• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2244-2248
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• 2008

This study was focused on estimated Stream Maintenance Flow and performed for simulate securing Stream Maintenance Flow in New town development area. Tributary streams were made of 6 small streams, joined Gong-ji Stream and Eu-am lake finally. For estimate Stream Maintenance Flow used Kajiyama and SWAT models for calculate available flow in study area. As a result the annual average stream flow dry years were $2,300{\sim}136,000\;m^/day3$, the annual average stream flow wet years were $4,800{\sim}136,031\;m^3/day$. The coefficient of determination($R^2$) and Nash-sutcliffe coefficient(EI) for comparison between Kajiyama and SWAT models were 0.88, 0.78 respectively.

• Journal of Environmental Health Sciences
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• v.23 no.2
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• pp.89-97
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• 1997

Most of urban streams in Korea have been changed channel forms and suffered from direct inflow of domestic sewage, etc. Therefore, maintenance of structure and function of those ecosystem are hard. The present study was carried out to examine the life survival maintenance ability of the stream by community analysis of aquatic animals in typical urban stream (Jungrang stream) in Seoul. The aquatic animals were composed of 31 species, 18 families, 8 orders, 5 classes in 4 phyla. Seasonal species number showed big fluctuation between 8 species in Winter and 24 species in Autumn. Major dominant species in Jungrang stream were Tubificidae sp.1, Chironomidae sp.1, Chironomidae sp.2 and Physa acuta, and above endurance species for water pollution occupied very high dominance indices. But, Cercion hieroglyphicum, Ischnura asiatica, Rantra chinensis, Herochares striatus, Agabus japonicus in benthic macroinvertebrates of a few individuals are appeared. Also, fry of Carassius auratus and Silurus asotus in fish are occurred. Therefore, we can be inferred on posibility of growth and spawning of above species in the stream. Jungrang stream has a small quantity of natural riffle areas, ponds and watergrass areas by channel form of water course. Aquatic animals in Jungrang stream has been suffered by reduction of self-purification reaction ability and have mass production of attached algae on the stream bed. For analysis of fluctuation of life survival maintenance ability in Jungrang stream, long-term survey is needed.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.317-328
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• 2013

The aim of this study is to compare the effects of the maintenance water supply methods on the ecological restoration of 5 urban streams such as Mugeo cheon, Yaksa cheon, Yeocheon cheon, Myeongjeong cheon and Cheokgwa cheon in Ulsan metropolitan city. Water quality of the streams have been innovatively improved and the ecosystems have gradually been restored by supplying maintenance water constantly. However, we found that if the maintenance water was in a state of higher salinity or low quality, even enough supply was not helpful and even harmful for ecological restoration. We confirmed that the most important things to create or maintain from the urban stream to the ecological stream are that facilities like a walkway construction should be installed at least, supplying appropriate maintenance water, and a connection with the main stream.

• Journal of Environmental Science International
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• v.16 no.8
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• pp.973-983
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• 2007

The eco-hydrologic effects of maintenance water supply on Oncheon stream are studied using hydrologic, hydraulic and ecologic models. SWMM (Storm Water Management Model) is used for long-term simulation of runoff quantity and water quality from Oncheon stream watershed. Using the output hydrologic variables from SWMM, HEC-RAS (River Analysis System) is then used to simulate the hydraulics of water flow through Oncheon stream channels. Such hydrologic, hydraulic and water quality output variables from SWMM and HEC-RAS are served as input data to execute PHABSIM (Physical Habitat Simulation) for the purpose of predicting the micro-habitat conditions in rivers as a function of stream flow and the relative suitability of those conditions to aquatic life. It is observed from the PHABSIM results that the weighted usable area for target fishes has the maximum value at $2m^3/s$ of instream flow. However, mid and down stream areas that have concrete river bed and covered region are unsuitable for fish habitat regardless of instream flow increment. The simulation results indicate that the simple maintenance water supply is limited in its effect to improve the ecological environment in Oncheon stream. Therefore, it is imperative to improve water quality and to recover habitat conditions simultaneously.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.263-274
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• 2019

The purpose of this study is to examine a monitoring method, management zones, and maintenance strategies for water friendly facilities in urban streams after the completion of ecological restoration projects. Maintenance monitoring items are composed of 'use space& facilities', 'trails& bike roads', 'access', and 'boards'. The evaluation standards of water friendly facilities are 'maintenance conditions', 'safety', and 'usage level' which are rated as 'good', 'moderate', and 'poor'. Through a field survey and evaluation of 15 stream sections in Jeonjucheon,the management levels of each water friendly facility are determined as 'priority maintenance', 'general maintenance', 'maintain/remove', and 'remove'. Based on the evaluation results, management zones and maintenance strategies are proposed for each stream section. As a results, the stream sections of J2, J3, J4, and J9 which have 5 to 9 facilities with 'priority maintenance' are determined as 'intensive management zone'. The stream sections of J5, J6, J7, J8, J11, and J14 which have 1 to 3 facilities with 'priority maintenance' are determined as 'regular management zone'. The stream sections of J1, J10, J12, J13, and J15 which have no facilities with 'priority maintenance' are determined as 'minimum management zone'. The process of monitoring & evaluation system and determining management zones can be applied to establish a systematic maintenance plan for water friendly facilities by participation of governance in the future.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.777-789
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• 2019

