The Quantatative Research About Surface Evaporation And Hydrological Processes In Karst Mountains Regions

Although the annual rainfall abundance in southwest China karst peak cluster depression area,but the rainfall distribution is very uneven in each season,lead to distinguish between wet and dry conditions.shallow soil and soil total amount less in karst mountainous areas,precipitation infiltration of the storage time is short after the rain.The rise and fall rapidly of the hydrology dynamic,be prone to lead water shortage after the drought. above is the background of the thesis,so in this paper selects typical karst rock slope surface to discuss the hydrological dynamic characteristics from water volume.Choosing the Xiaoyan Cave located on Yaji karst experimental site in guilin and the above water catchment slope as research area, this paper via conducting dynamic monitor of the slope interflow, epikarst flow and cave shaft flow in different rainfall conditions and analysis, Choosing two covering soil dement as research area in this karst rock slope, attempt to analysis the soil profile layer water content distribution,soil evaporation rate size and related influencing factors.Finally making the following conclusions through studies:Firstly, put the tracer at some point of the slope,after the rain,the result shows that each monitoring point are connected. Via conducting dynamic monitor of the slope runoff and cave shaft flow in different rainfall conditions and analysis, the results show:(1)The slope runoff and vadose zone hydrology dynamic change process in karst mountainous areas are decide by rainfall intensity, rainfall duration and the condition of the water-bearing medium prophase water situation;(2)In different rainfall condition, the hydrology dynamic changes of slope runoff and cave shaft flow rise and fall rapidly, and the slope runoff even more rapidly than the cave shaft flow.In general, the hydrology dynamic change process of slope runoff last for a few hours to ten hours,but the cave shaft flow can last one to three days.Secondly, this paper attempt to analysis the soil profile layer water content distribution,soil evaporation rate size and related influencing factors,the result shows:(1)The soil maximum moisture content layer lied at the junction of the bottom soil and rock;the middle transition layer soil water content at least and the surface soil water change significantly by external factors influence.(2)There high evaporation in karst mountains region in summer,the Diameter10cm soil column evaporative capacity is lOmL to12mL in the day time and OmL to3mL in the evening.(3)Short term in a few days,the main factor determining the soil evaporation is the solar radiation and wind speed,they linrarly dependent coefficient respectively0.8771and0.7529.,The temperature and soil temperature is aslo the more inportant factors to affect the soil evaporation.but in the short term,soil moisture content is not the main factors to effect the soil evaporation.Lastly, the rainfall can become slope runoff after the downpour(The precipitation can reached50mm within12hours),but under the condition of the heavy rain to torrential rain,a large difference among distribution of water yield by the every aquifer medium(overland flow,epakarst flow,cave shaft flow) depending on the intensity of the rain.But above research,water allocation is subject to a specific background conditions,such as specific slope topography and slope gradient ect.