• 한국물환경학회지
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• 제29권1호
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• pp.45-54
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• 2013

This study analyzes the reduction effects of runoff and flood damage through different arrangements of stormwater storage facilities. Three scenarios based on the spatial allocation of storage capacity are used: concentrated, decentralized and combinative. The characteristics of runoff and flood damage by scenario are compared. The XP-SWMM model is used for runoff simulation by the probable rainfall of return period. The result shows that the concentrated arrangement of storage facilities is most effective to reduce the amount of peak flow and to delay the time of peak flow. Yet, while the concentrated arrangement is most effective to reduce the inundation damage, it is not effective to reduce runoff volume. The decentralized arrangement is most effective to reduce runoff volume. The combinative arrangement is effective not only the runoff reduction but also the reduction of flood damage. The result indicates that the flood mitigation strategies against heavy rainfall need to consider decentralized on-site arrangement for the reduction of runoff volume along with concentrated off-site arrangement of storage facilities.

• 한국물환경학회지
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• 제26권4호
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• pp.654-663
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• 2010

Attention has increasingly focused on the pollutant load discharged from rural area since the enforcement of total maximum daily loads (TMDLs) in korea. As one of the methods to control the inflow of pollutant load during wet weather events, local governments are attempting to apply non-point source control facility. To design those facilities appropriately, it is essential to understand the runoff characteristics of pollutants such as TSS, $BOD_5$, $COD_{Cr}$, TP and TN. In the paper, the quantitative analyses for pollutant runoff characteristics were examined in a small rural watershed with the area of about 53 hectares. For a dry weather day and wet weather events, variation patterns of dry weather flow and runoff characteristics of wet weather flows were monitored and investigated. The runoff model using XP-SWMM reflecting the landuse types of the watershed in detail was simulated to perform the sensitivity analyses for several factors influencing on their hydrograph and pollutographs. As a result, for the case of medium and small rainfall events (i. e. total rainfall of 35.8 and 17.5 mm), the impervious area including green house, roof and road which covers relatively low portion of total area (i. e. 16%) caused substantial first flush and the majority of total runoff load. Therefore, it has been concluded that the runoff characteristics of each pollutant and distribution of impervious area should be considered for the establishment of the control strategy of non-point pollutant runoff at a rural area.

• 한국농공학회논문집
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• 제46권3호
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• pp.43-54
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• 2004

For a given watershed that consists of urbanized areas, it was essential to predict how the runoff characteristics, such as runoff peak and volume, and travel time, change with time far planning and designing various kinds of hydraulic facilities with given recurrence interval. In this study, Mushim stream watershed was simulated using HEC-HMS model to get runoff characteristics of an urbanization basin. The results was showed that runoff was increased $1794.20{\sim}2104.65\;m^{3}/s$> and $1751.90{\sim}1961.30\;m^{3}/s$ according to the increased of rainfall and CN value recurrence interval in years. Observed storm was increased $497.91{\sim}581.71\;m^{3}/s$ and $506.57{\sim}537.01\;m^{3}/s$ for increased of CN value and impervious area. This paper is also possible to evaluate the effect of urbanization quantitatively.

• 한국농공학회논문집
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• 제65권6호
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• pp.37-49
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• 2023

Rainfall data is one of the most important data in hydrologic modeling. In this study, the impacts of spatial resolution of precipitation data on hydrological responses were assessed using SWAT in the Santa Fe River Basin, Florida. High correlations were found between the FAWN and NLDAS rainfall data, which are observed weather data and simulated weather data based on observed data, respectively. FAWN-based scenarios had higher maximum rainfall and more rainfall days and events compared to NLDAS-based scenarios. Downstream areas showed lower correlations between rainfall and peak discharge than upstream areas due to the characteristics of study site. All scenarios did not show significant differences in base flow, and showed less than 5% of differences in high flows among NLDAS-based scenarios. The impact of resolution will appear differently depending on the characteristics of the watershed and topography and the applied model, and thus, is a process that must be considered in advance in runoff simulation research. The study suggests that applying the research method to watersheds in Korea may yield more pronounced results, and highlights the importance of considering data resolution in hydrologic modeling.

