淤地坝沟道植被覆盖/土地利用和土壤水分的分析

Analysis of vegetation cover,land utilization andsoil moisture in the controlled area of check dam in loess gully region

摘要:

水分条件是限制黄土丘陵沟壑区植被生长的决定性因素,在水土流失严重的沟道中淤地坝发挥着十分重要的作用。 用GF-2号卫星遥感影像和实地调查数据,基于Arc Map 10.5和eCognition 9.0、ENVI 5.3软件平台分析了甘肃省平凉市庄浪县西北部有坝沟道和无坝沟道植被覆盖度、土地利用类型和土壤水分的差异。结果表明:1)植被覆盖度,有坝沟道高于无坝沟道2.17%,有坝沟道在高覆盖度下林地覆盖率最高,占总面积的31.82%。而无坝沟道在极低覆盖度下草地覆盖度最高,占总面积的 27.53%,有坝草地和无坝草地均在极低覆盖度时达到最高值。2)土地利用类型,有坝沟道为:林地 ＞ 草地 ＞ 其他土地 ＞ 水域及水利设施用地;无坝沟道为:草地 ＞ 林地 ＞ 其他土地。3)土壤水分,有坝沟道土壤水分随土壤深度的增加而增加,无坝沟道则相反;土壤深度在180~200 cm 时,有坝沟道的土壤水分明显高于无坝沟道,是植被覆盖度高的主要因素。黄土沟壑区淤地坝可提高控制区域的植被质量及覆盖度,有坝沟道土地利用类型较优,土壤水分较高,对治理沟道水土流失和改善流域内生态环境有显著作用。

Abstract:

Water is the decisive factor for vegetation growth in loess hilly ravine area,and check dams play very important roles in ditches with serious soil erosion.The difference in the vegetation coverage,land utilization and soil moisture between the ditches with or without check dam were investigated in the northwest of Zhuanglang County,Pingliang,Gansu Province,using GF-2 remote sensing images and field survey data,and based on Arc Map 10.5 and eCognition 9.0,ENVI 5.3 software platforms.Our results showed that fractional vegetation coverage of the ditches with check dam was 2.17% higher than that of the ditches without check dam.For the ditches with check dam,forest coverage accounted for 31.82% of the total area;while the ditches without check dam was primarily covered by grassland,accounting for 27.53% of the total area.The land utilization area in the ditches with check dam followed the order of forestland＞grassland＞other land＞water area and land for water conservancy facilities;while it followed the order of grassland＞Forestland＞other land for the ditches without check dam.The soil moisture content of the ditches with check dam increased along the soil depth,but it showed the opposite trend for the ditches without check dam.At soil depth of 180?200 cm,the soil moisture of the ditches with check dam was significantly higher than that without check dam,which was attributable to higher vegetation coverage.Silt dams in the controlled area of loess gully area could improve the quality and coverage of vegetation.The land utilization of the ditches with check dam channel could be improved due to higher soil moisture,which would play significant roles in controlling soil erosion and improving the ecological environment.