未来发展情景选择对农业面源污染风险的影响分析

Impact analysis of the future development scenario on risks from agricultural non-point source pollution

为指导区域未来发展模式选择和农业面源污染(Agricultural non-point source pollution,ANSP)典型区域(涪陵区)风险调控,综合CLUE-S、Markov、GIS、改进的输出风险模型等模型和技术的优势,在ANSP典型区域(涪陵区)以2010、2015年土地利用数据为基础,进行未来2020-2030年的自然发展(ND)和耕地保护(CP)两种情景下的ANSP输出风险演变及对输出系数调整的响应分析。研究发现:涪陵区土地利用数据模拟精度较好,Kappa系数为0.75且FoM大于0.21。涪陵区2010-2030年期间ANSP风险等级明显降低,尤其是靠近大木山、武陵山区域的镇街和子流域。风险等级降低速率减缓明显,ND情景下,清溪镇在2010、2015、2020、2025、2030年各年份Ⅶ以上等级风险比例分别为46.20%、29.69%、25.72%、22.20%、20.00%。子流域输出风险等级对于耕地输出系数(即化肥施用水平)变化具有很好的响应关系。未来的情景模拟有利于探寻区域不同发展情景下输出风险与土地利用变化之间的响应关系,有利于聚焦分析各镇街或某子流域风险变化情况。本研究路径与方法有利于区县对各镇街、子流域未来的ANSP风险进行有效防控。

The results of China′s second national pollution source survey showed that agricultural non-point source pollution(ANSP)is still a main contributor to water pollution.In our analysis,we chose the Fuling District as a typical area of ANSP,based on land use data from 2010 to 2015.Our analysis integrated the advantages of CLUE-S,Markov,GIS,and an improved output risk model.This study analyzes the projected changes of ANSP risk and its response to the adjustment of output coefficients under the two scenarios of natural development(ND)and cultivated land protection(CP)from 2020 to 2030.The purpose of the study is to develop information that may help guide the selection of modes of future regional development and the establishment of polices for ANSP risk reduction.Study accuracy analysis results of the land use simulation show that the Kappa coefficient was 0.75 and the FoM exceeded 0.21,and the degree of preciseness was good.According to the modeled results,the risk of ANSP in the Fuling District decreases significantly from 2010 to 2030,especially in the towns and sub-basins near the Damu and Wuling mountains.However,the rate of risk reduction decreases over time.For example,under the ND scenario,using 5-year intervals from 2010 to 2030,the proportions of GradeⅦor above risk in Qingxi Town was 46.20%,29.69%,25.72%,22.20%,and 20.00%.The risk reduction in the sub-basins demonstrated a good response to the change of the output coefficient in cultivated land(i.e.,the amount of fertilizer application).The simulation of the future scenario was helpful in exploring the response relationship between pollution risk and changing land use under different regional development scenarios.It also revealed the benefit of focusing on analyzing the changes of pollution risks for each of the towns or sub-basins.These results demonstrate that this method is conducive to developing strategies for the effective prevention and control of future ANSP risks in each town and sub-basin.