• Journal of the Korean Geographical Society
• /
• v.46 no.4
• /
• pp.414-425
• /
• 2011

The aim of this research is to infer paleovegetation and paleoclimate in the Hwajeon archeological site of Gwangju city during mid-Holocene through the analysis of pollen, waterlogged woods, and sediments. Between 8200 ~ 6800 years ago, relatively dry climate resulted in a weakened dominance of oak and high diversity of tree genus. During the Holocene climatic optimum period (6800 ~ 5900 years ago), oak forests expanded while wetland areas diminished as warm/humid climate intensified. Between 5900 ~ 4700 years ago, the entire forest area as well as oak climax forests was reduced due to a relatively cool/dry climate. However at the end of this period, oak forests expanded since a favorable climate condition temporarily resumed. Lastly, between 4700 ~ 3300 years ago, oaks dominated but alders were weakened. The density of forest was low because of a relatively dry climate in this period.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.177-177
• /
• 2023

The impacts of dams on transboundary flow are complex and challenging to project and manage, given the potential moderating influence of a broad range of anthropogenic and natural factors. This study presents a global meta-analysis of 168 studies that examines the effect magnitude of dams on downstream seasonal, annual flow, and hydrological extremes risk on 39 hotspot transboundary river basins. The study also evaluates the impact of 13 factors, such as climate, basin characteristics, dams' design and types, level of transboundary cooperation, and socioeconomic indicators, on the heterogeneity of outcomes. The findings reveal that moderators significantly influence the impact of dams on downstream flow, leading to considerable heterogeneity in outcomes. Transboundary cooperation emerges as the key factor that determines the severity of dams' effect on both dry and wet season's flows at a significance level of 0.01 to 0.05, respectively. Specifically, the presence of water-supply and irrigation dams has a significant (0.01) moderating effect on dry-season flow across basins with high transboundary cooperation. In contrast, for wet-season flow, the basin's vulnerability to climate extremes is associated with a large negative effect size. The various moderators have varying degrees of influence on the heterogeneity of outcomes, with the aridity index, population density, GDP, and risk level of hydro-political tension being the most significant factors for dry-season flow, and the risk level of hydro-political tension and basin vulnerability to climate extremes being the most significant for wet-season flow. The results suggest that transboundary cooperation is crucial for managing the impacts of dams on downstream flow, and that various other factors, such as climate, basin characteristics, and socioeconomic indicators, have significant moderating effects on the outcomes. Thus, context-specific approaches are necessary when predicting and managing the impacts of dams on transboundary flow.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.222-222
• /
• 2015

Vietnam is one of the most vulnarable countries affected by climate change and sea level rise. One of the consequences of climate change and sea level rise is the increase of salinity intrusion into the rivers which is challenging to irrigation systems in coastal areas. This indicates the necessary to study the ability of taking water through sluice gates of irrigation systems in coastal zones, especially in the dry season with the effects of climate change and sea level rise in the future. In this paper, Nam Thai Binh irrigation system is selected as a case study. The irrigation system is one of 22 biggest irrigation systems of the Red River delta in Vietnam located in coastal region. The computed duration is selected in dry season to irrigate for Winter-Spring crops. The irrigation water for the study area is taken from different sluice gates along the Red River and the Tra Ly River. In this paper, MIKE-11 model was applied to assess the ability of taking water for irrigation of the study area in current situation and in the context of climate change and sea level rise senario in 2050 (under the medium emissions scenario (B2) published by the Ministry of Natural Resources and Environment of Vietnam published in 2012) with different condition of water availability. The operation of the gates depends on the water levels and sanility conditions. The sanility and water level at different water intake gates of Nam Thai Binh irrigation system were simulated with different senarios with and without climate change and sea level rise. The result shows that, under climate change and sea water level rise, some gates can take more water but some can not take water because of salinity excess and the total water taking from the different gates along the rivers decrease while the water demand is increase. The study indicates the necessary to study quantitatively some recommended solutions in the study area particularly and in coastal region generally in Vietnam to ensure water demand for irrigation and other purposes in the context of climate change and sea level rise in the future.

