Study on the Leymus Chinensis Community of Water Requirement and GSPAC System Water in the Otinday Sandy Area

The key research project of the National Natural Science Foundation of China , \community water demand simulation transpiration , evaporation and actual observations for validation . Canopy structural changes of meteorological elements and root zone soil moisture changes based on the physiological characteristics of Leymus chinensis community growth period , the analysis of the calculation results , draw water demand of various growth stages of the growth period , average daily evapotranspiration intensity and variation . SWAP model using the measured data , the rate of moisture transport parameters fixed , determined , and inspection of the shallow groundwater areas two different hydrological years unsaturated zone and the root zone soil moisture migration simulation to study the water system GSPAC continuous migration law . The main conclusions of this paper are as follows : ( 1 ) FAO56 new methods and SWAP simulation model are two ways to calculate water demand less and can be used to calculate the water demand . Based on the available information and research purposes , we can choose these two methods . ( 2 ) a day Leymus chinensis transpiration from small increases, reaches a maximum in the 11-12 point , and then gradually smaller , consistent with the diurnal variation of net radiation , temperature , wind speed and vapor pressure deficit . ( 3) L. chinensis community in the initial stage of growth , very little water consumption by transpiration , evaporation larger . Growth and development stage of transpiration water consumption increases for increased canopy cover , evaporation is reduced . The growth of the mid- stage water consumption by transpiration rapid growth , the average daily evapotranspiration consumption intensity maximum evaporation to a minimum . The growth of the late stage of transpiration water consumption gradually smaller coverage gradually reduce evaporation begins to increase . Unsaturated (4 ) 2005 ( dry year ) growth period with reduced water storage capacity of 72.7mm , falling water tables , the depth increase , resulting in reduced groundwater supplies . Growth period in 2006 ( wet ), water storage in the unsaturated zone increased 46.4mm , while the increase in the water content of the soil is a common result of rainfall infiltration and groundwater table elevation .