• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.44-44
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• 2020

최근 기후변화의 기온 상승 및 강수량 증가의 영향으로 농업용수 수요량이 증가하고 있다. 이에 따라 농업용수의 약 60%를 공급하는 농업용 저수지의 용수 수요의 변화와 그에 따른 공급능력에 대한 평가가 필수적이다(한국농어촌공사, 2019). 본 연구에서는 기후변화 시나리오를 기반으로 농업용저수지 물수지 모의 프로그램인 DIROM(Daily Irrigation Reservoir Operation Model) 모형을 활용하여 우리나라 미래 필요수량 변화에 따른 농어촌용수 수요 변화를 분석하고, 가뭄대책단계별 관리수위를 활용해 공급능력을 평가하고자 한다. 필요수량 분석을 위해 2018년 농업생산 기반시설 통계연보의 논면적 자료 및 농어촌용수 이용 합리화계획(2015~2024)의 수로손실, 삼투량 자료를 구축하였고, 공급능력 평가를 위해 한국농어촌공사 관할 3,666개 저수지 중 저수지 시설규모, 수혜면적 등을 고려하여 선정한 426개 저수지를 대상으로 농업기반시설관리시스템(RIMS)의 저수지 제원, 내용적 곡선 및 평년저수율 자료를 수집하였다. 기후변화 시나리오는 기상청으로부터 제공받은 HadGEM3-RA RCP(Representative Concentration Pathway) 8.5 시나리오를 이용하였으며 기후변화 시나리오 기간을 S1(2021-2040), S2(2041-2070), S3(2071-2099)로 구분하여 분석하였다. 전국 필요수량을 산정한 결과 평년(1981-2005) 대비 S1, S2, S3에서 각각 12.0%, 9.1% 16.4 % 증가하여 미래로 갈수록 증가하는 경향이 나타났다. 426개 저수지에 대한 물수지 분석을 통해 저수율을 산정하고 평년저수율을 통해 산정한 가뭄대책단계별 관리수위를 기준으로 용수공급능력을 파악한 결과 저수율이 40% 미만 일이 평년대비 S1, S2, S3에서 15.9일, 11.8일, 18.1일로 증가하였다. 본 연구의 결과는 미래 기후변화에 따른 농업용 저수지 용수관리계획 및 의사결정 자료로 활용 될 것이라 판단된다.

• Journal of the Korean association of regional geographers
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• v.2 no.1
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• pp.51-67
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• 1996

There are three main rice-growing regions in the United States: the prairie region along the Mississippi River Valley in eastern Arkansas; the Gulf Coast prairie region in southwestern Louisiana and southeastern Texas; and the Central Valley of California. The Central Valley of California is producing about 23% of the US rice(Fig. 1). In California. most of the crop has been produced in the Colusa, Sutter, Butte, Glenn Counties of the Sacramento Valley since 1912, when rice was commercially grown for the first time in the state(Fig. 2). Roughly speaking, the average annual area sown to rice in California is about 300,000 acres to 400,000 acres during the last forty years(Fig. 3). California rice is grown under a Mediterranean climate characterized by warm, dry, clear days, and a long growing season favorable to high photosynthetic rates and high rice yields. The average rice yield per acre is probably higher in California than in any other rice-growing regions of the world(Fig. 4). A dependable supply of irrigation water must be available for a successful rice culture. Most of the irrigation water for California rice comes from the winter rain and snow-fed reservoir of the Sierra Nevada mountain ranges. Less than 10 percent of rice irrigation water is pumped from wells in areas where surface water is not sufficient. It is also essential to have good surface drainage if maximum yields are to be produced. Rice production in California is highly mechanized, requiring only about four hours of labor per acre. Mechanization of rice culture in California includes laser-leveler technology, large tractors, self-propelled combines for harvesting, and aircraft for seeding, pest control, and some fertilization. The principal varieties grown in California are medium-grain japonica types with origins from the cooler rice climates of the northern latitudes (Table 1). Long-grain varieties grown in the American South are not well adapted to California's cooler environment. Nearly all the rice grown recently in California are improved into semidwarf varieties. Choice of variety depends on environment, planting date, quality desired, marketing, and harvesting scheduling. The Rice Experiment Station at Biggs is owned, financed, and administered by the rice industry. The station was established in 1912, as a direct result of the foresight and effort of Charles Edward Chambliss of the United States Department of Agriculture. Now, The station's major effort is the development of improved rice varieties for California.

