【作者】 田世英；

【导师】 罗纨；

【作者基本信息】 西安理工大学 ， 水文学及水资源， 2007， 硕士

【摘要】 湿地水文研究是湿地科学的重要分支,是进行湿地保护和恢复的基础。对于河边湿地这一特殊的湿地类型来说,其水文特征在受到天然降水影响的同时,河道对其水文特征的影响往往更为重要。一般来讲,河道对河边湿地水文的影响主要有地表水和地下水交换两种方式。本文在借鉴国内外河边湿地水文研究成果的基础上,以西安泾渭河边湿地为例,研究探讨了渭河对泾渭河边湿地水文的影响。首先根据历史水文资料,统计分析了1950年以来泾渭河边湿地漫滩洪水变化的规律,初步分析了引起变化的原因;接着利用MODFLOW模型就不同因素对河流与地下水相互作用所产生的影响展开了讨论与分析;最后针对泾渭湿地的实际情况分析了漫滩洪水在泾渭湿地水文恢复中的重要性,并对泾渭湿地在平水年中各月的水平衡要素以及不同水文年的水平衡要素进行了分析,取得了如下的研究成果;1)渭河漫滩洪水发生的次数、出现和持续的时间都发生了很大的变化。具体表现在: 1)泾渭湿地的淹没次数总体上处于减小的趋势,90年代以来减小幅度最大,相对与60年代减幅达到了80%以上;2)淹没持续时间在总体上也处于减小趋势;3)淹没出现时间发生了不少变化, 5、6月淹没次数的减少对于湿地植被的生长影响最大;4)降水量的变化是引起水文条件发生变化的主要因素,但是水利工程的建设加剧了干旱年份对湿地水文的不利影响,延长了干旱的影响时间。2)洪水的变化过程和持续时间以及河床的渗透系数和蒸发强度变化对河水与地下水之间的交换速度及大小都产生了较大的影响;河滩地渗透系数的变化对河道水位变化的影响范围较为明显;3)漫滩洪水是泾渭河边湿地水文形成的主要驱动力,河道通过地下水的补给只能对距离河道不足400米的范围产生明显的影响;4)包括漫滩洪水和天然降水在内的地表补给是泾渭河边湿地主要的水源补给形式,占到了总水源的60%左右,河道的地下水补给十分有限,只占到30%以下;湿地的水源排泄以蒸散发为主,占到了60%以上;年内各月的水平衡要素所占比例发生较大的变化时,不同水文年的年水平衡组成比例也发生了很大的变化。更多还原

【Abstract】 Research on wetland hydrology is the prerequisite for wetland protection and restoration. It is one of the most important branches of wetland scicncc.The ripafian wetland is a special type of wetlands because of its geographical location.The hydrology of reparian wetlands is affected not only by precipation,but also by interactions between fiver and the floodplain. Generally speaking,there are two types of interactions that include surface connection and subsurface connection.These connections are linked by over-bank flooding and groundwater water exchange.Taking the Jingwei riparian wetland for example,this research studied the effect of the Wei River on the hydrology of the Jingwei wetland.First,statistical analisis was performed on the variation of the over-bank floods and the cause of change was postulated based on historical records of hydrological data.The hydrology model-MODFLOW was then used to study groungwater interactions between river and the riparian wetland.Last,the importance of over-bank flood on restoration of the Jingwei wetland was studied from the pointview of monthly water banlance of different hydrological year.Major findings of this research are as follows:1)The number of annual over-bank flooding reduced sharply from 1950s to 1990s by 80%. The duration of over-bank flooding,which is mainly controlled by precipation and shapes of the river cross section , declined slightly between 1950 and 2000 . The number of floodingoccurrence has decreased,and the decrease in May and June has the most impact on growth of wetland vegetation.The reduced precipation has major impact on hydrological change of the wetland,and construction of hydraulic projects enhanced such impact by prolonging the duration of drought period.2)The changes in flooding process,duration,river bed hydraulic conductivity and evaporation rate have great impact on the interactions between river and groundwater.The hydraulic conductivity of the floodplain has significant impact on the range of river stage influence.3)The over-bank flooding is the major driving force of the Jingwei wetland hydrology. Groundwater recharge from the Wei River could affect wetness of the reparian wetland within a range of 400m from the river.4)The surface recharge,including over-bank floods and precipation,is the main water sourcefor the Jingwei riparian wetland. It consists of about 60% of the total water supply to the wetland. The effect of groundwater recharge from river is limited,taking part of no more than 30%of the total water supply.The main discharge of the Jingwei riparian wetland is through ET,which is about more than 60%of its total water loss.The annual water balance components change greatly with the large variation of monthly hydrologic factors.更多还原