中梁山岩溶槽谷区不同土地利用方式坡地产流规律

坡地产流是造成岩溶区水土流失的主要驱动力,研究典型岩溶槽谷区坡地产流规律,对岩溶区防治水土流失、合理利用地下水资源具有重要理论意义。在重庆市中梁山龙凤和龙车槽谷选取不同土地利用方式的4个标准径流小区,对降水、地表径流、壤中流、裂隙流和土壤含水率进行了同步监测,探讨了坡地产流特征。结果表明:(1)4个不同土地利用方式的径流小区,坡地总产流量从大到小依次为:耕地(3696.9L)果园地(3657.2L)竹林地(2922.9L)林地(2211.1L),总径流系数(3.1%—5.2%)远低于非岩溶区(约20%);(2)4个径流小区的产流形式主要为地表径流,壤中流和裂隙流产生滞后于地表径流;(3)降水因子、前期土壤含水率共同影响地表径流,但降水因子对地表径流的影响远大于前期土壤含水率。降水因子中,15min最大雨强是影响耕地、果园地的地表径流的主要因素,降水量是影响林地、竹林地的地表径流的主要因素;前期土壤含水率对耕地、林地、果园地地表径流影响较大,对竹林地地表径流影响较小。

Characteristics of different land-use types of slope runoff in a karst trough valley located in Zhongliang Mountain, Chongqing

Slope runoff is the most important soil erosion force in karst areas, the properties of which in a typical karst trough valley are of great significance for soil erosion prevention and for groundwater resources management. In this study, four standard runoff plots with different land-use patterns were set in a typical karst trough valley located in the Zhongliang Mountain, Chongqing. Land-uses in the trough valley, were farmland, orchard, bamboo land and forest. Hydrological characteristics, including precipitation, surface runoff, soil-layer flow, fissure flow and soil moisture content, were monitored simultaneously, and then slope runoff properties in the typical karst trough valley were determined by slope runoff plots. The results were:(1) In the four runoff plots, the total runoff coefficient (3.1%-5.2%) was significantly lower than that of non-karst areas (approximately 20%), and the total slope runoff of the four kinds of land-use decreased in an orderly way, with farmland being observed to have the greatest amount (3696.9L), followed by orchards (3657.2L), then bamboo land (2922.9L), and finally forest (2211.1L). (2) Surface runoff was the dominant runoff form in the four runoff plots, and this was followed by soil-layer flow and fissure flow. (3) Precipitation factors and antecedent soil moisture content together affected surface runoff discharge; however, precipitation factors were the predominant factor. Four precipitation factors were involved in the surface runoff formation analysis, in which the maximum intensity of continuous rainfall in 15 minutes was the predominant factor in farmland and orchards, and precipitation was the predominant factor in forests and bamboo land. Meanwhile, the antecedent soil moisture content had relatively greater impact on farmland, followed by forest land and then orchards, than bamboo land.