复合指纹法分析红壤区强度开发小流域泥沙来源

南方红壤区人口密集,土地资源开发利用强度大,水土流失类型多样。为研究不同土地利用类型下红壤区强度开发小流域侵蚀泥沙来源,选取感德镇红壤强度开发小流域为研究区,分析了流域内潜在泥沙源地和泥沙的41个地球化学特征,利用Kruskal-Wallis H检验及逐步判别分析确认最佳指纹因子组合,并通过多元混合模型计算各泥沙源地泥沙贡献率。结果表明:共有速效P、Cu、P、Y、Ca、Ga、Sn、Nd 8种因子通过检验被确认为最佳指纹因子组合,累计贡献率达90%以上,拟合优度均大于0.80。多元混合模型结果显示,锋面雨季流域泥沙主要来源于林地、茶园与矿区,贡献率分别为28.59%,28.20%,27.59%;在台风雨季,4种土地利用类型泥沙相对贡献率为茶园林地矿区耕地。通过对不同降雨特征下各土地利用类型泥沙贡献百分比数据进一步分析,结果显示矿区单位面积泥沙贡献百分比均值分别是耕地、林地与茶园单位面积泥沙贡献百分比均值的8,10,10倍,即单位面积下矿区土壤侵蚀强度最大。

Using Composite Fingerprints to Qualify Sediment Source in Watershed with Intensive Exploitation on Red Soil Region

The southern red soil region is densely populated, with strong development and utilization of land resources and diverse types of soil erosion. In order to research the eroded sediment sources in watershed with intensive exploitation under different land use types in red soil region, this study selected a small watershed in the town of Gande as researd object, and analyzed 41 geochemical properties of the potential sediment sources as well as sediment in the basin. Kruskal-Wallis H test and Stepwise discriminant analysis were used to identify the best combination of fingerprint factors and calculate the sediment contribution rates of each sediment source. The results showed that the best fingerprint combination was made up of eight factors, including A-P, Cu, P, Y, Ca, Ga, Sn, and Nd. The total cumulative contribution rate was over 90%, and the value of GOF was higher than 0.80. A multivariate mixed model was applied to identify the different sediment sources. It indicated that sediment mainly came from forest, tea plantations and mining area in the front rainy season, constituting 28.59%, 28.20%, and 27.59% respectively. The relative contribution rates of the four land use types were tea plantations > forest > mining area > farmland in the typhoon rainy season. The figures of sediment contribution percentages showed that the unit area sediment contribution rate in mining area was 8 times, 10 times and 10 times respectively of those in farmland, forest and tea plantation. That''s to say, the soil erosion intensity in mining area is the highest.