喀斯特区小流域山坪塘淤积泥沙颗粒分布特征  

Profile distribution of particle size of sediment at a check dam in small watershed in the Karst hilly region

作　　者：成六三[1] CHENG Liusan(Chongqing Vocational Institute of Engineering,402260,Chongqing,China)

机构地区：[1]重庆工程职业技术学院,重庆402260

出　　处：《中国水土保持科学》2024年第6期176-182,共7页Science of Soil and Water Conservation

基　　金：重庆市自然科学基金面上项目“武隆岩溶区小流域山坪塘淤积物的特征及其来源侵蚀影响因素研究”(cstc2019jcyj-msxmX0291);重庆市教委项目“武隆区退耕还林工程生态经济耦合效应研究”(KJQN202203409),“渝西红层丘陵区农村机井供水水质演变机理研究”(KJQN202103406),“新时代渝西红层丘陵区民生“打井工程”的农户福祉评价研究”(22SKGH573)。

摘　　要：山坪塘淤积泥沙的粒径特征是反演流域土壤侵蚀环境的重要信息载体。为探究喀斯特区小流域山坪塘淤积泥沙特征及其来源,采用野外泥沙分层与取样、室内测试和数学统计等方法,分析研究山坪塘淤积泥沙颗粒剖面的分布特征。结果表明:1)山坪塘淤积泥沙粒径成分主要以黏粒和中粉粒为主,其平均比例之和占总比的68.64%,且它们变异系数最小,其他粒径按平均比例占总比的顺序为粉粒13.69%、极细砂粒9.21%、细粉粒5.59%、细砂粒2.02%、粗砂粒0.82%和大砂粒0.05%;2)山坪塘淤积泥沙粒径剖面分3个层次,>0~30 cm,泥沙粒径较单一,以粉粒以下的为主,可指示控制流域内土地利用转型;>30~60 cm,泥沙粒径级配较好,各粒径类型基本都有分布,粗砂粒和大砂粒也有少量分布;>60~85 cm,泥沙粒径类型分布较均匀,相比上一层次,粗砂粒和大砂粒的比例有所增加,则可指示控制流域内存在暴雨事件;3)在深度60 cm处,山坪塘淤积泥沙特征粒径参数和分形维数数值都是剖面最大值,为剖面的转折点,该点可表明控制流域内水动力条件有变化。山坪塘淤积泥沙颗粒剖面分布特征与控制小流域内土地利用和水沙运移状况关系密切。[Background]The sediments is an important medium for retrieval of soil erosion characteristics,which indicates important information about the environmental process relation to soil erosion and deposition.[Methods]To investigate the characteristics and sources of sediment deposition in small watersheds of karst regions,the distribution characteristics of sediment particle profiles in small watersheds were analyzed and using field sediment stratification and sampling,indoor testing,and mathematical statistics.[Results]1)The particle size composition of sediment in a check dam is mainly composed of clay and medium silt particles,which account for 68.64%of the total proportion on average and their coefficient of variation is the smallest.The order of other particle sizes according to the average proportion of the total proportion is silt(13.69%),very fine sand(9.21%),fine silt(5.59%)fine sand(2.02%),coarse sand(0.82%)and large sand(0.05%);2)The sediment particle size profile of check dam siltation can be divided into three levels:>0-30 cm with relatively uniform sediment particle size dominated by particles finer than fine silt,indicating land use transformation within the small watersheds;>30-60 cm with better sediment particle gradation where all types of particle sizes basically distributed including a small amount of coarse sand and very coarse sand;>60-85 cm with more uniformly distrbuted sediment partical size type compared with the previous layer,showing an increased proportion of coarse sand and large sand,which indicates the existence of rainstorm events in the control watersheds.3)At the depth of 60 cm,the characteristic particle size parameters and fractal dimension values of check dam silt reaches their maximum values,which is the turning point of the profile.indicating that the hydrodynamic conditions in the control watersheds are changed.The distribution characteristics of sediment particles in a check dam are closely related to land use control and water-sediment transport in small watersheds.[Conclus

关 键 词：颗粒分形维数 粒径分析 反演 土壤侵蚀强度 

分 类 号：S157.1[农业科学—土壤学] S727.2[农业科学—农业基础科学]