The purpose of this study is to evaluate changes in water quality and aquatic ecosystem health by additional dam release of stream maintenance flow from multipurpose dams in Han river basin ($34,148km^2$) using SWAT (Soil and Water Assessment Tool). The period of additional release was spring (April to June) and autumn (August to October) to evaluate the changes with the data of aquatic ecosystem health survey. The amount of additional release was set proportional to the present dam release, and the maximum release amount was controlled not to exceed the officially notified stream maintenance flow from dam. The 10 percent to 50 percent additional releases showed that the stream water quality (T-N, $NH_4$, T-P, and $PO_4-P$) concentrations except $NO_3-N$ decreased in spring while increased in autumn period. Using the stream water quality results and applying with Random Forest algorithm, the grade of aquatic ecosystem health index (FAI, TDI, and BMI) was improved for both periods especially in the downstream of basin. This study showed that the additional release of stream maintenance flow was more effective in spring than autumn period for the improvement of water quality and aquatic ecosystem.

• Journal of Korean Society on Water Environment
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• v.31 no.1
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• pp.35-41
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• 2015

This study focuses on whether a physical habitat model, River2D, is useful to assess and design stream restoration. To achieve the aim, the habitat suitability for Zacco Platypus was analyzed using River2D at midstream of the Anyang-Cheon through modifying the low flow channel and changing the flow discharge. The River2D simulation results show that the inhabited environment for Zacco Platypus is improved by increasing the sinuosity of the low flow channel, and vice versa. Also the inhabited environment for Zacco Platypus gets worse when there is no additional flow for maintenance water supply at the stream flowing through cities. In this respect, the physical habitat simulation study based on the River2D model is useful because it provides a practical guidance in designing stream restoration.

• Journal of Environmental Science International
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• v.22 no.5
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• pp.571-580
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• 2013

In this study, compared with the result of water surface elevation and water velocity on the establishment of river maintenance basic plan and result of HEC-GeoRAS based GIS, and after use the result of water surface elevation and velocity were observed in the Han stream on Jeju island, analysis 2 dimensional stream flow. the lateral hydraulic characteristics and curved channel of the stream were analyzed by applying SMS-RMA2 a 2 dimensional model. The results of the analysis using HEC-RAS model and HEC-GeoRAS model indicated that the distribution ranges of water surface elevation and water velocity were similar, but the water surface elevation by section showed a difference of 0.7~2.18 EL.m and 0.63~1.16 EL.m respectively, and water velocity also showed differences of maximum 1.58m/sec and 2.67m/sec. SMS-RMA2 analysis was done with the sphere of Muifa the typhoon as a boundary condition, and as a result, water velocity distribution was found to be 1.19 through 3.91 m/sec, and the difference of lateral water velocity in No. 97 through 99 the curved channel of the stream was analyzed to be 1.59 through 2.36 m/sec. In conclusion it is anticipated that the flow analysis of 2 dimension model of stream can reflect the hydraulic characteristics of the stream curved channel or width and shape, and can be applied effectively in the establishment of river maintenance basic plan or management and designing of stream.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.5
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• pp.1-17
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• 2013

We researched the fauna restoration of 5 urban streams in Ulsan established as ecological streams by improving water quality and river environment. The fauna inhabitation were compared according to the conditions of geometrical feature such as river width, low-water channel width, ect and water quality, water volumn, inland and forceland. The Mugeo cheon has clearly shown the fauna restoration effects resulting from supplying sustainable maintenance water and wastewater treatments. In the Yaksa cheon, on the other hand, the restoration effects were low due to the inflow of wastewater and sledges in some part of stream ever though the improvement of water quality. The Yeocheon cheon was found to have disadvantage on the ecological inhabitations due to supplying the maintenance water with highly concentrated salinity. The fauna restoration effect of the Meongjeong cheon was low due to the inflow of wastewater to the down stream. Therefore by supplying the maintenance water and improving the connection to the Taehwa river at the estuary, better restoration effects could be observed. In the Cheokgwa cheon, which is almost a natural river, the ecological integrity of the fauna population has been maintained quite well. It was concluded that the project to transform urban streams into ecological streams should focus on not only keeping water volume and quality but also maintaining favorable conditions for the migration and settlement of animal species close to the natural state.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.5
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• pp.65-77
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• 2014

The ecosystem of Jaemin stream, flowing into the center of Gongju-si, had been damaged by low water quality and lack of water quantity of the steam. However, after applying the SSB (Sustainable Structured wetland Biotop) system to the flood plain and the upstream of Jaemin stream, the efficiency of ecological water purification and ecological restoration are as follows. Through the constant maintenance and monitoring from year 2009 to year 2013 after restorative design and construction the average influent concentration of BOD5 was 4.2 mg/L, and the average effluent concentration was 1.8 mg/L, reaching ecological water purification rate of 57%. As for the T-N, the average influent concentration was 9.983 mg/L, and the average effluent concentration was 6.303 mg/L, showing the rate of 37%. For the T-P, the average influent concentration was 0.198 mg/L, and the average effluent concentration was 0.098 mg/L, being the rate of 51%. The vegetation of Jaemin stream monitored for 2 years after the restoration was composed of 51 species in 28 families which show high ratio of planted native species. As for the animals in the site, 5 species in 3 families of reptiles and amphibians, 34 species of 23 families of birds, and 3 species in 2 families of mammals were monitored, indicating that the bio-diversity of the site has improved, as well.