• 한국농공학회지
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• 제29권4호
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• pp.59-72
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• 1987

Although long-term runoff analysis is important as much as flood analysis in the design of water works, the technological level of the former is relatively lower than that of the latter. In this respect, the precise estimation model for the volume of successive runoff should he developed as soon as possible. Up to now, in Korea, Gajiyama's formula has been widely used in long-term runoff analysis, which has many problems in applying in real situation. On the other hand, in flood analysis, unit hydrograph method has been exclusively used. Therefore, this study aims at trying to apply unit hydrograph method in long-term runoff analysis for the betterment of its estimation. Four test catchment areas were selected ; Maesan area in Namlum river as a representative area of Han river system, Cheongju area in Musim river as one of Geum river system, Hwasun area in Hwasun river as one of Yongsan river system, and Supyung area in Geum river as one of Nakdong river system. In the analysis of unit hydrograph, seperation of effective rainfall was carried out firstly. Considering that effective rainfall and moisture condition of catchrnent area are inside and outside of a phenomenon respectively and the latter is not considered in the analysis, Initial base flow(qb)was selected as an index of moisture condition. At the same time, basic equation(Eq.7) was established, in which qb can take a role as a parameter in relating between cumulative rainfall(P) and cumulative loss of rainfall(Ld). Based on the above equation, computer program for estimation model of qbwas seperately developed according to the range of qb, Developed model was applied to measured hydrographs and hyetographs for total 10 years in 4 test areas and effective rainfall was estimated. Estimation precision of model was checked as shown in Tab- 6 and Fig.8. In the next stage, based on the estimated effective rainfall(R) and runoff(Qd), a runoff distribution ratio was calculated for each teat area using by computerised least square method and used in making unit hydrographs in each test area. Significance of induced hydrographs was tested by checking the relative errors between estimated and measured runoff volume(Tab-9, 10). According to the results, runoff estimation error by unit hydrograph itself was merely 2 or 3 %, but other 2 or 3 % of error proved to be transferred error in the seperation of effective rainfall. In this study, special attentioning point is that, in spite of different river systems and forest conditions of test areas, standardized unit hydrographs for them have very similar curve shape, which can be explained by having similar catchinent characteristics such as stream length, catchinent area, slope, and vegetation intensity. That fact should be treated as important factor ingeneralization of unit hydrograph method.

• 한국농공학회지
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• 제37권5호
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• pp.81-89
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• 1995

One of the most difficult problem to estimate the flood inflow is how to understand the effective rainfall. The effective rainfall is absolutely influenced by the condition of soil moisture in the watershed just before the storm event. DAWAST model developed to simulate the daily streamflow considering the meteologic and geographic characteristics in the Korean watersheds was applied to understand the soil moisture and estimate the effective rainfall rather accurately through the daily water balance in the watershed. From this soil moisture and effective rainfall, concentration time, dimensionless hydrograph, and addition of baseflow, the rainfall-runoff model for flood flow was developed by converting the concept of long-term runoff into short-term runoff. And, real-time flood forecasting model was also developed to forecast the flood-inflow hydrograph to the river and reservoir, and called RETFLO model. According to the model verification, RETFLO model can be practically applied to the medium and small river and reservoir to forecast the flood hydrograph with peak discharge, peak time, and volume. Consequently, flood forecasting and warning system in the river and the reservoir can be greatly improved by using personal computer.

• 한국농공학회논문집
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• 제49권6호
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• pp.3-9
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• 2007

Stream flow and water quality were measured and analyzed with respect to flow-weighted mean concentrations (FWMCs) of 21 rainfall events from a forested watershed (Forest Research Watershed: FRW) and two mixed watersheds of agriculture and forest (YuPo-Ri Watershed: YPW and WolGog-ri Watershed: WGW) located in the middle of the North Han River basin. The monitoring of each watershed was one year and conducted between 2004 and 2006. YPW showed more intensive agricultural practices than WGW where traditional practices were common. The average of the 21 FWMCs were in the order of YPF>WGW>FRW and were significantly different from each other at the level of 0.05. It was shown that the land use with intensive agricultural practices produced and discharged more NPS pollutants than that with traditional practices and forest. Specially, SS concentrations from the mixed watersheds were significantly higher than those from FRW. Influencing factors on runoff were analyzed rainfall and watershed area. And rainfall intensity was greater impact on runoff than daily rainfall. Measured water quality indices were shown positive correlations among them in general. However, no significant correlation was shown between COD and nutrients(T-N and T-P).

