• Water for future
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• v.25 no.4
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• pp.109-119
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• 1992

The purpose of this study is to develop real-time streamflow forecasting models in order to manage effectively the flood warning system and water resources during the storm. The stochastic system models of the rainfall-runoff process using in this study are constituted and applied the Recursive Least Square and the Instrumental Variable-Approximate Maximum Likelihood algorithm which can estimate recursively the optimal parameters of the model. Also, in order to improve the performance of streamflow forecasting, initial values of the model parameter and covariance matrix of parameter estimate errors were evaluated by using the observed historical data of the hourly rainfall-runoff, and the accuracy and applicability of the models developed in this study were examined by the analysis of the I-step ahead streamflow forecasts.

• Journal of Forest and Environmental Science
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• v.34 no.4
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• pp.293-303
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• 2018

Sumber Jaya (54,194 hectares) is a district in West Lampung, Indonesia, located at the upper part of Tulang Bawang watershed. This watershed is one major water resource for Lampung Province, but has become a focal point of discussion because of the widespread conversion of forestland to coffee plantations and human settlements which lead to environmental and hydrological problems. This research aimed to evaluate Sumber Jaya watershed affecting by rapid land use change using hydrological methods as a base for watershed management. Nested catchment structure consisted of eight sub-catchments was employed in this research to assess scaling issues of land use change impacts on rainfall-runoff connections. Six tipping bucket rain gages were installed on the hill slopes of each sub-catchment and Parshall flumes were installed at the outlets of each sub-catchment to monitor stream flow. First, unit hydrograph that expressed the relationship of rainfall and runoff was computed using IHACRES model. Second, unit hydrograph was also constructed from observations of input and response during several significant storms with approximately equal duration. The result showed that most of the storm flow from these catchments consisted of slow flow. A maximum of about 50% of the effective rainfall became quick flow, and only less than 10% of remaining effective rainfall which was routed as slow flow contributed to hydrograph peaks; the rest was stored. Also, comparing peak responses and recession rates on the hydrograph, storm flow discharge was generally increased slowly on the rising limb and decreased rapidly on the falling limb. These responses indicated the soils in these catchments were still able to hold and store rain water.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.4
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• pp.52-59
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• 2006

This study was conducted to find end-members and tracers which are effective to be applied in the End Member Mixing Analysis (EMMA) model for runoff separation at the Gwangneung coniferous forest catchment (13.6ha), Gyeonggido, Korea. We monitored three successive rainfall events during two weeks from June 26, 2005 to July 10, 2005, and analysed chemical properties of rainfall, throughfall, stemflow, groundwater and soil water considered as main components of storm runoff. The followings are the results of analyses of each component and tracer. Groundwater, soil water and rainfall (or throughfall) were dominant runoff components. Rainfall and groundwater were selected as main components for the two components-one tracer mixing model, and groundwater, soilwater and throughfall were selected as main components for the three components-two tracers mixing model. Tracers were selected from anion ($Cl^-$ and ${SO_4}^{2-}$), cation ($Na^+$, $K^+$, $Mg^{2+}$, and $Ca^{2+}$) and Acid Neutralizing Capacity (ANC) in event 1, 2, and 3. $Na^+$, $Ca^{2+}$ and ANC were selected in the two components-one tracer mixing model and ${SO_4}^{2-}-K^+$, ${SO_4}^{2-}-Na^+$, ${SO_4}^{2-}-Ca^{2+}$, ${SO_4}^{2-}$-ANC, and $Ca^{2+}$-ANC were selected in the three components-two tracers mixing model. Selected main runoff components and tracers can provide basic information to determine the contribution rate of each runoff component and identify the runoff process in a forest watershed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.2
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• pp.3438-3453
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• 1974

