Understanding the distinct hydro-biogeochemical dynamics of lotic and lentic systems is crucial for integrated watershed management, particularly in regions with complex land-use patterns. This study investigated the spatiotemporal water quality variations in Gunsan City, Republic of Korea. Monthly monitoring was conducted at 17 sites (8 rivers and 9 reservoirs) from May 2024 to May 2025 to analyze 11 physicochemical parameters. Multivariate statistical approaches, including Factor Analysis of Mixed Data and K-means clustering, were employed to elucidate the interactions between water body types and seasonal factors. Factor analysis identified two primary gradients explaining 42.7% of the total variance: anthropogenic nutrient loading (Axis 1) and seasonal metabolic-physical drivers (Axis 2). The study revealed distinct spatial heterogeneity; rivers exhibited significantly higher electrical conductivity and nutrient concentrations (e.g., TN, TP) compared to reservoirs, clustering into a high-pollution group driven by point and non-point sources. Seasonally, rivers showed a marked concentration effect during the dry winter season due to reduced base flow, whereas reservoirs maintained relatively stable water quality attributed to the dilution capacity of larger water volumes. Shallow reservoirs like Backseokje exhibited characteristic water quality pattern, such as hypoxia related to organic matter decomposition and high vegetation cover. These findings suggest that a differentiated management approach is essential: mitigating point-source and non-point-source pollution and securing base flow for rivers during dry seasons, while regulating internal biogeochemical processes and inflows for reservoirs.

Homing behavior is a fundamental ecological trait influencing site fidelity and the success of translocation programs for endangered species. This study evaluated the homing ability and effective homing range of the Reeves’ turtle (Mauremys reevesii), a Class II Endangered Wildlife species and a Natural Monument in South Korea. Six adult turtles were captured from reservoirs in Gurye-gun, attached with GPS transmitters, and artificially displaced to terrestrial release sites at distances ranging from 200 to 600 m from their original habitats. Monitoring from May 2023 to July 2024 revealed a distance-dependent homing response: individuals displaced by 200 m and one of two displaced by 300 m successfully returned to their original reservoirs. However, all turtles displaced by distances greater than 300 m (400~600 m) failed to return. These results suggest that while M. reevesii possesses homing instincts, its effective homing range on land is relatively limited compared to other freshwater turtles. This study provides the first empirical evidence of the spatial limits of homing in Korean M. reevesii populations. Technical challenges, such as signal loss due to mud accumulation on solar-powered tags in wetland environments, were also identified as a factor to consider in future telemetry studies. For successful translocation, we recommend selecting release sites within 300 m of core habitats to maximize settlement success.

A dilution method for reducing chlorophyll a concentration of downstream reservoir through upstream dam discharge was reviewed at Seungchon Weir and Juksan Weir reservoirs in the Yeongsan River. The applied model equations were divided into 1) a case of accepting the inflow of upstream water with non-discharge state, and 2) a case of accepting the water after discharging the same amount of weir water. We found the positive effect of dilution in chlorophyll a reduction, and accepting upstream water after predischarging is more effective. The larger the amount pre-discharged, the greater the dilution effect. Therefore, under conditions that do not affect the downstream environments of the weir, it is appropriate to pre-discharge high chlorophyll a water first and then dilute it. However, the method of reducing chlorophyll a concentration in weir reservoir using clean upstream water is not recommendable except critical cases. The upstream dams of the Yeongsan River basin were constructed for multipurpose including agricultural use, and discharge of dam water can cause the disputes over water rights. Therefore, the dilution method can only be implemented limitedly when weir reservoirs are critically polluted and upstream dam water is sufficient enough not to affect agricultural use in Yeongsan River watersheds.

The absence of standardized, biology-based assessment criteria for lake ecosystems at the national level underscores the need for developing systematic and integrative phytoplankton-based evaluation tools. Phytoplankton are primary producers that regulate energy flow and nutrient cycling in lake ecosystems, and their rapid responses to environmental changes such as eutrophication, altered hydrodynamics, and seasonal fluctuations make them highly effective biological indicators. Multimetric indices (MMIs) offer a structured and integrative approach for capturing complex community level responses to environmental stressors, thereby enhancing the ecological relevance and management utility of biological assessment tools for lentic systems. This study presents the Lake Phytoplankton Assessment Index (LPAI), developed using long term ecological and water quality data from 90 lakes and reservoirs across South Korea. The LPAI comprises six ecologically meaningful metrics: total cell density (M2), cell density of flagellated algae (M10), cell density of harmful cyanobacteria (M17), cell density of eutrophic Chlorophyta (M18), relative abundance of saprophilous diatoms (M23), and relative abundance of eutraphentic diatoms (M25). Application of the LPAI demonstrated that lake health grades exhibited a broad and near-normal distribution across seasons, while summer assessments showed a marked increase in lower grade (C~E) lakes associated with elevated temperatures and cyanobacterial blooms. Conversely, winter assessments showed improved conditions due to reduced phytoplankton biomass and the dominance of low eutrophic diatom assemblages. Correlation analyses confirmed that the selected metrics captured distinct ecological gradients, particularly nutrient enrichment and organic matter driven turbidity, while PCA results indicated that the LPAI performed consistently across lake types without structural bias. Overall, the LPAI reliably reflects trophic conditions, harmful algal risks, and structural changes in phytoplankton communities, offering a scientifically grounded and management-relevant tool for evaluating the ecological health of Korean lakes and reservoirs.

