Agricultural Reservoirs Research Articles

Ecosystem health evaluation of agricultural reservoirs using multi-metric lentic ecosystem health assessment (LEHA) model

Ecosystem health evaluation of agricultural reservoirs using multi-metric lentic ecosystem health assessment (LEHA) model

AHP를 이용한 농업용저수지 수문학적 안전성평가 방법 개발 및 적용

요 약현재국내일정규모이상댐들에대해서는「안전점검및정밀안전진단세부지침(댐)」기준에따라정밀안전진단을수행하고있다. 하지만여러평가기준중수문학적안전성평가는가능최대홍수량(ProbableMaximum Flood, PMF)에대한기존댐안전성을평가하는것으로대부분의농업용저수지에대해서는적용성이많이떨어진다. 따라서본연구에서는계수화모델과AHP 기법을통해다각적위험요인을고려한농업용저수지의수문학적안전성을재평가하고자한다. 이를위하여농업용저수지의다양한인자를반영하기위한수문학적안전성상·하위평가항목을선정하여계수화모델을개발하였다. 평가항목별지표점수의총합을산출한후전문가집단의응답에대한검증절차를실시하였고, 평가항목의가중치를산정하여최종적으로다각적위험요인을고려한농업용저수지의수문학적안전성평가를위한실용계수를산정하였다. 본연구결과기존평가기준은댐의가능최대홍수량에대한수문학적안전성을평가하는기준으로대부분의농업용저수지에대해서는홍수방어능부족에따른제체의월류로저수지의파괴위험성이큰것으로분류되었다. 그리고가능최대홍수량에대한여유고기준을만족하는저수지에대해서는댐의형식및상태별여유고에대한평가만으로필댐을평가하는것으로나타났다.핵심용어:수문학적안전성평가, 가능최대홍수량, 농업용저수지, 분석적계층화과정AbstractAccording to the「Safety Evaluation Detailed Instructions (Dam)」, precise safety inspection is carried out fordams that exceed a certain scale. However, as the Hydrological Safety Evaluation from various evaluationstandards is designed to evaluate the safety of existing dams considering PMF, the evaluation is much lessapplicable for most agricultural reservoirs. Therefore, the Hydrological Safety Guidelines for agriculturalreservoirs are expected to be re-evaluated considering the diverse risk factors with the coefficient model andAHP in this study. The coefficient model has been developed by selecting the hydrological safetysuperordinate․subordinate evaluation factors to reflect diverse risk factors of agricultural reservoirs. Aftercalculating the sum of indicators score for each evaluation factors, validation procedures were performed forthe questionnaire which a panel answered. The practical coefficient has eventually been estimated for thehydrological safety evaluation considering the diverse risk factors. The conclusions acquired based on thestudy done are that both most agricultural reservoirs were classified as flood defense capability is insufficientand agricultural reservoirs which meet embankment-freeboard standards considering PMF was overestimated.

Development of an irrigation vulnerability assessment model in agricultural reservoirs utilizing probability theory and reliability analysis

The primary goal of water resource management is to maintain a secure and reliable supply of water that can meet the demands of responsible water resource planning. The development of a sustainable agricultural water management system is necessary to evaluate the capability of the water supply to adapt to changes in environmental conditions in relation to the passage of time. Because each reservoir has specific properties related to its watershed, irrigation district, and changes in inflow, they are essential to improve the current assessment methods. The purpose of this study is to propose an irrigation vulnerability assessment method that considers a probability distribution that uses time-dependent change analyses of the irrigation water requirements by paddy fields and the water supply capacity of agricultural reservoirs. Irrigation vulnerability indices are estimated to evaluate the performance of the water supply on the agricultural reservoir system using a probability theory and reliability analysis as an objective method to evaluate the stability of the water supply. The work presented in this paper addresses the potential impact of environmental changes on water supply and demand, as well as the associated reservoir operation performance, with an emphasis being placed on the probability of the current vulnerability. The environmental impact is particularly marked for irrigated paddy fields that utilize a reservoir agricultural vulnerability evaluation model to classify the relative and quantitative severity of irrigation vulnerabilities. Thus, it is a recommended practice in the development of water supply management strategies to manage the risk of an uncertain future.

