岩溶峰丛洼地不同环境水土流失差异及防治研究——以广西果化岩溶生态研究基地为例

与碎屑岩地区相比,特殊的岩溶水文地质结构,导致岩溶区存在不同的水土流失过程和特点,尤以峰丛洼地区最具代表性。通过广西平果县果化岩溶峰丛洼地土壤地表侵蚀和地下漏失的调查研究显示:洼地不同地貌部位水土流失差异较大,从山峰、垭口、山坡、山麓到洼地底部,土壤地下漏失模数分别为49.09 t/(km2·a)、212.06 t/(km2·a)、727.71 t/(km2·a)、1104.03 t/(km2·a)、909.11 t/(km2·a),分别占该点年均总土壤侵蚀模数的92.43%、96.24%、78.57%、70.88%和38.68%;不同土地利用方式下的土壤侵蚀存在差异,其土壤侵蚀模数大小依次为坡耕地苦丁茶地苏木林地灌草坡牧草地。通过对该地区水土流失防治及石漠化综合治理,山峰主要涵养水源林、山坡主要发展生态产业防治水土漏失、洼地修建排水系统工程得到良好的效果,治理区土壤侵蚀模数从2003年到2010年下降了65%。

The Difference in Soil Erosion in Different Environments of Karst Peak-cluster Depression and the Study of Soil Erosion Prevention: A Case Study of Guohua Karst Ecological Experimental Site, Guangxi

In the special karst ground water system, there exist different processes and features of water and soil loss in karst mountains. Especilly in karst peak cluster depression, much more water and soil are lost from the leakage of karst fissures than from the surface flow. Some monitoring stations of water and soil loss were built in Guohua karst ecological experimental site, Pingguo County, Guangxi, with the purpose of investigating the difference between the surface soil erosion and the soil leakage in different environments of the karst peak-cluster depression. The monitoring results reveal the most remarkable differences in different geomorphologic positions. From peak, paddle, hill slope, hill foot to the bottom of depression, the mean annual soil leakage loss moduli are 49.09 t/(km2?a), 212.06 t/(km2?a), 727.71 t/(km2?a), 1104.03 t/(km2?a) and 909.11 t/(km2?a) respectively, which possess 92.43%, 96.24%, 78.57%, 70.88% and 38.68% of the total mean soil loss moduli in the points respectively. There are five kinds of main land uses in the karst peak-cluster depression, i.e., slope farmland, young secondary forest, kuding tea garden, grass land, and brush and grass land. In the slope farmland, thare is not only the biggest soil erosion modulus but also a annual increase tendancy. The soil erosion modulus has an annual decrease tendancy in the other four lands, and the lowest value is in the grass land. Therefore, the prevention of soil erosion should be based on different measures in different geomorphologic positons of the peak cluster depression. In the peak, the water source forest should be mainly developed. In the hill slope, the attention should be paid to the eco-prodution and the decrease of the soil leakage. And in the depression, the water drainage system should be the key engineering. With the harnessing of rocky desertification and the rehabilitation of the ecology in Guohua karst ecological experimental site, the mean water and soil loss modulus of the karst peak cluster depression decreased by about 65% from 2003 to 2010.