• Journal of the Korean association of regional geographers
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• v.3 no.2
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• pp.37-87
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• 1997

As a results of researches on the cultivation processes and settlement developments on the Mangyoung river valley as a whole could be have four 'Space-Time Continuity' through a [Origin-Destination] theory model. On a initial phases of cultivation, the cultivation process has been begun at mountain slopes and tributory plains in upper part of river-basin from Koryo Dynasty to early Chosun Dynasty. At first, indigenous peasants burned forests on the mountain slopes for making 'dryfield' for a cereal crops. Following population increase more stable food supply is necessary facets of life inducing a change production method into a 'wetfield' in tributory plains matching the population increase. First sedentary agriculture maybe initiated at this mountain slopes and tributory plains on upper part of river basin through a burning cultivation methods. Mountain slopes and tributory plains are become a Origin area in cultivation processes. It expanded from up to down through the valleys with 'a bits of land' fashion in a steady pace like a terraced fields expanded with bit by bit of land to downward. They expanded their land to the middle part of river basin in mid period of Chosun Dynasty with dike construction techniques on the river bank. Lower part of river cultivated with embankment building techniques in 1920s and then naturally expanded to the tidal marshes on the estuaries and river inlets of coastal areas. 'Pioneer fringes' are consolidated at there in modern times. Changes in landscapes are appeared it's own characters with each periods of time. Followings are results of study through the Mangyoung river valley as a whole. (1) Mountain slopes and tributory plains on the upper part of river are cultivated 'dryfields' by indigenous peasants with Burning cultivation methods at first and developed sedentary settlements at the edges of mountain slopes and on the river terrace near the fields. They formed a kind of 'periphery-located cluster type' of settlement. This type of settlement are become a prominant type in upper part of river basin. 'Dryfields' has been changed into a 'wetfields' at the narrow tributory plains by increasing population pressure in later time. These wetfields are supplied water by Weir and Ponds Irrigation System(제언수리방법). Streams on the tributory plains has been attracted wetfields besides of it and formed a [water+land] complex on it. 'Wetfields' are expanded from up to downward with a terraced land pattern(adder like pattern, 붕전) according to the gradient of valley. These periphery located settlements are formed a intimate ecological linkage with several sets of surroundings. Inner villages are expanded to Outer villages according to the expansion of arable lands into downward. (2) Mountain slopes and tributory plains expanded its territory to the alluvial deposited plains on the middle part of river valley with a urgent need of new land by population increase. This part of alluvial plains are cultivated mainly in mid period of Chosun Dynasty. Irrigation methods are changed into a Dike Construction Irrigation method(천방수리방법) for the control of floods. It has a trend to change the subjectives of cultivation from community-oriented one who constructed Bochang along tributories making rice paddies to local government authorities who could be gather large sums of capitals, techniques and labours for the big dike construction affairs. Settlements are advanced in the midst of plains avoiding friction of distances and formed a 'Centrallocated cluster type' of settlements. There occured a hierarchical structures of settlements in ranks and sizes according merits of water supply and transportation convenience at the broad plains. Big towns are developed at there. It strengthened a more prominant [water+land] complex along the canals. Ecological linkages between settlements and surroundings are shaded out into a tiny one in this area. (3) It is very necessary to get a modern technology of flood control at the rivers that have a large volume of water and broad width. The alluvial plains are remained in a wilderness phase until a technical level reached a large artificial levee construction ability that could protect the arable land from flood. Until that time on most of alluvial land at the lower part of river are remained a wilderness of overgrown with reeds in lacks of techniques to build a large-scale artificial levee along the riverbank. Cultivation processes are progressed in a large scale one by Japanese agricultural companies with [River Rennovation Project] of central government in 1920s. Large scale artificial levees are constructed along the riverbank. Subjectives of cultivation are changed from Korean peasants to Japanese agricultural companies and Korean peasants fell down as a tenant in a colonial situation of that time in Korea. They could not have any voices in planning of spatial structure and decreased their role in planning. Newly cultivated lands are reflected company's intensions, objectives and perspectives for achieving their goals for the sake of colonial power. Newly cultivated lands are planned into a regular Rectangular Block settings of rice paddies and implanted a large scale Bureaucratic-oriented Irrigation System on the cultivated plains. Every settlements are located in the midst of rice paddies with a Central located Cluster type of settlements. [water+land] complex along the canal system are more strengthened. Cultivated space has a characters of [I-IT] landscapes. (4) Artificial levees are connected into a coastal emnankment for a reclamation of broad tidal marshes on the estuaries and inlets of rivers in the colonial times. Subjectives of reclamation are enlarged into a big agricultural companies that could be acted a role as a big cultivator. After that time on most of reclamation project of tidal marshes are controlled by these agricultural companies formed by mostly Japanese capitalists. Reclaimed lands on the estuaries and river inlets are under hands of agricultural companies and all the spatial structures are formed by their intensions, objectives and perspectives. They constructed a Unit Farming Area for the sake of companies. Spatial structures are planned in a regular one with broad arable land for the rice production of rectangular blocks, regular canal systems and tank reservoir for the irrigation water supply into reclaimed lands. There developed a 'Central-located linear type' of settlements in midst of reclaimed land. These settlements are settled in a detail program upon this newly reclaimed land at once with a master plan and they have planned patterns in their distribution, building materials, location, and form. Ecological linkage between Newly settled settlemrnts and its surroundings are lost its colours and became a more artificial one by human-centred environment. [I-IT] landscapes are become more prominant. This region is a destination area of [Origin-Destination] theory model and formed a 'Pioneer Fringe'. It is a kind of pioneer front that could advance or retreat discontinously by physical conditions and socio-cultural conditions of that region.

