【作者】 张萍；

【导师】 史志华；

【作者基本信息】 华中农业大学 ， 资源环境信息工程， 2008， 硕士

【摘要】 中国是土壤侵蚀最为严重的国家之一。小流域是我国生态环境恢复重建与水土流失综合治理的基本单元,其侵蚀产沙规律及发展趋势预报一直为土壤侵蚀与水土保持学界研究的热点。景观生态学是研究空间格局与生态过程相互关系的科学,对特定的生态过程研究,具有重要的指导作用。在流域产流产沙研究中引入景观生态理论是一个新的研究方法。“源汇”生态过程思想为探讨土地利用格局与土壤流失的关系提供了直接的研究思路。对于水土（养分）流失来说,“源”就是径流、土壤和养分流失的地方。在流域尺度上,目前仅能获得一个流域沟口站的径流和泥沙数据,这些监测数据实际上反映的是一个流域内土地利用空间分布格局对径流和泥沙的影响,如何将这些监测点的数据与流域空间上的土地利用空间分布相联系起来仍旧是一个难点,但又十分重要。本文基于SCS降雨径流模型以及RUSLE模型,引入“源汇”的生态理论,模拟不同降雨条件下流域侵蚀产沙分布情况以及空间的输移。主要结论如下:（1）研究了基于DEM的流域信息提取方法,并对王家桥流域进行信息提取,主要包括DEM的预处理、流向提取、排水网络的确定、河流分段、子流域划分等。（2）根据水文资料,分析不同降雨场次的相关降雨指标,分析其降雨量、I₁₀、I₃₀及降雨动能与流域产沙的关系。结果表明,由于王家桥流域的次降雨量不大,所以降雨量对流域产沙的影响不明显,I₁₀、I₃₀及降雨动能对流域的产沙影响较大。（3）基于“源汇”生态理论,建立了“源汇”景观类型区分的方法与指标体系,提出了基于基本计算单元的“源汇”能力值的函数关系式。探讨不同景观因子（降雨、地形、土壤、土地利用等）条件下流域的侵蚀产流产沙过程,分析产沙分布与土壤侵蚀各因子之间的关系。（4）根据土壤、土地利用等因素确定了王家桥流域的水文土壤组分类,获得了王家桥流域的CN值空间分布,分析了土壤流失的危险性。（5）根据SCS降雨径流模型和“源汇”计算关系式,通过将RUSLE模型修正为次降雨产沙模型,结合GIS技术、计算机编程技术,建立了基于“源汇”景观理论的流域侵蚀产沙模拟模型,该模型能模拟不同降雨条件,不同土地利用,不同土壤条件下的流域产沙情况。（6）根据所建的模型,以王家桥流域为研究区域,研究了不同降雨条件下“源汇”的空间分布,定量地分析了“源汇”能力值的空间分布,模拟了径流和泥沙的空间输移。研究结果表明:模拟的结果与实际值基本吻合,而且该模型结构简单,输入的更多还原

【Abstract】 China is one of the countries, which are facing most serious soil erosion. The small basin is the basic unit for rebuilding or restoring our country’s ecological environment and comprehensively soil erosion. Its regularity of erosive sediment yield and the forecast of develop trend are continuously hot spot in the study field of soil erosion and soil & water conservation . Landscape ecology is a science that studies the relations between spatial pattern and ecological process, and has an important instructive function to the study of specific ecological process. It is a new study method to introduce the theory of landscape ecology to the study of water and sediment yield in the watershed. The thought of "source sink" ecological process provides a direct research mentality to discuss the relations between land use pattern and soil erosion. Regarding the water and soil loss or nutrient loss, "source" is the place where runoff, soil and the nutrient flow out.On the basin scale, we can only obtain the data of runoff and sediment at the ditch mouth at present. In fact these monitoring data reflects the influence of the spatial distribution pattern of land use to the runoff and the silt. How to relate the data of monitoring site with the spatial distribution of land use is still a difficulty, but extremely important.Based on the SCS rainfall-runoff model as well as the RUSLE model, introducing the ecological theory of "source-sink", this article carried out simulations of sediment yield distribution and its transport in the watershed under different rainfalls.The results that our study achieved are as follows:（1） We have studied the method to extract the basin information based on DEM, and carried out information extraction in Wang Jiaqiao watershed. It mainly includes the preparation of DEM, extraction of flow direction, draining network determination, rivers partition, sub-basin division, and so on.（2） According to the hydrological data, we analyzed the related rainfall indexes of different rainfall events, then we analyzed the relation between its precipitation, I₁₀, I₃₀, kinetic energy and sediment yield in the watershed .The result indicated that, because the amount of each rainfall event is not big in the Wang Jiaqiao watershed, its influence to sediment yield in the watershed is not obvious, while the influence of I₁₀, I₃₀ and its kinetic energy to sediment yield is relatively big.（3） Based on the ecological theory of "source-sink", we established a system of method and criterion to discriminate the source landscape and the sink landscape, and proposed functions to calculate the capability of source or sink based on basic computing unit. We also have discussed the yield of runoff and sediment process under different landscape factors condition, rainfall, terrain, soil, land use and so on, analyzed the relation between distribution of sediment yield and various factors of soil erosion.（4） According to the factors of soil, land use, and so on, we had determined the classification of hydro-soil group in Wang Jiaqiao watershed, and then we obtained the spatial distribution of the CN value in our study area, and analyzed the risk of soil erosion accordingly.（5） According to the SCS rainfall-runoff model as well as the relation functions to calculate the source and the sink, through revising the RUSLE model to adapt to rainfall events, combines the technology of GIS and programming, we have established a model to simulate sediment yield in the watershed based on the ecological theory of "source-sink". This model could simulate the sediment yield situation under different rainfall condition, different land use, and different soil condition.（6） According to the established model, taking Wang Jiaqiao watershed as the study area, we have analyzed the spatial distribution of "source-sink" under different rainfall condition, and qualified the spatial distribution of "source-sink" capability, and lastly we simulated the spatial transport of runoff and silt.The result indicated that, the simulation result basically agrees with the actual value, moreover its structure is simple, and its input parameters are relatively few. This model can simulate the process of sediment transport well, even includes the output at each fixed-point.更多还原