This study investigated seasonal variations in phytoplankton community composition and physicochemical water quality across 90 lakes in South Korea surveyed 2022 to 2024, and examined their relationships with environmental factors. Over the course of four seasons, a total of 952 phytoplankton taxa were identified, with Bacillariophyta (diatoms) and Chlorophyta (green algae) accounting for 64.2% of the total species richness. Diatom species such as Aulacoseira granulata, Fragilaria crotonensis, and Cyclotella meneghiniana were frequently observed regardless of season. In terms of cell density, Cyanophyta were dominant, comprising 85.1% on average, with particularly high summer densities driven by blooms of Microcystis aeruginosa and Aphanizomenon sp. In contrast, diatoms accounted for the highest relative abundance in winter (54.1%). Canonical correspondence analysis (CCA) revealed that Cyanophyta and Chlorophyta were positively correlated with water temperature, TP, COD, and Chl-a, whereas Bacillariophyta and Cryptophyta showed negative correlations with these variables. These results indicate that phytoplankton communities in Korean lakes are highly responsive to variations in temperature and nutrient concentrations, and that summer rainfall-driven nutrient inflow plays a critical role in triggering cyanobacterial blooms. This study provides a scientific basis for understanding seasonal ecosystem dynamics in Korean lakes and offers foundational data for eutrophication management and the development of biological water quality assessment indices.

본 연구에서는 안전한 수질의 밭 관개용수를 확보하기 위한 다기능 저류조 용수공급시스템을 현장에 적용하여, 효과를 검증하여 현장 적용성을 분석하였다. 용수의 수질 특성을 고려하여 적정 모듈 프로세스로 AOP (Advanced Oxidation Process), SF (Soil Filter)를 적용하였으며, 저류조의 효과 검증은 앞서 다기능 저류조 수처리 저감효율, 미생물 위해성 평가 등을 통해 수행하였다. 시범시설의 조사는 유입수(지표수, 지하수) 2개, 유출수 1개 지점을 2022년 5월부터 9월까지 월 1회(총 5회), 수온, TOC, COD 등 13개 수질항목을 측정하였다. 유출수에서 전항목 수질기준을 만족하였다. 다기능 저류조의 저감효율은 지표수에서 TOC 평균 19.2%, SS 평균 43.8%, T-N 평균 28.1%, T-P 평균 46.9%, Chl-a 평균 70.1%, 지하수에서 수온 평균 7.5% 상승, EC 평균 54.3%의 저감효율을 보여, 다기능 저류조의 수질정화 개선효과를 검증하였다. 미생물 위해성 평가 결과, 평균 위해도 값은 유입수(지하수) –3.02 × 10-6, 유입수(지표수) 2.79 × 10-5로 나타났으며, 다기능 저류저 처리 후 E.coli가 전량 사멸함에 따라 영농작업자의 위해성은 없을 것으로 나타났다.

The occurrence of cyanobacteria and the formation of cyanotoxins in lakes and reservoirs are influenced by many environmental factors. In this study, the harmful cyanobacteria occurrence and cyanotoxins concentrations was investigated in three agricultural reservoirs in the southern Gyeonggi-do in 2023. Although harmful cyanobacteria growth and cyanotoxins formation are influenced by various environmental factors in the actual ecosystem, the cell density of harmful cyanobacteria reached its maximum in September when the water temperature was relatively high, and the highest cyanotoxins (microcystin and anatoxin-a) concentrations were observed in October when the water temperature dropped to the range of 20~23℃. From this investigation, harmful cyanobacteria blooms and cyanotoxins residence in investigated three agricultural reservoirs was observed.

