岩溶槽谷区不同土地利用方式下的坡地产流产沙规律

[目的]研究岩溶槽谷区坡地产流产沙规律,为槽谷区坡面水土流失防治提供理论基础。[方法]基于重庆市北碚区中梁山岩溶槽谷区径流小区,探讨了土地利用类型(耕地、林地、果园和竹林地)、降雨等级、降雨特征对坡地产流产沙的影响。[结果]①不同土地利用方式的径流小区坡地总产流量为:耕地(3534.64 L)>果园地(3150.60 L)>竹林地(2347.75 L)>林地(1957.41 L);径流系数(3.12%~5.70%)远低于非岩溶区(约20%);地表产沙量耕地(3.37 kg)>果园地(2.60 kg)>林地(1.60 kg)>竹林地(1.43 kg);②虽然暴雨占总降雨场次的1.53%,但产流量占年产量的42.28%,产沙量占年总产沙量的33.42%。中雨占年产流总量的16.61%,产沙量占年总产沙量的20.47%,但是由于中雨的降雨次数多,其造成的泥沙流失也不可忽视。③降雨量对不同土地利用方式下的坡面产流的影响最大,是坡面产流的主要影响因素。I30对耕地和果园产沙量的影响最大,降雨量对林地和果园产沙量的影响最大。[结论]在相同的降雨条件下,耕地的产流产沙量最大,果园次之。在坡度一定的条件下,不同等级的降雨是影响产流产沙的主要因素,因此,在安排农事活动时,应尽量避开高强度降雨,减少严重侵蚀事件的发生。

Characteristics of Runoff and Sediment on Slope Land with Different Land Use in Karst Trough Valley Area

[Objective]The law of sediment yield in a karst trough valley was studied to provide a theoretical basis for the prevention and control of soil and water loss on the slope of the trough area.[Methods]Based on the runoff plots of Zhongliang Mountain at Beibei District of Chongqing City,the effects of land use types(cultivated land,woodland,orchard,and bamboo forest land),rainfall grade,and rainfall characteristics on runoff and sediment yield on slopes were investigated.[Results]①The total runoff of the four runoff plots was as follows:cultivated land(35.35 mm),followed by orchard land(31.51 mm),bamboo forest land(23.47 mm),and forest(19.57 mm).The runoff coefficient of them(3.12%~0.5.70%)was much lower than that of the nonkarst area(approximately 20%).The slope sediment yield of the four land uses decreased orderly,and that of the cultivated land was the largest(3.37 kg),followed by orchards(2.60 kg),forest(1.60 kg),and bamboo forest(1.43 kg).②Although rainstorm accounted for 1.53%of the total rainfall,the runoff and sediment yield accounted for 42.28%and 33.42%,respectively.Moderate rain accounted for 16.61%of the total annual runoff,and sediment yield accounted for 20.47%of the total annual sediment yield.However,because of the frequent rainfall of moderate rain,the sediment loss caused by it can not be ignored.③Rainfall had the greatest impact on the runoff on slopes under different land uses.Moreover,I30 had the greatest impact on the sediment yield of cultivated land and orchards,and rainfall had the greatest impact on the sediment yield of forest land and orchards.[Conclusion]Under the same rainfall conditions,the runoff and sediment yield of cultivated land are the largest,followed by those of orchards.Under certain slope conditions,different levels of rainfall are the main factors affecting runoff and sediment yield.Therefore,when arranging agricultural activities,it is necessary to avoid high-intensity rainfall to reduce the occurrence of serious erosion events.