Search Results (12)

Rhynchocypris kumgangensis, endemic to Korea, is limited to the upper Hangang River and Gucheondongcheon Stream. As a key and climate-sensitive biological indicator species in the Deogyusan National Park, it has a southern range limit in the Gucheondong Valley. Due to climate change, notable shifts in the activity, distribution, and population of R. kumgangensis on the Gucheondongcheon Stream are expected. This study examined trends between the 2020 field survey and previous surveys (2014–2018) for fish faunal changes at 13 sites in the Deogyusan National Park and for the population changes of R. kumgangensis at four sites in the Gucheondongcheon Stream. At 13 sites, we identified 996 individuals of 17 fish species in seven families, including 2 endangered (Pseudopungtungia nigra, Hemibarbus mylodon) and 11 Korea-endemic species. The Fish Assessment Index (FAI) of the 13 sites in the Deogyusan National Park was analyzed and found to be of A-grade in both the 2020 and past surveys, with high scores in all M1–M8 categories. Both the results of CCA and field surveys between the entire fish community and pH, DO, and water temperature revealed that the population of R. kumgangensis had a narrower distribution range and was more sensitive to water temperature than the same cold-water fish, R. oxycephalus. Climate change has been identified as causing the annual maximum temperature (°C) in the Deogyusan National Park to increase year on year and the R. kumgangensis population to decline, suggesting that the time for conservation efforts is “now”. Full article

In 2011, Korea installed artificial structures on four rivers to secure water resources and reduce flood damage; however, these structures have altered ecosystems and aquatic communities. This study analyzed fish communities and environmental variables at 72 sites in the Geumgang River. Fish communities and environmental variables before weir installation were examined using site data from 2008 to 2009. The results showed that Cyprinidae dominated the 70 observed species. A self-organizing map categorized the 72 sites into four groups based on fish communities. Sensitive and insectivorous species decreased, whereas tolerant and omnivorous species increased from Groups I to IV. Twenty-one indicator species were identified, with fewer and less distinct distribution patterns in Groups II and III than in Groups I and IV. The fish assessment index (FAI) showed a decline in grades A and B and an increase in grades C and D from Groups I to IV. Correlation analysis between the FAI and environmental variables indicated that fish communities in the Geumgang River were mainly influenced by water quality, reflecting altitude gradients and pollution levels. This study’s findings are anticipated to significantly inform water management strategies for the Geumgang, Yeongsangang, Nakdonggang, and Hangang Rivers. Full article

Microphysogobio longidorsalis is endemic to South Korea and inhabits small areas of the Namhangang, Bukhangang, and Imjingang Rivers in the Hangang River water system. Endemic species usually are more vulnerable than species with a wide distribution. Notably, there is a lack of basic conservation data for M. longidorsalis. We analyzed 19 microsatellite loci in six populations of M. longidorsalis in South Korea to characterize their population structure and genetic diversity. The genetic diversity of the microsatellites was 0.741–0.779, which is lower than that of other freshwater fishes. The pairwise genetic differentiation of microsatellite (F_ST) values ranged from 0.007 to 0.041, suggesting low genetic differentiation between the populations. The Jojongicheon stream population (CP) had an effective population size of <100. Therefore, conservation efforts are required to prevent inbreeding depression in M. longidorsalis. Discriminant analysis of principal components showed that the Hangang River water system would be a single management unit (MU). Our findings provide fundamental genetic insights for the formulation of conservation strategies for M. longidorsalis. Full article

Cities worldwide are developing strategies to cope with heat waves, extreme colds, floods, wildfires, hurricanes, earthquakes, droughts, pandemics, and other disasters caused by climate change. To this end, a resilience theory is being expanded and applied as a methodology to secure social and spatial systems that respond to climate change while providing ecological habitats and spaces for more diverse human activities. This study evaluated resilient redevelopment strategies for the Hangang River in Seoul by drawing on practices grounded in resilience theory. This study analyzed the nine proposals from the Resilience by Design Challenge, which aimed to gather response strategies for climate change in the San Francisco Bay Area in 2017 to identify practical physical design and social system strategies. Each team’s strategy for implementing urban resilience focused on six categories: governance systems, financial planning, public engagement, accessibility, ecology, and diversity. The guidelines to consider during the redevelopment of the Hangang River in Seoul were formulated by applying these criteria to the review of the river. This process has also yielded the following implications and characteristics for resilient design. First, ensuring the resilience of a city necessitates prioritizing the resolution of regional imbalances. Second, the social and ecological resilience of cities is intricately intertwined. Moreover, comprehending the dynamics between the two can guide effective, resilient design. Third, resilient design’s spatial and temporal scales are extensive and varied, highlighting the importance of understanding the relationships among categories and subcategories at different hierarchies. Finally, the value of urban waterfront space, traditionally associated with positive cultural and economic contributions to cities, must be reevaluated more profoundly and meaningfully in light of climate change. Full article

