【作者】 张钰娴；

【导师】 穆兴民； 王飞；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2009， 博士

【摘要】 近些年来,渭河下游水沙问题日渐复杂和突出,河道淤积严重,水患频发,严重影响到渭河健康发展,并直接威胁到下游地区人民生命和财产安全,渭河下游已经成为社会广泛关注和研究的热点地区之一。渭河及其支流上游土壤侵蚀严重、三门峡水库抬高渭河河口水位导致泥沙下泻不畅、河道水资源利用过度和全球气候变化导致的降水减少等是引起和加剧渭河下游水沙矛盾的主要原因。作为黄河最大的支流,渭河中下游地区水资源与水环境特征不仅直接决定着陕西自然、经济和社会的发展,也直接影响着黄河及其中下游地区的可持续发展,亟需进行水沙调控,缓解下游水沙矛盾。建立渭河水沙综合调控体系,是解决渭河下游水沙问题的根本。由于水土保持可从源头上减少土壤侵蚀和河流泥沙,不同措施减少单位泥沙量时对径流量的影响程度(减流减沙比)存在差异,通过水土保持措施类型和区域配置,可以实现以减沙、增流和调节水沙过程为核心的河流水沙调控。由于不同区域径流量和入河泥沙量对渭河水沙贡献程度不同,通过分析渭河流域产水产沙区域分异特征,既可以促进对渭河流域产水产沙格局的认识,也可以为渭河流域水土保持措施布设提供科学依据。本文以渭河流域28个主要水文站1971年~1986年实测降雨、径流和泥沙系列资料,通过统计分析和现场调查相结合的方法,运用水文学、土壤学等理论基础,借助于地理信息系统等新方法,进行渭河流域产水产沙区划分,并分析了渭河流域产水产沙区域分异特征,主要结论如下。(1)渭河流域水文分区、侵蚀分区:根据流域地形地貌、气候、植被、水文并结合水文站特征,分别以年降水量、径流深、产流模数、径流系数为水文分区指标体系,以年降水量、产沙模数、地面坡度、流域比降、沟壑密度为侵蚀分区指标体系;通过模糊聚类分析法将渭河流域划分为3个一级水文分区,11个二级水文分区,3个一级侵蚀分区和13个二级侵蚀分区。(2)渭河流域产水产沙模型及其适宜性评价:根据研究目的,选择SCS径流曲线数模型作为研究区产水模型,通过对不同水文区降雨产生的径流量进行模拟,表明SCS模型能够较好的模拟渭河流域的产流特征。以降雨量作为降雨因子的量化指标,以地面坡度、沟壑密度、植被净初级生产力等指标作为流域下垫面总体特征的量化指标,输沙模数作为侵蚀产沙指标,建立了渭河流域不同侵蚀分区输沙模数与降雨量和下垫面总体特征之间的回归模型,作为渭河流域不同侵蚀分区侵蚀产沙预报模型,通过对不同侵蚀分区输沙模数模拟,表明该模型能够较好的模拟渭河地区的侵蚀产沙情况。(3)渭河流域产水产沙区的划分:运用“水文-地貌”法,借助于RACGIS9.0将渭河流域划分为280个产沙区和46个产水区。进一步分析表明渭河流域产流中心集中在渭河下游及渭河南山支流诸流域。流域产水呈现明显的地带性特征,即从北到南,产水过程呈现从小到大—变小—增大的过程,其中位于渭河流域西北部(洪德以上)流域,产流模数最小,其产流模数<1.0万m3/km2·a,位于渭河下游的流域,尤其是渭河以南流域,产流模数最大,产流模数>20.0万m3/km2·a。渭河流域产沙亦呈现明显的地带性特征,即从北到南,侵蚀产沙强度呈现从小到大—变小的过程,其中位于渭河流域西北部(洪德以上)流域,北洛河流域刘家河以下、渭河(支流)下游产沙模数最小,其产沙模数<1000t/km2·a。泾河流域雨落坪、杨家坪以上至洪德区间、渭河(支流)天水以上、北洛河流域刘家河以上,产沙模数最大,其产沙模数>5000t/km2·a,是渭河流域侵蚀产沙中心。(4)流域产水产沙区域分异规律:结果表明渭河流域年均产流强度5.37万m3/km2·a,年产流量74.43亿m3,其中北洛河状头以上产流强度4.71万m3/km2·a,泾河张家山以上产流强度3.76万m3/km2·a,渭河(支流)华县以上产流强度7.64万m3/km2·a。单位面积产流贡献率北洛河流域最小,为21.48%,渭河(支流)最大,为52.64%,泾河流域次之,为25.89%。渭河流域年均侵蚀强度为2796.03t/km2·a,年产沙总量33063.79万t。其中北洛河状头以上侵蚀强度2888.48t/km2·a,泾河张家山以上侵蚀强度3225.85t/km2·a,渭河(支流)华县以上侵蚀强度2273.78t/km2·a。单位面积产沙贡献率北洛河流域最小,为22.3%,泾河流域最大,为45.58%,渭河(支流)次之,为32.13%。更多还原