• Journal of Korea Water Resources Association
• /
• v.54 no.11
• /
• pp.999-1009
• /
• 2021

As the frequency and intensity of extreme weather events due to climate change are increasing in recent years, it is very important to evaluate and analyze climate conditions to manage and respond to the negative effects of climate change in advance. In this study, the trends and characteristics of regional climate change were analyzed by calculating the climate indices for the Chungcheong Province. Annual and monthly UNEP-MP, UNEP-PM and MDM indices were calculated using daily data from 1973-2020 collected from 10 synoptic meteorological stations operated by the Korea Meteorological Administration. The normality of climate data was analyzed through the KS test, and the climate change trend was analyzed by applying the Spearman and Pearson methods. The Chungcheongnam-do region had a relatively humid climate than the Chungcheongbuk-do region, and the annual climate indices showed a dry climate trend in Cheongju and Chungju, while the climate of Seosan and Buyeo was becoming humid. Based on the monthly trend change analysis, a humid climate trend was observed in summer and autumn, while a dry climate trend was observed in spring and winter. Comparison of climate indices during the past (2001-2010) and the recent (2011-2020) years showed a higher decrease in the average climate indices during the last 10 years and a gradually drying climate change trend was recorded.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.2
• /
• pp.244-250
• /
• 2019

We investigated the relationship between morphological characteristics and individual dry weight to develop a method for estimating the individual dry weight of sheet form macroalgae: Ulva australis, Ulva linza, Pachymeniopsis lanceolata, and Pyropia yezoensis. In Total, 319 thalli of various sizes were collected at six sites from February 2017 to December 2018. An interspecific allometric exponent of 0.28 was found for length-biomass allometry in four sheet form macroalgae, corresponding to a 1/4-power law for primary producers. The relationships between surface area and individual dry weight, as well as between individual fresh weight and individual dry weight, were found to fit significantly using linear regression equations. This explained 94-99 % of individual dry weight, indicating that surface area and individual fresh weight can be used to accurately estimate individual dry weight. We propose the use of this method when experimental processes do not allow individual dry weight to be measured directly, so researchers can save both time and expense.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.271-271
• /
• 2015

The Ecuadorian coast has two different climate regions. One is humid region where the annual rainfall is above 2000 mm and rain falls in almost all months of the year, and the other is dry region where the annual rainfall can fall below 50 mm and rainfall can be very seasonal. The agriculture is frequently limited by the seasons during the year and the availability of rainfall amounts. The corn fields in Ecuador are cultivated during the rainy season, due to this reason. The weather conditions for optimum development of corn growth require a monthly average rainfall of 120 mm to 140 mm and a temperature range of $22^{\circ}C{\sim}32^{\circ}C$ for the dry region, and a monthly average rainfall of 200 mm to 400 mm and a temperature range of $25^{\circ}C{\sim}30^{\circ}C$ for the humid area. The objective of this study is to predict how the weather conditions are going to change in corn fields of the coastal region of Ecuador in the future decades. For this purpose, this study selected six General Circulation Models (GCM) including BCC-CSM1-1, IPSL-CM5A-MR, MIROC5, MIROC-ESM, MIROC-ESM-CHEM, MRIC-CGC3 with different climate scenarios of the RCP 4.5, RCP 6.0, and RCP 8.5, and applied for the period from 2011 to 2100. The climate variables information was obtained from the INAMHI (National Institute of Meteorology and Hydrology) in Ecuador for the a base line period from 1986 to 2012. The results indicates that two regions would experience significant changes in rainfall and temperature compared to the historical data. In the case of temperature, an increment of $1^{\circ}C{\sim}1.2^{\circ}C$ in 2025s, $1.6^{\circ}C{\sim}2.2^{\circ}C$ in 2055s, $2.1^{\circ}C{\sim}3.5^{\circ}C$ in 2085s were obtained from the dry region while less increment were shown from the humid region with having an increment of $1^{\circ}C$ in 2025s, $1.4^{\circ}C{\sim}1.8^{\circ}C$ in 2055s, $1.9^{\circ}C{\sim}3.2^{\circ}C$ in 2085s. Significant changes in rainfall are also projected. The rainfall projections showed an increment of 8%~11% in 2025s, 21%~33% in 2055s, and 34%~70% in 2085s for the dry region, and an increment of 2%~10%, 14%~30% and 23%~57% in 2025s, 2055s and 2085s decade respectively for humid region.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.15 no.4
• /
• pp.314-322
• /
• 2012

