Myoung-Jin Um

Estimating the Total Precipitation Amount with Simulated Precipitation for Ungauged Stations in Jeju Island

In this study, the total precipitation amount in Jeju Island was estimated with the simulated precipitation for ungauged stations missing precipitation data using the spatial precipitation analysis. The missing data were generated through the modified multiple linear regression in this study, and the analysis of spatial precipitation was conducted with the PRISM(Parameter-elevation Regression on Independent Slope Model). The generated data with modified multiple linear regression model have similar pattern with original data. Thus, the model in this study shows good applicability to estimate the missing data. The difference of annual average precipitation between Case 1 (original data) and Case 2 (modified data) appears very small ratio which is about 1.5%. However, the difference of annual average precipitation according to elevation shows the large ratio up to 37.4%. As the results, the method of estimating missing data in this study would be useful to calculate the total precipitation amount at the low station density area and the places with the high spatial variation of precipitation.

Spatial Analysis of Precipitation with PRISM in Gangwondo

In this study, the regional factors in Gangwondo were used to analysis the relationship between point precipitation and areal precipitation. The most province area in Gangwondo is consist of mountainous terrain. At the east part of the Taebaek Mountains, the slope is very steep and the coastal plains don`t exist. At the west part of the Taebaek Mountains, the slope is mild, there are many rivers, such as South Han-river and North Han-river, and the regions are very complex terrain. The data of 66 stations in Gangwondo and the PRISM (Parameter-elevation Regression on Indepedent Slope Model) were used to estimate the spatial distribution of precipitation. According to the topographic conditions, such as elevation and slope, and the regional conditions, such as Youngdong and Youngseo, the spatial distribution of precipitation is well shown. At the results of cross-validation, the RRBIAS and the RRMSE are under 0.1 and therefore the analysis of the PRISM are well conducted. Consequently the PRISM in this study is a appropriate method to estimate the spatial distribution of precipitation in Gangwondo.

Analysis of Non-stationary Characteristics for Rainfall with the Trend Analysis of L-Moments

In this study, the non-stationary characteristics of rainfall were analyzed with the trend analysis. Among the observations in KMA (Korea Meterological Administration), the 10 sites having at least 40 years of sample data were selected such as Seoul, Daejeon, Daegu, Busan, Gwangju and Chucheon because it was difficult to estimate the trend of rainfall when the period of data was short. The L-moments such as mean, L-CV and L-skewness were estimated with over 30-year data for the four durations (1-, 12-, 24- and 48-hours). And then the trend analysis was conducted using the results of L-moments. As the results of trend analysis, among the 600 cases, the 438 cases (73%) have the tendency of rainfall data. The results show that seven stations show increasing trend for 24-hour-duration rainfall while two stations show decreasing trend, and Kwangju station does not show any trend. Thus, non-stationary frequency analysis may be required for those stations with trend.

Robust Decision-Making Technique for Strategic Environment Assessment with Deficient Information

This study developed a framework for an evaluative decision–making system that compensates for information deficiencies by considering the sensitivity of weight factor criteria. The developed decision–making system was applied to the strategic environmental assessment (SEA) for dam planning in South Korea. The SEA investigation included ten potential dam sites (four sites in the Han River, four in the Nakdong River, and two in the Geum River), performing an evaluative comparison of dam construction effects using environmental adequacy criteria and ranking the ten potential sites appropriately. Six different deficient information filling methods were applied: the normal and uniform distribution generations, Maximax, Maximin, Hurwicz, and the equal likelihood criterion. Results indicated sites GM2, HN3, ND4, and GM2 demonstrated the highest environmental adequacies across the combined effected rivers, the Han River, the Nakdong River, and the Geum Rivers, respectively. The probabilistic distribution generations, Hurwicz and the equal likelihood criterion methods produced similar priority scores and rankings based on different river conditions; however, the Maximax and Maximin methods calculated different priority scores and rankings, indicating users should be careful when applying the latter two methods for use in a decision support system (DSS) with deficient information. In future works, it will be necessary to apply other deficient data conditions or SEA examples to perform a more robust verification of the proposed framework.

Assessment of water use vulnerability in the unit watersheds using TOPSIS approach with subjective and objective weights

In the present specification, selected is an indicator considering a situation of each watershed for assessing vulnerability of each small watershed. Indicator data is constructed by using national statistics and reports based on a current point of time and a SWAT model that can be simulated for each watershed. Also, multiple weights are applied by using subjective and objective weights. The vulnerability of each unit watershed by applying a TOPSIS method among multiple criteria decision methods. When assessing water resource vulnerability, a water resource is classified according to water quantity and water quality/aquatic ecology, thereby grasping a part with high vulnerability according to each watershed.