• Land and Housing Review
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• v.1 no.1
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• pp.75-82
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• 2010

Urban development is a cause of expansion of impervious area. A permanent storage is operated as a method of reducing runoff of watershed. The purpose of study is to propose reasonable choice of simulation model for rainfall-runoff in the prior review system on disaster effect. First, we indicated problem about concentration time choice in the flood simulation. To test the adequacy of a rainfall-runoff simulation model, We analyzed characteristics of rainfall-runoff about urban and natural watersheds. A simulation model was calibrated with the storm of july 7 to July 9 in 2009. From the result, we proposed that SWMM and kinematic wave method as the flood simulation models for urban and natural watersheds. A simulation model and design method of a permanent storage for flood that is proposed in this study will be useful for practical design of flood simulation. The hydrologic analysis method of the study can be used for capacity evaluation of permanent storage plan.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.39-39
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• 2012

Data assimilation techniques have received growing attention due to their capability to improve prediction in various areas. Despite of their potentials, applicable software frameworks to probabilistic approaches and data assimilation are still limited because the most of hydrologic modelling software are based on a deterministic approach. In this study, we developed a hydrological modelling framework for sequential data assimilation, namely MPI-OHyMoS. MPI-OHyMoS allows user to develop his/her own element models and to easily build a total simulation system model for hydrological simulations. Unlike process-based modelling framework, this software framework benefits from its object-oriented feature to flexibly represent hydrological processes without any change of the main library. In this software framework, sequential data assimilation based on the particle filters is available for any hydrologic models considering various sources of uncertainty originated from input forcing, parameters and observations. The particle filters are a Bayesian learning process in which the propagation of all uncertainties is carried out by a suitable selection of randomly generated particles without any assumptions about the nature of the distributions. In MPI-OHyMoS, ensemble simulations are parallelized, which can take advantage of high performance computing (HPC) system. We applied this software framework for several catchments in Japan using a distributed hydrologic model. Uncertainty of model parameters and radar rainfall estimates is assessed simultaneously in sequential data assimilation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6B
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• pp.551-560
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• 2010

This study presents the export of constituent transport loads through a river system. The proposed constituent transport load estimating procedure can be operated with the on-going Korean TMDL monitoring system. This study firstly discusses the use of a hydrologic simulation model (TANK) to estimate stream-flow for the 40 sub-catchments. Model parameters are estimated from 8-days intervals flow data which has been monitored by NIER since 2004. Constituent transport loads are estimated with the 7-parameter log linear model whose parameters are estimated by the minimum variance unbiased estimator. Results from Nakdong river basin reveals that the proposed procedure provides satisfactory TN, TP and SS transport load estimates. As an application, a representative load duration curve is derived to represent the overall hydrologic flux of TN, TP and SS at Nakdong river basin.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.58-58
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• 2011

The Texas Commission on Environmental Quality(TCEQ) WAM(Water Availability Modeling) System consists of the generalized Water Rights Analysis Package(WRAP) river/reservoir system water management simulation model, 22 sets of WRAP hydrology and water rights input files for the 23 river basins of Texas, geographic information system tools, and other supporting databases. The WRAP/WAM modeling system, as routinely applied since the late 1990s, has not included consideration of water quality. Recently developed WRAP-SALT(Water Rights Analysis Package) is designed primarily for computing concentration frequency statistics and supply reliability indices at locations of interest in a river system for alternative water development and management scenarios. Though motivated primarily by natural salt pollution, WRAP-SALT water quality modeling features are applicable to essentially any conservative water quality constituent. The Brazos River studies discussed in this paper focus on total dissolved solids, though the available observed data also includes chloride and sulfate which can be modeled as individual constituents. The WRAP-SALT salinity input file contains loads or concentrations of salinity inflows during each month of the hydrologic period-of-analysis and reservoir storage at the beginning of the simulation. The WRAP-SALT model computes salt loads and concentrations for each control point of a river/reservoir system for inflows and outflows during the month and end-of-month reservoir storage for each month of the hydrologic period-of-analysis, for given loads entering the system. River reaches connect control points. The mass balance algorithms proceed from upstream to downstream, with outflow from one river reach contributing to inflow to the next downstream reach. In a given month, for each control point in sequence, the inflow loads are first computed. Loads and concentrations of outflows and reservoir storage at the control point are then determined. Complete mixing during the month is assumed at locations without reservoir storage.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.411-421
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• 2014

At present, the development in rainwater management approach is still insufficient due to the numerous adverse effects of urbanization. Storm water management is being developed to restore the natural state of water cycle undergoing several processes which were hindered such as infiltration and evapotranspiration. Low Impact Development (LID) was established in order to reduce the negative effects of urbanization to our environment. These developments can be used to respond to the effects of climate change such as heat island phenomenon. The effects of the development of new town in the district plan with application of LID facilities were studied and reported. Typically, LID facilities were applied in small scale development and were rarely used in large-scale development. Most of studies, however, did not assessment the effects of large-scale development projects with LID application to the natural water cycle. This study was conducted to simulate the urban hydrologic cycle simulation on Asan-Tangjeong in Korea. This study may be used in urban hydrologic cycle simulation and establishment of an urban water management plan in the future. Lastly, this study generated a model using the recently updated SWMM5 which determined the hydrologic cycle simulation after installation of LID facilities.

