【作者】 杨启红；

【导师】 陈丽华； 张富；

【作者基本信息】 北京林业大学 ， 生态环境工程， 2009， 博士

【摘要】 黄土高原水资源短缺,生态环境脆弱,特别是土壤侵蚀不断加剧,恶化了区域生态环境,严重制约了社会、经济的发展。目前,随着大规模水土保持生态建设,研究黄土高原区流域径流泥沙与土地利用变化和沟道工程建设的协同变化规律,对于该区土地利用规划和管理及生态环境建设工程具有重要理论参考意义。本论文以黄土高原丘陵沟壑区——甘肃省定西市安家沟流域为研究对象,基于1987年、1997年、2007年3期土地利用数据和1986-2007年22年气候、水文资料,以定性描述与定量分析相结合的方法,运用GIS&RS、数理统计分析、水文模型模拟等技术,对安家沟流域土地利用变化对径流泥沙的作用进行了分析与模拟,同时对不同水土保持措施的拦沙蓄水作用进行了研究。结论如下:流域降水年际分布不均,多年平均降水量414.4mm,以2003年降水最多,为536.5mm,最少的1997年,仅为312.8mm;流域降水年内分布以6-9月居多,其中7、8月的降水量占年降水量的61.16%。流域降水空间分布不均,面离差系数Cv值平均为0.35。不同的降水水平年,各类型暴雨发生的频率不同,A、B类型暴雨以平、丰水年发生频率较高,C类型暴雨丰水年发生频率较高。径流小区和流域两种不同尺度下,降雨因子和土壤侵蚀的相关性随着研究尺度的变化,K_e、EI30、降雨量、平均雨强等降雨因子与侵蚀的相关性大小也变化;降雨动能K_e在各尺度相关性都较好。采用流域内3个雨量站的降雨动能数据,通过空间插值建立流域1988-1997年以及1998-2007年两期的降雨动能场,利用USLE方程计算流域内各处的侵蚀模数,结果表明:侵蚀模数最大的区域出现在流域南部马家岔,而沟口地区,地形相对平缓,近几年又很好地实施了退耕还林(草)等工程,侵蚀模数较小。SWAT模型应用于安家沟流域时,径流模拟效果好于泥沙,年径流相关系数为86.1%,Nash-Suttcliffe系数为0.79,年输沙相关系数为70.5%,Nash-Suttcliffe系数为0.62。年际尺度模拟计算结果比月尺度理想,其次是丰水季节各月的径流模拟,再次是泥沙月尺度模拟。在SWAT模型的模拟基础上,分析了流域在1987、1997和2007三年的径流、泥沙的空间分布特征以及不同土地利用类型对侵蚀产沙的影响。结果表明:降雨和土地利用变化对径流、泥沙产生了较大的影响,年内降雨较多的月份,产生的径流和泥沙量也较大;随着坡耕地面积的减少和林地面积的增加,径流、泥沙量逐渐减少。利用构建好的SWAT模型,采用固定一个因子(气候或土地利用变化)的方法,区分了土地利用与气候变化因子对径流和泥沙的影响程度。降雨情景模拟的结果表明:在土地利用相同的情景下,径流在汛期受降雨量的影响,变化幅度较大;在枯水期,基本无径流,不受降雨的影响;泥沙量的变化随径流量变化而变化,集中降雨产生的径流挟持大量的泥沙,以7、8月份的产沙量最大,平均占年产沙量的60%左右,其变化幅度大于径流量。土地覆被情景模拟的结果表明:当植被覆盖度大于80%以后,继续增加植被覆盖度,其减沙率变化明显下降;随林草植被盖度从100%、80%、50%、20%到裸地不断减少,汛期产沙所占年产沙量的比例增加,其产沙量占年产沙量的比例分别为73.37%、75.07%、85.27%、87.34%、90.80%。黄土高原水土保持措施情景模拟结果表明:淤地坝在枯水年径流拦蓄率较高,在所有措施量(梯田、林草和淤地坝)中,淤地坝面积最小,但是拦减泥沙最多。通过SWAT模型和水保法对水土保持措施调控作用进行了研究,并修正了水保法中的坡面措施指标,确定了安家沟流域梯田拦沙系数为0.80,林草拦沙系数为0.52。就安家沟这样一个干旱缺水的流域而言,在防止水土流失的前提下,实行“退耕还林还草”政策应遵循“适地适树、适地适草”的原则,并适当考虑从增加流域产水量的角度来进行植被建设规划,在保持林草面积的前提下,加强退耕还林(草)措施的质量管理。更多还原

