黄土丘陵区典型流域植被与水沙变化响应关系模型比较研究

发布时间：2018-05-02 13:05

本文选题：延河流域 + RUSLE模型　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：植被是影响土壤侵蚀重要因素,定量分析植被的水土保持作用,有利于准确评估植被的水土保持作用,对区域生态环境恢复重建工作具有重要意义。随着流域水文模拟技术的发展,水文模型成为流域水文管理的有效手段。不同的模型有各自的侧重点,采用不同的模型在同一流域进行水文模拟最终产生的结果也不尽相同。如何来区别模型间的差异?如何因地制宜地选择模型?是需要解决的问题。鉴于此,本研究在土壤侵蚀最为严重的地区黄土丘陵沟壑区,选择典型流域延河流域为研究对象,分析了流域1970—2010年间的水沙变化特征及其与降雨的关系;分析了植被变化特征及其与水沙的关系;采用Revised Universal Soil Loss Equation(RUSLE)模型和Morgan Morgan Finery(MMF)模型对流域内不同时期典型年的土壤侵蚀进行了模拟,评价了两个模型的准确性和适用性。研究取得结论如下:(1)延河流域的径流量、输沙量在近40年内发生了明显的阶段性变化。延河径流、输沙量的变化趋势的突变点年份发生在1996年。1970-1996年为波动上升期,1996年以后延河流域的径流量、输沙量呈明显的下降趋势。(2)延河流域的植被发生了显著变化。从1978年到2010年,耕地面积不断下降,林草面积持续增长,耕地面积由5248.63km2减少到1217.13km2,林草地由1854.35km2增加到6281.45km2,同时林地和草地之间呈现出此消彼长的现象。流域内增加的林草植被多是由退耕地或撂荒地转化而来的,流域整体植被变化趋势特征与90年代初的林权制度改革、2000年前后实施大规模退耕还林还草等研究区内发生的重大历史事件产生的影响相符。(3)基于RUSLE模型对延河流域的土壤侵蚀进行了模拟。1978年、2010年的平均土壤侵蚀模数分别为4434.7 t/(km2·a)、1026.7 t/(km2·a),后者较前者土壤侵蚀模数约减少76.8%;流域东南部林区和较为平坦的沟道两侧的土壤侵蚀强度均较低,而西北部草原区和零星分布的耕地区的土壤侵蚀强度则较高。考虑淤地坝拦沙情况下,1978年、2010年的模拟输沙量与实测值之间相对误差分别为-3%、36%,淤地坝在流域水土保持中起着重要的拦沙效益。(4)基于MMF模型对延河流域的土壤侵蚀进行了模拟。1978年、2010年的输沙量模拟值分别为3691×104 t、2586×104 t,经修正后输沙量分别为2506×104 t、868×104 t,相对误差分别为-29%、49%。2010年模拟径流量为1978年模拟径流量的56.7%,而其输沙量仅为1978年的16.5%。(5)对RUSLE模型和MMF模型两个模型进行了一系列的比较和评估。MMF模型比RUSLE模型能更好的描述土壤侵蚀的物理过程;MMF模型更为复杂,模型的建模较RUSLE模型更为不易;考虑淤地坝拦蓄作用修正时RUSLE模型的模拟精度相对于MMF模型而言较好。
[Abstract]:Vegetation is an important factor affecting soil erosion. The quantitative analysis of soil and water conservation of vegetation is beneficial to the accurate assessment of soil and water conservation of vegetation and is of great significance to the restoration and reconstruction of regional ecological environment. With the development of watershed hydrological simulation technology, hydrological model has become an effective method for watershed hydrological management. Different models have their own emphases, and the results of hydrological simulation in the same watershed by different models are different. How to distinguish the differences between models? How to choose the model according to local conditions? It is a problem that needs to be solved. In view of this, in the loess hilly and gully region where soil erosion is the most serious, the Yanhe River Basin, a typical watershed, is selected as the research object, and the characteristics of water and sediment variation and its relationship with rainfall during 1970-2010 are analyzed. The characteristics of vegetation change and its relationship with water and sediment were analyzed, and the model of Revised Universal Soil Loss equation Rusle and Morgan Morgan FineryMMP were used to simulate the soil erosion in different periods of the watershed, and the accuracy and applicability of the two models were evaluated. The conclusions are as follows: (1) the runoff and sediment discharge of Yanhe River Basin have changed significantly in the past 40 years. The abrupt point year of the change trend of the runoff and sediment discharge occurred in 1996 ~ 1970-1996 as the rising period of fluctuation. After 1996, the runoff and sediment discharge of the Yanhe River basin showed an obvious downward trend.) the vegetation of the Yanhe River Basin changed significantly. From 1978 to 2010, the area of cultivated land decreased, the area of forest and grass continued to increase, the area of cultivated land decreased from 5248.63km2 to 1217.13 km ~ 2, and the area of forest and grassland increased from 1854.35km2 to 6281.45 km ~ 2. The increased forest and grass vegetation in the watershed is mostly converted from abandoned or abandoned land. The trend characteristics of overall vegetation change in the basin are consistent with the influence of the major historical events in the study area, such as the reform of forest tenure system in the early 1990s and the implementation of large-scale conversion of farmland to forest and grass around 2000.) based on RUSLE model, the Yanjiang River is affected. The average soil erosion modulus in 1978 and 2010 was 4434.7 t/(km2 / a and 1026.7 t/(km2 / a, respectively, and the soil erosion modulus of the latter was reduced by 76.8g than that of the former, and the intensity of soil erosion was lower in the forest region of the southeastern part of the basin and on both sides of the flatter channel. However, the soil erosion intensity was higher in the northwest grassland and scattered cultivated land areas. In the case of silt dam, the relative error between simulated sediment discharge and measured value in 1978 and 2010 is -336, respectively. Silt dam plays an important role in soil and water conservation in river basin. The effect of silt dam on soil erosion in Yanhe river basin is based on MMF model. The simulated values of sediment discharge in 1978 and 2010 were 3691 脳 10 ~ 4 t ~ (2 586 脳 10 ~ 4 t) and 2506 脳 10 ~ 4 t ~ (10 ~ 4) 脳 10 ~ 4 t, respectively. The relative error was -290.49%. The simulated runoff in 2010 was 56.7% of that in 1978, while its sediment transport was 16.555 t (1978). The RUSLE model and the MMF model are compared and evaluated. MMF model is more complex than RUSLE model in describing the physical process of soil erosion. The modeling of the model is more difficult than that of the RUSLE model, and the simulation accuracy of the RUSLE model is better than that of the MMF model.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157

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