• Water Engineering Research
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• v.4 no.3
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• pp.111-126
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• 2003

Meteorological data are often needed to evaluate the long-term effects of proposed hydrologic changes. The evaluation is frequently undertaken using deterministic mathematical models that require daily weather data as input including precipitation amount, maximum and minimum temperature, relative humidity, solar radiation and wind speed. Stochastic generation of the required weather data offers alternative to the use of observed weather records. The precipitation is modeled by a Markov Chain-exponential model. The other variables are generated by multivariate model with means and standard deviations of the variables conditioned on the wet or dry status of the day as determined by the precipitation model. Ultimately, the objective of this paper is to compare Richardson's model and the improved weather generation model in their ability to provide daily weather data for the crop model to study potential impacts of climate change on the irrigation needs and crop yield. However this paper does not refer to the improved weather generation model and the crop model. The new weather generation model improved will be introduced in the Journal of KWRA.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.63-73
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• 2013

The objectives of this study were to develop a hydrologic simulation model to estimate surface drainage for irrigation districts consisting of paddy and protected cultivation, and to evaluate the applicability of the developed model. The model consists of three sub-models; agricultural supply, paddy block drainage, and protected cultivation runoff. The model simulates daily total drainage as the sum of paddy field drainage, irrigation canal drainage, and protected cultivation runoff at the outlets of the irrigation districts. The agricultural supply sub-model was formulated considering crop water requirement for growing seasons and agricultural water management loss. Agricultural supply was calculated for use as input data for the paddy block sub-model. The paddy block drainage sub-model simulates paddy field drainage based on water balance, and irrigation canal drainage as a fraction of agricultural supply. Protected cultivation runoff is calculated based on NRCS (Natural Resources Conservation Service) curve number method. The Idong reservoir irrigation district was selected for surface drainage monitoring and model verification. The parameters of model were calibrated using a trial and error technique, and validated with the measured data from the study site. The model can be a useful tool to estimate surface drainage for irrigated districts consisting of paddy and protected cultivation.

• Journal of Environmental Science International
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• v.18 no.9
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• pp.1035-1043
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• 2009

High turbid water in the River has been one of the major concerns to the downstream residence. Especially in the Nakdong River basin severe turbid water problem occurred in year 2002 and 2003 due to the typhoon Rusa and Maemi consecutively. The main objective of this study is to develop turbid water management system in reservoir downstream of the Nakdong River combining physically based semi-distributed hydrologic simulation model SWAT with 1-dimensional dynamic water quality simulation model. SWAT model covers the area from the upstream of the Imha and Andong reservoir to the Gumi gage station for the purpose of estimating flow rates and suspended sediment of the tributaries. From year 1999 to 2007 runoff simulation for 8 years $R_{eff}$ and $R^2$ ranges $0.46{\sim}0.9$, $0.54{\sim}0.99$ respectively. Through the linkage of models, outputs of SWAT model such as suspended sediment and flow rates of the tributaries can be incorporated into the 1-dimensional dynamic water quality simulation model, KoRiv1 to support joint reservoir operation considering the turbidity released from Imha and Andong reservoir. The applicability of model simulation has been tested for year 2006 and compared with measured data.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.49-60
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• 2007

The alpine agricultural activities are usually performed at higher and steep areas in nature. Thus, significant amounts of soil erosion are occurring compared with those from other areas. Thus, the soil erosion induced environmental impacts in these areas are getting greater. The Doam watershed is located at alpine areas and it has been well known that the agricultural activities in the watershed are causing accelerated soil erosion and water quality degradations. Many modeling approaches were employed to solve soil erosion and water quality issues. In this study, the Soil and Water Assessment Tool (SWAT) model was utilized to simulate the hydrologic and sediment behaviors in the Doam watershed. In many previous modeling studies, the digital soil map and its corresponding soil properties were used without modification to reflect soil conditioning at many agricultural fields of the Doam watershed. Thus, the soil sample was taken at the agricultural field within the Doam watershed and analyzed for its physical properties. In this study, the digital topsoil properties in the agricultural fields within the Doam watershed were replaced with the soil properties for reconditioned soil analyzed in this study to simulate the impacts of using soil properties for reconditioned soil in hydrologic and sediment modeling at the Doam watershed using the SWAT model. The hydrologic component of the SWAT model was calibrated and validated for measured flow data from 2002 to 2003. The $R^2$ value was 0.79 and the EI value was 0.53 for weekly simulated data. The calibrated model parameters were used for hydrologic component validation and the $R^2$ value was 0.86 and the EI value was 0.74 for weekly data. For sediment comparison, the $R^2$ value was 0.67 and the EI value was 0.59. These statistics improved with the use of soil properties of the reconditioned soil in the field compared with the results obtained without considering soil reconditioning. The simulated sediment amounts with and without considering the soil properties of the reconditioned soil were 284,813 ton and 158,369 ton, respectively. This result indicates that there could be approximately 79% of errors in estimated sediment yield at the Doam watershed, although the model comparison with the measured data gave similar satisfactory statistics with and without considering soil properties from the reconditioned soil.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.5
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• pp.35-42
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• 1995

his paper is to develop a GIS application model (GISCELWAB) for the spatial simulation of surface runoff from a small watershed. The model was constituted by three submodels : The input data extraction model (GISINDATA) which prepares cell-based input data automatically for a given watershed, the cell water balance model (CELWAB) which calculates the water balance for a cell and simulates surface runoff of watershed simultaneously by the interaction of cells, and the output data management model (GISOUTDISP) which visualize the results of temporal and spatial variation of surface runoff. The input data extraction model was developed to solve the time-consuming problems for the input-data preparation of distributed hydrologic model. The input data for CELWAB can be obtained by extracting ASCII data from a vector map. The output data management model was developed to convert the storage depth and discharge of cells into grid map. This model enables to visualize the spatial formulation process of watershed storage depth and surface runoff wholly with time increment.