模拟土地利用变化对地下水硝酸盐面源污染影响的研究

发布时间：2017-12-31 05:28

本文关键词：模拟土地利用变化对地下水硝酸盐面源污染影响的研究　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来农业生产过程中,过量的肥料向下渗透污染地下水,地下水中硝酸盐浓度日益增加。特别是我国一些平原地区,农业生产发达、地势平坦、地表径流量小、降雨入渗量高并且地下水埋深浅等特点,导致地下水中硝酸盐含量超标现象尤为突出。本文以地下水开发利用时间早,程度高,具有较完整的水文地质参数资料的德阳市旌阳区作为研究区,基于ArcMap软件平台分析历年土地利用数据并以此开展硝酸盐污染负荷时空估计,建立和校正地下水污染迁移模型,预测不同土地利用变化情景及其对地下水硝酸盐的影响程度,从而揭示土地利用变化在农业面源污染控制方面的功效。研究结果表明:(1)2000年至2016年整个研究区硝酸盐负荷逐年上升并出现明显的区域特征,污染由城区向北演化。德新镇地下水硝酸盐因地下水流向向黄许镇区域迁移,导致黄许镇2010年至2016年污染羽面积增长10倍以上。在城区附近,农业污染负荷低于230 kg/km2,且由于绵远河和石婷江附近地下水补给排泄途径较短,因此有利于地下水中硝酸盐污染迁移稀释,使得城区及城区以南的硝酸盐污染逐渐降低。(2)研究区硝酸盐负荷受季节影响较大,7、8月的大量降雨一方面加快了硝酸盐下渗,另一方面会稀释地下水中硝酸盐含量;9、10月月平均降雨量和月平均硝酸盐负荷都较高,从而进入地下水含水层的硝酸盐含量增加;12、1月,月平均降雨量和月平均硝酸盐负荷较低,进入地下水含水层的硝酸盐含量显著减少;2月施肥负荷量大,但降雨量低,因此淋溶进入含水层的硝酸盐量有限。(3)通过对研究区土地利用变化的综合分析预测,单纯地增长耕地面积会使污染面积进一步扩大,局部地下水硝酸盐浓度将超过20 mg/L。若全区推广测土配方施肥,肥料利用率的提高可以减少农业面源污染负荷,使污染面积显著减少。但总体上来说,部分区域地下水硝酸盐的污染较2016年严重,污染羽面积扩大9.33%。本研究揭示出土地利用变化对地下水硝酸盐面源污染影响伴有很强的时空特征,地下水数值模拟结合ArcGIS空间分析较好地解决了面源污染复杂性和随机性的难题,为控制地下水农业面源污染提供了理论依据。
[Abstract]:In recent years, in the process of agricultural production, excessive fertilizer downward infiltration of contaminated groundwater, increasing nitrate concentration in groundwater. Especially some plain areas in China, agricultural production developed, flat terrain, surface runoff, rainfall infiltration volume and high depth of groundwater, resulting in nitrate content in groundwater is exceed the standard phenomenon prominent. In this paper the groundwater exploitation time early, with a high degree of hydrogeological parameters more complete information Jingyang District of Deyang city as the study area, analysis of ArcMap software platform in land-use data and to carry out the nitrate pollution load estimation based on time and space, the establishment and correction of groundwater pollution migration model, different land use change and forecast effect of nitrate in groundwater level, so as to reveal the effect of land use change in agricultural non-point source pollution control results. Show that: (1) from 2000 to 2016 in the study area of nitrate load increased year by year and the emergence of obvious regional characteristics, pollution from urban evolution. North De Xin Zhen groundwater nitrate because of underground water to Huang Xu Zhen Huang Xu Zhen lead to regional migration, from 2010 to 2016 plume area increased more than 10 times. In the vicinity of the city. Agricultural pollution load is lower than 230 kg/km2, and the Mianyuan River and stone Tingjiang near the groundwater replenishment and drainage way is short, it is beneficial to the migration of dilution of groundwater nitrate pollution, makes the city and the city to the south of nitrate pollution gradually reduced. (2) the study area of nitrate load affected by season, heavy rainfall 7,8 month on the one hand to speed up the nitrate infiltration, on the other hand will dilute the nitrate content in groundwater; 9,10 month average rainfall and monthly average nitrate load is higher, thus entering groundwater nitrate Increased acid salt content; 12,1 months, average monthly rainfall and monthly average nitrate load is low, the content of nitrate into groundwater aquifer was significantly reduced; fertilization in February load, but the low rainfall, so the leaching of nitrate into the amount of aquifer is limited. (3) based on the research of comprehensive analysis to predict the changes of the land the study area, simply increase cultivated area will further expand the area of pollution, local groundwater nitrate concentration will be more than 20 mg/L. if the promotion of soil testing and fertilizer, increase the utilization ratio of fertilizer can reduce agricultural non-point source pollution, the pollution area was significantly reduced. But on the whole, part of the regional groundwater nitrate pollution compared with 2016, serious pollution plume, expand the area of 9.33%. in this study reveal spatial and temporal characteristics of land use change on groundwater nitrate pollution effects associated with strong groundwater, numerical simulation with Arc The GIS spatial analysis solves the problem of the complexity and randomness of non-point source pollution, and provides a theoretical basis for controlling the pollution of groundwater agricultural non-point source.

【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X523

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