Optimization of irrigation regime in a sand dune soil field using HYDRUS-1D
2018
Kameyama, K. (Institute for Rural Engineering, NARO, Tsukuba, Ibaraki (Japan)) | Iwata, Y. | Miyamoto, T. | Sasaki, K.
In this study, we investigated the optimum irrigation regime for a sand dune soil field using a numerical simulation model. For this purpose, we used HYDRUS-1D to simulate the soil water regime in the root zone of an irrigated sand dune soil and evaluated the effects of irrigation scenario (matric potential threshold for irrigation and daily irrigation depth) on the cumulative irrigation amount, cumulative water discharge from the root zone, ratio of cumulative irrigation amount over potential evapotranspiration, and ratio of transpiration reduction using the triggered irrigation module in HYDRUS-1D. When a soil water characteristic parameter determined from undisturbed soil samples in the laboratory was used, volumetric water contents simulated by HYDRUS-1D differed from field measurements (RMSE = 0.031 - 0.039). Estimation accuracy was improved using a soil water characteristic parameter derived from an inverse analysis (RMSE = 0.007 - 0.009). Based on the results of scenario simulation with different matric potential thresholds for irrigation and daily irrigation depths, the matric potential threshold set at -75cm and the daily irrigation depth of 3.2 mm are recommended to decrease transpiration reduction and water discharge from the root zone.
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