岩溶关键带植被对水循环过程的影响作用研究

The Effect of Vegetation on Groundwater Cycle in the Critical Zone of the Karst Area

随着农村能源结构的调整和多项林草植被保护政策的实施,我国西南石漠化趋势得到初步的遏制。岩溶作用过程是由水循环驱动的碳循环过程。岩溶区森林植被的水文效应,不仅促进植被自身的生长,还能进一步促进岩溶作用过程。在西南岩溶区选择了2个不同植被覆盖条件的地下水系统为研究对象,通过地下水系统降水量、地下水径流量、水化学组分和同位素组分等监测指标的对比分析,发现岩溶关键带中,森林植被对水循环过程具有明显的影响。植被通过蒸腾作用而在林区激发二次降水,使林区降水量明显增大;森林植被对强降水的截流消洪作用比较明显,在降水-径流曲线上表现为森林覆盖区降水洪峰产生比较滞后而排泄过程中退水曲线上较为平滑;森林植被对岩溶关键带地下水中无机碳的贡献比较大,并能有效的增强岩溶作用。

With the adjustment of rural energy structure and the implementation of a few forest and grass vegetation protection policies,the trend of rocky desertification in southwest China has been initially contained.Karstification is a carbon cycle process that is driven by the water cycle.The hydrological effect of forest vegetation can not only promote the growth of vegetation itself but also further promote the karstification process.In this paper,two karst groundwater systems with different vegetation coverages in the karst critical zone of southwest China were chosen as study areas.The monitoring of indicators,including precipitation,groundwater discharge,hydrochemical components,and isotope composition,was conducted,and the effect of vegetation on groundwater cycle was discussed.The results indicate that forest can effectively enhance precipitation in the forest critical zone.Because vegetation can stimulate secondary precipitation by transpiration,the precipitation in the forest area is larger than that in other places obviously.Forest vegetation has obvious function of water interception and flood elimination.The max value of groundwater discharge in the forest cover area is more lagging behind and the rainfall-runoff curve is smoother than other regions with poor vegetation.In addition,forest vegetation contributes a lot to inorganic carbon in groundwater of karst critical zone and can effectively enhance karst process.