on the production and output of pollutants iations

Objectives

Results

Conclusion