11/22/2023 0 Comments Hydrological processes journal swatIn many watersheds, it is difficult to adequately quantify hydrologic partitioning. Watershed-scale modeling can be a valuable tool to aid in quantification of water quality and yield however, several challenges remain. Based on the results of initial simulation shows the value that was satisfactory with a reduction in discharge simulation, influence algorithm module to paddy totaling 1.37%, after going through the process of calibration and validation of the results of the model grades more satisfactory, with grades R2 0.72 and NSE 0.71 for daily period and R2 0.70, NSE 0.63 for monthly periods. It was also analyzed the effect of modifications toward water balance on paddy fields. For evaluating the results of developed a module was seen from the value of determination (R2) and the Nash-Sutcliffe of efficiency (NSE) based on the comparison between discharge results simulation with observation. Module testing was carried out on sub – upper watershed Cisadane. It was developed by making modifications to module pothole from source code in SWAT program. This research aims to develop modules rice crop that accordance with the management of paddy fields in Indonesia. However, for usage SWAT in Asia, especially in Indonesia, where water management for rice crop is different from America, the existing module was in SWAT need to be adapted to the condition watering paddy field. SWAT has been widely used and applied to various countries in the world. The simulation using a seepage rate of 0.12 cm day À1 had the most accurate prediction of mefenacet concentration in river water with an R 2 of 0.61 and an E NS of 0.65. Occasional major precipitation events caused the mefenacet concentration in streams to peak quickly due to a corresponding loss of mefenacet from paddy areas, and then rapidly decrease due to dilution by excess rainfall discharge. The model successfully simulated the fate and transport of mefenacet in the Sakura River in which measured mefenacet concentrations peaked soon after the initial herbicide application in May, and decreased gradually during the months of June and July. High seepage rates gave a slight overestimation of the predicted base flow during the rice growing period, whereas the base flow predictions using lower seepage rates were comparable to measured data. The use of different seepage rates had appreciable influence on the simulations. The water flows predicted by the model in the Sakura River basin were accurate throughout the whole simulation year, with R 2 and E NS statistics exceeding 0.74 and 0.71, respectively for daily flow. The modeling procedures for simulating pesticide fate and transport in a Japanese river basin were demonstrated by providing model parameters related to hydrology, land use, pesticide fate, and rice field managements methods. Next, the model was calibrated and validated on the Sakura River basin (Ibaraki prefecture, Japan) using mefenacet concentrations measured during the rice growing season in 2008. The new combined model, model, was first used on some base-case scenarios to verify that the PCPF-1 algorithm and the routing of variables were correctly implemented. A plot scale model simulating pesticide fate and transport in rice paddies (PCPF-1) was incorporated into the Soil and Water Assessment Tool (SWAT) basin scale water and pollutant transport model. The objective of this study was to develop, verify, and validate a new GIS-based model for simulating the fate and transport of rice pesticides in river basins.
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