【作者】 刘卉芳；

【导师】 朱清科； 魏天兴；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2004， 硕士

【摘要】 国内外有关森林植被对流域水沙过程的影响尚未得出统一的研究结论，已成为学术界长期争论的焦点问题之一。森林的空间异质性决定了森林水沙作用功能在不同的自然地理区域和不同的空间尺度上具有不同的特点和规律，本研究以北京林业大学试验基地晋西黄土区蔡家川嵌套小流域为研究对象，以单株—林分—集水区—小流域构成的尺度嵌套流域树冠截留、流域径流及泥沙运动过程为切入点，分析研究了树冠最大截留、黄土坡面土地利用／覆盖对产流产沙的影响、流域泥沙来源分析、森林植被覆盖率对流域产流产沙的研究、流域尺度对洪水过程的影响等内容。该研究为晋西黄土区正在实施的退耕还林还草工程、天然林保护工程和防护林体系建设工程提供理论依据。 通过实验分析表明，各种土地利用类型年平均土壤侵蚀量为：裸露地174.76t／km~2，荒草地为68.31 t／km~2，虎榛子林为2.13 t／km~2，沙棘林为4.37 t／km~2，油松林为18.74 t／km~2，刺槐林为20.58t／km~2，油松+刺槐混交林为7.36 t／km~2。各种类型的土地利用侵蚀产沙量由大到小的顺序：坡耕地＞裸地＞草地＞刺槐＞油松＞刺槐+油松＞虎榛子。侵蚀泥沙主要来源于沟谷坡地(沟头、沟道和沟坡)，沟谷地侵蚀模数是沟间地的1.28～2.48倍。 在黄土高原小流域中，有林地比无林地的雨季径流深和径流系数小。森林植被覆盖度较高的流域雨季径流深和径流系数低于森林植被覆盖率较小的流域，试验数据表明：全农流域的雨季径流深大约是有林流域的5-20倍。森林植被对流域枯水季节的河川径流具有一定的补枯作用，且随着森林覆盖率的增加增枯作用明显。如在蔡家川嵌套流域多林流域的枯水流量约是少林流域枯水流量的9.2倍。森林植被具有巨大的减沙作用，当降雨量为60.4mm时，无林流域的输沙模数是有林流域的31.4倍，森林植被的减沙效益达到了96.81％。森林在不同雨洪作用下，减沙作用是不同的，一般在降雨量较小，洪水径流量较小时，森林的拦减效益较大；而在降雨洪水径流量较大，洪峰流量较大时，森林的减沙效益较小。 在黄土高原尺度较大的流域产生峰值流量的时间滞后于尺度较小的流域，在羽状流域条件下，前者洪水过程线比较对称，且洪水过程线多为多峰曲线。后者洪前洪后退水过程线不相似，退水过程漫长，并且表现出一定的偏态，且洪水过程线多为单峰曲线。此外，尺度较大的流域受复杂地形地貌的影响，产流模式相对复杂，既有超渗产流形式又有蓄满产流形式。而尺度较小的流域产流模式相对单一。流域形状、流速是决定洪水过程的主要因素，通过流速公式计算各嵌套流域的洪水过程线在到达蔡家川主沟道流域后的迭加洪水过程线，将它作为模拟洪水过程线。试验数据表明：实际洪水过程线与模拟洪水过程线吻合较好。 本论文创新点是以单株—林分—集水区—小流域构成的尺度嵌套流域截留、径流及泥沙运动过程观测及分析研究为切入点，依据森林植被的生态结构功能、影响水文过程的原理，运用MAI，LAB软件对流域地形地貌进行了相似性分类，易U除了地形地貌对流域径流的影响，分析研究了森林植被对流域径流的影响，并且探讨了时空尺度对流域径流的影响。更多还原

【Abstract】 In the China and foreign country, there are not the unitary result about the impact of forestry vegetation on the water and sediment. It has been one question of augmentative focus in the academic circle. The airspace heterogeneity of forestry determine that the water and sediment function of forestry is provided with different characteristics and regular in the different the nature airspace and air scale. The paper looks on net watershed of Caijiachuan in shanxi of Beijing forestry University experiment base, as object of study, and looks on runoff and sediment movement process of scale watershed constituted by single tree-forest-district of collecting water-small watershed., as enter point. The paper analyze the most interception of tree crown, the impact of the land use/ cover on the runoff and sediment, the sediment source of watershed, the impact of forest vegetation on runoff and sediment of watershed, the impact of the different scale of time and airspace on the flow process, and so on. The study provide the theory basis for the project of receding plough and returning forest and grass, the project of natural forest protection, the project of protection forest building in the loess, western of shan xi province.The main study results as follows: the average soil erosion of diversified land use: naked land 174.76 t / km2, barren grass land 68.31 t / km2, Ostryopsis davdiana Decne 2.13 t / km2, Hippophae Rhamnoides Woodlands 4.37 t / km2, china pine 18.74 t / km2, black locust 20.58t / km2, china pine and black locust 7.36 t / km2, the erosion sediment: the slope plough land > naked land > grass land > black locust > china pine > black locust and china pine > Ostryopsis davdiana Decne. The erosion sediment mainly comes from gully slope (gully head, gully bed, valley side ), Erosion modulus of valley is 1.28-2.48 times as that of the area between channels.In the rain season, the runoff deep and coefficient of land of forest covered is smaller than no forest land. The runoff deep and coefficient of rain season in the watershed of watershed of bigger forest covering is lower than the watershed of smaller forest covering, the experiment data declare: in the rain season, the runoff deep of all farm watershed is or so 5-20 times than watershed of forest covered. The forest is provided with supplying water. The experiment declare: in the lack rain season, the flow of more forest watershed is or so 9.2 times than lower forest watershed. Forest vegetation is provided with function of decreasing sediment. When the rain amount is 60.4mm, the sediment modulus of no forest watershed is 31.4 times than covered forest watershed, and the deceasing sediment benefit of forest vegetation reach to 96.81%. in the function of different rain and flow, the function of deceasing sediment is different, in the general, if rain amount is small, the flow runoff is small, then the benefit of deceasing is large. But when rain and flow is big, the benefit of deceasing is small.In the loess, the peak flow time of large area watershed is lag with small area watershed. The flow process line of large area watershed is symmetry, the flow process line is more peak. The flow process line of the small area watershed is gently, the falling process line of flow isn’t coincide, with partial form, the flow process lineis single peak. In the large area watershed, due to the flex landform, the runoff model is flex, but in the small area watershed, the runoff model is single. The watershed shape and the flow speed is the main element deciding the flow process, by the flow speed formula calculating the flow line when net watershed flow process arrive at the main watershed, that is the model flow process. The data show: the reality flow process is coincide with the model flow process.The innovation point of paper: the paper looks on runoff and sediment movement process of scale watershed constituted by district of collecting water-small watershed., as enter point. According to the ecology and frame function of forest vegetation, the principal of i更多还原