Soil plant atmosphere continuum (SPAC) model for soil water consumption analysis on various topographic conditions

摘要

The soil plant atmosphere continuum (SPAC) model was adopted for computing irrigation water demand on various topographic conditions (it stands for fields with south facing, north facing and fiat topography) through analyzing radiation energy balance on each topographic conditions, which is inevitable for precise analysis of evapotranspiration and it was still lacking to be investigated. The precise analysis of evapotranspiration is required for reliable computation of water consumption. The proposed SPAC model was consisted of three sub-models to perform the soil water consumption analysis on various topographic conditions. Those three sub-models were: (1) Radiation energy evaluation sub-model, (2) Soil moisture and heat flow analysis sub-model and (3) Soil water uptake evaluation sub-model. Experiments were conducted in October on suitably prepared south and north facing fields, with 20 inclination, as well as on fiat field to verify accuracy of the simulation model. Analysis was performed with considering LAI 0, 2.0 and 4.0 for comparision of results. Results have shown that at each level of LAI evapotranspiration of south facing field was about 1.5 times higher than that of north facing field. Similarly, soil temperature of south facing cropped field at various depths in day time were also remarkably higher than in north facing cropped field. The results of simulation model were well matched with their respective observed values. Therefore, this model could be used for analysis of crop water consumption on various topographic conditions and thereby contribute for irrigation planning on those areas.