Regionalization of Agricultural Nonpoint Source Pollution over China with a Combination of Qualitative and Quantitative Method

Yunqiang Zhu,Shengli Huang,Qiang Fu

doi:10.3390/su12010405

Abstract

Agricultural nonpoint source pollution has been a serious problem in China; however, currently a lack of basic data and quantitative analysis hinders control and reduction of agricultural nonpoint source pollution. Therefore, it is necessary to explore a regionalization method in the study of nationwide agricultural nonpoint source pollution over China. This paper proposes a method of combining both quantitative calculation and qualitative analysis. Based on agricultural nonpoint source pollution mechanism, we first proposed the natural environment index, which was calculated from relief degree of land surface, thermal humidity index, water resources quantity and precipitation index, and land cover index. Second, we proposed basic agricultural environment index, which was calculated based on the area of cultivated land use and the quality of integrated soil fertility. Third, we simplified the spatial distribution of natural environment and basic agricultural environment with the method of choropleth map classification, thematic map series, and gravity centers curve. Fourth, we conducted a qualitative analysis for both the natural environment and basic agricultural environment by overlaying the classification and existing regionalization maps to reveal the intra-region homogeneity and inter-region heterogeneity with a high reliability. The regionalization method used in this study resulted in a nationwide regional zoning of agricultural nonpoint source pollution over China, and China can be divided into 10 regions, which can be a trustworthy reference for agricultural nonpoint source pollution study and management.

Highlights

In recent years, with livestock pollution playing a more and more prominent role in agricultural nonpoint source (NPS) pollution [1], agricultural nonpoint source (NPS) pollution has become a serious problem for water quality management in China [2]
We aimed to explore a solution for nationwide agricultural NPS pollution regionalization over China
Dividing the index into several levels needs a subjective methodology, which could be addressed with choropleth map classification, thematic map series, and gravity centers curve methods

Summary

Introduction

With livestock pollution playing a more and more prominent role in agricultural nonpoint source (NPS) pollution [1], agricultural nonpoint source (NPS) pollution has become a serious problem for water quality management in China [2]. Many studies have focused on agricultural NPS pollution estimation [3], evaluation [4,5,6], and management [7,8,9,10,11], studies on the entirety of China have rarely been carried out This is because when Chinese scholars pay attention to the problem of agricultural NPS pollution, at first, the research area is limited only to the region where agricultural NPS pollution is located [8,9,11]. Under this circumstance, it is necessary to develop an environmental management policy on agricultural NPS pollution on a large scale, including livestock pollution. Developing and applying regional management policies to combat agricultural NPS pollution is necessary, which requires a regionalization map of agricultural nonpoint source pollution

Objectives

Methods

Results

Conclusion