西安城区绿地雨水下渗特征与影响分析
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摘要
强化雨水入渗是目前海绵城市建设的重要内容之一.本文通过现场实测和计算模拟探讨了西安城区雨水下渗特征,构建以湿陷性黄土层为约束条件的城市绿地渗水地层模型,采用HYDRUS软件模拟分析了西安城区下凹式绿地深度(入渗作用水头)与雨水下渗深度的关系,并分析了雨水在土壤下渗过程中污染物浓度在土壤中的迁移消减变化规律.结果显示,以地下5.0 m处存在湿陷性黄土为约束,25.0 cm入渗水头作用下对应的连续渗水时间为16.6 d,小于西安城区历史连续降雨极限天数(19 d),因此在西安城区进行雨水下渗措施建设必须考虑地质条件的约束;以降雨径流在5.0 cm水头下渗为初始条件,雨水中典型污染物的变化表明,氨氮在土壤以及植物根系作用下基本去除,而COD_(Cr)、总磷和总氮在40～50 cm深度土壤中污染物仍然有很高残存.研究结果为湿陷性黄土地区城市雨水下渗系统和径流面源污染治理了提供依据.
Currently, strengthening rainwater infiltration is one of the important contents of sponge city construction. This paper investigated the infiltration characteristics of Xi′an through field measurement and computer simulation, established the corresponding relationship between green subsurface pit depth and rainwater infiltration depth, constructed a water-infiltrating stratum model of urban green space with the collapsible loess layer as the constraint condition, and analyzed the water head of infiltration in depressed greenland with infiltration depth by using HYDRUS software. The results revealed that the collapsible loess at the depth of 5.0 m underground was the constraint while the time corresponding to the continuous action of the 25.0 cm infiltration head was 16.6 days, which is shorter than the climate history of continues rainfall time(19 days) in Xi′an. Therefore, the construction of rainwater infiltratiosn in Xi′an must take into account the geological conditions of constraint. With the initial condition of the rainfall runoff head infiltration at 5.0 cm, changes in typical pollutants in rainwater showed that ammonia nitrogen in rainwater can be removed easily by soil adsorption and bio-degradation of plant root system. However, CODcr, TP and TN concentration remained high at the depth of 40～50 cm soil. The results provide evidence for construction of urban rainwater infiltration system and runoff non-point source pollution control in the collapsible loess area.
Currently, strengthening rainwater infiltration is one of the important contents of sponge city construction. This paper investigated the infiltration characteristics of Xi′an through field measurement and computer simulation, established the corresponding relationship between green subsurface pit depth and rainwater infiltration depth, constructed a water-infiltrating stratum model of urban green space with the collapsible loess layer as the constraint condition, and analyzed the water head of infiltration in depressed greenland with infiltration depth by using HYDRUS software. The results revealed that the collapsible loess at the depth of 5.0 m underground was the constraint while the time corresponding to the continuous action of the 25.0 cm infiltration head was 16.6 days, which is shorter than the climate history of continues rainfall time(19 days) in Xi′an. Therefore, the construction of rainwater infiltratiosn in Xi′an must take into account the geological conditions of constraint. With the initial condition of the rainfall runoff head infiltration at 5.0 cm, changes in typical pollutants in rainwater showed that ammonia nitrogen in rainwater can be removed easily by soil adsorption and bio-degradation of plant root system. However, CODcr, TP and TN concentration remained high at the depth of 40～50 cm soil. The results provide evidence for construction of urban rainwater infiltration system and runoff non-point source pollution control in the collapsible loess area.
引文
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[8]聂发辉,李田,姚海峰.上海市城市绿地土壤特性及对雨洪削减效应的影响[J].环境污染与防治,2008,30(2):49-52.NIE Fahui,LI Tian,YAO Haifeng.Characteristics of soil samples of five Shanghai urban green areas and their effects on reduction of storm water runoff[J].Environmental Pollution&Control,2008,30(2):49-52
[8]程冬兵.三峡库区等高绿篱坡地农业系统紫色土水分特性研究[D].武汉:华中农业大学,2008.CHEN Dongbing.Study on the Purple Soil water properties Under Control Hedgerow-intercroping System in the three gorges reservoir area[D].Wuhan:Huazhong Agricultural University,2008.
