| In recent years,with the development of the society,water resource shortage has became one of the main factors restricting the development of our country’s economy.In our country traditional selling irrigation methods,mainly by the surface infiltration irrigation water directly into the root zone of soil,because of the limitation of soil water infiltration capacity for deeper root distribution of fruit trees,water will not be fully taken advantage of.Professor Xihuan Sun presented a new selling irrigation method both solve the problem of drought and soil erosion in northern--water storage pit irrigation at the end of the20th century.Water storage pit irrigation method is a kind of stereoscopic depth irrigation method,has the advantages of saving water,kepting drought et.At present,soil water infiltration and evaporation,water transport and numerical simulation about water storage pit irrigation have achieved some results,but in view of the field moisture dynamics and numerical simulation is also a lack of systematic study.Therefore, the research on time and space dynamic distribution of soil moisture and numerical simulation about water storage pit irrigation is significant.Time and space dynamic change of soil moisture with different pit depth and different irrigation water was conducted in this paper,we also compare it with surface irrigation. Conclusions as following:(1)Study of space and time dynamic change under the condition of different pit deep soil pongdage have shown that:①The overall trend of two kinds of pit deep soil pongdage changes over time is roughly the same.Soil pondage decrease over time in the absence of water supply;②The vertical distribution of different pit deep under the condition of soil pongdage in different time is similar.It increased with the increase of depth,and then reduce.The greater the deep,the larger of reservoir capacity is;③The radial distribution under the condition of soil pongdage in different time is similar,soil pondage are centered in water storage pit;④Regression analysis for different pit deep soil pongdage vertical and radial distribution trend in different time are exponential functions;⑤The analysis of time variability soil pongdage vertical and radial distribution for different pit deep shows that the greater depth, the greater the coefficient of variation of depth is.The variation coefficient of around the water storage pit is greater.(2)The soil pongdage dynamic research on time and space under the condition of different irrigation water shows:①Due to the affected by evaporation and root water absorption,three kinds of irrigation water soil pongdage changes over time were showing similar volatility,the bigger the irrigation volume, the greater the soil pondage is in each period;②Three kinds of irrigation water under the condition of soil pongdage are all increase with depth first increases then decreases.The bigger irrigation water, the greater the deep in the soil pondage;③Three kinds of irrigation water in radial distribution trend is the same, soil reservoir capacity is large in the close water storage pit radialthe more irrigation water,the greater the radial on soil pondage;④Different irrigation water vertical and radial distribution of soil pongdage in different time are exponential functions;⑤Different irrigation water soil pongdage vertical and radial distribution based on the analysis of time variability analysis shows that,the greater depth,the greater the coefficient of variation of depth is,the greater the variation coefficient of around the water storage pit.(3)The analysis and comparison between water storage pit irrigation and surface irrigation dynamics in spatial and temporal change of soil pongdage show that:①Soil pongdage in two kinds of irrigation are present certain volatility over time,the surface soil pongdage fluctuations is apparent and in the deep is sTab.;②Soil pongdage in different period of vertical first increases and then decreases trend.On the radial, away from the water storage pit surrounding soil pondage is bigger under the condition of water storage pit irrigation;Under the condition of surface irrigation,soil pongdage from the surface of the vertical distribution decreasing,on the radial, there are no obvious difference;③80cm is a boundary,the ground soil pondage under80cm is greater than the water storage pit irrigation upon80cm,water storage pit irrigation is greater than surface irrigation.④The ertical and radial variation of soil pongdage on the different time are exponential functions.⑤Water in the storage pit irrigation is active both on the surface and in deep.The variation coefficient is bigger in the vicinity of water storage pit radial distance.The coefficient of variation is larger on the surface under the ground irrigation.Coefficient variation of water storage pit irrigation is larger than the ground irrigation in the deep.(4)Three-dimensional soil moisture movement model was established based on the analysis of water storage pit irrigation soil moisture migration rule.The simulation values and measured values coincide degree is better when verified by the measured data. |
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