The Korean endemic aucha perch, Coreoperca herzi, belongs to the family Centropomidae. Thus far, studies on C. herzi have focused on mitochondrial genomes, egg development, and early life history, while studies on their genetic diversity or genetic structure are lacking. We investigated these aspects in this study using mitochondrial DNA data. Haplotypes were divided into the Hangang River, Nakdonggang River, Geumgang River, and southwest region water system populations. A translocated population, the Yangyang Namdaechun Stream, was confirmed to have originated from the Hangang River water system population based on haplotype distribution and genetic structure results. The F_ST of the mitochondrial DNA indicated distinct genetic differentiation in the Hangang, Nakdonggang, Geumgang, and southwest regions. According to COI and analyses, the analysis of molecular variance revealed a higher variance in the four water system groups (98.41%) than in the southwest region water system versus the Hangang River water system (80.27%) groups. This study presents basic data for conservation by providing extensive information on the genetic diversity, genetic structure, and translocation population of C. herzi. Full article

The design of urban spaces, including waterfronts, must consider the flexibility to respond to urban and environmental changes and the continuity that respects the existing urban factors that have determined the essential characteristics of the place. The Hangang River in Seoul, South Korea, has been susceptible to significant changes over the years and has accumulated considerable historical traces and an irrevocable relationship with its urban contexts. On the other hand, as the country experienced rapid development, most urban plans have been executed based on shortsighted perspectives without considering sustainability. This study suggests adaptability as the main driver to achieve sustainability of the urban riverfront by viewing the site condition dichotomously. The components of the site were distinguished as fixed and variable factors. Considering fixed factors, six design intervention types were applied to the site through extensive macroanalysis and correlation studies, and each intervention was proposed to respond to the variable factors of the site. This study proposed four strategies to upgrade the riverfront as an adaptable space. First, five types of waterfronts were introduced with more distinct functions and identities to accommodate various activities. Second, commercial development was introduced to build a stable financial base that could respond to economic fluctuations. Third, the ecological waterfront space was expanded to react to climate change in the long term and achieve the goals of improving the microclimate, biodiversity, and educational function in the short term. Lastly, connective infrastructure was introduced to address the rapidly increasing demand for open space. The significance of this study was twofold. First, the site condition was interpreted more comprehensively by applying a framework for analysis by distinguishing the fixed and variable factors. Second, the strategy presented in this study can be applied to establish a waterfront redevelopment plan in other cities that have a context similar to the Hangang River of Seoul. Full article

This study concerns the lithologic characteristics of the stone used as the main construction materials of ancient Korean tombs, and aims to understand how they were supplied. Specifically, we investigated the main ancient tombs in the Songpa district, south of the Hangang River in Seoul, composing the connected stone-mound tombs in the Seokchon-dong tomb complex, Bangi-dong tomb No. 3, and 13 horizontal stone-chamber tombs in the Gamil-dong tomb complex. There are major differences among the tombs reflected in the types of rock used as construction materials in these sites. Tombs at Seokchon-dong and Bangi-dong were built mainly using biotite gneiss, whereas those at Gamil-dong are composed of amphibole schist. By comparing the characteristics of the rocks collected from the provenance sites, we concluded that the quartzite used at the Gamil-dong tombs was from Cheonma Mountain, the gneiss at the Bangi-dong sites was from Daemo Mountain, and the amphibole schist and diabase at the Gamil-dong sites were from Cheonma Mountain. On the other hand, gravel-shaped stone materials are found in the tombs of Seokchon-dong and Bangi-dong, but not in Gamil-dong tombs. Therefore, it can be seen that between Seokchon-dong, Bangi-dong, and Gamil-dong tombs, there is a difference not only in the main constituent rock types, but also in the shape of the stone materials. These gravel-shaped stones are assumed to have been transported via the Hangang River drainage system and supplied to Seokchon-dong and Bangi-dong tombs. Therefore, we consider that the constructors of the tombs in the ancient Songpa district locally sourced materials of different rock types. Full article