• Journal of Soil and Groundwater Environment
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• v.14 no.2
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• pp.1-9
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• 2009

This study was objected to identify the effect on water quality and contamination by non-agricultural facilities in 'A' reservoir watershed located in OO city, Kyounggi-do, Korea. Ground- and stream water samples showed (Na+K)-Cl, Ca(Cl, SO$_4$) and Ca-Cl type in an illegally discharging area of sewage and a densely industrial area indicating water contamination. Stream water of an illegally discharging area of sewage had high COD, T-N and T-P. In this area, direct incoming of sewage into stream water was induced ground water system by well pumping, and it made a progress of ground water contaminations with those components. Groundwater of a densely industrial area showed high concentrations of T-N, NO$_3$N. From a nitrogen isotope analysis, stream water of an illegally discharging area of sewage has ${\delta}^{15}N-NO_3$values of 0.7%0 was strongly affected by nitrogen originated from agrochemicals, and a densely industrial area of 19.7%0 from septic system. Ground- and stream water of a livestock fanning area were contaminated with NH$_3$-N and Mn, which was affected by intensive livestock facilities. SAR-conductivity plot indicates the water does not pose either alkalinity or salinity hazard for irrigation. COD, T-N, T-P, NO$3$-N, NH$_3$N and Mn concentrations from contaminated areas were diminished by mixing with 'A' reservoir water. There were no water contaminations in silver towns, vacationlands around reservoir and golf links. Consequently, it should be made a plan of systematic managements for past and- present possible contaminants and sewage systems in preventing water contamination by non-agricultural facilities.

• Journal of Wetlands Research
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• v.15 no.2
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• pp.223-231
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• 2013

Excessive precipitation, drought, heat waves, strong typhoons and rising sea levels are just some of the common indicators of climate change. In the Philippines, excessive precipitation never failed to devastate and drown the streets of Metro Manila, a highly urbanized and flood-prone area; such problems are expected to occur frequently. Moreover, the water supply of Metro Manila is dependent only to Angat Reservoir. Rainwater harvesting can serve as an alternative source of raw water and it can mitigate the effects of flooding. The harvested rainwater can be used for: potable consumption if filtered and disinfected; and non-potable consumptions (e.g., irrigation, flushing toilets, carwash, gardening, etc.) if used untreated. The rainfall data were gathered from all 5 rainfall stations located in Metro Manila namely: Science Garden, Port Area, Polo, Nangka and Napindan rain gauge stations. To be able to determine the potential volume of rainwater harvested and the potentiality of rainwater harvesting system as an alternate source of raw water; in this study, three different climatic conditions were considered, the dry, median and wet rainfall years. The frequent occurrence of cyclonic events in the Philippines brought significant amount of rainwater that causes flooding in the highly urbanized region of Metro Manila. Based from the results of this study, the utilization of rainwater harvesting system can serve as an alternative source of non-potable water for the community; and could also reduce the amount of surface runoff that could result to extreme flooding.

• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.35-47
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• 2008

The low flow analysis is an important part in water resources engineering. Also, the results of low flow frequency analysis can be used for design of reservoir storage, water supply planning and design, waste-load allocation, and maintenance of quantity and quality of water for irrigation and wild life conservation. Especially, for identification of the uncertainty in frequency analysis, the Bayesian approach is applied and compared with conventional methodologies in at-site low flow frequency analysis. In the first manuscript, the theoretical background for the Bayesian MCMC (Bayesian Markov Chain Monte Carlo) method and Metropolis-Hasting algorithm are studied. Two types of the prior distribution, a non-data- based and a data-based prior distributions are developed and compared to perform the Bayesian MCMC method. It can be suggested that the results of a data-based prior distribution is more effective than those of a non-data-based prior distribution. The acceptance rate of the algorithm is computed to assess the effectiveness of the developed algorithm. In the second manuscript, the Bayesian MCMC method using a data-based prior distribution and MLE(Maximum Likelihood Estimation) using a quadratic approximation are performed for the at-site low flow frequency analysis.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.79-86
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• 1985

In order to judge appropriately the suitability as the second intermediate host of Clonorchis sinensis, the present experiments were proposed to survey the metacercaria of C. sinensis in the fish host, Cuztriculus eigenmanni, in the 6eld, and to observe, by experimental infection of the fish with Clonorchis cercaria, the penetrating ability of the cercaria, maturity, the process of degeneration and extinction, and infectivity of the metacercaria. The following is a brie summary of the leading facts gained through the experiments. 1. All the ten fish (mean body weight $13.4{\pm}3.439$) which were caught in Ok-ku irrigation reservoir were in acted with the metacercariae and the average number of the metacercariae found in the fish body/gram was 4.55. 2. The Bish was easily subject to invasion of the cercaria, and the examination of the cercariae after having the fish infected disclosed that 5:l hours after the infection, all of the cercariae formed their cysts in muscle and the metacercariae kept growing, that 7 days later the metacercariae were found folding their bodies twice, and that in 15 days the characteristic structure of the metacercariae was complete and made a vigorous rotary movement intermittently. 3. In the case of control fish, Pseudorasbora parka, both penetrating ability of the cercariae and the infective degree of the metacercariae to control host were stronger as compared with the 5sh host because that the control fish had higher suceptibility to C. sinensis. 4. Afterwards, the metacercariae in the fish host came to a state of maturity and beyond this stage some metacercariae started the Process of degeneration and extinction in as early as 30 days, and as more days elapsed, mortality of the metacercariae was not uniformly increased but difference of mortality appeared to be according to the individual of Ssh host. That is, in 390, 540 and 586 days, all of the metacercariae in the fish hosts became dead, meanwhile almost all of those found in the fish host of 596 days after the infection survived (mortality; 8, 51%) , Percentage of orally administered metacercariae developing to maturity in rabbit is 10.465 in the last case. 5. As the days were progressed the shapes of the metacercariae in the fish host tended to change from ellipsoid to almost round shapes, the length became shorter while the width was wider. The results shown above revealed that C. eigenmanni was, though it could not be proper host than p. larva. suitable as the second intermediate host in addition to our previous observation results.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.344-355
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• 2003

Water quality model applicable paddy field was developed using field experiment during 1999 ${\sim}$ 2002. This model involves inputs from fertilization and sediment release as dirac delta function and continuous source function, respectively, and can simulate various processes such as ponded depth, surface drainage, total nitrogen concentration and total phosphorus concentration in a daily basis. The model was calibrated using data collected from field experiments which was irrigated with ground water and validated from field experiments which was irrigated with surface water. The nutrient concentration of surface water depended on the fertilization and dirac delta function can efficiently explain the valiance of nutrient concentration of surface water by fertilizer. As a result of calibration and validation, this model demonstrates good agreement. The model fit efficiencies ($R^2$) of ponded depth, surface concentration of TN and TP were 0.93,0.98 and 0.95, respectively for calibration, and those of TN and TP were 0.99 and 0.70, respectively for validation. We can apply lake and reservoir model to analysis paddy field considered with shallow ponded system, but it will need so many parameters and have much uncertainty. Fortunately, paddy field have a series of cultural practices yearly basis, such as irrigation-fertilization-forced drain-harvest with a similar time , so simple model may explain the mechanism for paddy field. Water quality model for paddy field developed in this study is simply, needs little parameters, but appeared high applicability to evaluate paddy filed drainage. We recommend this model to estimate nutrient loading from paddy field and establish best management practice.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.538-538
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• 2015

