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西藏尼洋河流域河谷地带土壤可蚀性K值空间分布特征
梁万栋1, 王小姣1, 高志康,等1
西藏农牧学院 资源与环境学院
摘要:
【目的】研究西藏尼洋河流域河谷地带土壤可蚀性K值的空间分布特征,为降低该区域土壤侵蚀风险提供参考。【方法】以位于藏东南尼洋河流域的冻融侵蚀区(海拔>4 200 m)、冻融水力侵蚀交错区(海拔3 800~4 200 m)和水力侵蚀区(海拔<3 800 m)为研究对象,共布设122个样地,测定流域内表层土壤的基本理化性质,在此基础上运用EPIC模型计算土壤可蚀性K值,采用普通克里金插值法获取尼洋河流域河谷地带土壤可蚀性K值的空间分布图,并分析土壤可蚀性K值与海拔和土壤理化性质的相关性。【结果】①尼洋河流域冻融侵蚀区、冻融水力侵蚀交错区和水力侵蚀区的土壤理化性质存在明显差异,其中冻融侵蚀区土壤体积质量最小,土壤孔隙度、含水率和有机质、粉粒、黏粒含量均最高。②冻融侵蚀区、冻融水力侵蚀交错区和水力侵蚀区的土壤可蚀性K值分别为0.263~0.431,0.218~0.374,0.104~0.409 t·hm2·h/(MJ·mm·hm2),3个研究区土壤可蚀性K值的平均值分别为0.349,0.310,0.292 t·hm2·h/(MJ·mm·hm2),变异系数分别为11.7%,12.7%和21.5%,属于中等变异。尼洋河流域土壤可蚀性K值总体上由西北向东南呈降低趋势。在尼洋河流域,较低可蚀性、中可蚀性、较高可蚀性和高可蚀性土壤均有分布,但是主要土壤侵蚀类型在3个研究区的分布存在一定差异,其中高可蚀性土壤主要分布在冻融侵蚀区,而较低可蚀性和中可蚀性土壤主要分布在水力侵蚀区和冻融水力侵蚀交错区。③土壤可蚀性K值与海拔和土壤理化性质的相关性均达极显著水平(P<0.01),其中与砂粒、粉粒、黏粒含量的相关系数均较高,分别为-0.98,0.99和0.62。【结论】探明了西藏尼洋河流域河谷地带土壤可蚀性K值的空间分布特征,土壤机械组成是该流域可蚀性K值的主要影响因素。
关键词:  尼洋河流域  土壤可蚀性  EPIC模型  空间分布
DOI:
分类号:
基金项目:国家自然科学基金重点项目(41930754);西藏农牧学院柔性人才项目(604419042)
Spatial distribution characteristics of soil erodibility K value in the valley of Niyang River Basin,Tibet
LIANG Wandong,WANG Xiaojiao,GAO Zhikang,et al
Abstract:
【Objective】This study investigated the spatial distribution characteristics of soil erodibility K value in the valley of the Niyang River Basin in Tibet to provide references for reducing soil erosion risk in this region.【Method】A total of 122 sample plots were set up in the freeze thaw erosion area (altitude>4 200 m),the crisscross areas of freeze thaw and hydraulic erosion crisscross area (altitude 3 800-4 200 m) and the hydraulic erosion area (altitude<3 800 m) in the Niyang River Basin in southeastern Tibet.Basic physical and chemical properties of surface soil in the basin were measured and the EPIC model was used to calculate soil erodibility K value.The spatial distribution of K value in the valley was obtained using the ordinary Kriging interpolation method.Finally,the correlations between soil erodibility K value and elevation and soil physical-chemical properties were analyzed.【Result】① Physical and chemical properties of soil in the freeze-thaw erosion area,the crisscross area of freeze-thaw and hydraulic erosion and the hydraulic erosion area in the Niyang River Basin were significantly different.The freeze-thaw erosion area had the lowest soil volume quality and the highest soil porosity and contents of water,organic matter,silt and clay.② The K values of soil erodibility in freeze-thaw erosion area,the crisscross area of freeze-thaw and hydraulic erosion and hydraulic erosion area were 0.263-0.431,0.218-0.374 and 0.104-0.409 t·hm2·h/(MJ·mm·hm2) with average values of 0.349, 0.310 and 0.292 t·hm2·h/(MJ·mm·hm2) and medium variation coefficients of 11.7%,12.7% and 21.5%,respectively.The K values of soil erodibility factor in the Niyang River Basin decreased gradually from northwest to southeast.There were less low,medium,less high and high erodible soils in the basin without different main soil erosion types among areas.High erodible soils were mainly distributed in the freeze-thaw erosion areas,while less low and medium erodible soils were mainly distributed in the hydraulic erosion area and the freeze-thaw hydraulic erosion crisscross area.③ The soil erodibility K value had very significant correlation with elevation and soil physical and chemical properties (P<0.01),with high correlation coefficients of -0.98,0.99 and 0.62,respectively.【Conclusion】The spatial distribution characteristics of soil erodibility K value in the valley of Niyang River Basin in Tibet were investigated and the mechanical composition of soil was the main affecting factor.
Key words:  Niyang River Basin  soil erodibility  EPIC model  spatial distribution