干湿交替条件下小湾水库消落带土壤抗冲抗蚀性变化

The full impoundment of the Xiaowan Reservoir has created an artificial riparian zone with a vertical height of 74 m and a total area of 110 km2, which has been subjected to seasonal inundation and exposure due to regular reservoir impoundment and the occurrence of natural floods. The soil physical and chemical properties in the riparian zone change significantly with the alternation of drying and wetting. Soil physicochemical properties have important influence on soil anti-erosion capability. However, few studies is related to the changes of soil anti-scourability and anti-erodibility under the extreme condition of long-term wetting and drying cycle with wide water level fluctuation. Based on field surveys, soil sampling, determination of soil physical and chemical properties, evaluation of soil anti-erodibility and soil anti-scourability test, combined with analyses of reservoir water regulations and land-surface characteristics, this study attempts to evaluate the impact of wetting and drying cycles on the capacity of soil resistance to erosion and to reveal the influencing mechanism of drying and wetting cycles on soil anti-scourability and anti-erodibility. The research results would be helpful for areas selection for soil and water conservation and ecological management in the riparian zone of the Xiaowan Reservoir.

澜沧江干流中下游梯级龙头水电－小湾水库运行在库区形成高差达74 m、面积将近110 km2的峡谷陡坡型消落带，该区域在长时间淹水和落干交替作用下，土壤理化特性发生明显改变。土壤理化特性对其抗侵蚀性能有重要影响。目前，长时间、大幅度水位变化这一极端干湿交替条件下的土壤抗冲抗蚀性变化研究较少。本研究通过野外调查、土壤采样及理化性质分析、土壤抗蚀性评价和土壤抗冲性的试验测定，结合消落带坡度、植被覆盖状况、库水位变化分析，阐明小湾水库消落带土壤在长时间高压水淹和落干暴露反复交替作用影响下的抗冲抗蚀性变化规律；揭示干湿交替作用对消落带土壤抗侵蚀性能的影响机理，以期为水库消落带的生态治理理和水土保持工作提供指导。

澜沧江干流中下游梯级龙头水电－小湾水库运行在库区形成高差达74 m、面积将近90 km2的峡谷陡坡型消落带，该区域在长时间淹水和落干交替作用下，土壤理化特性发生明显改变，岸坡稳定性降低。土壤理化特性对其抗侵蚀性能有重要影响。本研究通过野外调查、土壤采样及理化性质分析、土壤抗蚀性评价和土壤抗冲性的试验测定、岸坡崩塌滑坡调查，结合消落带地质地貌、植被覆盖状况、库水位变化、人为活动等因子分析，阐明了小湾水库消落带土壤在长时间高压水淹和落干暴露反复交替作用影响下的抗冲抗蚀性变化规律；揭初步示干湿交替作用对消落带土壤抗侵蚀性能的影响机理，以期为水库消落带的土壤侵蚀防治和植被恢复工作提供指导。同时本研究基于库区10m分辨率dem、高分一号和Google Earth影像数据，利用ArcGIS空间分析功能，对小湾水库消落带和崩塌、滑坡信息进行识别提取，明晰了消落带和崩滑体的空间分布特征，并耦合区域地质地貌、地形条件、水位波动、降水等因子，分别采用信息量模型和层次分析法对小湾水库消落带的崩塌滑坡危险性进行了评价。然后，结合库区人类活动实地调查，确定库岸区承灾体类型，评估了库岸崩滑灾害的易损性。最后，综合研究区危险性评价和易损性评估结果，对小湾库区做出风险性评估和区划，研究结果可为库区管理者和当地政府提供防灾减灾规划依据。