• 한국수자원학회논문집
• /
• 제53권7호
• /
• pp.493-505
• /
• 2020

현재 유역단위 수문해석을 목적으로 장기간 자료 확보가 용이하고 신뢰도가 확보된 지상관측소 강수량 자료를 강우-유출 모형을 활용하여 유출량을 평가하고 있다. 지상관측소 강수량 자료를 이용하여 면적평균 강수량을 산정하는데 있어 일반적으로 지상관측소의 위치 정보를 바탕으로 Thiessen 다각형법을 널리 이용하고 있으나 지상관측소의 공간적 편중으로 인해 면적평균 강수량 산정과정에서 제약이 있다. 본 연구에서는 시공간적으로 연속적인 강수량 관측이 가능한 기상레이더 자료를 이용하여 유역단위 면적평균 강수량을 산정하고 이를 PRMS 모형의 입력 자료로 활용하여 유출량을 평가하였다. 세부적으로 레이더 강수량의 편의 오차를 해결하기 위하여 G/R Ratio 기법을 적용하여 유역별로 레이더 강수량을 보정하였다. 레이더 강수량을 이용한 유출특성은 Thiessen 면적강수량을 이용한 유출의 통계적 특성을 현실적으로 재현하였다. 지상 관측소에 의존하여 생산하는 Thiessen 면적강수량에 비하여 레이더 강수량을 활용하는 것이 유역에 발생하는 강수의 공간적 특성을 효과적으로 반영하는 것으로 사료되며 향후 수문해석에서 정확도를 확보한 유출량을 제시할 것으로 판단된다.

• 한국농공학회지
• /
• 제45권2호
• /
• pp.45-57
• /
• 2003

An artificial neural network model was developed to analyze and forecast Short-term river runoff from the Naju watershed, in Korea. Error back propagation neural networks (EBPN) of hourly rainfall and runoff data were found to have a high performance In forecasting runoff. The number of hidden nodes were optimized using total error and Bayesian information criterion. Model forecasts are very accurate (i.e., relative error is less than 3% and $R^2$is greater than 0.99) for calibration and verification data sets. Increasing the time horizon for application data sets, thus mating the model suitable for flood forecasting. decreases the accuracy of the model. The resulting optimal EBPN models for forecasting hourly runoff consists of ten rainfall and four runoff data(ANN0410 model) and ten rainfall and ten runoff data(ANN1010 model). Performances of the ANN0410 and ANN1010 models remain satisfactory up to 6 hours (i.e., $R^2$is greater than 0.92).

• 한국환경복원기술학회지
• /
• 제22권6호
• /
• pp.115-124
• /
• 2019

In a climate change environment where heat damage and drought occur during a rainy season such as in 2018, a vegetation-based LID system that enables disaster prevention as well as environment improvement is suggested in lieu of an installation-type LID system that is limited to the prevention of floods. However, the quantification of its performance as against construction cost is limited. This study aims to present an experiment environment and evaluation method on quantitative performance, which is required in order to disseminate the vegetation-based LID system. To this end, a 3^rd quartile huff time distribution mass curve was generated for 20-year frequency, 60-minute probable rainfall of 68mm/hr in Cheonan, and effluent was analyzed by recreating artificial rainfall. In order to assess the reliability of the rainfall event simulator, 10 repeat tests were conducted at one-minute intervals for 20 minutes with minimum rainfall intensity of 22.29mm/hr and the maximum rainfall intensity of 140.69mm/hr from the calculated probable rainfall. Effective rainfall as against influent flow was 21.83mm/hr (sd=0.17~1.36, n=20) on average at the minimum rainfall intensity and 142.27mm/hr (sd=1.02~3.25, n=20) on average at the maximum rainfall intensity. In artificial rainfall recreation experiments repeated for three times, the most frequent quartile was found to be the third quartile, which is around 40 minutes after beginning the experiment. The peak flow was observed 70 minutes after beginning the experiment in the experiment zone and after 50 minutes in the control zone. While the control zone recorded the maximum runoff intensity of 2.26mm/min(sd=0.25) 50 minutes after beginning the experiment, the experiment zone recorded the maximum runoff intensity of 0.77mm/min (sd=0.15) 70 minutes after beginning the experiment, which is 20 minutes later than the control zone. Also, the maximum runoff intensity of the experiment zone was 79.6% lower than that of the control zone, which confirmed that vegetation unit-type LID system had rainfall runoff reduction and delay effects. Based on the above findings, the reliability of a lab-level rainfall simulator for monitoring the vegetation-based LID system was reviewed, and maximum runoff intensity reduction and runoff time delay were confirmed. As a result, the study presented a performance evaluation method that can be applied to the pre-design of the vegetation-based LID system for rainfall events on a location before construction.