【Abstract】 Loess Plateau with heavily soil erosion is limited in water resources and sensitive to hydrological environment,especially,this fragile ecological environment has a deep affect on the harmonious development of social economy,natural resources and eco-environment.At Present,many of massive ecological constructions aimed at soil and water conservation have been executed.Research on typical watershed sedment and runoff and their synergistic changes based on land use change（LUCC） and the building of gully engineerings.It has an important theoretical significance of land use planning and management and environmental constructions in Loess Plateau.This thesis was carried out in Anjiagou watershed in loess hilly-gully region.Based on the methods of GIS&RS technical,landscape ecology,systemic hydrological observation,and the information data of land use of 1987,1997 and 2007,hydrology and meteorology,mathematical statistic methods and so on,this thesis analyzed the land use change and its driving force system,the different heterogeneities of precipitation distribution,and deeply studied the the dynamics response of land use change to sediment and runoff in typical watershed in Loess Plateau.And we studied the benefit of different water and soil conservation measure to block the sand.The conclusions are as follows:In the basin,The inter-annual rainfall distribution of the Basin is uneven,multi-year average precipitation is 414.4mm,the maximum precipitation in 2003 is 536.5 mm,the lowest precipitation in 1997 is only 312.8mm;the distribution of precipitation in the basin during the year is June to September, and the precipitation in July and August accounted for 61.16%of the annual rainfall.the spatial distribution of precipitation is Uneven,surface deviation Cv value of the average coefficient is 0.56. In Different precipitation level year,the frequency of various types of heavy rains are different,the frequency of type A,B heavy rain in normal rain year and in wet years are higher,and the frequency of type C heavy rain in wet year is higherBy the analysis of the correlation of erosion and rainfall factor,the results show that the correlation of erosion and rainfall factor tchanges together,such as k_e,EI₃₀,p,andⅠ,under the conditions of different scales.The correlation of rainfall kinetic energy Ke and erosion is better in all scales.On the basis of three rainfall stations Formation of rainfall kinetic energy data,spatial interpolation through the establishment of Anjiagou Basin in 1987-1997 and 1998-2007 rainfall kinetic energy of the two courts, USLE equation was used to calculate the erosion modulus of the basin,The max-relativity region of rainfall kinetic energy and sediment of opening of the basin is the vicinity of the middle reaches in the basin,gully erosion and sediment yield in the basin occupies an important position,and in opening basin areas,the terrain is relatively flat,especially in recent years,a very good returning farmland to forest（grassland） projects has implemented,so erosion modulus is also smaller,and it is not sensitive to rainfall erosivity.According to the simulated results by SWAT model on the base of yearly step,the simulated mean annually runoff has the best veracity,a correlation coefficient of annual runoff is 86.1%, Nash-Suttcliffe coefficient is 0.79;a correlation coefficient of annual sediment is 70.5%,Nash-Suttcliffe coefficient is 0.62;the veracity of simulated value in yearly step is better than that in monthly step.The veracity of monthly simulated value in rainy season is better than that in dry season.The simulated mean monthly sediment has not good veracity;Three different land cover of 1987,1997 and 2007,land use change scenarios of the basin were simulated with SWAT model,the results show that:Rainfall and land-use change had a great impact on runoff and sediment;The Month of the year with more rainfall,larger amount runoff and sediment was produced.The main land use change in the watershed is the reduction of slop land and forestland area increased,the corresponding changes in hydrological is the reduction of runoff and sediment.by using the method of fixed-a factor（climate or land-use change）,contribution affection of land use and climate change to runoff and sediment were obtained.The rainfall scene scenarios result indicated that:with same land use,in rainy season,along with reduction of the rainfall amount,the runoff is influenced by rains,it’s variation is large;in the dry season,the runoff does not exist,the runoff is not influenced by rains;the sediment changes along with runoff change,the runoff produced by the centralism rainfall hold massive sands,it produces large amount of sand in July and August,which occupies 60%yearly produces,the variation is larger than the amount of runoff.Therefore,we can see rainfall factor and produces primary influence on runoff and the sand t,and the influence to the silt is bigger than to the runoff.The land use scene scenarios result indicated that the runoff and sediment change scope is declining,when land use occupied 80%area in the basin.With the vegetation cover decreasing from 100%,80%,50%,20%to bare land,the runoff is rising in rainy season,the percent is 73.37%,75.07%,85.27%,87.34%and 90.80%.The scene of Loess Plateau conservation measure of water and soil result indicated that runoff control rate of the silt dam is higher in dry year,in all measures（terraced field,forest and grass,silt dam）,it’s area is smallest,but it reduces most of the sediment.The theses calculates various single items measure using experience way and SWAT model,and the block sand coefficient of the territory terraced field is modified as 0.80;the blocks the sand coefficient of grass and forest land is modified as 0.52.As for the Anjiagou basin which is such an arid water basin,the ecological construction projects on the Basin should be considered on the point of increasing water yield of the basin.Converting farmland for grassland should be emphasized based on containing the status of certain quantity and quality forestland.更多还原