In this study, 46 reservoirs in South Korea were characterized based on heavy metal concentration in sediments. We analyzed the relationship between heavy metal concentrations, physicochemical water quality and hydromorphological factors in each reservoir. Study reservoirs were classified into five groups of reservoirs, by hierarchical cluster analysis based on the similarities of heavy metal concentration. Group 1 had the most severe sediment heavy metal contamination among the groups, whereas Groups 2 and 3 showed low levels of heavy metal contamination. Group 4 displayed high value of Ni, and Group 5 showed high contamination of Pb, Cu, Cr, Ni, and Hg. Groups 1 and 5, which had high concentration of heavy metals in sediments, showed a high density of mines in the catchment of reservoirs. Heavy metal concentration was high in reservoirs with large capacity or the ones located at higher elevation, and also highly related with number of mines in the catchment of reservoir. This study can contribute to the systematic management of sediment heavy metals in reservoirs.

Understanding the characteristics of reservoir water quality is fundamental in reservoir ecosystem management. The water quality of reservoirs is affected by various factors including hydro-morphology of reservoirs, land use/cover, and human activities in their catchments. In this study, we classified 83 major reservoirs in South Korea based on nine physicochemical factors (pH, dissolved oxygen, chemical oxygen demand, total suspended solid, total nitrogen, total phosphorus, total organic carbon, electric conductivity, and chlorophyll-a) measured for five years (2015~2019). Study reservoirs were classified into five main clusters through hierarchical cluster analysis. Each cluster reflected differences in the water quality of reservoirs as well as hydromorphological variables such as elevation, catchment area, full water level, and full storage. In particular, water quality condition was low at a low elevation with large reservoirs representing cluster I. In the comparison of eutrophication status in major reservoirs in South Korea using the Korean trophic state index, in some reservoirs including cluster IV composed of lagoons, the eutrophication was improved compared to 2004~2008. However, eutrophication status has been more impaired in most agricultural reservoirs in clusters I, III, and V than past. Therefore, more attention is needed to improve the water quality of these reservoirs.

빈번한 가뭄의 피해는 수자원의 양극화를 초래하고 있다. 국내에서는 2011년부터 2017년 사이에 국지적이고 주 기적인 이상 가뭄이 지속되어 10년 가뭄 빈도로 설계된 소규모 저수지의 저수율이 감소하였다. 이러한 저수율의 감소 는 수질을 떨어트릴 수 있고 이미 확보된 용수의 사용마저 제한할 수 있다. 따라서 가뭄에 대비하고 극복하기 위해서 는 수질관리와 가뭄 빈도의 재산정이 필요하다. 이 연구는 저수지에서 수질 변화의 원인인 잠재적 오염물질을 추정하고, 가뭄 기간 동안 저수지의 저수율 감소와 그에 따른 수질 변화를 검토한 것이다.

The present study investigated species richness and phytoplankton community structure in lakes in the Geum River Basin during autumn and spring seasons. Surveys were conducted between September and November 2019, and between April and May 2020, which corresponded to the autumn and spring seasons, respectively, to explore the distribution characteristics of the species. A total of 49 species of phytoplankton belonging to 31 genera and seven classes were identified in Cho Pyeong-ji, 51 species belonging to 29 genera and six classes were identified in Song Ak-ji, 49 species belonging to 32 genera and seven classes were identified in Cheong Cheon-ji, 82 species belonging to 45 genera and six classes were identified in Ye Dangji, and 70 species belonging to 40 genera and six classes were identified in Ganwol Lake. A total of 43 species belonging to 74 genera and seven classes were identified. The ranges of phytoplankton standing crop were as follows: 223~3533 cells mL-1 in Cho Pyeong-ji, 881~176018 cells mL-1 in Song Ak-ji, 402~6139 cells mL-1 in Cheong Cheon-ji, 262~10460 cells mL-1 in Ye Dang-ji, and 20413~330695 cells mL-1 in Ganwol Lake. Phytoplankton diversity in Cho Pyeong-ji, Song Ak-ji, Cheong Cheon-ji, Ye Dang-ji, and Ganwol Lake were 1.10~2.60, 0.56~2.03, 0.21~2.03, 0.65~2.57, and 0.44~1.12, respectively. Phytoplankton species richness in Cho Pyeong-ji, Song Ak-ji, Cheong Cheon-ji, Ye Dang-ji, and Ganwol Lake were 1.91~4.99, 1.82~3.26, 1.26~4.17, 2.07~5.37, and 1.90~2.43, respectively. Phytoplankton evenness indices in Cho Pyeong-ji, Song Ak-ji, Cheong Cheon-ji, Ye Dang-ji, and Ganwol Lake were 0.38~0.78, 0.18~0.69, 0.08~0.71, 0.22~0.72, and 0.14~0.38, respectively. Phytoplankton dominance indices in Cho Pyeong-ji, Song Ak-ji, Cheong Cheon-ji, Ye Dang-ji, and Ganwol Lake were 0.40~0.83, 0.55~0.96, 0.44~0.99, 0.42~0.93, and 0.89~0.97, respectively.