In order to elucidate temporal variations of temperature, salinity, pH, dissolved oxygen (DO), suspended particulate matter (SPM), dissolved inorganic nutrients, and chlorophyll a, we performed 25-hour continuous monitoring in the Seomjin River Estuary in March (dry season) and July (rainy season) 2006. We also investigated spatial variations of marine environmental parameters across a saline gradient. In the Seomjin River Estuary, continuous monitoring results revealed that salinity variations were mainly affected by tidal cycle in the dry season and by river discharge in the rainy season. In the dry season, the spatio-temporal distribution of dissolved inorganic nutrient (nitrate, nitrite, and silicate) concentrations showed a good correlation with tidal cycle. While nutrient concentrations in rainy season showed not much variance in time. There were 6 and 4 times higher dissolved inorganic nitrogen and phosphorus concentrations in the rainy season than those in the dry season, respectively. Silicate concentration was 43 times higher in the rainy season than that in the dry season. Chlorophyll a concentration was higher in the dry season than that in the rainy season showing high nutrient concentrations. The results of this study, spatio-temporal variations of marine environmental factors are determined by both tidal cycle and river discharge. It seems that chlorophyll a concentration is related to the river discharge than dissolved inorganic nutrient distribution.

• Journal of Korea Water Resources Association
• /
• v.46 no.8
• /
• pp.873-884
• /
• 2013

In Korea, the rainfall is concentrated in summer under the influence of monsoon climate. Thus, even a small climate change can be significant problems in water resources. As a result, a lot of attention has been focused on climate changes and a number of researches have been conducted in a manner commensurate with the attention to the climate change. This study is intended to forecast the changes in the flow and water quality of the Nam river resulting from the future climate changes in the Nam river basin using a watershed and water quality model. An SWAT model, as a watershed hydrologic model, was established after estimating a climate scenario using an artificial neural network method, and the established model was verified and adjusted using date from the Ministry of Environment to evaluate the applicability of the model. As a consequence, $R^2$ showed more than 0.7 in the simulation test, which satisfies the minimum required level. Results from the SWAT model and the future Namgang dam discharge calculated by HEC-ResSIM is used as input date for QUALKO. The results showed a huge variation in BOD depending on the annual flow of the river, which recorded a maximum difference of 2 mg/L between a rainy season and a dry season. It can be deduced that because rainfall and the runoff of a basin significantly account for the water quality of a river, higher water concentrations are recorded in a dry season in which the flow is not as much as that in a rainy season. It also can be said that water should be reserved in advance to secure water in the Nam river downstream for a dry season and be controlled in an effective and efficient manner to provide better water quality.

• Atmosphere
• /
• v.17 no.3
• /
• pp.241-253
• /
• 2007

This paper investigates summer precipitation change in East Asia according to switching surface boundary condition over South Korea and Shantung. Simulations are carried out by ECHO-G/S for 20 years (1980-1999). Surface condition over both areas in ECHO-G/S is represented by ocean (OCN experiment). In OCN experiment, the summer precipitation is considerably underestimated around the Korean peninsula (the dry region) and overestimated over the eastern Tibetan Plateau (the wet region). It may be related that the lack of the heat sources from the unrealistically prescribed land-sea mask weakens northward expansion of rainband and the development of convective precipitation. Moreover the simulated rainband retreats before June in connection with the early genesis of summer monsoon circulation. The systematic bias of the summer precipitation over the dry and wet regions are reduced comparing with the OCN experiment when the land-sea masks over South Korea and Shantung are realistically considered as land (LND experiment). These improvements can be explained by the thermodynamical dissimilarity between land and ocean. Enhanced warming by switching the areas from sea to land has led to develop the thermal low over Yellow Sea with the cyclonic circulation. Thus, this cyclonic circulation supports moistures from the south to the dry region and blocks to the wet region. The heat transport from the land surface to atmosphere plays a key role in the developing convective precipitation in local scale and maintaining the precipitation and the rainband. Therefore, this results indicate that the design of the realistic land-sea distribution is required for the accurate simulation of the regional precipitation.

• Journal of the Economic Geographical Society of Korea
• /
• v.15 no.2
• /
• pp.192-205
• /
• 2012

This study estimates how much climate variables affect the land price and acreage of rice paddy and dry farm field in agriculture with the case of Gangwon-do in Korea. To this end, we capitalize upon the Ricardian approach based upon the panel data on climate, soil and geography, farmland prices and acreage, other economic and social variables for 11 municipal units comprising Gangwon-do during the period of 1992-2010. Our empirical analysis shows that the temperature variable has negative economic impacts on the price and acreage of rice paddy and dry farm field, confirming that the temperature variable is much significant than that of precipitation in global warming. On the other hand, the other determinants of farmland price and acreage are different with the type of farmland in Gangwon-do.