An assessment for leakage reduction methods of reservoir embankments through estimation of CO2 emissions during the construction process

Abstract Many stability issues may occur as agricultural reservoir embankments become superannuated in South Korea. Reinforcement of reservoir embankments is necessary because of the potential for the loss of lives and property damage can occur, if an embankment is failed due to its faults. However, construction activities that are associated with repairing reservoir embankments are not recognized as environmentally friendly, although the importance of reservoirs is increasing. Therefore, the objective of this research was to assess the environmental effect for leakage reduction methods of reservoir embankments through estimation of CO 2 emissions during the construction using hybrid method for a rational selection considering economic and environmental characteristics. Based on an estimate of the construction cost and CO 2 emissions at the scale assumed, the Jumbo Special Pattern (JSP) method had the highest cost and emissions and the surface impermeable wall method had the lowest cost and emissions. However CO 2 emissions for the sheet pile method were relatively low compared to the total construction cost due to use of steel sheets, which have a high unit price but low basic unit of CO 2 emissions. Among the causes of emissions, material division is the largest contributor to total emissions for all of the methods. The suggested process of estimating CO 2 emissions is applied to the targeted reservoir where curtain grouting was applied. For both the total construction cost and CO 2 emissions, results were similar to those of the scale that was assumed. The total CO 2 emissions for most of the methods were smaller than that of the curtain method that was installed in the study area, except for the JSP method. Thus, the method for estimating CO 2 emissions for leakage reduction methods properly described the characteristics of each of the methods proposed in this study, and may provide a basis for establishing a policy to reduce CO 2 emissions in the selection of repair methods.

Evaluation of dams and weirs operating for water resource management of the Geum River

As part of the Four Major Rivers Restoration Project, 16 multi-functional weirs have recently been constructed in each river system in Korea. The Project has pursued ecological approaches through constructing artificial weirs in waterways to ensure sufficient flow even in the dry seasons, improving agricultural reservoirs to supply environmental flow for the rivers, and thereby enhancing the water quality of the rivers. However, these anthropogenic activities have been accompanying a significant change in the riverine environment. In this study, the SSARR (Streamflow Synthesis and Reservoir Regulation) model was used to estimate natural flow in the 14 sub-basins of the Geum River. The natural flow determined by the SSARR model was used in estimation of environmental flow and input data of reservoir operation model. Hec-ResSim was used to assess runoff variations, water supply and energy generation based on the protocols for the associated operation of dams and multi-functional weirs. In addition to this, a method developed by the IWMI (International Water Management Institute) was also used to analyze the environmental flow, considering channels, water fronts and flow variations, and thereby assess the environmental management class of changing the riverine environment and to take countermeasures to mitigate the resulting adverse environmental impacts. It is hoped that the results of this study will provide basic data to establish policies for the effective operation and management of the existing dams and the newly constructed multi-functional weirs, and the effective monitoring and preservation of aquatic ecosystems in the Geum River basin.

