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- 주제어 : 갈수기 (검색결과 7 건)
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반폐쇄성 내만 해역에서 홍수기 및 갈수기의 해수유동 변동특성
본 연구에서는 반폐쇄성 내만 해역인 광양만 내의 송도 인근 해역을 대상으로, 홍수기와 갈수기의 해수유동 변동특성을 규명하기 위해 하계 및 동계에 조석·조류 현장 관측을 수행하고, 3차원 수치모델(Delft3D-FLOW)을 이용하여 검증하였다. 해수유동 특성 분석 결과, 갈수기에는 전층에서 서북서–동남동 방향의 왕복성 조류가 지배적으로 나타났으며, 잔차류는 전층에서 창조류가 우세하였다. 반면 홍수기에는 표층과 중층에서 창조류가 우세하고, 저층에서는 낙조류가 우세하게 나타났다. 홍수기 대조기에는 조석 에너지의 증폭으로 주 수로에서 조류세기가 증가하며 왕복성 유동이 지배적으로 나타났다. 홍수기 소조기에는 담수 유입과 조석 유동의 상호작용으로 인해 송도 서측 천해역을 중심으로 국지적인 체류 및 순환 경향이 나타났다. 부표추적 실험 결과, 홍수기에는 담수 유입의 영향으로 물질 수송이 제한되고 체류 경향이 강화된 반면, 갈수기에는 조석 지배적인 유동에 의해 물질 수송이 보다 원활하게 이루어지는 특징을 보였다. 본 연구 결과는 반폐쇄성 내만 해역에서 홍수기와 갈수기에 따라 해수유동 및 물질 수송 특성이 크게 달라질 수 있음을 보여주며, 향후 지속적인 현장 관측과 정량적 분석이 병행된다면 해수유동 재현의 정확도를 더욱 향상시킬 수 있을 것으로 판단된다.
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GIS를 이용한 무안군 무청지구의 지하수위·수질자료의 변화연구
본 연구지역은 동쪽에는 산지가, 서쪽에는 바다와 접하는 전형적인 동고서저형의 지형으로 기후변화에 따른 지하수의 변화가 큰 지역이며, 소규모 지역에 지질의 변화가 크고 단층대가 발달하였다. 총 6개의 소유역으로 나뉘며, 유역 면적은 87.32㎢이다. 추출한 수계망은 1차수부터 4차수까지를 보인다. 지난 30년간의 목포기상대의 기상자료를 토대로 분석한 연평균 기상현황은 강수량 1,133.4mm, 기온 13.8℃, 증발량 1,114.7mm, 일조량 2,149.6hr, 풍속 4.1m/sec, 습도 72.7%를 보였다. 물수지분석결과 증발산량은 70.0%, 유출량은 10.0%, 함양율은 20.0%로 나타났으며, 총 함양량은 2천백7만4천톤이다. 현장조사결과 갈수기와 풍수기에 평균 수두는 갈수기 13.84m, 풍수기 15.57m로 1.73m의 수두차를 보였다. 또한 pH는 6.2에서 5.9로 감소, EC는 306㎲/cm에서 371㎲/cm로 증가하는 양상을 보인다. 양·음이온분석 결과는 양이온은 Na^(+)>Ca^(2+)>Mg^(2+)>K^(+)순이며, 음이온은 HCO_(3)^(-) >Cl^(-)>NO_(3)^(-)>SO_(4)^(2-) 순으로 나타났다. 배경치로 알아본 조사지역의 수질은 해수의 영향을 받은 지하수는 총 11개로 전체대비 73%로 대단히 높게 나타났다. Variation of water table and water quality are an important parameter in the basin analysis. There are probably more records of precipitation than of most other hydrologic variables. The study of water table height and water quality require a knowledge of the geology and the regions surface. In dry season to rainy season pH values decreased averagely 6.5 to 5.9. But EC values in dry season were averagely 306㎲/cm. Meanwhile, these in rainy season increased 371㎲/cm. Hydrochemistry of the studied normal waters are characterized by the relatively significantly enrichment of Na^(+), Ca^(2+), HCO_(3)^(-) and Cl^(-). Water quality of study area through the background values are classified into four group. Among the groundwater samples, 73% influenced by sea water. And they strongly influence to the lineament density in situ area. Changes of these are maybe owing to dilute water by heavy rainfalls and water quality are largely controlled by geological settings around the upper regions.