[9]李贵玉.黄土丘陵区不同土地利用类型下土壤入渗性能对比研究[D].西安:西北农林科技大学,2007.LI Guiyu.Comparative study of soil infiltration under different land uses in loess hilly regions[D].Xi′an:Northwest A&F University.2007.
[10]WINZIG G.The concept of storm water infiltration[C].Burghardt W,Dornauf C,eds.//First International conference on soils of Urban,Industrial,Traffic and Mining Areas.Essen,Germany:University of Essen,Areas.,2000:427-433
[11]陆东旭,刘金涛,尚熳廷,等.土壤表面积水深度对入渗的影响[J].干旱地区农业研究,2009,27(1):140-142.LU Dongxu,LIU Jintao,SHANG Manting,et al.Effects of soil surface ponding depth on infiltration[J].Agricultural research in the arid area.2009,27(1):140-142.
[2]陈开圣,彭小平.关中地区黄土的湿陷特性研究[J].水文地质工程地质,2005,32(1):37-40.CHEN Kaisheng,PENG Xiaoping.Study on loess′s collapsibility in the Guanzhong area[J].Hydrogeology Engineering Geology,2005,32(1):37-40.
[3]宋扬,周维博,马聪,等.西安主城区地下水埋深空间变异性分析[J].人民黄河,2015,37(8):56-59.SONG Yang,ZHOU Weibo,MA Cong,et al.Analysis of spatial variability of groundwater depth in Xi′an downtown area[J].Yellow River,2015,37(8):56-59.
[4]杨金玲,张甘霖,袁大刚.南京市城市土壤水分入渗特征[J].应用生态学报,2008,19(2):363-368.YANG Jinling,ZHANG Ganlin,YUAN Dagang.Characteristics of water infiltration in urban soils of Nanjing city[J].Chinese Journal of Applied Ecology,2008,19(2):363-368.
[5]杨清海,吕淑华,李秀艳,等.城市绿地对雨水径流污染物的削减作用[J].华东师范大学学报(自然科学版),2008(2):41-47.YANG Qinghai,LShuhua,LI Xiuyan.Reduction function of runoff contaminants by the urban greenbelt[J].Journal of East China Normal University(Natural Science),2008(2):41-47.
[6]陈晓键,西安城市规划建设中的工程地质环境问题探讨[J].西北大学学报(自然科学版),2003,33(3):325-328.CHEN Xiaojian.The engineering geological problems in city construction and planning[J].Journal of Northwest University(Natural Science Edition),2003,33(3):325-328.
[7]魏俊岭,金友前,郜红建,等.合肥市绿地土壤水分入渗性能研究[J].中国农学通报,2012,28(25):302-307.WEI Jinling,JIN Youqian,GAO Hongjian,et al.Investigation on Soil Water Infiltration in Different Urban Green Lands in Hefei City[J].Chinese Agricultural Science Bulletin,2012,28(25):302-307
[8]聂发辉,李田,姚海峰.上海市城市绿地土壤特性及对雨洪削减效应的影响[J].环境污染与防治,2008,30(2):49-52.NIE Fahui,LI Tian,YAO Haifeng.Characteristics of soil samples of five Shanghai urban green areas and their effects on reduction of storm water runoff[J].Environmental Pollution&Control,2008,30(2):49-52
[8]程冬兵.三峡库区等高绿篱坡地农业系统紫色土水分特性研究[D].武汉:华中农业大学,2008.CHEN Dongbing.Study on the Purple Soil water properties Under Control Hedgerow-intercroping System in the three gorges reservoir area[D].Wuhan:Huazhong Agricultural University,2008.
[9]李贵玉.黄土丘陵区不同土地利用类型下土壤入渗性能对比研究[D].西安:西北农林科技大学,2007.LI Guiyu.Comparative study of soil infiltration under different land uses in loess hilly regions[D].Xi′an:Northwest A&F University.2007.
[10]WINZIG G.The concept of storm water infiltration[C].Burghardt W,Dornauf C,eds.//First International conference on soils of Urban,Industrial,Traffic and Mining Areas.Essen,Germany:University of Essen,Areas.,2000:427-433
[11]陆东旭,刘金涛,尚熳廷,等.土壤表面积水深度对入渗的影响[J].干旱地区农业研究,2009,27(1):140-142.LU Dongxu,LIU Jintao,SHANG Manting,et al.Effects of soil surface ponding depth on infiltration[J].Agricultural research in the arid area.2009,27(1):140-142.