• 한국관개배수논문집
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• 제4권2호
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• pp.48-61
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• 1997

Drought index calculation method using principal hydrological factors, such as precipitation amount and reservoir storage ratio, can estimate the duration and the intensity of drought. It is not easy to establish an universal criteria of drought, since th

• Ocean Science Journal
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• 제43권4호
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• pp.175-182
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• 2008

Bottlenose dolphins are the only cetaceans regularly observed in the northern Adriatic Sea, but they survive at low densities and are exposed to significant threats. This study investigates some of the factors that influence habitat use by the animals in a largely homogeneous environment by combining dolphin data with hydrological and physiographical variables sampled from oceanographic ships. Surveys were conducted year-round between 2003 and 2006, totalling 3,397 km of effort. Habitat modelling based on a binary stepwise logistic regression analysis predicted between 81% and 93% of the cells where animals were present. Seven environmental covariates were important predictors: oxygen saturation, water temperature, density anomaly, gradient of density anomaly, turbidity, distance from the nearest coast and bottom depth. The model selected consistent predictors in spring and summer. However, the relationship (inverse or direct) between each predictor and dolphin presence varied among seasons, and different predictors were selected in fall. This suggests that dolphin distribution changed depending on seasonal forcing. As the study area is relatively uniform in terms of bottom topography, habitat use by the animals seems to depend on complex interactions among hydrological variables, caused primarily by seasonal change and likely to determine shifts in prey distribution.

• 환경영향평가
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• 제20권1호
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• pp.1-11
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• 2011

This study was carried out to suggest the baseline data necessary for vegetation restoration at riverine wetland within stream corridor. We used the prevalence index for wetland assessment by applying the method of weighted averages with index values based on five hydrophyte indicator status as defined by estimated probability occurred in wetland. We selected near nature and urbanized reach of Gap and Yanghwa streams as experimental site. Although two sites have some different disturbance and characteristics of watershed, they showed that similarity of vegetation community including three dominant species - Salix koreensis, Phragmites communis, Miscanthus sacchariflorus - was very high. But in case of Yanghwa stream, various kinds of emergent plants along wetted condition were distinctly occurred, resulted from difference of hydrological regime and substrate, etc. Degree of naturalness of vegetation at the sampled areas indicated that near nature area of Gap stream and all area of Yanghwa stream were fitted as riverine wetland, while urbanized area of Gap stream has changed into upland condition. In conclusion assessment system using prevalence index would be considered an effective method for evaluating of natural states of riverine wetland, but further integrated consideration of physical, hydrological, and biological factors of stream process, and also with considering the difference between those qualitative data of vegetation community.

• 대기
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• 제23권1호
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• pp.13-21
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• 2013

In this study, the effects of atmospheric stability and surface temperature on the microscale local airflow are investigated in a hydrological suburban area using a computational fluid dynamics (CFD) model. The model domain includes the river and industrial complex for analyzing the effect of water system and topography on local airflow. The surface boundary condition is constructed using a geographic information system (GIS) data in order to more accurately build topography and buildings. In the control experiment, it is shown that the topography and buildings mainly determine the microscale airflow (wind speed and wind direction). The sensitivity experiments of atmospheric stability (neutral, stable, and unstable conditions) represent the slight changes in wind speed with the increase in vertical temperature gradient. The differential heating of ground and water surfaces influences on the local meteorological factors such as air temperature, heat flow, and airflow. These results consequentially suggest that the meteorological impact assessment is accompanied by the changes of background land and atmospheric conditions. It is also demonstrated that the numerical experiments with very high spatial resolution can be useful for understanding microscale local meteorology.

