SWAT modeling of best management practices for Chungju dam watershed in South Korea under future climate change scenarios

Suitable and practicable best management practices (BMPs) need to be developed due to steadily increasing agricultural land development, intensified fertilization practices, and increased soil erosion and pollutant loads from cultivated areas. The soil and water assessment tool model was used to evaluate the present and future proper BMP scenarios for Chungju dam watershed (6,642 km²) of South Korea, which includes rice paddy and upland crop areas. The present (1981–2010) and future (2040s and 2080s) BMPs of streambank stabilization, building recharge structures, conservation tillage, and terrace and contour farming were examined individually in terms of reducing nonpoint source pollution loads by applying MIROC3.2 HiRes A1B and B1 scenarios. Streambank stabilization achieved the highest reductions in sediment and T-N, and slope terracing was a highly effective BMP for sediment and T-P removal in both present and future climate conditions.     

Evaluation of MODIS NDVI and LST for indicating soil moisture of forest areas based on SWAT modeling

This study examined the capability of remotely sensed information gained using the terra moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) and land surface temperature (LST) to explain forest soil moisture. The soil and water assessment tool (SWAT) was used for the analysis. Nine years (2000–2008) of monthly MODIS NDVI and LST data from a 2,694.4 km² watershed consisting of forest-dominant areas in South Korea were compared with SWAT simulated soil moisture. Before the analysis, the SWAT model was calibrated and verified using 9 years of daily streamflow at three gauging stations and 6 years (2003–2008) of daily measured soil moisture at three locations within the watershed. The average Nash–Sutcliffe model efficiency during the streamflow calibration and validation was 0.72 and 0.70, respectively. The SWAT soil moisture showed a higher correlation with MODIS LST during the forest leaf growing period (March–June) and with MODIS NDVI during the leaf falling period (September–December). Low correlation was observed in the year of frequent rains, regardless of the leaf periods.     

The SRI (system of rice intensification) water management evaluation by SWAPP (SWAT–APEX Program) modeling in an agricultural watershed of South Korea

Paddy and Water Environment - In this study, a potential system for achieving rice intensification (SRI) water management in an agricultural watershed of South Korea was evaluated using the...     

A grid-based rainfall-runoff model for flood simulation including paddy fields

A grid-based, KIneMatic wave STOrm Runoff Model (KIMSTORM) is described. The model adopts the single flow-path algorithm and routes the water balance during the storm period. Manning’s roughness coefficient adjustment function of the paddy cell was applied to simulate the flood mitigation effect of the paddy fields for the grid-based, distributed rainfall-runoff modeling. The model was tested in 2296 km² dam watershed in South Korea using six typhoon storm events occurring between 2000 and 2007 with 500 m spatial resolution, and the results were tested through the automatic model evaluation functions in the model. The average values of the Nash–Sutcliffe model efficiency (ME), the volume conservation index (VCI), the relative error of peak runoff rate (EQ_p), and the absolute error of peak runoff (ET_p) were 0.974, 1.016, 0.019, and 0.45 h for calibrated storm events and 0.975, 0.951, 0.029, and 0.50 h for verified storm events, respectively. In the simulation of the flood mitigation effect of the paddy fields, the average values of the percentage changes for peak runoff, total runoff volume, and time to peak runoff were only −1.95, −0.93, and 0.19%, respectively.     

Hydrologic impact of climate change with adaptation of vegetation community in a forest-dominant watershed

This study evaluated the impact on watershed hydrology by predicting future forest community change under a climate change scenario. The Soil and Water Assessment Tool (SWAT) was selected and applied to Chungju dam watershed (6,642 km²) of South Korea. The SWAT was calibrated and validated for 6 years (1998–2003) using the daily streamflow data from three locations. For the future evaluation of forest community and hydrology, the MIROC3.2 HiRes monthly climate data were adopted. The future data were corrected using 30 years (1977–2006, baseline period) of measured weather data, and they were daily downscaled by the Long Ashton Research Station-Weather Generator statistical method. To predict the future forest vegetation cover, the baseline forest community was modeled by a multinomial LOGIT model using variables of baseline precipitation, temperature, elevation, degree of base saturation, and soil organic matter, and the future forest community was predicted using the future precipitation and temperature scenario. The future temperature increase of 4.8 °C by 2080s (2070–2099) led to prediction of 30.8 % decrease of mixed forest and 75.8 % increase of coniferous forest compared to the baseline forest community. For the baseline evapotranspiration (ET) of 491.5 mm/year, the 2080s ET under the forest community change was 591.1 mm/year, whereas it was 551.8 mm/year with the remaining forest community stationary. The different ET results considering the future forest community clearly affected the groundwater recharge and streamflow in sequence.     

Application of distributed KIneMatic wave STOrm Runoff Model (KIMSTORM) for flood simulation considering dam release in the NamHan river basin of Korea

Paddy and Water Environment - This study describes the application of distributed hydrologic model, KIneMatic wave STOrm Runoff Model (grid-based KIMSTORM) to simulate the flood discharge...     

Utilization of waste paper for an environmentally friendly slow-release fertilizer

To help address the physical, chemical, and biological degradation of agricultural soils resulting from indiscriminate use of chemical fertilizers, we developed a slow-release fertilizer from waste paper and urea. This approach has the advantage of a slow-release fertilizer in that it avoids surface runoff or leaching of nutrients, while providing an excellent medium for the recycling of waste paper. The successful impregnation of urea into waste paper was confirmed by scanning electron microscopy. This study also evaluated the release patterns of N from impregnated waste paper using a simulated soil solution and distilled water as leaching solutions. The release patterns of N were examined in both static and continuous-flow conditions for 720 h. Release of N from impregnated waste paper was found to be slow and steady, although the release rate of N was lower in distilled water than soil solution under both conditions. Part of this report was pesented at the Korean Society of Wood Science and Technology in Korea, April 2007, and the 3rd International Conference on Environmental Science and Technology in Houston, USA, August 2007