喀斯特江河上游区植被恢复的水文过程综合响应研究

Vegetation change is an important factor affecting hydrological processes in watershed. In recent years, the vegetation restoration Vegetation change is an important factor affecting hydrological processes in watershed. In recent years, the vegetation restoration projects in the karst area have achieved remarkable results, which greatly changed the relationship between rainfall and runoff. However, due to the strong dissolution in carbonate rock area, resulting in a higher degree of fracture and pipe development in the carbonate rocks, the aquifer in the karst area is highly heterogeneous. Because the relationship between vegetation and hydrological processes in karst areas is more complex than other regions, the influence of vegetation restoration to hydrological processes in karst areas is still unclear. In this study, the field observation, remote sensing inversion and geoscience calculation methods are used to obtain the hydrological parameters. By coupling muti-sources spatial data with the distributed hydrological model for karst areas, watershed hydrological process simulation was carried out. Based on the results of hydrological process simulation, the changes of hydrological factors such as vegetation interception, evapotranspiration, soil water, surface karst water and so on during vegetation restoration were analyzed. On this basis, the scene simulation method is used to simulate the hydrological processes under different vegetation spatial distribution patterns and vegetation coverage conditions, and the variation of hydrological elements is also analyzed. The effects of vegetation restoration on hydrological processes in the basin were evaluated to reveal the hydrological response characteristics of vegetation restoration in the upper reaches of the karst area. The study can provide an effective scientific basis for ecological construction and rational utilization of water resources in karst area.

植被变化是影响流域水文过程的重要因素，喀斯特江河上游区近年植被恢复取得了显著效果，极大地改变了降雨径流关系。但是，由于溶蚀作用强烈，裂隙和管道发育，喀斯特地区含水层呈现高度异质性。与其它区域相比，喀斯特地区植被与水文过程的关系更复杂，目前喀斯特地区植被恢复的流域水文过程综合响应特征仍不明晰。课题以乌江上游响水河流域为研究区，采用野外观测与实验、生态水文参数遥感反演与地学计算方法，耦合适用于喀斯特地区的分布式水文模型，开展流域水文过程模拟。分析植被恢复过程中植被截留、蒸散发、土壤水、表层岩溶带含水量等水量平衡分量的响应。在此基础上，采用情景模拟方法，分析不同植被空间配置及植被覆盖状况下，流域生态水文要素的变化情况。从而评估植被恢复对流域水文过程的影响，揭示喀斯特江河上游区植被恢复的水文过程综合响应特征。研究可为喀斯特地区生态建设及水资源合理利用提供有效的科学依据。

喀斯特江河上游区是重要的生态屏障，在近20年的生态建设过程中植被恢复取得了显著的效果。在此背景下，本项目通过野外定位观测、遥感反演、模型模拟等手段，定量分析了植被恢复的水文综合效应。（1）贵州省34年间植被覆盖呈总体改善趋势，生态建设与保护工作成效显著，且未来短时间内持续增长。植被变化总体以轻微改善和稳定为主，非喀斯特区、峰丛洼地和岩溶槽谷区的植被覆盖较好，且改善较为明显，岩溶高原次之，岩溶峡谷和岩溶盆地的植被覆盖较差，退化现象较为显著。（2）不同恢复年限样地土壤含水量差异显著，随着植被恢复过程的进行，土壤含水量是减少的，但是减少的幅度较小。植被恢复年限与土壤含水量呈显著负相关（P<0.01），两者Spearman相关系数为-0.621。不同土层深度和不同季节上，也表现出土壤含水量随林地植被恢复减少的特征。（3）月尺度上，植被变化总体导致平均土壤水分降低，其中以5、12月降低量最大。导致土壤水分变异系数上升，其中以5月份的上升量最大。季节尺度上，植被变化导致平均土壤水分总体降低，其中以春季降低的量最大，平均降低了7.60%。土壤水分变异系数总体上升，春季上升的量最大，平均上升了45.20%。降水是植被引起的平均土壤水分和变异系数变化空间格局的最大影响因子，其次为岩性。包括气候、植被变化等的综合因素引起的土壤水分变化与仅由植被引起的土壤水分变化存在明显差异。（4）选取的代表性流域研究结果表明，该流域1985-2012年期间气温呈明显上升趋势，径流略有增加，降水呈不显着下降趋势。在修文河流域，人类活动对径流变化的贡献最大，占68.12%，其次是降水，占19.23%；对径流变化的最小贡献来自温度升高（12.65%）。喀斯特高原或喀斯特峰丛洼地地表径流受人类活动影响远大于气候变化。鉴于气候变化和人类活动对喀斯特地区径流的影响存在明显的空间异质性，应针对各流域的具体情况采取针对性的管理措施。