소규모 농업용 전대저수지의 수환경 변화와 조류발생 특성

소규모 농업용 전대저수지의 수환경 변화와 조류발생 특성

RCP4.5 시나리오에 따른 IDF 곡선 분석: 우리나라 30개 저수지를 대상으로

본 연구의 목적은 우리나라 30개 저수지의 미래 IDF (Intensity-Duration-Frequency) 곡선을 산정하여 기후변화로 인한 영향을 분석하는 것이다. RCP (Representative Concentration Pathways) 시나리오를 기반으로 하는 미래 강수자료에 내재하는 계통적 오차를 분위사상법을 이용하여 보정하였고, 미래를 3기간(2025s: 2011~2040, 2055s: 2041~2070, and 2085s: 2071~2100)으로 나누어 미래 강수량의 변화를 분석하였다. 강수자료의 최적 분포형과 매개변수 추정 방법으로 Gumbel 분포와 확률가중모멘트법을 선정하였다. 한강유역, 금강유역, 영산강유역의 강우강도는 현재 1990s 기간에 비해 미래 2085s 기간에 크게 증가하였고, 낙동강유역의 강우강도는 현재 1990s 기간에 비해 미래 2025s 기간에 크게 증가하는 것으로 분석되었다. 본 연구에서 새롭게 도출한 IDF 곡선은 기후변화를 구조물 설계에 반영함으로써 농업용 저수지의 안정성을 증진시킬 수 있을 것이라 사료된다. The main objective of this study is to evaluate the impact of climate change on Intensity-Duration-Frequency (IDF) curves for the selected 30-Reservoirs in South Korea. A bias inherent in future precipitation data based on Representative Concentration Pathways (RCP) scenario was corrected by a quantile mapping method. The trends in future precipitation changes were analyzed for the three different time periods (correspond to 2025s: 2011~2040, 2055s: 2041~2070, and 2085s: 2071~2100). Gumbel distribution was selected as the probability distribution and parameters were estimated by probability weighted moment method. Rainfall intensity of Han, Geum and Yeongsan river watersheds was greatly increased in 2085s period than 1990s period. Rainfall intensity of Nakdong river watershed appeared to increase sharply in 2025s period than 1990s period. The newly developed IDF curve might enhance the stability of agricultural reservoirs through considering climate change impact into structure design process.

실시간 저수위 및 용수공급 취약성 지표를 활용한 농업용 저수지 운영 기준 개발

The efficient operation and management strategies of reservoirs in irrigation periods of drought events are an essential element for drought planning and countermeasure. Korea Rural Community Corporation has developed the real-time water level observation system of agricultural reservoirs to efficiently operate reservoirs, however, it is not possible to predict drought conditions, and only provides information of current situation. Hence, it is necessary to evaluate accurate irrigation vulnerability and efficiently reservoir operation rules using current water level. In this paper, the improvement methods of reservoir operation planning were developed with water supply vulnerability characteristic curves comparing to automatic water gauge at agricultural reservoirs. The 11 reservoirs were simulated applying the reservoir operation rules which was determined by irrigation vulnerability characteristic curves criteria and real time water level, and evaluated water supply situation in 2012 year. The analysis of results can be identified probabilistic possibility of water supply failures compared with the existing reservoir operation criteria. These results of efficient reservoir operation rules can be achieved enable irrigation planners to optimally manage available water resources for decision making, and contributed to maintain the water supply according to demand strategy for agricultural reservoirs management.

농업용 저수지 준설토의 처리 공법에 따른 경제성 분석

The economical feasibility was conducted to find the adequate method to treat the dredged sediments from agricultural reservoirs in a pilot project that had been operated to improve the quality of water and benthic environments by dredging of contaminated sediments. For benefit/cost (B/C) analysis, the net expenses were considered as the costs of project, and the benefits were calculated from the saving of waste-treatment cost through reuse of dredged sediment, the saving of construction cost of settling pond, and the values of retained water by dredging. Although the economic feasibility depended on the sites of operation, the average B/C value of the pilot project was estimated as 1.32, indicating this project is economically feasible. Depending on the treatment methods, the B/C values were in the order of the methods of coagulating sedimentation, machinery dewatering, stabilization through exothermic reaction, and soil improvement and stabilization. The machinery dewatering method is estimated as the most adequate one to treat the dredged sediments because of the minimum riskiness of secondary pollution, the recyclability, and its economic feasibility.