【Abstract】 As the largest tributary of the Yellow River, the Wei River is the ’Mother River’ of Guanzhong region in Shaanxi province. It plays a very important role in the development of West China and the health of the ecosystem of the Yellow River. Runoff and sediment problem has been complicated in the downstream area of the Wei River Basin in the last several decades because of the Sanmen reservoir that rising the outlet water level, the excessive demand of the channel water resources and the precipitation reduction caused by the global climate change, and so on. The severe sedimentation and the frequent flood do not only affect seriously the Wei River healthy development, but threaten directly the people life and the property security of its lower reaches area. Therefore the Wei River already becomes one of the hot spot areas drawing wide social and study attention.The integrated management including of the runoff and sediment regular is the key method to solve the runoff and sediment problems of the whole Wei River. Soil and water conservation may reduce soil erosion on the slope and sediment load of the river that would alleviate the sedimentation and the water to flush the sediment into lower stream of the river; furthermore, the water cost of sediment control (the ratio of runoff reduced and sediment reduced in the same time) of different soil and water conservation practices varied greatly that water or runoff would increase when reducing the same weight of sediment through the distribution of different practices of water and soil conservation in different region of the basin. It is necessary to study the regional difference of the runoff and sediment yield rate and contribution of each units for better understanding of runoff and sediment yield pattern in the Wei River basin, and the results would also be scientific reference of river basin management and soil and water conservation planning in the Wei River basin.The dataset covers precipitation, runoff and sediment of 28 main hydrology stations from 1971 to1986, DEM with 90 meter resolution and vegetation are used to study the runoff and sediment yield and to divide the whole basin into different runoff and sediment generation units with GIS. The regional difference of runoff and sediment are analyzed. The main results are as following.(1) Hydrology regions and erosion sub-regions in the Wei River basin Based on the distribution of existing hydrology observation stations, topography, climate, vegetation, river system characteristic, the different indicator systems are selected to divide the hydrology and soil erosion sub-regions in the Wei River basin. The indicators for hydrology sub-regions include mean annual precipitation, runoff depth, runoff yield rate, runoff coefficient,and soil erosion sub-regions division using mean annual precipitation, sediment modulus, ground slope, mean drop slope and drainage density. With the fuzzy clustering analysis, the Wei River basin would be divided 3 one level of hydrology regions, and 11 two level of hydrology sub-regions, and then 3 one level of erosion regions and 13 two level of erosion sub-regions in the Wei River basin respectively.(2)Runoff and sediment simulation models and their suitability in the Wei River basinSCS-CN (runoff curve model of Soil Conservation Service, USDA) model is selected to simulate runoff in different hydrology sub-regions in the Wei River basin. The simulation shows that results of 20 of rainfall events, accounting for the total rainfall simulation 83%, are good and the SCS-CN model could be used to simulate the runoff in the Wei River basin.Mean annual precipitation P selected take as quantitative index of rainfall factors, ground slope, drainage density and NPP (Net Primary Pproductivity) are selected as variables of land surface in the Wei River basin, and the statistics model of sediment yield rate are regressed in different erosion and sediment regions. The model were tested with 28 field actual sediment data and 24 of field simulation results were good that the regression model could simulate sediment yields very well in the Wei River basin.(3) Unit of Runoff and Sediment production Divided in the Wei River basinThere are 46 runoff yield units of and 280 sediment yield units in the Wei River basin when using“hydrology- landform”composition and ARC GIS 9.0.Centralization of runoff was distributed to the lower Wei River and some branches of nanshan areas. Runoff production shows clearly zonal features, that is, from north to south, runoff process shows from small to large - smaller - larger process. Runoff yield rate of the northeast region located in the Wei River basin (above the Hongde stations) was the smallest, its produces yield rate runoff were less than 10,000 m3/km2·a. Runoff yield rate of the south region located in the Wei River basin, especially the south Wei River, was the biggest, its produces yield rate runoff were more than 200,000m3/km2·a.Sediment yield shows clearly zonal features slso, that is, from north to south, Sediment yield shows from small to large - smaller - larger process. Sediment yield rate of the northeast region located in the Wei River basin (above the Hongde stations), beiluo river catchment (below the liujiahe stations) was the smallest, its sediment yield rate was less than 1,000 t/km2·a. But between yangjiaping station,yuluoping station and hongde station in the jing river catchment, above of tianshui station in the main stream weihe catchment, above of liujiahe station in the beiluo river catchment were the biggest, its sediment yield rate was more than 5,000 t /km2·a.(4) Regional different of runoff and sediment in the Weihe River BasinThe annual mean runoff yield rate was equal to 53,700 m3/km2a, the annual runoff was 7,443,000,000 m3 in the Wei River basin. Runoff yield rate of about zhuangtou station in the beiluo river catchment was 47,100 m3/km2a, for 11.38% of the total output. Runoff yield rate of about zhangjiashan station in the jing river catchment was 37,600 m3/km2a, for 21.89% of the total output. Runoff yield rate of about huaxian station in the main stream of weihe catchment was 76,400 m3/km2a, for 66.73% of the total output. Contribution rate of runoff displayed that the beiluo river is the smallest, the main stream of weihe is the biggest, and the jing river is the next biggest. Its values were respectively 21.48%, 52.64%, 25.89%.The average annual erosion intensity in the Wei basin was 2796.03t/km2·a, and the total amount of annual sediment yield was 330,637,900 t; at the above of zhuangtou station in the beiluo river basin, which sediment yield yield rate was 2888.48t/km2·a, the total amount of annual sediment yield was 42,882,300t, for 12.97%; at the above of zhangjiashan station in the jing river catchment, which sediment yield yield rate was 3225.85t/km2·a, the total amount of annual sediment yield was 139,898,600 t, for 42.31%; at the above of huaxian station in the main stream of weihe catchment, which sediment yield yield rate was 2273.78t/km2·a, the total amount of annual sediment yield was 147,857,000 t, for 44.72%.The contribution rate of sediment yield per unit area was the smallest in beiluo river basin, for 22.3 percent, and jing river basin was the largest for 45.58 percent, followed by the main stream of the weihe basin for 32.13%, which further clarified the major regional of sediment yield was concentrated in the jing river watershed and the main stream of the weihe, for more than 77%.更多还原