• 한국수자원학회논문집
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• 제51권10호
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• pp.917-927
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• 2018

본 연구에서는 대전 관평천의 도시유역에서 2017~2018년에 발생한 강우 20건의 유출수를 연속적으로 채취하여 As, Cd, Cr, Cu, Ni, Pb 및 Zn의 중금속 및 총고형물질(TSS) 농도와 유량을 분석하고, 강우특성과 수질 변화의 강우사상별 및 시간별 상관관계를 조사하였다. 일정 강우강도에서 오염물질의 최대농도는 강우 초기에 발생하는 경향을 나타냈으나, 강우량 및 강우강도가 작은 경우에는 일정 시간 경과 후 발생하는 것이 관찰되었다. 강우지속시간은 중금속 농도 및 부하량과 큰 상관성을 보이지 않았다. Cu와 Zn을 제외한 중금속 질량은 강우강도(0.60~0.88) 및 총강우 유출량(0.74~0.89)과 상대적으로 높은 상관관계를 나타냈다. 강우 시 유량가중평균농도와 선행무강우일수 또한 양의 상관성(0.54~0.73)을 보이는 반면, 30분 강우강도로 표현된 시간별 유출량과 TSS 및 중금속 농도는 전혀 상관성을 나타내지 않았다. 무강우 기간 동안 지표면에 축적된 오염물질이 최소한의 강우 에너지에도 세척효과가 발생하여 강우특성과는 무관하기 때문인 것으로 추정된다. 중금속과 TSS 농도의 시간에 따른 변화특성은 상관계수가 0.68~0.87로 양호한 수준을 나타냈다. 이는 고형물질의 이동과 중금속 물질의 이동이 함께 발생한다는 것을 시사하며 동시에 중금속이 고형물질에 흡착되어 이동한다는 것을 의미한다. 따라서 비강우 시에 유역 표면의 고형물질을 청소 등으로 사전에 제거할 경우 하천으로 유입되는 중금속오염물질의 양을 현격하게 저감할 수 있을 것으로 판단된다.

• 한국습지학회지
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• 제11권3호
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• pp.81-88
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• 2009

본 연구는 축산퇴비(우분)의 농지환원시 비점오염원으로써 수계에 미치는 영향을 연구하였다. 실제 농지에 작물을 재배하여 강우에 따라 농지표면으로 직접적으로 유출되는 유출수의 성분을 조사하였다. 축산퇴비(우분)의 농지환원시 수계유출율을 산정한 결과 단기유출의 강우시 BOD5는 0.6 %, CODcr은 0.3 %, CODMn은 0.1 %, T-N은 0.8 %, T-P는 1.0 %로 나타났다. 장기유출의 강우시 BOD5는 3.6 %, CODcr은 1.0 %, CODMn은 0.9 %, T-N은 4.9 %, T-P는 4.8 %로 나타나 강우유출시간이 증가될수록 수계유출율이 증가되는 것으로 나타났다.

• 한국농공학회논문집
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• 제49권3호
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• pp.21-31
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• 2007

This study is aimed at the development of a runoff forecasting model by using the Fuzzy inference system and Neural Network model to solve the uncertainties occurring in the process of rainfall-runoff modeling and improve the modeling accuracy of the stream runoff forecasting. The Neuro-Fuzzy (NF) model were used in this study. The NF model, recently received a great deal of attention, improve the existing Neural Networks by the aid of the Fuzzy theory applied to each node. The study area is the downstreams of Naeseung-chun. Therefore, time-dependent data was obtained from the Wolpo water level gauging station. 11 and 2 out of total 13 flood events were selected for the training and testing set of model respectively. The schematic diagram method and the statistical analysis are conducted to evaluate the feasibility of rainfall-runoff modeling. The model accuracy was rapidly decreased as the forecasting time became longer. The NF model can give accurate runoff forecasts up to 4 hours ahead in standard above the Determination coefficient $(R^2)$ 0.7. In the comparison of the runoff forecasting using the NF and TANK models, characteristics of peak runoff in the TANK model was higher than ones in the NF models, but peak values of hydrograph in the NF models were similar.