• Journal of Environmental Science International
• /
• v.27 no.10
• /
• pp.845-851
• /
• 2018

In this study, the runoff characteristics of the non-rainfall period were examined using daily rainfall data from 1977 to 2017 and the data of runoff into the dam. Results showed that, the mean runoff decreases with longer non-rainfall periods in the Andong dam basin. The correlation coefficient between non-rainfall days and average runoff reaches 0.85. The results of the analysis of the runoff characteristics during the non-rainfall period, based on the preceding rainfall of Andong dam are as follows. The runoff characteristics of the entire non-rainfall period, shows that, for a rainfall of 1.0 mm or less, the runoff height was larger than the rainfall size and the base runoff larger. The correlation between the antecedent rainfall and runoff height was reached as high as 0.9864 in the 30 ~ 50 mm interval of the antecedent rainfall period, and this is the interval where the linearity of rainfall and runoff was at its maximum in the Andong dam basin. The correlation between the antecedent rainfall and the runoff height reached 0.92 for rainfalls of 100.0 mm. However, for rainfalls of 100.0 mm greater, the correlation between the antecedent rainfall and runoff height during the rainfall period was 0.64, which is relatively small. In this study, we investigated the runoff characteristics of the rainfall period in the Andong dam watershed. As a result, it was confirmed that the mean runoff decreased with rainfall duration. The linearity was found to be weak for rainfall events greater than 100.0 mm. The results of this study can be used as data for water balance analysis and for formulating a water supply plan to establish water resource management of Andong dam.

• Journal of Environmental Science International
• /
• v.12 no.9
• /
• pp.949-955
• /
• 2003

The subject basin of the research was the basin of Yeongcheon Dam located in the upper reaches of the Kumho River. The parameters of the model were derived from the results of abstracting topological properties out of rainfall-runoff observation data about heavy rains and Digital Elevation Modeling(DEM) materials. This research aimed at suggesting the applicability of the CELLMOD Model, a distribution-type model, in interpreting runoff based on the topological properties of a river basin, by carrying out runoff interpretation far heavy rains using the model. To examine the applicability of the model, the calculated peaking characteristics in the hydrograph was analyzed in comparison with observed values and interpretation results by the Clark Model. According to the result of analysis using the CELLMOD Model proposed in the present research for interpreting the rainfall-runoff process, the model reduced the physical uncertainty in the rainfall-runoff process, and consequently, generated improved results in forecasting river runoff. Therefore it was concluded that the algorithm is appropriate for interpreting rainfall-runoff in river basins. However, to enhance accuracy in interpreting rainfall-runoff it is necessary to supplement heavy rain patterns in subject basins and to subdivide a basin into minor basins for analysis. In addition, it is necessary to apply the model to basins that have sufficient observation data, and to identify the correlation between model parameters and the basin characteristics(channel characteristics).

• Membrane and Water Treatment
• /
• v.10 no.1
• /
• pp.45-55
• /
• 2019

Climate change has significantly affected the rainfall characteristics which can influence the pollutant build-up and wash-off patterns from the catchment. Therefore, this study explored the influence of varying rainfall characteristics on urban and agricultural runoff pollutant export using statistical approaches. For this purpose, Mann-Kendall and Pettitt's test were applied to detect the trend and breakpoint in rainfall characteristics time series. In addition, double mass curve and correlation analysis were used to drive the relationship between rainfall-runoff and pollutant exports from both catchments. The results indicate a significant decreased in total rainfall and average rainfall intensity, while a significant increased trend for antecedents dry days and total storm duration over the study periods. The breakpoint was determined to be 2013 which shows remarkable trend shifts for total rainfall, average rainfall intensity and antecedents dry days except total duration. Double mass curve exhibited a straight line with significant rainfall-runoff relationship indicates a climate change effect on both sites. Overall, higher pollutant exports were observed at both sites during the baseline period as compared to change periods. In agricultural site, most of the pollutants exhibited significant (p< 0.05) association with total rainfall, average rainfall intensity and total storm duration. In contrast, pollutants from urban site significantly correlated with antecedent dry days and average rainfall intensity. Thus, total rainfall, average rainfall intensity and total duration were the significant factors for the agricultural catchment while, antecedents dry days and average rainfall intensity were key factors in build-up and wash-off from the urban catchment.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.49 no.1
• /
• pp.3-13
• /
• 2007

In this study, spatial characteristics of rainfall in Imha basin were investigated by cross-correlation analysis among rainfall gaging stations and rainfall-runoff analysis used in HEC-HMS model for analysis of influence on observed rainfall. The Kriging technique was applied to rain(all analysis in Imha basin to reflect spatial characteristics of regional rainfall. Their results are compared to rainfall-runoff data with spatially distributed rainfall data as well as the classical thiessen method. The results by kriging technique approached by geostatistical method could reflect spatial characteristics of regional rainfall properly in Imha basin.

• Journal of Environmental Science International
• /
• v.23 no.4
• /
• 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.

