都匀市剑江河水环境修复调控方法及效果分析

水生态文明城市建设对水环境承载能力提出了较高要求,都匀市作为全国水生态文明城市建设试点示范市,修复与调控剑江河的水环境成为都匀市水生态文明城市建设的重要课题。为此,采用负荷历时曲线(LDC)法并结合SWAT模型分析了流域各控制单元的污染因子总氮和总磷的承载情况;针对剑江河流域总磷、总氮负荷超标情况,提出了以削减施肥量和优化耕作方式两类生态措施为核心的水环境修复定量调控方案,并分析不同代表年采取这两类生态措施对流域水环境的改善情况。结果表明,在不影响作物产量的前提下,采用削减30%化肥施用量方案时,最高能减少24%的面源污染,且对总磷的削减效果比对总氮的削减效果更为明显;优化耕作措施的调控效果由好到差依次为等高条植>植草水道>等高种植>植被过滤带;同一种调控措施在枯水年的调控效果优于丰水年的调控效果。研究成果对水环境修复调控方案的制定以及水生态文明城市的建设有指导意义。

Water Environment Restoration and Regulation Method and Effect Analysis of Jianjiang River in Duyun City

The construction of water ecological civilization city has put forward a highly requirement on the water and environmental carrying capacity. Duyun City has been selected as one of the demonstration city for this construction. How to restore the overloaded water and environment of the Jianjiang River becomes an important issue for Duyun City. Therefore, load duration curve(LDC) and distributed hydrological model SWAT were employed to investigate the overloaded pollutant status of the total nitrogen (TN) and total phosphorus (TP) in each control unit of the Jianjiang River basin. In order to solve the overloaded TP and TN problem, the quantitative schemes for the restoration of water environmental carrying capacity have been proposed. The schemes are based on two kinds of ecological measures: fertilizer reduction and optimized modes of agricultural cultivations. The effectiveness of the two ecological measures is evaluated on the basis of simulated results in different representative hydrological years. The results show that the maximum pollution reduction efficiency of total nitrogen (TN) and total phosphorus (TP) is about 24% by reduction of 30% fertilizer usages, in which the reduction efficiency of TP was more obvious than that of TN. The optimized cultivation measures in efficiency sequence from large to small are as follows: strip cropping, vegetated waterway, contour farming and plants filter strip. The control effect in dry years is better than that in wet year with a same ecological control measure. The research has guidance significance for formulating water environment regulation measures and construction of water ecological civilization city.