• 한국농공학회논문집
• /
• 제58권4호
• /
• pp.57-66
• /
• 2016

Harmonized World Soil Database (HWSD) including the global soil information has been implemented to the runoff analysis in many watersheds of the world. However, its accuracy can be a critical issue in the modeling because of the limitation the low resolution reflecting the physical properties of soil in a watershed. Accordingly, this study attempted to assess the effect of HWSD in modeling by comparing parameters of the rainfall-runoff model using HWSD with the detailed soil map. For this, Grid based Rainfall-runoff Model (GRM) was employed in the Hyangseok watershed. The results showed that both of two soil maps in the rainfall-runoff model are able to well capture the observed runoff. However, compared with the detailed soil map, HWSD produced more uncertainty in the GRM parameters related to soil depth and hydraulic conductivity during the calibrations than the detailed soil map. Therefore, the uncertainty from the limited information on soil texture in HWSD should be considered for better calibration of a rainfall-runoff model.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2015년도 학술발표회
• /
• pp.439-439
• /
• 2015

The temporal and spatial relationship of the weather elements such as rainfall and temperature is closely linked to the streamflow simulation, especially, to the flood forecasting problems. For the study area, Imjin river basin, which has the specific characteristics in geography with river cross operation between North and South Korea, the meteorological information in the northern area is totally deficiency, lead to the inaccuracy of streamflow estimation. In the paper, this problem is solved by using the combination of global (such as soil moisture content, land use) and local hydrologic components data such as weather data (precipitation, evapotranspiration, humidity, etc.) for the model-driven runoff (surface flow, lateral flow and groundwater flow) data in each subbasin. To compute the streamflow in Imjin river basin, this study is applied the hydrologic model SURR (Sejong Univ. Rainfall-Runoff) which is the continuous rainfall-runoff model used physical foundations, originally based on Storage Function Model (SFM) to simulate the intercourse of the soil properties, weather factors and flow value. The result indicates the spatial variation in the runoff response of the different subbasins influenced by the input data. The dependancy of runoff simulation accuracy depending on the qualities of input data and model parameters is suggested in this study. The southern region with the dense of gauges and the adequate data shows the good results of the simulated discharge. Eventually, the application of SURR model in Imjin riverbasin gives the accurate consequence in simulation, and become the subsequent runoff for prediction in the future process.

• 한국물환경학회지
• /
• 제24권1호
• /
• pp.107-117
• /
• 2008

Infiltration facilities are effective instruments to mitigate flood and can increase base runoff in urban watersheds. In order to analyze effects of infiltration trenches physical model experiments were conducted. The physical model facility consists of two soil tanks, artificial rainfall generators, tensiometers, and piezometers. The experiment was conducted by nine times and each case differed in rainfall intensity, rainfall duration and the type of ground surface. Measured quantities in the experiments are as follows: surface runoff, subsurface runoff, trench pipe runoff, groundwater level, water content, etc. The following resulted from the model experiment: The volume of subsurface runoff at trench watershed was maximum 78.3% compared with rainfall. This value is bigger than that of ordinary rate of subsurface runoff, and shows a groundwater recharge effect of trench. The time of runoff passing through the trench became earlier and the volume of runoff became larger with the increase of inflow into the trench, while trench exfiltration into ground became relatively smaller. The results of this study presented above show that infiltration trenches are effective instruments to increase base runoff during dry periods.

• 한국환경과학회지
• /
• 제23권4호
• /
• pp.553-560
• /
• 2014

The rainfall-runoff characteristics in Jeju Island significantly differ from those in inland, due to highly permeable geologic features driven by volcanic island. Streams are usually sustained in the dry conditions and thereby the rainfall-runoff characteristics changes in terms of initiating stream discharge and its types, depending highly on the antecedent precipitation. Among various the rainfall-runoff characteristics, lag time mainly used for flood warning system in river and direct runoff ratio for determining water budget to estimate groundwater recharge quantity are practically crucial. They are expected to vary accordingly with the given antecedent precipitation. This study assessed the lag time in the measured hydrograph and direct runoff ratio, which are especially in the upstream watershed having the outlet as $2^{nd}$ Dongsan bridge of Han stream, Jeju, based upon several typhoon events such as Khanun, Bolaven, Tembin, Sanba as well as a specific heavy rainfall event in August 23, 2012. As results, considering that the lag time changed a bit over the rainfall events, the averaged lag time without antecedent precipitation was around 1.5 hour, but it became increased with antecedent precipitation. Though the direct run-off ratio showed similar percentages (i.e., 23%)without antecedent precipitation, it was substantially increased up to around 45% when antecedent precipitation existed. In addition, the direct run-off ration without antecedent precipitation was also very high (43.8%), especially when there was extremely heavy rainfall event in the more than five hundreds return period such as typhoon Sanba.