• Environmental Engineering Research
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• 제21권3호
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• pp.226-232
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• 2016

Rainfall is one of crucial factors that impact on our environment. Rainfall data is important in water resources management, flood forecasting, and designing hydraulic structures. However, it is not available in some rural watersheds without rain gauges. Thus, effective ways of interpolating the available records are needed. Despite many widely used spatial interpolation methods, few studies have investigated rainfall center characteristics. Based on the theory that the spatial distribution of convective rainfall event has a definite center with maximum rainfall, we present a mathematical interpolation method to estimate convective rainfall distribution and indicate the rainfall center location and the center rainfall volume. We apply the method to estimate three convective rainfall events in Santa Catalina Island where reliable hydrological data is available. A cross-validation technique is used to evaluate the method. The result shows that the method will suffer from high relative error in two situations: 1) when estimating the minimum rainfall and 2) when estimating an external site. For all other situations, the method's performance is reasonable and acceptable. Since the method is based on a continuous function, it can provide distributed rainfall data for distributed hydrological model sand indicate statistical characteristics of given areas via mathematical calculation.

• 물과 미래
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• 제28권2호
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• pp.115-124
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• 1995

수문순환과정의 해석을 위한 기본 자료로써 하천유역의 형태학적 요인들은 그 형태에 따라 다양할 뿐 아니라 광범위하여 인간의 접근이 곤란하다. 이러한 하천유역의 기하형태학적 특성을 정량화하기 위해서는 많은 시간, 경비 및 인력을 필요로 한다. 최근 컴퓨터 주변기기 및 소프트웨어의 개발로 수자원 분야에서 GIS를 이용, 유역과 유추분석을 위한 응용연구를 시작으로 수질 및 물분배 등과 같은 문제에 적용하기 시작하였으며 여기서 추출된 자료를 이용하여 수자원의 많은 공가적 분석이 시도되었다. 따라서 본 연구에서는 지형정보시스템을 이용하여 평창강 유역을 대상으로 1:250,000의 지형도를 scanning하여 vectorizing함으로서 DEM(digital elevation model)자료를 생성하였고 이를 사용하여 지형도를 이용한 유역경계를 추출하였다. 또한 추출된 자료로부터 지표유출량을 산정하기 위한 수문학적 유역특성인자들을 정량화하여 기존 자료들과 비교 검토하였다. 여기서 얻은 결과를 토대로, 수자원의 운용 및 관리를 위한 정확하고 신속한 하천유역의 기하형태학적 자료를 수문정보로 사용함으로써 지형정보시스템을 이용한 하천유역의 공간정보 즉, 수문 및 지형학적 인자의 추출과정을 자동화할 수 있는 방법을 제시하고자 한다.

• 한국물환경학회지
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• 제25권1호
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• pp.7-17
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• 2009

Soil and Water Assessment Tool (SWAT) was used to assess the impact of potential future climate change on the water cycle and soil loss of the Daecheong reservoir watershed. A sensitivity analysis using influence coefficient method was conducted for two selected hydrological input parameters and three selected sediment input parameters to identify the most to the least sensitive parameters. A further detailed sensitivity analysis was performed for the parameters: Manning coefficient for channel (Cn), evaporation (ESCO), and sediment concentration in lateral (LAT_SED), support practice factor (USLA_P). Calibration and verification of SWAT were performed on monthly basis for 1993~2006 and 1977~1991, respectively. The model efficiency index (EI) and coefficient of determination ($R^2$) computed for the monthly comparisons of runoffs were 0.78 and 0.76 for the calibration period, and 0.58 and 0.65 for the verification period. The results showed that the hydrological cycle in the watershed is very sensitive to climate factors. A doubling of atmospheric $CO_2$ concentrations was predicted to result in an average annual flow increase of 27.9% and annual sediment yield increase of 23.3%. Essentially linear impacts were predicted between two precipitation change scenarios of -20, and 20%, which resulted in average annual flow and sediment yield changes at Okcheon of -53.8%, 63.0% and -55.3%, 65.8%, respectively. An average annual flow increase of 46.3% and annual sediment yield increase of 36.4% was estimated for a constant humidity increase 5%. An average annual flow decrease of 9.6% and annual sediment yield increase of 216.4% was estimated for a constant temperature increase $4^{\circ}C$.

