石漠化峰丛坡地土壤优先流的形成机制及其岩溶效应

It’s a special structure of double hydrogeology in karst areas. There are many environmental problems in karst areas of Southwest China, such as rocky desertification, soil erosion, drought and waterlogging disasters, karst collapse and others. In order to solve these problems, soil and water conservation is very important .In this project,Potential stony desertification, light stony desertification and middle stony desertification were selected, and hope to carry out karst dynamics features and formation mechanism of soil preferential flow. Soil preferential flow of morphological characteristics, path type, quantity distribution will be studied by using the combined methods of fieldtest and indoor. Meanwhile, dynamic conditions of CO2-H2O-CaCO3 karst pathway of soil preferential flow will be monitored. According to the karst-cranny developing condition, hydrological conditions, vegetation factors and results of seepage and slope runoff process features, analyze the differences of karst dynamics characteristic of soil preferential flow among different rocky desertification.Furtheremore, reveal the formation of soil preferential flow and its mechanism. From the point of view of the karst dynamic conditions, soil preferential flow will be taking into the typical peak-cluster depression area to carry out the project. This study is a very important complementarily content to better understanding the mechanism of soil preferential flow and karst dynamics under the conditions of rocky desertification in karst areas. Furthermore,this research provides theoretical basis and practical exploration of utilizing karst soil and water resource,rocky desertification control,soil and water resource conservation.

石漠化峰丛山区具有特殊的地下、地表双层水文地质结构，土壤优先流对岩溶发育和水土调蓄具有重要的作用和影响。本课题以位于广西平果县境内的潜在石漠化、轻度石漠化、中度石漠化三种坡面土壤优先流为研究对象，通过野外示踪试验、现场监测与室内分析相结合的方法，对土壤优先流形态特征、路径类型、数量分布进行观测，结合岩溶发育状况、土壤条件和植被根系以及剖面入渗流和坡面径流的过程特征，讨论分析石漠化峰丛坡地土壤优先流形成和发生的影响因子，并重点监测土壤优先流途径中碳-水-钙等岩溶动力条件，研究土壤优先流的岩溶动力强度，系统研究不同石漠化程度下土壤优先流的形成过程和发生机制，揭示土壤优先流的岩溶效应。该项研究从岩溶动力条件的角度将土壤优先流引入典型石漠化峰丛洼地地区开展研究工作，是对岩溶石漠化条件下的岩溶水土研究的重要补充，对西南岩溶石漠化治理、水土保持及水土调蓄理论探索和实践具有重要的理论价值和现实意义。

石漠化峰丛山区具有特殊的地下、地表双层水文地质结构，土壤优先流不但与地表水、岩溶地下水密切相关，而且还是评价土壤水源涵养作用、抗侵蚀能力、土壤地球化学特征的重要指标，开展土壤优先流的研究对探讨岩溶区域水文生态过程、岩溶动力作用、水土保持等具有重要的研究价值。本课题以石漠化峰丛洼地、潜在石漠化坡地、轻度石漠化坡地、中度石漠化和重度石漠化坡地等类型土壤优先流为研究对象，通过野外示踪试验、现场监测与室内分析相结合的方法，对土壤优先流发生的形态特征、形态变化规律、路径数量、路径宽度分布、发生类型进行观测与分析，并对岩溶发育状况、土壤条件和植被根系以及剖面入渗流（土壤水）地球化学特征进行了采样与分析。研究结果表明：石漠化峰丛山区不同土壤类型条件下均有土壤优先流发生，具有普遍性；坡地土壤优先流主要以垂直方向分布为主，大部分剖面优先路径可向地下延伸至碳酸盐基岩与土壤接触面，受岩溶裂隙发育、植被根系、昆虫、土壤物理化学性质的影响，不同石漠化坡地类型的土壤优先流染色面积比、染色面积最大与最小区域深度、优先路径数量和优先流发生类型等表现出明显的差异特征。四种石漠化等级条件下示踪染色面积比的最大值分别为90%、40.7%、86%、35.2%，对应的土壤深度分别为30cm、10cm、40cm、10cm；受耕种条件和土壤物理特征的影响，洼地部位土壤优先流以基质流为主，局部分布有少量大孔隙流，而坡地部位不同深度、不同坡面土壤优先流类型包括基质流、非均质指流、高相互作用大孔隙流、混合作用大孔隙流等多种多样；不同的土壤渗流水地球化学性质与土壤环境因子关联性及其对应的影响作用程度差异明显。研究结果对岩溶石漠化治理、水土保持及水土调蓄理论探索和实践具有积极的理论价值和现实意义。