농업가뭄에 대한 연구는 주로 가뭄지표의 개선과 제안 등에 초점이 맞추어져 있으며 관개기의 강수량에 중점을 둔 사례가 대부분이다. 그러나 대부분의 논 관개용수는 저수지를 통하여 공급되기 때문에 관개가 시작되는 4월 초순의 저수량은 상당히 중요한 가뭄 대응 요소이다. 이에 따라 가뭄에 대비하기 위해서는 관개가 종료되는 10월부터 이듬해 3월까지 충분한 저수량이 확보될 필요가 있다. 그러나 기후변화에 의해 대부분의 강우가 관개기에 집중될 수 있으며 이에 따라 미래에는 비관개기 동안 충분한 저수량을 확보하는데 어려움이 발생할 수 있다. 이에 본 연구에서는 기후변화에 따른 비관개기의 강수량을 확률기반으로 분석하고, 이를 관개기 필요저수량과 비교하여 저수지의 미래 가뭄 대응 능력을 분석하고자 하였다. 기후변화에 따른 비관개기의 강수량 변화를 분석하기 위하여 RCP(Representative Concentration Pathways) 시나리오를 적용하여 미래 비관개기 동안의 연도별 비관개기 누적강수량을 분석하였다. 과거와 미래시기를 30년 단위로 구분하여 1995s, 2025s, 2055s, 2085s의 비관개기 동안의 비초과확률 10%, 50%, 90%의 강수량을 분석하였다. RCP 4.5 시나리오를 기반으로 모의한 미래강우의 비초과확률 10% 누적강수량 산정 결과에 따르면 주요 곡창지대인 전라남북도는 1995s에는 10월부터 이듬해 3월까지의 누적강수량이 약 215mm 정도로 나타났으나 2025s에는 약 150mm로 줄어드는 것으로 나타났다. 즉, 비초과확률 10%의 강우가 내릴 경우 비관개기 동안에 충분한 저수량의 확보가 어렵게 되고 관개기의 심각한 가뭄을 초래할 수 있었다. 비관개기 누적강수량과 저수량변화의 관개를 모의한 개운저수지와 계룡저수지의 경우 그 관계식은 y=1.442x-198.81, y=5.8105x-752.92와 같이 나타났다. y는 비관개기의 저수량변화를 나타낸 것이고 x는 비관개기의 누적강우량을 나타낸 것이다. 식을 통해 향후 100년 중 비초과확률 10%의 강수를 가정한다면 개운저수지는 관개종료시점의 저수율이 최소 96.93% 이상이여야 다음해 관개시작시점의 저수위가 만수위가 될 수 있었고, 계룡 저수지는 최소 86.84%의 저수위를 만족해야 다음해 관개시작시점의 저수위가 만수위가 될 수 있었다.

• Journal of Korea Water Resources Association
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• v.57 no.1
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• pp.59-72
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• 2024

Agricultural reservoirs supply water for various purposes such as irrigation, maintenance, and living. Since agricultural reservoirs respond sensitively to seasonal and climate changes, it is essential to estimate supply and inflow for efficient operation, and water management should be done based on these data. However, in the case of agricultural reservoirs, the measurement of supply and inflow is relatively insufficient compared to multi-purpose dams, and inflow-supply analysis in agricultural reservoirs through water balance analysis is necessary for efficient water management. Therefore, rainfall-runoff analysis models such as ONE model and Tank model have been developed and used for reservoir water balance analysis, but the applicability analysis for ungauged watersheds is insufficient. The ONE model is designed for daily runoff calculation, and the model has one parameter, which is advantageous for calibration and ungauged watershed analysis. In this study, the water balance was analyzed through the ONE model and the Tank model for 15 watersheds upstream of dams, and R² and NSE were used to quantitatively compare the performance of the two models. The simulation results show that the ONE model is suitable for predicting the inflow of agricultural reservoirs with the ungauged watershed