The safety behavior of agricultural reservoirs due to raising the embankment

This study was carried out to investigate safety evaluation of agricultural reservoirs due to raising the embankment. The seepage analysis and large-scale model test were performed to compare and analyze the pore water pressure(PWP), leakage quantity, settlement and piping phenomenon in the inclined core type and the vertical core type embankments. The PWP after raising the embankment showed smaller than before raising the embankment and the stability for piping after raising the embankment. The allowable seepage quantity and the allowable leakage for the steady state and transient conditions is within the range of safe management standard. After raising the embankment in the inclined core, there was no infiltration by leakage. For the vertical core, the PWP showed a large change by faster infiltration of pore water than in the inclined core. In a rapid drawdown, inclined core was remained stable but the vertical core showed a large change in PWP. Settlement after raising the embankment showed larger amounts of settlement than before raising the embankment. The leakage quantity before raising the embankment and the inclined core type showed no leakage. From the result, an instrument system that can accurately estimate a change of PWP shall be established for the rational maintenance and stabilization of raising the embankment for agricultural reservoirs.

가중치 분석을 통한 농업용 저수지 평가항목 산정에 관한 연구

본 연구의 목적은 가중치 분석을 통하여 지자체에서 수행하는 정기점검 리스트를 결정하는 것이다. 국내 외 저수지 파괴의 유형을 사례점검과 함께 분석하고 저수지의 파괴 및 손상요인을 종합하여 점검항목을 결정하였다. 따라서 가중치를 고려한 분석을 통하여 농업용 저수지에 최적화된 평가항목을 제안하였다. The object of this study is to determine checklists of agriculture reservoirs which local government managed at routine inspection by Analysis Hierarchy Process (AHP). Suggest definition of agriculture reservoirs and distinguish type of destruction of reservoirs through the analysis of domestic reservoirs or overseas. Draw damage factors of reservoirs from survey on specific area. Combine type of destruction and damage factors of reservoirs for decision of evaluation type of reservoirs. Then, determine optimized routine inspection checklists for agriculture reservoirs and reservoirs by means of AHP considering a weighting.

농업용 보의 수차 발전기 효율 분석

If the factory test efficiency and field operation efficiency of water turbine are different from each other, issues for efficiency warranty can be raised. So, This paper shows the result for comparative analysis of field operating efficiency vs plant testing efficiency of the water turbine generator installed in agricultural reservoir. The efficiency of the induction generator is analyzed by the change of rotational speed with the parameter obtained by test, the efficiency of water turbine is calculated by the change of head with the design flow. Efficiency deviation of induction generator is lower but the variation of developed power is pretty high near the rated speed and the efficiency variation of water turbine is high by the fluctuation of head for constant flow. It was found that factory test efficiency and total efficiency of water turbine generator calculated according to the rotational speed are very close.

농업용 둑높임저수지의 다중 용수공급을 위한 이수운영기준곡선 개발

ABSTRACT This study developed an operating rule curve (ORC) for multipurpose water supply (irrigation and environmental water) in height ened agricultural reservoir. Among the 20 reservoirs in improvement pr oject of agricultural reservoir dam heightening, the 4 represe ntative reservoirs (Ungyang, Gungchon, Yongam and Unam) were selected for the study according to the analysis of statistical characteri stics. Available environmental water supply amounts during irrigation and non-irrigation periods, which is the range from release rest ricted water level to high water level were estimated by water balance analysis using reservoir operation model. Reliability, resiliency and vulnerability criteria for water system performance were used to assess the multiple water supply capacity. The ORC was present ed as the percentile rank for the daily reservoir water level from the results of reservoir operation using the past couple of decade s weather data. The water levels for each percentile were divi ded into 3 buffer sections representing drought (5 ～25%), normal (25 ～75%), and flood (75～95%) year to operate the heightened agricultural reservoir with ORC.

Characterization of CO2 emissions during construction of reservoir embankment elevation in South Korea

Purpose The environmentally friendly construction of agricultural infrastructure is much needed for sustainable development because construction is recognized as a cause of environmental degradation. The objective of this study was to estimate and characterize carbon dioxide (CO2) emissions during construction of agricultural reservoir embankments for the quantitative environmental assessment and management of CO2 emissions using life cycle assessment method.

