喀斯特坡地表层岩溶带发育,入渗强烈,产流机制与非喀斯特坡地有较大差异,为提高喀斯特坡地土壤流失模型预测准确性,以贵州省普定县陈旗小流域6个不同土地利用类型径流小区为观测对象,分析2007-2010年、2015-2019年2期泥沙和地表径流数据,了解产流产沙规律,并利用降雨侵蚀力偏差法计算各小区侵蚀性降雨量。结果表明:(1)植被覆盖率与喀斯特坡地地表产流产沙量呈负相关,高植被覆盖下,暴雨和极端暴雨是造成喀斯特坡地水土流失的主要降雨事件;(2)植被恢复十余年随着覆盖度的提高,年均土壤流失量呈显著下降趋势,多小于10 t/km2;(3)喀斯特坡地裂隙发育,地下漏失严重,土壤量少且不易被侵蚀,除少数极端暴雨外,多数降雨不产流不产沙,因此建议将喀斯特坡地侵蚀性降雨量阈值定为50 mm,该阈值显著高于非喀斯特地区。
A large number of epi-karst zones have developed on karst slopes, with strong infiltration, and the runoff production mechanism is very different from that of non-karst slopes. In order to improve the prediction accuracy of soil erosion models in karst areas, six runoff plots of different land-use types in the Chenqi Small Watershed of Puding County, Guizhou Province, were taken as the observation objects. The sediment and surface runoff data under different vegetation cover from two periods of 2007-2010 and 2015-2019 were analyzed to understand the laws of runoff and sediment production, and the erosive rainfall of each plot was calculated by using the rainfall erosion force deviation method. The results showed that:(1) Vegetation coverage was negatively correlated with runoff and sediment production on karst slopes. Under high vegetation coverage, heavy rains and extreme heavy rains were the main rainfall types that cause soil erosion on karst slopes. (2) Over the past decade of vegetation restoration, with the improvement of coverage, the annual average soil loss showed a downward trend, mostly less than 10 t/km2. (3) The karst slope developed fissures, serious underground leakage, small amount of soil and was not easy to be eroded. Except for a few extreme heavy rainstorm, most rainfall did not produce runoff and sediment. Therefore, it is recommended to set the threshold of erosive rainfall on karst slopes at 50 mm, which is generally significantly higher than that in non-karst areas.
焦锡桦, 彭韬, 李社红, 张林, 顾再柯, 张信宝, 王世杰.喀斯特坡地侵蚀性降雨阈值初探[J].水土保持学报,2023,37(5):57~63复制