高级检索

    模糊聚类方法在南方红壤小流域土壤属性制图中的应用———以长汀朱溪河小流域为例

    Soil property mapping using fuzzy clustering method in small watershed of the red soil region in southern China: A case study of Zhuxi Watershed

    • 摘要: 详细的土壤属性空间分布数据是流域过程模拟和情景分析所需的重要基础数据,尤其是在土壤母质分布复杂、空间变异性大的南方红壤区,土壤采样的成本及数字土壤制图的有效性往往限制了详细土壤属性数据的获取。近年出现的基于模糊聚类进行目的性土壤采样及数字土壤制图的方法,可有效地降低所需土壤样点数并推测土壤属性的详细空间分布。为探索该方法在南方红壤区的可用性,本文选取福建长汀朱溪河小流域,利用模糊聚类方法设计少量的目的性土壤采样,在5 m 空间分辨率上进行土壤表层(0 ~ 20 cm)砂粒质量分数、有机质质量分数的预测性制图。对比利用已有1颐5万土壤类型图以分层随机布点结合普通克里格方法,以及土壤类型图属性数据连接法的土壤属性制图结果,基于30 个独立验证点及制图结果空间分布进行评价。结果表明:与普通克里格方法和土壤类型图属性数据连接法相比,模糊聚类方法仅需要很少的土壤样点,制图结果精度较好(表层砂粒质量分数和有机质质量分数的均方根误差分别为13郾81%、12郾56 g/ kg),且能很好地体现该流域内土壤的空间分布特点。因此,模糊聚类方法可适用于南方红壤小流域,能在显著降低数字土壤制图采样成本的同时,获得较好的制图精度。

       

      Abstract: The detailed spatial distribution of soil properties which is essential for watershed modeling and scenario analysis,is mainly acquired through field soil sampling and digital soil mapping. Especially in the red soil region of southern China where the distribution of soil parent material is complex and with large spatial variability, the acquisition of detailed spatial distribution of soil properties is often one of the main bottlenecks in watershed modeling and scenario analysis, due to both the cost of field soil sampling soil sampling and predictive soil property mapping can effectively reduce the required number of soil samples and predict the detailed spatial distribution of soil properties. To explore the applicability of this method over the red soil region in southern China, we applied this method to conducting purposive soil samplingin a small,red-soil watershed (Zhuxi) in Fujian Province,and then predictive soil property mapping of sand content and organic matter content in the soil of 0 -20 cm at a spatial resolution of 5 m. A set of five topographic attributes ( i. e., elevation, slope gradient, profile curvature, horizontal curvature, and topographic wetness index) were derived from the gridded digital elevation model with 5 m resolution and then were used as environmental variates. Fuzzy clustering method was applied to this set of topographic attributes and got the result of nine fuzzysoil-landscape classes. Purposive soil sampling was carried out at the center of each fuzzy soil-landscape class. Then the value of a soil property at each location can be predicted as the average of the soil property value at every purposive sampling pointweighted by the fuzzy membership value of the location to the fuzzy soil-landscape class represented by the purposive sampling point. The ordinary kriging method with 42 modeling points and a traditional method of linking the typical soil property value to soil-type polygon map were chosen as the comparative methods. Based on the validation with 30 random points independent with the modeling points, the fuzzy clustering method requires only a very few soil samples (only nine modeling points used to build the soil-landscapemodel in this study), and can achieve better prediction accuracy based on the validation with an independent soil sample set. RMSE values of mapping results of sand content and organic matter contentin the soil of 0 - 20 cm are 13.81% and 12.56 g/ kg, respectively. And the predictive soil map from fuzzy clustering method can well reflect the spatial variation of the soil in the study area. Therefore, the fuzzy clustering method is applicable over the red soil region in southern China when the sampling cost of digital soil mapping can be significantly reduced.

       

    /

    返回文章
    返回