Though the upper stream basin area of Gwanpyung-Cheon in Daejeon, Korea is protected as Green Belt Zone, the stream is under constant environmental pressure due to current agricultural practices and infrastructure development in its basin area. To develop appropriate integrated water resources management plan for the stream, it is necessary to consider not only water quality problems but also water quantity aspect. In this study, Storm Water Management Model (SWMM) was calibrated and validated with sets of field measurements to predict for future water flow and water quality conditions for any rainfall event. While flow modeling results showed good agreement by showing correlation coefficient is greater than 0.9, water quality modeling results showed relatively less accurate levels of agreements with correlation coefficient between 0.67 and 0.87. Hypothetical basin development scenarios were developed to compare effect on stream water quality and quantity when Low Impact Development (LID) technologies are applied in the basin. The results of this study can be used effectively in decision making processes of urban development Gwanpyung-Cheon area by comparing basin management alternatives such as LID methods.

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Application of LID Methods for Sustainable Management of Small Urban Stream Using SWMM

This research was to estimate quantitative infiltration volume of permeable block which is one of runoff reduction infiltration facilities. In this research, the permeable block experiments estimating infiltration volume for 50, 100, 150, 200 mm/hr rainfall intensity were carried out and hydraulic experiments results were compared with numerical simulation output to produce feasibility of numerical simulation. Final infiltration capacity analysis of permeable block hydraulic experiments reveals that every estimated infiltration volume before runoff beginning was above approximately 300.0 l despite rapid reduction of infiltration ratio and runoff initiation time were occurred in every rainfall intensity. Statistical calculation for coefficient of determination based on cumulative infiltration volume of hydraulic experiment and numerical simulation resulted in a high correlationship as .

An Experimental Study on the Analysis of Infiltration Capacity of the Permeable Block

This study provides results from the experiment on the rainfall distribution using a large Experimental rainfall simulator with fixed nozzle arrangement. Results from the experiment on the nozzles which are crucial for rainfall simulation show standard errors expressed as percentage are 0.15~0.38% at the indoor flow testing apparatus and 0.37~0.59% at the KICT-ERS. To examine spraying range of the nozzles, radial and triangular rainfall measurement test are done. In the radial test, coefficient of uniformity (CU) lies in 0.348~0.657 in the single nozzle spraying case, while it increases up to 0.854~0.895 in the seven nozzle spraying case. This means increase of both rain rate and uniformity by means of superimposition of spraying. The CU of the triangular test falls to 0.845~0.896. The results from the experiment on the whole-scale of the KICT-ERS show that CU exceeds 0.7 for every case except the one experimental condition where a 1.5φ nozzle is used. The CU tends to increase with increasing rainfall intensity. Comparison with the previous studies shows that KICT-ERS provides rainfall distribution above average CU.

Analysis on Rainfall Distribution in a Large Experimental Rainfall Simulator with Fixed Nozzle Arrangement

Permeable pavement systems, an Low Impact Development technique, are widely used for pedestrian and bicycle roads, and parking lots, to relieve the flooding and enhance water cycle, which arises due to climate change and urbanization. However, due to lack of analytical means, permeable pavements are constructed most of time without knowing their performance in reducing runoff. In this paper, saturated permeability and porosity of a pervious concrete sample were experimentally estimated, and a set of infiltration model test was conducted; then, finally, the soil-water characteristics curve of the sample was back-calculated. In inverse analysis, van Genuchten model was selected, and Levenberg-Marquardt method was used for parameter searching algorithm. The results of soil-water characteristics curve presents the air-entry suction pressure is little below 1 kPa, and all the water expels at a suction pressure of 10 kPa. When compared to typical sands, the volumetric water content of pervious concrete drops more steeply with increasing suction pressure.

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Back-Calculation of Soil-Water Characteristics Curve for Permeable Pavement Material Based on Infiltration Tests

Climate change and urbanization have affected a increase of peak discharge and water pollution etc. In a view of these aspects, the LID(Low Impact Development) technology has been highlighted as one of adjustable control measures to mimic predevelopment hydrologic condition. Many LID technologies have developed, but there is a lack of studies with verification of LID technology efficiency. Therefore this study developed a rainfall-runoff simulator could be possible to verify LID technology efficiency. Using this simulator, this study has experimented the rainfall verification through the rainfall distribution experiment and the experiment to show the relation between inflow and effective rainfall in order to sprinkle the equal rainfall in each unit bed. As a result, the study defined the relation between allowable discharge range and RPM by nozzle types and verified the hydrologic cycle such as the relation between infiltration rate, surface runoff and subsurface runoff at pervious area and impervious area through the rainfall-runoff experiment.

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Papers

Lid 기술의 효율성 검증을 위한 강우-유출 모의장치 개발 및 검증실험에 관한 연구