A New Method For Monitoring Water Potential In Slope Protection Plants And Soil Moisture

In recent years,the concept of plant slope protection has been gradually known by people.This technique overcomes the contradiction between the simple engineering slope protection and the destruction of ecological environment.It can not only prevent slope geological hazards and reduce the cost of slope protection,but also improve the environment,enhance soil moisture,beautify ecological landscape and promote ecological balance.Therefore,it has a very wide application prospect.But,there are few studies on the effect of transpiration on soil water and lack of quantitative analysis.Therefore,AHFO method was used in this paper to study the migration law of water during horizontal seepage in soil.Three kinds of plants were selected to analyze the changes of water distribution in soil during plant growth.The relationship between soil water content and water absorption time of plants was analyzed,and the influence of different plants on water content in soil was analyzed;Filter paper method was used to monitor leaf water potential.The influence of plant leaves and root system on soil water content and the relationship between water potential and water content in soil were analyzed.The research work and achievements are summarized as follows:(1)The measurement methods and techniques of water field in soil and water potential of vegetation used in slope protection were introduced and analyzed and the advantages and disadvantages of those methods were analyzed.On this basis,the Actively Heated Fiber Optic method(AHFO)based on distributed fiber temperature measurement system was introduced.(2)The basic principle of AHFO method was introduced,including:the basic principle of monitoring soil water content and the principle of using piecewise function model to describe the relationship between the temperature and soil water content;the basic principles of DTS and its applications in some engineering fields.Two kinds of heating cables were analyzed:wire type heating cable and carbon fiber heating cable.The fiber cable structure and heating method of carbon fiber heating cable were introduced.(3)The current method of monitoring leaf water potential and the principle of using filter paper to measure leaf water potential were introduced,.(4)An indoor test using AHFO method to monitor the movement of water in the horizontal infiltration process in soil was designed.The profile of water horizontal movement was analyzed and evaluated.The Green-Ampt model applied in the process of water migration was evaluated.The saturation permeability coefficient was modified to apply to unsaturated soil seepage.(5)The relationship between leaf water potential and soil water content was introduced and the indoor test using filter paper to measure leaf water potential was designed.(6)An indoor model test was designed to study the rule of water movement from soil to the root system.The relationship between soil water content and plant water absorption was analyzed.The effect of different plants on soil water content was studied.The Feddes model which is plant root water uptake model was modified with root density distribution function.The modified Feddes model was used to evaluate the results which were monitored by AHFO method.The mechanism of plant in slope protection was analyzed and the selection basis of slope protection plants was given.(7)The relationship between vegetation growth and soil water content was analyzed,including the effect of plant leaves and roots on soil water content,and the relationship between leaf water potential,root water potential and soil water content.