【作者】 李淼；

【导师】 沈冰； 宋孝玉；

【作者基本信息】 西安理工大学 ， 水文学及水资源， 2006， 硕士

【摘要】 植被建设是根治我国水土流失和改善生态环境质量的重大政策措施,开展植被建设(变化)的水文生态效应研究对正确评价植被建设的水文生态效益具有重要的现实意义。本文以黄土沟壑区南小河沟中4种不同径流小区及杨家沟和董庄沟小流域实测资料为基础,并结合大量的相关文献资料,采用横向对比、定量与定性模型模拟与实测对比相结合的方法,系统地分析了人类活动及植被变化对小流域区域水分环境的影响。论文取得的主要成果如下:1.以杨家沟小流域为主要研究对象,与董庄沟(未治理区)对比,得出杨家沟多年平均拦蓄径流效益为57.9%,拦泥效益为81.3%。通过对杨家沟各个时段的产流产沙比较发现,受水保治理影响而增加的拦蓄水量占未治理前的46.13%;减少的年均输沙量占未治理前的10.9%。同时分析了不同植被变化对汛期产流产沙、雨能以及抗侵蚀能力的影响,并建立了经验关系。随着植被度的增加,降雨产流、产沙量减少,蓄水拦沙效益增大。2.采用小流域4种径流小区(农地、林地、人工牧草和天然荒坡)平行对比和流域自身对比两种方法,分析了黄土沟壑区植被变化对年产流、年产沙的影响,随着植被度的增加,降雨产流、产沙量减少。农地的径流系数和产沙量随着降雨量的变化都快于其他三种植被(林地、人工牧草和天然荒坡)。在降雨量相同的情况下,分析4种植被汛期产流产沙关系,得出:农地的径流系数和产沙量最大,高于林地、草地和荒坡。3.对不同径流小区植被措施对土壤含水量影响分析表明:相同植被条件下,土壤含水量主要受到前期降雨量和雨强的共同作用,土壤含水量随着前期降雨量的增大而增大;相同植被条件下,分层土壤含水量随着土层深度的增加而减少。4.以降雨量作为主要影响因素,应用BP神经网络对杨家沟小流域产流产沙进行模拟与预测,模拟效果较好;同时以次降雨量、最大雨强、雨前土壤含水量、小区植被度为参数对南小河沟4种不同植被小区的产流产沙进行模拟与预测,达到实用要求。更多还原

【Abstract】 Vegetation structure is an important measure to control soil and water loss and to improve ecological environment. So the study on eco-hydrological effects of vegetation structure/change has great practical significance.Based on the data measured from different runoff plot in Yangjiagou and Nanxiaohegou watershed and refer to a large amount of documents, the aquatic environment effects of man’s activity and vegetation change in watershed are generally analyzed by the methods of pairing, quantization and modeling. The main findings of this study are as fallows:1. Based on the measured date of Yangjiagou watershed, the yearly average benefit of dammed up runoff is 57.9% by comparing with Dongzhuanggou, the dammed up sediment is 81.3%. Through comparing and pairing runoff yield and sediment yield with the every period, the increase water quantity which is influenced by man’s activity accounting to 45.13% before the harnessing; the reduced yearly average sediment accounting to 10.9% before the harnessing. In flood season, the influence of different vegetation change on the runoff, the sediment, the raindrop energy and the erosion resistance have been analyzed, and have established empirical relationships, along with vegetation increase, the runoff and the sediment decrease; the benefit of impoundment and sediment trapping increasing.2. The impacts of vegetation change of small watershed in loess gulley area on yearly runoff and sediment are analyzed by parallel observation in the comparable watershed and by historic date in one watershed. With the increase of vegetation coverage the runoff and the sediment decrease. The relationship of runoff in flood season is analyzed at the same rainfall, the result of runoff coefficient shows: the runoff and sediment yield of farmland is the biggest.3. The impacts of vegetation change of different runoff plot on the soil moisture content are analyzed, the identical vegetation, the soil moisture content increase with increase of antecedent rainfall amount , at the same time also came under the rain strong influence; The soil moisture content reduce with soil increase of layer depth.4.The BP neural network is applied in Yangjiagou to simulate and predict the runoff and the sediment yield, based on the date of rainfall, and the simulation results is good; The BP neural network is applied indifferent runoff plot to simulate and predict the runoff generation and the sediment yield, based on the date of rainfall, the most heavy rain intensity in a short duration, the soil moisture content before raining and the vegetation coverage from the 1978 to 1984, the result meets the general practical requirements.更多还原