【作者】 杨士娟；

【导师】 冯利华；

【作者基本信息】 浙江师范大学 ， 自然地理学， 2007， 硕士

【摘要】 河川基流量是指河川径流量中由地下水渗透补给河水的部分,是枯水期河川径流量的主要补给来源,维持河川基流量对河道生态环境保护至关重要。基流分割就是将地下径流从总径流中分割出来,进而确定各种径流成分的比例。基流分割是流域水文分析和区域水资源评价中常遇到的问题,但由于它涉及到气候、自然地理、水文地质等科学,因此与其它水文水资源分析技术相比,它的进展和突破难度很大。因为直接径流和地下径流这两个组成部分的定义是比较任意的,分割方法同样存在人为性和任意性,重要的是在整个分割过程中方法要保持一致。基流分割的方法有很多种,在众多的分割方法之中,直线斜割法成果相对可靠,也是技术细则中要求采用的方法,本文采用的分割方法就是直线斜割法,并且在直线斜割的基础上借助了AutoCAD的一些绘图功能,利用AutoCAD自动生成径流曲线和计算分割面积,成果能够更加客观地反映基流变化趋势且人为性较小,工作快速高效,使得切割结果更加接近实际情况。无定河流域是黄河中游水土流失最为严重的一条支流,该流域全年干旱少雨,基流是该流域非汛期河川径流主要补给来源,基流在无定河流域占有较大比例,基流的变化严重影响流域经济的发展和流域的生态环境。探索流域的基流变化对研究流域水循环有重要的意义。本文选取无定河流域为研究区域,应用直线斜割法并借助AutoCAD的一些功能对无定河流域的径流过程进行分割,求其基流量,并对基流变化和特性进行分析,主要研究内容和成果如下:(1)选取无定河流域11个代表性水文站(曹坪、殿市、韩家峁、横山、丁家沟、李家河、马湖峪、青阳岔、绥德、白家川、赵石窑),对现有的数据资料进行分析和校对之后,选取了符合要求的代表年份作为研究资料。(2)本次基流分割采用直线斜割法,并借助AutoCAD的一些绘图功能,分别对11个代表性水文站进行基流分割。(3)依据各个代表性水文站基流分割数据,分析基流变化及其影响因素,结果表明:①基流在无定河流域占有较大比例无定河流域按照地貌特点可以分为风沙区、河源涧区和黄土丘陵沟壑区三个地区,基流在这三个区内都占有较大的比例。②整个流域内基流呈显著减少的趋势近年来由于气候和人类活动的影响,整个流域的基流都在减少,风沙区基流减少更是十分明显。基流的减少必将影响整个流域水资源的分析和利用,因此要加强这个流域基流变化的研究。③无定河流域基流量和流域的下垫面的构造有关基流量的大小一方面取决于下垫面的地表组成和入渗状况,如土壤成分、坡面比降、地表植被等;另一方面还取决于地下不透水层的走向地、质构造及地域水源补给等。它是一个更大范围更深层更长期的汇流过程,因而不同地貌地区基流量是不同的,在无定河流域风沙区内基流量所占总径流量的比例较大,而河源涧和黄土丘陵沟壑区基流所占径流的比例相对小一些。更多还原

【Abstract】 River base flow is the replenishing part which is the infiltration of groundwater, and it is a primary source of stream flow in the drought period. To maintain a certain amount of base flow plays a crucial part in the riverway ecological protecting. Base flow separation means to separate the underground stream flow from its total flow, thereby to ascertain the ratio of the components in various stream flows. Base flow separation is often encountered in hydrological analysis and in the evaluation of regional water resources. But since it relates to climate, physical geography, and hydrogeology and so on, it is very difficult to break through compared with other technical analysis of hydrological water resources. Now that the definitions of direct stream flow and groundwater stream flow are quite arbitrary, separation methods also have the traits of artificial and arbitrary, while the consistence of methods in the whole separation process is of a great importance.There are a variety of ways of base flow separation. Among these segmentation methods, beeline separation is not only relatively reliable, but also requested in technical details, and it is the very separation method used in this paper. On the basis of the beeline separation, some AutoCAD drawing functions are also employed. Automatically generating stream flow curves and calculating as well as separating the area with AutoCAD, the findings could be more objectively reflecting the trends of changes of the base flow with little artificial work. It functions quickly and efficiently, making the results of separation more close to the actual situation.The Wuding River basin is the most serious branch in the middle of Yellow River valley in water and soil erosion. It is drought all the year. Base flow, accounting for a large proportion in the Wuding River Basin, is the main supply of the stream flow in the non-flood season. The change of the base flow will significantly affect the economic development and the ecological environment of the basin area. Exploring the change of the base flow has a great significance in studying the water cycling in the basin area. This paper takes the Wuding River Basin as the studying region, applying beeline separation method and the AutoCAD to the separation of the stream flow in Wuding River basin to obtain the base flow capacity and analyzing the changes and characteristics of base flow. The major studying contents and findings are as follows:(1) 11 representative hydrological stations in Wuding River Valley (Cao Ping, Dian City, the Han’s Hilly, Yokoyama, the Ding’s Canal, the Li’s River, Ma Lake Valley, Qingyang Fork, Suide, the Bai’s River, and Zhaoshiyao) are selected. After analyzing and proof-reading the existing data, representative years which meet the requirements are selected as research datas.(2) Beeline Separating method is employed in this base flow separation, and with some drawing functions of AutoCAD, 11 representative hydrological stations are conducted base flow separation.(3) Analyzing the changes of the base flow and the reflecting factors according to the base flow separation data of every representative hydrological station. The findings suggest:①Baseflow accounts for a large proportion in Wuding River Basin.According to the features of landscape, Wuding River Valley can be divided into three districts: sandstorm district, riverhead gully, and loess plateau district. Baseflow takes a large proportion in all the three districts.②Every tributary throughout the watershed was significantly decreasing basically.In recent years, due to the impact of climate and human activities, the baseflows in the whole valley are declining, especially in the sandstorm area. The reduction of the baseflow will affect the analysis and use of water resources in the entire basin. So to strengthen the study of baseflow changes in the watershed is needed.③Base rate of flow in Wuding River basin is relevant to the structure of the underlying surface.On the one hand, the size of base rate of flow depends on the surface composition and surface infiltration conditions, such as soil composition, slope gradient, surface vegetation and so on, and on the other hand, it depends on the direction and geographical structure of underground impermeable layer, as well as the water supplies and others. It is a convergence process of greater scope and more profound longer-term. So the flow of areas with different landscape is different. The base flow accounts for a larger ratio in sandstorm areas of WuDing River Valley, and smaller in riverhead gully district and the loess plateau district.更多还原