• Journal of Korean Society on Water Environment
• /
• v.28 no.4
• /
• pp.523-530
• /
• 2012

Runoff, NPS pollution load and flow-weighted mean concentration (FWMC) occurred by snowmelt and rainfall runoff were compared by a variance analysis. Snowmelt runoff ranged between 1,449 and $19,921m^3$. The peak snowmelt runoff was similar to the runoff that occurred by about 40mm/day rainfall. And average snowmelt runoff was not significantly different from the runoff that occurred by 25.5 mm/day rainfall. Average values of SS loads and FWMCs were 5,438 kg/day and 954.9 mg/L, respectively. SS loads and FWMCs were in the similar range with those that occurred by 39.0 mm/day and 53.0 mm/day rainfall, respectively. Daily SS and COD loads and FWMCs occurred by snowmelt and rainfall were analyzed not to be significantly different. Overall assessment led that the NPS pollution loads by snowmelt runoff had a similar characteristics with the loads by about 40 mm/day rainfall runoff. It was recommended that the agricultural fields in snowy region needs to managed not only for rainfall runoff but also snowmelt runoff for an effective water quality management.

• Journal of Korea Water Resources Association
• /
• v.50 no.5
• /
• pp.347-358
• /
• 2017

This study examined characteristic differences by the rainfall direction on the runoff responses. The directional characteristics of hydrological components in a basin were quantified by von Mises distribution. The runoff hydrograph was derived using the result of convolution integration of each distribution and this hydrograph was compared with GIUH model and observed data. As a result, it was found that runoff response by rainfall direction was more similar the observed rainfall-runoff data than the runoff result using GIUH model. These results implies that runoff modeling could be improved by considering directional components in hydrologic analysis. This study would be helpful to reduce uncertainties of hydrologic analysis considering a non-linearity of rainfall-runoff process by the rainfall direction.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.1
• /
• pp.47-54
• /
• 2012

This study analyzed influence factors and the correlation among pollutants which affect occurrence of leaked pollution based on the long-term runoff flow and water quality investigation results to understand the characteristics of highway rainfall runoff pollution load. According to the result of correlation analysis on TSS (Total Suspended Solid) concentration, anteceded dry days, rainfall intensity, traffic volume and etc. as major influence factors of highway rainfall runoff pollution loads, the correlations were weak or scarce in most items. These results might be attributed that runoff pollutant concentration changes vary severely on changes of rainfall intensity and rainfall duration within rainfall and it is affected by disturbances of vehicles and street cleaning and etc. as characteristics of the highway. While Cu, Fe and Zn which are discharged with high concentrations out of heavy metals showed high correlation with particulate matter, organic matter(COD), nutrient(TN, TP), Ni and Pb showed relatively low correlation in a correlation evaluation by pollutant. Significant correlation with traffic volumes was not shown and TSS concentration even decreased in accordance with increase of the traffic volume. In the comparison with precedent studies, it was considered necessary additional analysis of the effects of rainfall section analysis, road type, disturbances of surface contaminants by vehicles, rainfall and climate conditions, surrounding terrains etc.

• Journal of Environmental Health Sciences
• /
• v.31 no.1
• /
• pp.1-6
• /
• 2005

This study was conducted to identify the runoff characteristics of non-point source according to rainfall in Nam watershed. Land-uses of the Nam watershed were surveyed paddy field 4.5%, crop field 6.8%, mountainous 78.7%, urban 2.4%, and etc. 7.7%. Mean runoff coefficients in each area were observed Ⅰ area 0.08, Ⅱ area 0.08, and Ⅲ area 0.05. In the relationship between the rainfall and peak-flow, correlation coefficients(r) were investigated Ⅰ area -0.8609, Ⅱ area 0.6035, and Ⅲ area -0.4913. In the relationship between the antecedent dry period and first flow runoff, correlation coefficients(r) were investigated Ⅰ area -0.9093, Ⅱ area -0.1039, and Ⅲ area -0.7317. The discharge of pollutant concentrations relates to the flow rate of storm-water. In the relationship between the rainfall and watershed loading, exponent values of BOD, COD, SS, and T-N were estimated to 1.2751, 1.2003, 1.3744, and 1.1262, respectively.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2001.10a
• /
• pp.93-98
• /
• 2001

This study was performed to analyse the rainfall and the rainfall-runoff characteristics of a rural watershed. The Sangwha basin($105.9km^{2}$) in the Geum river system was selected for this study. The arithmetic mean method, the Thiessen's weighing method, and the isohyetal method were used to analyse areal rainfall distribution and the Huff's quartile method was used to analyse temporal rainfall distribution. In addition, daily runoff analyses were peformed using the DAWAST and tank model. In the model calibration, the data from June through November, 1999 were used. In the model calibration, the observed runoff depth was 513.7mm and runoff rate was 45.2%, and the DAWAST model simulated runoff depth was 608.6mm and runoff rate was 53.5%, and the tank model runoff depth was 596.5mm and runoff rate was 52.5%, respectively. In the model test, the data from June through November, 2000 were used. In the model test, the observed runoff depth was 1032.3mm and runoff rate was 72.5%, and the DAWAST model simulated runoff depth was 871.6mm and runoff rate was 61.3%, and the tank model runoff depth was 825.4mm and runoff rate was 58%, respectively. The DAWAST and tank model's $R^{2}$ and RMSE were 0.85, 3.61mm, and 0.85, 2.77mm in 1999, and 0.83, 5.73mm, and 0.87, 5.39mm in 2000, respectively. Both models predicted low flow runoff better than flood runoff.