본 연구에서는 영산강, 섬진강 유역에서 호소 간의 동물 플랑크톤의 군집구조 특성이 만수면적에 따라 분류된 소· 중·대형의 저수지에서 종 수 및 개체수가 유의한 차이를 보이는 것을 확인하였다. 윤충류보다 지각류에서 민감도가 높은 것을 확인하였으며, 특히 두 분류군 모두 양의 상관 관계를 나타냈지만, 지각류에서 조사지점이 늘어날수록 개체수 증가가 확연한 것을 알 수 있었다. 또한 네트워크 분석 개념을 활용한 고유벡터 중심성 및 그룹화 분석을 사용 하여 호소 간의 동물플랑크톤 군집구조를 비교했을 때, 만수면적에 따른 대·중·소형 호소 내에서도 지리적 특성과 미소환경 공간의 차이점을 구별할 수 있었다. 따라서 이러한 특성을 볼 때, 네트워크 분석은 담수 동물플랑크톤 군집구조 분석에 있어 만수면적 크기, 지리적 특성, 미소환경 특성을 반영할 수 있는 것으로 고려된다. 마지막으로, 네트워크 분석은 다양한 군집분석을 간소화하며 시각화를 통한 직관적 이해를 돕는 데 유용할 것이다.

수산자원보호구역인 춘천호와 안동호에서 어류 군집 분석을 실시하였다. 조사는 2017년부터 2018년까지 수행되었으며, 어류상을 파악하고 우점종 및 아우점종을 확인한 결과 춘천호에서 채집된 어류는 총 13과 34종 1,197개체였다. 채집된 어류 중 블루길(Lepomis macrochirus)이 23.2%로 우점하였으며, 피라미(Zacco platypus)가 17.4%로 아우점하였다. 안동호에서 채집된 어 류는 총 9과 24종 1,393개체였다. 우점종은 블루길이 15.7%로 가장 많이 채집되었으며, 붕어 (Carassius carassius)가 15.2%로 아우점하였다. 두 조사지점의 종다양도는 과거보다 증가하는 경향을 보였으며, 균등도는 안동호에서는 차이가 보이지 않았으나 춘천호에서는 증가하는 경 향을 보였다. 두 인공호 모두 어류상 및 군집구조 측면에서 안정된 상태를 유지하고 있으나 외래종 비율을 감소시키기 위한 지속적인 노력이 필요하고, 다양한 어종이 안정적으로 개체 수를 유지할 수 있도록 수산자원 종자 방류 및 인공산란장 설치 등과 같은 관리가 필요하다.

본 논문은 최근 이상기후에 따른 재해·재난대비수단으로 유용하게 활용되고 있는 저수지의 개보수사 업에 대한 경제적 효과를 계량적으로 분석한다. 이를 위해 저수지개보수사업의 목적을 자연재해에 대비 한 안정적인 농업용수 공급과 시설노후에 따른 붕괴예방으로 나누어 그 효과를 각각 측정한다. 저수지 개보수사업에 대한 효과 측정은 저수지 일대에 거주하고 있는 주민들을 대상으로 개보수사업에 대한 지 불의사와 금액을 가상가치평가법(CVM)을 이용하여 추정한다. 분석 결과, 자연재해와 재난 예방 관련 지불의사금액의 분포는 유사하게 나타났다. 표본 지역 주민들의 66%가 개보수사업에 지불할 의향이 있 다고 응답하였다. 전체 표본에 대한 자연재해 예방 관련 지불의사금액은 주민 평균 32,250~46,147원이 고, 재난 예방 관련 지불의사금액은 28,427~47,308원으로 나타났다. 지역유형별로 지불의사금액을 비 교해 보면 논 농업 지역, 시설재배 지역, 도시 지역 순으로 높게 나타났다. 한편, 주민별 지불의사금액 에 기초하여 각 지역의 저수지개보수사업에 대한 총 기대가치를 산출한 결과 논 농업 지역과 시설재배 지역의 총 기대가치는 실제 사업비 규모에 비해 상당히 높게 나타났다. 이는 주민들이 자연재해 및 재 난 예방을 위한 저수지개보수사업의 중요성을 충분히 인지하고 있으며 현재 사업비가 충분치 않을 경우 추가적인 비용을 부담할 용의가 있음을 시사한다.