• 물과 미래
• /
• 제14권4호
• /
• pp.27-34
• /
• 1981

The design flow of the urban strom drainage systems has been assessed largely on a basis of empirical relations between rainfall and runoff, and the rational formula has been widely used for the cities in our country. In order to estimate it more accurately, the urban runoff simulation model based on the RRl method has been developed and applied to the sample basin in this study. The rainfall hyetograph of the design stromfor the design flow has been obtained by the determination of the total rainfall and the temporal distributions of that rainfall. The total rainfall has been assessed from the empirical formula of rainfall intensity and the temporal distribution of that rainfall determined on the basis of Huff's method from the historical rainfall data of the basin. The virtual inflow hydrograph to each inlet of the basin has been constructed by computing the series of discharges in each time increment, using design strom hyetograph and time-area diagram. The actual runoff hydrograph at the basin outlet has been computed from the virtual inflow hydrographs by developing a relations between discharge and storage for the watershed. The discharge data for verification of the simulated runoff hydrograph are not available in the sample basin and so the sensitivity analysis of the simulation model has not been possible. The peak discharge for the design of drainage systems has been estimated from the computed runoff hydrograph at the basin outlet and compared to thatl obtained form the rational formula.

• 한국습지학회지
• /
• 제12권3호
• /
• pp.155-163
• /
• 2010

돌발홍수는 짧은 지속기간, 급격한 경사와 불투수층에 대해 강한 강우로 인하여 피해를 유발하는 홍수를 말한다. 돌발홍수는 강우가 돌발홍수기준(Flash Flood Guidance)을 초과하는 경우에 발생하게 되며, 따라서 돌발홍수기준을 정확히 산정하는 것이 돌발홍수예보의 정확성에 크게 기여한다. 즉, 강우-유출관계가 갖고 있는 불확실성(uncertainty)을 최소화 할수록 돌발홍수기준을 정확하게 산정할 수 있으며, 강우-유출 모형은 각각 고유의 매개변수와 특성을 갖고 있으므로 어떠한 강우-유출 모형을 사용하여 강우-유출관계를 도출하느냐에 따라 불확실성의 정도가 크게 좌우된다. 본 연구에서는 4개의 강우-유출모형(HEC-HMS 모형, 저류함수모형, SSARR 모형, TANK 모형)의 모의값에 Monte Carlo 모의 방법을 적용하여 95%신뢰수준에 대한 신뢰한계를 추정하여 제시하였다.

• 한국조경학회지
• /
• 제36권4호
• /
• pp.111-119
• /
• 2008

합리식은 배수시설을 설계하기 위한 기본방정식으로 이용되고 있으며, 유출계수, 강우강도와 유역면적의 함수이다. 본 연구에서는 조경공간의 배수시설설계에 이용되는 합리식의 유출계수를 블록포장지역을 대상으로 지역적 강우분포를 고려하여 산정하였다. 합리식의 유출계수는 강우강도와 유출량의 비로 나타낼 수 있다. 강우강도는 재현기간과 강우지속기간의 함수로, 강우의 특성상 지역에 따라 변한다. 따라서 합리식의 유출계수는 동일한 재현기간과 강우지속기간일지라도 지역에 따라 강우강도가 변하므로 지역에 따라 변한다. 또한, 강우강도와 유출량의 비는 강우량에 대한 손실량에 따라 결정되므로, 손실량을 산정하기 위하여 본 연구에서는 Horton의 침투법칙 중 종기침투능을 이용하였다. 블록포장지역의 침투는 줄눈을 통하여 발생하며, 줄눈은 시간이 지남에 따라 황사, 오염물질, 꽃가루 등에 의하여 공극이 메워지고, 답압 등에 의하여 다져질 것이므로, 침투능은 감소할 것이다. 시공연한이 다른 6개 지역의 블록포장지역을 대상으로 Horton의 종기침투능을 산정하여 시간이 지남에 따라 침투능이 감소하는 것을 확인하였고, 지역별 재현기간 10년에 대한 강우지속기간 10, 20 및 30분에 해당하는 강우강도를 선정하여, 합리식의 유출계수를 산정하였다. 본 연구의 결과로, 산정 된 블록포장지 역의 유출계수 범위는 재현기간 10년, 강우지속기간 10분의 경우 지역에 따라 $0.94{\sim}0.84$의 범위를 가진다.