Since predicting rapidly fluctuating water levels is very important in water resource engineering, Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) were used to evaluate water-level-prediction accuracy at Hangang Bridge Station in Han River, South Korea, where seasonal fluctuations were large and rapidly changing water levels were observed. The hydrological data input to each model were collected from the Water Resources Management Information System (WAMIS) at the Hangang Bridge Station, and the meteorological data were provided by the Seoul Observatory of the Meteorological Administration. For high-accuracy high-water-level prediction, the correlation between water level and collected hydrological and meteorological data was analyzed and input into the models to determine the priority of the data to be trained. Multivariate input data were created by combining daily flow rate (DFR), daily vapor pressure (DVP), daily dew-point temperature (DDPT), and 1-hour-max precipitation (1HP) data, which are highly correlated with the water level. It was possible to predict improved high water levels through the training of multivariate input data of LSTM and GRU. In the prediction of water-level data with rapid temporal fluctuations in the Hangang Bridge Station, the accuracy of GRU’s predicted water-level data was much better in most multivariate training than that of LSTM. When multivariate training data with a large correlation with the water level were used by the GRU, the prediction results with higher accuracy ($R^2=0.7480–0.8318$; $NSE=0.7524–0.7965$; $MRPE=0.0807–0.0895$) were obtained than those of water-level prediction results by univariate training. Full article

Two new benthic freshwater species belonging to the genus Achnanthidium were found in Korea. Achnanthidium ovale sp. nov. and A. cavitatum sp. nov. are described as new species based on light and scanning electron microscopy observations and molecular analyses. Both species are compared with the type material of morphologically similar taxa. Achnanthidium ovale differs from other species belonging to the A. pyrenaicum complex in outline, striation pattern, raphe central endings, and freestanding areolae at the apices. Achnanthidium cavitatum differs from other species in the A. minutissimum complex in outline, broad axial central area in the raphel ess valve, and slit-like areolae near the axial central area. We assessed their molecular characteristics by analyzing nuclear small subunit (SSU) rRNA and chloroplast-encoded rbcL gene sequences. Both the morphological comparison and the SSU and rbcL sequence analyses provide strong evidence to support the recognition of A. ovale and A. cavitatum as new species. Full article

The volatile metabolite, 2-Methylisoborneol (2-MIB) produced by cyanobacterial species, causes odor and taste problems in freshwater systems. However, simple identification of cyanobacteria that produce such off-flavors may be insufficient to establish the causal agent of off-flavor-related problems as the production-related genes are often strain-specific. Here, we designed a set of primers for detecting and quantifying 2-MIB-synthesizing cyanobacteria based on mibC gene sequences (encoding 2-MIB synthesis-catalyzing monoterpene cyclase) from various Oscillatoriales and Synechococcales cyanobacterial strains deposited in GenBank. Cyanobacterial cells and environmental DNA and RNA were collected from both the water column and sediment of a eutrophic stream (the Gong-ji Stream, Chuncheon, South Korea), which has a high 2-MIB concentration. Primer sets mibC196 and mibC300 showed universality to mibC in the Synechococcales and Oscillatoriales strains; the mibC132 primer showed high specificity for Pseudanabaena and Planktothricoides mibC. Our mibC primers showed excellent amplification efficiency (100–102%) and high correlation among related variables (2-MIB concentration with water RNA r = 689, p < 0.01; sediment DNA r = 0.794, p < 0.01; and water DNA r = 0.644, p < 0.05; cyanobacteria cell density with water RNA and DNA r = 0.995, p < 0.01). These primers offer an efficient tool for identifying cyanobacterial strains possessing mibC genes (and thus 2-MIB-producing potential) and for evaluating mibC gene expression as an early warning of massive cyanobacterial occurrence. Full article

To date, physical, numerical or data-driven models have been used to forecast water surface elevation in rivers for specific times or locations in the literature. Recently, the trend of forecasting water surface elevation changed from physical and numerical models to data-driven models with the help of the development of big data processing technology and fast simulating time of data-driven models. In this study, a data-driven model with Long Short-Term Memory (LSTM) was developed using TensorFlow, one of the famous deep learning frameworks and forecasting of water surface elevation affected tidal river was performed in Hangang River, Korea. From many types of field measurements, the hourly hydrological data, precipitation, outlet discharge of dam upstream and tidal levels were selected as the input dataset through a t-test and a p-value. In particular, the hybrid activation function was proposed to alleviate the vanishing gradient and dying neuron problems generally issued in the application of the activation function. The model showed that the root mean square error (RMSE) and peak error (PE) decreased by 0.22–0.25 m and 0.11–0.21 m, respectively, and the Nash-Sutcliffe efficiency (NSE) increased up to 79.3%–97.0% compared with the single activation functions. For $w_1=0.6$ and $w_2=0.4$ in the hybrid activation function, the improvement of accuracy and the enhancement of the application range of the leading time interval were obtained through a sensitivity analysis. Moreover, the hybrid activation function showed a good performance. The forecasting results provided by this model can be used as reference data for the establishment of the emergency action plan (EAP). Full article