Unmeasured value of water for human lives is widely approved, but the water as one of natural resources cannot be evaluated with ease since it changes itself ceaselessly by flowing-out or transforming the phase. Major objectives of the study concerned consequently with investigating its potentiality and evaluating its time seriesly availabity in a volumatic unit. And the study was performed to give the accurate original data to the planners concerned. Some developed rational methods of predicting runoff related to hydrological factors as precipitation, were to be discusseed for their theorical background and to be introduced whether they needed some corrections or not, comparing their estimation with actual runoff from synthetic unit-hydrograph methods. To do so, the study was performed to select Kongju Station, located at the watershed of the Keum River, and to collect such hydrological data from 1962 to 1972 as runoff, water level, precipitation, and so on. On the other hand, the hydrological characteristics of runoff were concluded more reasonably in numerical values, with calculating the the ratio of daily runoff to annual discharge of the flow in percentage, as. the distribution ratio of runoff. The results of the study can be summarized as follows; (1) There needed some consideration to apply the Kajiyama's Formula for predicting monthly runoff of rivers in Korea.(2) The rational methods of predicting runoff might be recommended to become less theorical and reliable than the unique analyzation of data concerned in each given water basin. The results from the Keum River prepared above would be available to any programms concerned. (3) The most accurate estimation for runoff could be suggested to synthetic unithydrograph methods calculated from the relation between each storm and runoff. However it was not contained in the study. (4) The relations between rainfall and runoff at KongJu Station were as following table. The table showed some intersting implications about the characteristics of runoff at site, which indicated that the runoff during three months from July to September approached total of 60% of quantity while precipitation concentrated on the other three from June to August. And there were some months which had more amount of runoff than expected values calculated from the precipitation, such as Febrary, March, August, September, Octover, and December, shown in the table. Such implications should be suggested to meet any correction factors in the future formulation concerned with the subjects, if any rational methods would be required.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.886-895
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• 2009

The guideline of selection of Integrated Management Practices (IMPs), such as wood, green roof, lawn, and porous pavement, for Low Impact Development (LID) design was proposed by ranking the reduction rate of surface runoff using LIDMOD1.0. Based on the guideline, LID was designed with several scenarios at two apartment complexes located at Songpa-gu, Seoul, Korea, and the effect of LID on surface runoff was evaluated during last 10 years. The effect of runoff reduction of IMP by land use change was highly dependent on the kind of hydrologic soil group. The wood planting is the best IMPs for reduction of surfac runoff for all hydrologic soil groups. Lawn planting is an excellent IMP for hydrologic soil group A, but reduction rate is low where soil doesn't effectively drains precipitation. The green roof shows constant reduction rate of surface runoff because it is not influenced by hydrologic soil group. Compared to the rate of other IMPs, the green roof is less effect the surface runoff reduction for hydrologic soil group A and is more effect for hydrologic soil group C and D followed to planing wood. The porous pavement for the impervious area is IMPs which is last selected for LID design because of the lowest reduction rate for all hydrologic soil group. As a result of LID application at study areas, we could conclude that the first step of the strategy of LID design at apartment complex is precuring pervious land as many area as possible, second step is selecting the kind of plant as more interception and evapotranspiration as possible, last step is replacing impervious land with porous pavement.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.122-127
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• 2000

A stream purification system was applied to the upper reaches of the Masan Reservoir to improve the water quality. This system consisted of two channels which were constructed on both sides of the stream, one side packed with crushed gravels and the other with plastic filter media. The system operated under low pollutant concentrations and high hydraulic loadings during a dry season to avoid clogging of the filter media. Removal rate and efficiency of chemical oxygen demand (COD) in the channel packed with crushed gravel were $14.8g/m^3/d$ and 11.5%, and for the channel with plastic filter media, $50.1g/m^3/d$ and 13.5%, respectively. Removal efficiencies of total phosphorus (T-P) were 6.6% (gravel) and 10.0% (plastic media). These results indicated plastic filter media having relatively high specific surface areas were more efficient than crushed gravels in removing pollutants. However, due to low influent water quality during dry season, the removal efficiencies were low. The proportion of nitrate nitrogen to total nitrogen (T-N) of the inflow was high but, as the system operated under aerobic condition, nitrate nitrogen could not denitrified. Accordingly, total nitrogen was not attenuated with this system. To improve the reservoir water quality effectively, this system should be able to treat the storm runoff containing higher pollutant loadings. When the filter materials are clogged by the storm runoff instead of backwashing, it would be more efficient to replace them, Therefore, the use of natural materials which are light, easily obtaining and replaceable, and have high specific surface areas is recommended.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1199-1203
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• 2005

