【作者】 舒若杰；

【导师】 吴普特； 高建恩；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2007， 硕士

【摘要】 支离破碎的黄土高原由不同大小的(小)流域组成,是黄河泥沙的主要来源区。研究小流域产流产沙过程和机理,可深入理解小流域土壤侵蚀的时空分布规律,为小流域侵蚀预报模型研究和水土流失防治提供思路和数据。目前小流域坡沟系统土壤侵蚀研究的取得了一批高水平的研究成果。但由于问题的复杂性,迄今为止,对坡沟关系还没有一个较为完满的答案,尤其在泥沙来源、治理策略等一些基本问题上还存在较大分歧与争议。本文针对以上问题,将小流域沿沟缘线分为坡面与沟道两部分,运用正态整体模型试验的方法研究小流域沟道水沙运移规律。全文主要包括以下三部分内容:1.小流域模型人工模拟降雨在模型试验的基础上,运用计算机矢量化软件和色斑法相结合,分析了模型人工降雨雨强率定、雨滴取样、雨滴大小组成分布、降雨能量等降雨特性参数,得出不同喷头组合、不同水头压力条件下模型降雨强度、以及不同雨强条件下降雨雨滴中数直径与模型降雨总动能,为模拟黄土高原小流域水沙运移试验降雨尺度的选择提供依据。2.小流域沟道产流针对以往小流域沟道产流产沙研究建立在小区模拟降雨试验,或小区观测,以及由完整小流域水文资料推导的问题,在小流域的纯沟道上进行试验,研究了人工降雨条件下小流域沟道产流、汇流以及沟道降雨入渗跟降雨强度的关系,最后根据验证的相似比尺向原型进行了转换。在跟坡面产流比较的结果表明:沟道径流量、产流系数均高于坡面,其中次降雨径流量为该小流域坡面径流量的1.14～1.2倍。3.小流域沟道产沙基于延安燕沟康家圪崂沟小流域模型,通过人工降雨试验研究沟道产沙情况,得出沟道平均含沙量、泥沙输移量、侵蚀模数与降雨强度均存在aI b的关系,沟道次降雨平均含沙量为小流域坡面的3.17～4.33倍,侵蚀模数是坡面的3.78～5.10倍。对沟道产沙过程用相似比尺进行转换,并跟原型小流域降雨产沙过程进行比较,结果表明:转换后沟道起沙过程与含沙量峰值与原型产沙对应过程一致,基本能正确反应出这两过程的变化趋势;含沙量的消退过程与原型产沙不符,通过对沟道产沙过程的修正,推导得出原型沟道输沙变化过程。更多还原

【Abstract】 The Loess Plateau is composed by fragmentized watershed, which is the sediment source of yellow river. The research about watershed runoff and sediment producing process and mechanism which can help us deeply comprehend the laws of Temporal-Spatial distribution of small watershed soil erosion, and it also can provide us the thoughts and data about small watershed erosion prediction model and soil and water conversation measures. Presently, there are masses of high-level research results about soil erosion of slope and channel system. Therefore, there isn’t a perfect answer for this problem because of its complicacy. Especially, there is serious differences point of view to resolve the above problems, such as producing source of sediment and soil erosion controlling strategy. And so, we partition the small watershed to the both of slope and channel first time, and, we can research runoff and sediment transportation laws of channel by using small watershed normal model. The experiments include three parts as follows:1. Research of watershed model rainfall stimulationBased on the model experiment, using the combined methods of vector software and splash methods, the rainfall characteristics parameters were analyzed such as rainfall intensity of watershed model, the diameter median of raindrop, the raindrop sampling, the rainfall energy, and we got rainfall intensity at different spray nozzles composed and head pressure, we also got raindrops median diameter and entire rainfall kinetic energy at different rainfall intensity. It provides basis to research the simulation of runoff and sediment transportation at Loess Plateau small watershed.2. Runoff of small watershed channelFor past research methods, however, there are some shortcomings about rainfall simulation of runoff and sediment transportation research, and it also has shortcoming about plot observation data and the hydrologic data analysis methods of the entire watershed. And so, we carry on our experiments on small watershed channel, they were analyzed such as runoff and flow concentration of watershed channel, the relationships between channel rainfall infiltration and rainfall intensity. We convert the experiments data to the prototype, the results comparing with slope runoff show that: the channel runoff and flow coefficients are large than slope’s, and the channel runoff is the slope runoff 1.14~1.2 times.3. Sediment transportation of small watershed channelBased of small watershed model of kangjia gelao gou, yangou at yan’an. Using rainfall simulation to research the channel sediment transportation, we got the relationships are aI bwhich between rainfall intensity and average sediment concentration and sediment yield transportation and modulus of erosion. The channel sediment concentration is the slope’s 3.17～4.33times, the modulus of erosion is the slope’s 3.78～5.10 times. We convert the channel sediment producing process to the prototype by using similarity scale. Comparing with past observed rainfall erosion data of phonotype, the results show that: the converted changing process of sediment production and concentration is consistent with prototype, and it can show the two changing process accurately. But the sediment concentration reducing process isn’t consistent of the prototype’s, and we got theoretical sediment transportation process of prototype channel which was corrected.更多还原