홍동저수지 퇴적토의 유기물 용출 특성 분석을 통한 효율적인 저수지 관리 방안 연구

This study proposes an efficient management plan for improving the water quality of agricultural reservoirs. Hongdong reservoir is located in an area that includes farmland, forest, residential housing, and livestock farms. The levels of pollutants in Hongdong reservoir were investigated with the aim of improving the water quality in the reservoir. The potential concentrations of total nitrogen (T-N) and total phosphorus (T-P) in Hongdong reservoir were 1.06-3.67 and 0.52-1.12 , respectively. An analysis of leaching characteristics was performed under anaerobic conditions for 72 hours at . The concentrations of T-P and -P were measured by general leaching for a set period. In the case of T-P, the leaching was measured by irregular leaching due to denitrification of nitrite nitrogen (-N) and nitrate nitrogen (-N). A very small amount of -N on nitrogen () was measured due to the low pH in the column, as a consequence of the anaerobic conditions.

간접하수재이용에 따른 논에서의 수질 및 토양환경 영향 분석

The objectives of this study were to monitor and assess the environmental impacts of indirect wastewater reuse on water quality and soil in paddy fields. Yongin monitoring site (YI) irrigated from agricultural reservoir and Osan monitoring site (OS) irrigated with treated wastewater diluted with stream water were selected as control and treatment, respectively. Monitoring results for irrigation water quality showed a significant statistical difference in salinity, exchangeable cation and nutrients. Pond water quality showed a similar tendency with irrigation water except for the decreased difference in nutrients due to the fertilization impact. Soil chemical properties mainly influenced by fertilization activity such as T-N, T-P, and were changed similarly in soil profiles of both monitoring sites, while the properties, EC, Ca, Mg, and Na, mainly effected by irrigation water quality showed a considerable change with time and soil depth in treatment plots. Heavy metal contents in paddy soil of both control and treatment did not exceed the soil contamination warning standards. This study could contribute to suggest the irrigation water quality standards and proper agricultural practices including fertilization for indirect wastewater reuse, although long-term monitoring is needed to get more scientific results.

저수지 가뭄지수를 활용한 농업가뭄 위험도 평가

Drought risk assessment is usually performed qualitatively and quantitatively depending on the definition a drought. The meteorological drought indices have a limit of not being able to consider the hydrological components such as evapotranspiration, soil moisture and runoff, because it does not consider the water demand in paddies and water supply in reservoirs. Agricultural drought was defined as the reservoir storage shortage state that cannot satisfy water requirement from the paddy fields. The objectives of this study were to suggest improved agricultural drought risk assessment in order to evaluate of regional drought vulnerability and severity studied by using Reservoir Drought Index (RDI). The RDI is designed to simulate daily water balance between available water from agricultural reservoir and water requirement in paddies and is calculated with a frequency analysis of monthly water deficit based on water demand and water supply condition. The results indicated that RDI can be used to assess regional drought risk in agricultural perspective by comparing with the historical records of drought in 2012. It can be concluded that the RDI obtained good performance to reflect the historical drought events for both spatially and temporally. In addition, RDI is expected to contribute to determine the exact situation on the current drought condition for evaluating regional drought risk and to assist the effective drought-related decision making.

둑높이기 농업용저수지의 운영기준에 따른 환경용수 방류패턴 분석

The importance of environmental water has been risen in terms of river ecosystem soundness with preventing stream flow depletion in rural area, while enlarging agricultural reservoir project is conducted under the 4 main river restoration project for supplying more water to 4 main rivers. The aim of this study was to estimate the amount of environmental water release and analyze the release pattern during non-irrigation season in enlarged agricultural reservoirs. The 4 reservoirs (Dansan, Samga, Geumbong, Changpyeong) located on the upper region of Nakdong river were simulated applying the operation rule which was determined by release criteria curves. The simulated results indicated that the more environmental water could be released than the spillway release and continuous release was achieved with smaller range of fluctuation. In case of Changpyeong reservoir, average 506.0 thousand <TEX>$m^3$</TEX> environmental water could be released on Feb., and it was about twice as much as the spillway release before the enlargement, and also, the 18 thousand <TEX>$m^3$</TEX>/day environmental water could be supplied to a stream consistently after enlargement. From the results, it was expected that the additional environmental water release will improve stream water flow during dry season in terms of quantity and quality of water.

