Numerical Analysis Of Coupled Water-Vapor-Heat Transport And Energy Balance Of GSPAC System In The Otindag Sandy Area

This study was supported by the Chinese National Science Foundation Program"Study for Evapotranspiration and Water Consumption Mechanism of Natural Vegeta- tion in the Otindag Sandy Land Region, China"(50769005) and the Chinese National Science Foundation Key Program"The scientific allocation of water resources in the ecological construction area between Inner Mongolia and Beijing, China"(50139040). We carried out open test and interior experiment carefully, use different hydrological years meteorological observation, crop index, and soil texture data during the there hydrological years to calculate and analysis.Measured surface soil physicochemical property and soil texture data were used to determined soil hydraulic properties. Four methods were used to calculate reference crop evapotranspiration and adjust by meteorological data. Evapotranspiration was calculated and evaluated using FAO-56 dual crop coefficient approach and Isareg model, analyze the characteristics and the key influences factors on actual evapotranspiration during the different hydrological years. Analyz and compare the variation and fluxes of the water- vapor-heat in surface, root-zone and variably-saturated media. Compare the water-vapor flux between sunny and rainy. Energy balance and photosynthetic properties were analyzed and influences of environmental factors were considered. The main conclusions are as follows:1. RETC-PTFs (pedo-transfer functions) and local-PTFs function structureded by SPSS were used to simulate soil hydraulic properties with measured surface soil physico- chemical property and soil texture data. The simulation results were assessed by the approach of fitting curve and by RMSE. Saturated hydraulic conductivity, saturated water contents and physicochemical property, soil texture are not linear relation and local-PTFs is effective. It is an innovation that linearity is turned into non-linear by SPSS.2.Four methods were used to calculate reference crop evapotranspiration and adjust by meteorological data. Analysis the characteristics and the key influences factors on evapotranspiration during the different hydrological years.(1) Relevant parameters estimation of reference crop evapotranspiration was determined by Genetic Algorithm. The results show that in those areas which lack net solar radiation, as and bs determined by Genetic Algorithm can be used in the estimation of reference crop evapotranspiration with preferable accuracy.(2) Other three common formulas were adjusted by meteorological data basing on universality strongly, high precision FAO56 Penman-Monteith. Provide a new simple way for reference crop evapotranspiration calculated, and the practical and universal needs to be research.(3) Inquire into the relationship between actual crop evapotranspiration and meteor- ological factors. Different hydrological year's actual crop evapotranspiration has the same impact factor. The moisture influence is greater than the influence of the tempe- rature in low flow year, and the opposite in high flow year.3.Natural vegetation soil water-vapor-heat flux of synchronize time and space, analyze the day and night water-vapor-heat flux and characteristics; the paper studies the soil profile migration regularity of water-vapor-heat day and night. To model with experimental data in low flow year, test parameters with data in high flow year. Analyz and compare the variation and fluxes of the water-vapor-heat in surface, root-zone and variably-saturated media. Summarize the differences and similarities during different hydrological years. The soil profile has same vapor flux trends and characteristics. Compare the water-vapor flux between sunny and rainy.4.Analyze and compare the energy balance. The relationship between canopy of latent heat flux and the energy efficient in low flow year isλE_c=0.965 Ln(A_c)+3.803, R~2= 0.59; in high flow year it isλE_c=1.158A_c+1.479, R~2=0.79. The canopy full coverage in high flow year can be judged by the change processes ofλE_s/(λE_c+λE_s), the correspond- ing LAI =2.17 and the same results can not be judged in low flow year.