Combined sewer overflows(CSOs) are themselves a significant source of water pollution. Therefore, the control of urban drainage for CSOs reduction and receiving water quality protection is needed. Examples in combined sewer systems include downstream storage facilities that detain runoff during periods of high flow and allow the detained water to be conveyed by an interceptor sewer to a centralized treatment plant during periods of low flow. The design of such facilities as stormwater detention storage is highly dependant on the temporal variability of storage capacity available(which is influenced by the duration of interevent dry periods) as well as the infiltration capacity of soil and recovery of depression storage. As a result, a contiunous approach is required to adequately size such facilities. This study for the continuous long-term analysis of urban dranage system used analytical Probabilistic model based on derived probability distribution theory. As an alternative to the modeling of urban drainage system for planning or screening level analysis of runoff control alternatives, this model have evolved that offer much ease and flexibility in terms of computation while considering long-term meteorology. This study presented rainfall and runoff characteristics or the subject area using analytical Probabilistic model. Runoff characteristics manifasted the unique characteristics of the subject area with the infiltration capacity of soil and recovery of depression storage and was examined appropriately by sensitivity analysis. This study presented the average annual COSs and number of COSs when the interceptor capacity is in the range 3xDWF(dry weather flow). Also, calculated the average annual mass of pollutant lost in CSOs using Event Mean Concentration. Finally, this study presented a dicision of storage volume for CSOs reduction and water quality protection.

• Journal of Wetlands Research
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• v.15 no.4
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• pp.543-553
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• 2013

In Korea, there have been many studies and progresses on various types of pilot scale or commercialized field scale Best Management Practices(BMP) during the last 10 years. Runoff characteristics of diffuse pollutants from different land uses are well identified and documented. However, for the coastal area connected directly with shoreline, runoff patterns and management schemes of non-point pollution were not fully studied. Recently, coastal area is emerging as a new development axis especially in west coast side of Korea such as Incheon city and Chungnam province, thus urbanized area rapidly increased but there are no buffer zones and BMP facilities to aim at preventing direct discharge of the first flush into coastal sea and beaches. In this study, parking area in Deacheon harbor, Boryeong City in Chungnam Province was selected and rainfall runoff was monitored for two year period in order to examine run-off features from which proper type of BMP suitable for coastal area is proposed. Coastal area usually has a low ground water level and consists of plain land, so that large scale BMP such as storm water retention pond and wetland requiring great excavation works is not best management plan. In addition, monitoring study shows that storm water from the paved parking area has a high salinity compared with those in storm water from the inland. High salinity is detrimental for the vegetation. Therefore, BMP employing least vegetative cover and also in terms of maintenance is a good option such as infiltration trench and porous pavement.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1737-1741
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• 2007

Using kinematic wave equation, the influence of moving rainstorms to runoff was analysised with a focus on watershed shapes and rainfall distribution types. Watershed shapes used are the oblong, square and elongated shape, and the distribution types of moving storms used are uniform, advanced and intermediate type. The runoff hydrographs according to the rainfall distribution types were simulated and the characteristics were explored for the storms moving down, up and cross the watershed with various velocity. And the hydrographs were compared in the case of varing the rainstorm intensity and varing the rainstorm length in order to make the same total runoff volume. When the rainstorm intensity was varied the shape, peak time and peak runoff of a runoff hydrograph are significantly influenced by spatial and temporal variability in rainfall and watershed shapes. The peak time of down and upstream moving strorms appeared latest in the case of the elongated shape basin, meanwhile at cross stream moving storms, the peak time of elongated shape basin is earlier than the others. For storms moving downstream peak time was more delayed than for other storm direction in the case of elongated watershed. The runoff volume and time base of the hydrograph decreased with the increasing storm speed.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.95-101
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• 2002

Much of domestic city is served by combined sewer system rather than separate sanitary or storm sewers. During wet weather, when the volume of sanitary sewage and storm water entering the combined sewers exceeds the system capacity, the system is designed to overflow at several designated CSOs. The objective of this research is to have grasp of characteristics of combined sewer runoff and to evaluate efficiently the intercepted volume of CSOs. During the wet weather in first rainfall, SS load at each site H-1, H-2, and H-3 were 600kg/event, 370kg/event, and 289kg/event, SS load at each site in second rainfall were 216kg/event, 113kg/event, and 37.2kg/event. EMCs at each site were 702mg/L, 816mg/L, 861mg/L in first rainfall and 99.9mg/L, 161.9mg/L, 103.6mg/L in second rainfall, respectively. First flush coefficients b at each site were 0.237, 0.166, and 0.151.