Paddy fi elds in the Republic of Korea greatly contribute to nonpoint sources (NPS) pollutionto the downstream. The objective of this study was to develop paddy fi eld modelling systemfor predicting pollutant nutrient loads, and evaluating various BMPs (Best ManagementPractices) on paddy fi elds. The system consists of a pre-processing, the CREAMS-PADDY(Chemicals, Runoff, and Erosion from Agricultural Management Systems for PADDY), and apost-processing components. The CREAMS-PADDY model, a revised version of a physicallybased a fi eld-scale CREAMS to simulate drainage, sediment, and nutrient from paddy fi eldsin ponded water condition, was selected as a core model. The pre-processing componentincludes manipulations of meteorological data, a management of input parameters such asspatial characteristics and farming methods, and a support of batch running and implementingvarious scenarios. The post-processing component contains visualization of a water balanceand a nutrient balance components and statistical analysis for the build, calibration andvalidation phase of the baseline model application and for documenting scenarios results. Toevaluate the applicability of the developed system, reduction effects on water control methodsin paddy fi elds were simulated. Model parameters related to hydrology and water qualitywere calibrated and validated by comparing model predictions with the fi eld data collectedfor 2 years. The results indicated that T-N (total nitrogen) and T-P (total phosphorous)concentrations were reasonably close to the observed data. Nine different scenarios weredeveloped though combination of three height of drainage outlet (80, 100, and 120 mm) andminimal ponding depth (20, 40, and 60mm), and tested in terms of nutrient loads reductionfrom paddy fi elds. The simulation results indicate that reducing nutrient loss through surfacedrainage by water-saving irrigation and raising the height of drainage outlet could protectdownstream water quality. The simulation system appears to be a useful tool for planningBMPs (Best Management Practices) to reduce nutrient loads from paddy fi elds in Korea.
展开▼