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Hedging Rule을 利用한 漢江水系 多目的댐 連繫 運營 最適化
The major reason to construct large dams is to strore suplus water during rainy seasons and utilize it for water supply in dry seasons. Reservoir storage has to meet a pre-defined target to satisfy water demands and cope with a dry season when the availability of water resources are limited temporally as well as spatially. It is hard to determine reservoir operation policy because of the uncertain future data. In this study, a Hedging rule that reduces total reservoir outflow as drought starts is applied to alleviate severe water shortages. Five stages for reducing outflow based on the current reservoir storage are proposed as the Hedging rule. The objective function of this approach is to minimize the total discrepancies between the target and actual reservoir storage, water supply and demand, and required minimum river discharge and actual river flow. Mixed Integer Linear Programming (MILP) is used to develop a deterministic multi-reservoir operation system with the Hedging rule. However, this system does not consider the future uncertainties so the results cannot used as a hedge against the possible system failure due to the future realization. Two-stage stochastic linear programming(2-SLP), thus, is developed with the basically same objective function. The reservoir storage is determined in the first stage before knowing the future conditions and then, in the second stage when the future realization is determined, the water distribution to users and over the stream is designed. The inflow to the basin and water demand of users are considered as the uncertain data and various scenarios were examined to consider future uncertainty. The developed systems are applied in the Han River basin that includes four multi-purpose dams and one water supplying reservoir. One of the four multi-purpose dams is primarily for power generation. Ten-day-based multi-reservoir system is developed and optimized by GAMS/CPLEX which is LP/MIP solver using a branch-and-cut algorithm. As results, most demands are satisfied when no uncertainty is involed in the system, and the discrepancies between reservoir target and real storage is more decreased than the real operation in year 2003. Only the most upstream subbasins where are no other water sources rather than natural inflow experienced water shortage at some periods. When the future uncertainties on the basin outflow and water demands are involved in the system, the water shortage of users and reservoirs in the system become severe under the extreme future conditions. Therefore the results can provide the guideline for preparing a emergency action plan under the various future climate and demand conditions.
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윤여송 성균관대학교 대학원 1989 국내박사
The purpose of synthethic jeneration of river flows based on the stochastic theory is to make possible better design and control of water resources system by generation of long term data which have the same characteristics of historical discharge data. Specially, prediction of daily river flows is very important to control and planning water resource. In this study, daily (5 days mean) river flow prediction equation is developed with great increase in the predictabillity. In the inferential model type, autoregrresive model and finite fourier approximate model are compared, and the result are analized. In the discriptive model type, exponential smoothing method and Winter's exponential smoothing method are applied, and them results are compared. As a results lf study, fllowing conclusions are derived : AR model fits in forecasting about dry days and ordinary days, but does not fit well about wet days. Finite fourier approximate model represents periodic components of time series very well. but is not so good in forcasting of flows when used without any other methods. Exponential smoothing method and Wintrer's exponential smoothing method produce good results about dry days or ordirnary days, but not about wet days. When the fllows vary significantly, Winter's exponential smoothing method produce rather good results then exponential smoothing method. For the developement of equation of equation of flow forcasting about wet days (June, July, August, September), multiregrresive equation is used, and rainfall is included in that process. A univariate time series of daily average river flows is compared to a regression model that incorporates precipitation in a nonlinear fashion. The regression model produces superior predictions to those of the time series model. The regression model forms the basis for simulations that permit comparisons of model prameters and precipitation as contributors to variation in river flow.
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