농업용 저수지를 고려한 홍수경보 강우량 산정

현재 우리나라 중소하천에서의 홍수 예경보 시스템은 저수지의 저류효과를 고려하지 않고 홍수를 예측하는 경우가 대부분이다. 이것은 대부분 홍수조절 능력이 방치되고 있는 농업용 저수지에 대한 홍수추적 자료 확보에 어려움이 있기 때문이다. 따라서 본 연구에서는 경상남도에 위치한 남강유역을 대상으로 저수지의 저류효과를 고려한 한계유출량에 따른 경보강우량을 산정하였다. 소유역 구분 및 유역특성은 ArcGIS와 HEC-GeoHMS를 이용하여 자료를 구축하였으며, HEC-HMS를 이용하여 홍수량을 산정하였다. 경보강우량을 산정하기 위하여 경상남도에 위치한 농업용 저수지의 특성을 분석하였으며, 선행 연구결과를 바탕으로 소하천 유역의 유출에 큰 영향을 미치는 4개의 주요 인자를 산정하여 상관분석을 수행하였다. 경상남도 시군구별 농업용 저수지 특성분석결과, 6월부터 9월까지 우기시 평균 저수율은 79.2%이고, 잉여수량을 저류할 수 있는 능력은 실제 약 20%내외로 조사되었다. 본 연구에서 제안된 새로운 방법의 결과로, 농업용 저수지 영향을 고려하여 모의된 홍수량으로 산정한 한계유출량으로부터 강우 지속시간 20분에 대한 경보강우량을 산정하였다. Most flood forecasting and warning systems provide flood predictions without considering the storage effects of reservoirs for small and mid-sized watersheds in Korea. It is due to lack of data available for the flood routing in most agricultural reservoirs, leading to flood control functions. Therefore, this study has estimated the flood warning rainfall amount for the threshold runoff considering the reservoir storage effects in the Nam River watershed located in Gyeongsangnamdo. The watershed delineation and basin characteristics are constructed using HEC-GeoHMS and ArcGIS, and the flood runoff is simulated by HEC-HMS. For flood warning rainfall estimates, this study has characterized agricultural reservoirs located in Gyeongsangnamdo and performed regression analysis of their four main factors that have significant impacts on runoff in small and mid-sized watersheds, based on results from the previous research. The analysis of agricultural reservoir characteristics analyzed for city/county/town units in Gyeongsangnamdo show that the average of reservoir storage rate is 79.2%, and the actual additional water storage capacity is approximately 20% in the rainy season from June to September. As a result of the new method proposed in this study, the flood warning rainfall threshold for 20-minute duration is obtained from the threshold runoff estimated by the flood simulations considering agricultural reservoir effects.

하천의 인공구조물이 저서성 대형무척추동물 군집에 미치는 영향

This study was conducted for determining the influence of artificial structures on benthic macroinvertebrate communities in stream. Sampling was taken at upper(pool), down(riffle) and control(riffle) from two check dams, two weirs, one agricultural reservoir, and one multipurpose dam in northern part of Gyeongsangbuk-do. The benthic macroinvertebrate communities of these structures were surveyed during 2009 to 2011. The simple habitat of benthic macroinvertebrates occurred at the upper sites due to pooling effects from artificial structures. Specifically, Check dam1, Jusanji, Imha dam showed very low biological attribute values compared to the down and control sites, which have greater difference in substrate characteristics. However, in the upper sites of Check dam2, Weir1 and Weir2, the difference of values of biological attributes was relatively smaller. Also, proportion of functional feeding groups and functional habit groups were relatively simpler at upper stream and the degree of community differences was greater between upper and down, control sites. Spearman's correlation between biological attributes and substrate characteristics, water quality parameters had significant correlations; particularly, the substrate characteristics were more significantly related. In conclusion, the pool caused by artificial structures had negative effects on benthic macroinvertebrate communities thus leading to simplified stream habitats at upper stream ecosystems.