• Journal of Ecology and Environment
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• 제44권2호
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• pp.62-71
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• 2020

Understanding vegetation structure and the relationship with environmental factors has been crucial for restoration and conservation of riparian zones. In this study, we conducted field survey in a riparian zone of Namhan River in South Korea both before and after flooding in order to understand temporal and spatial variations of riparian vegetation. There were significant temporal and spatial variations in species composition, and distribution patterns of vegetation were different along a gradient of elevation above the water level. At low elevation, Zizania latifolia was dominant throughout the field survey periods, and Bidens frondosa began to grow late and dominated both in post-flooding 1 and 2. Prior to flooding, Scirpus radicans and Polygonum thunbergii were widely distributed at middle elevation, while Artemisia vulgaris, Phragmites australis, and Miscanthus sacchariflorus were dominant at high elevation. After flooding, P. thunbergii was dominant at middle elevation with most other species decreasing, and more invasive or pioneer plants, including Artemisia princeps, H. scandens, and Sicyos angulatus, were observed at high elevation. Species composition and distribution patterns were homogeneous at low elevation, whereas dynamic variations of vegetation were observed both temporally and spatially at higher elevations. Elevation and distance from the water front were the most principal factors governing vegetation structure. Furthermore, soil physicochemical properties were also found to determine species composition and distribution patterns. These results indicate that vegetation structure in the riparian zones is formed by the combined effects of hydrological regime and soil physicochemical properties, inherent characteristics of species, and interspecific competition. Understanding of temporal and spatial variations of riparian vegetation may provide useful insights into ecological restoration and conservation of the vegetation within the riparian zones.

• 대한공간정보학회지
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• 제4권1호
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• pp.115-119
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• 1996

수문학(水文學) 해석(解析)에 있어서 기본자료로 사용되는 유역의 하천(河川) 형태학적(形態學的) 특성(特性)은 매우 다양하고 광범위하다. 지금까지의 하천형태학적 특성의 추출 방법은 수작업(手作業)에 의존하는 전통적 방법이어서 많은 시간과 경비가 필요하였다. 최근들어 컴퓨터 및 주변기기의 발달로 지형과 밀접한 관련이 있는 수문학에 GIS가 도입되어 유역과 유출분석을 위한 응용연구가 활발히 진행되고 있다. 본 연구에서는 GIS를 활용하여 국제수문개발계획(國際水文開發計劃(IHP))의 대표유역(代表流域)인 남한강(南漢江)의 평창강류역(平昌江流域)을 대상으로 GIS를 활용한 공간분석(空間分析)을 시도 하므로써 수문학적으로 참고가 되는 하천 형태학적 특성을 추출하고 수작업에 의한 결과와 비교하여 GIS의 적용 타당성을 검토하고자 한다. 이를 위하여 평창강유역을 포함하는 1:50,000 지형도(地形圖) 4도엽을 스캐닝하고 백터라이징하여 DEM을 생성하였고 이것을 ARC/INFO의 GRID 모듈을 이용하여 유역경계를 추출하였다. 또한 추출된 자료로부터 지표 유출량 산정을 위한 유역의 하천 형태학적 특성 인자들을 정량화하여 기존의 자료들과 비교 검토하였다.

• 대한공간정보학회지
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• 제11권1호
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• pp.3-12
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• 2003

하천유역의 수문학적 지형정보는 자료가 방대하여 이들을 획득하기 위해서는 많은 시간과 노력이 필요하였으며 현실적으로 사용이 곤란한 경우가 많다. 본 연구에서는 수자원의 효율적인 관리를 위한 수문정보 자료를 획득하기 위한 수단으로서 GIS를 이용하여 수문지형정보를 추출하기 위하여 DEM(Digital Elevation Model)의 처리방법을 기초로 한 GIS 소프트웨어인 Arc View를 이용하여 하천의 기하학적 요인 및 지형학적 특성을 정량화 하는 방법을 제시하며, CRID 모델을 이용하여 하천차수와 유역면적, 유역특성의 정량적 결과를 산출하는 것을 가능하게 했다. 총유로연장과 흐름누적셀 수의 관계식은 $Y=14632.87{\cdot}X^{-0.542444}$이며, 총유로연장과 셀크기의 관계식은 $Y=37014.1{\cdot}X^{-1.058808}$이다. 이들 식으로부터 탐진강 유역의 적정흐름누적셀의 수는 383개, 적정 셀의 크기는 44m임을 알 수 있었다.