• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3B
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• pp.243-255
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• 2010

The spatial distribution of pan evaporation and pan evaporation trends have been studied. In this study, pan evaporation data from 1973 to 1990 for 56 climatological stations were analyzed. In addition to annual average daily pan evaporation, monthly average daily pan evaporation in April, July, October and January were analyzed, considering seasonal effect. The study results indicate that in case of annual average daily pan evaporation, 38 stations out of 56 stations show decreasing trend. In case of average daily pan evaporation in January, 33 stations show decreasing trend. In April, 38 stations show increasing trend. In July, 47 stations show decreasing trend. In October, 35 stations show increasing trend. Therefore, on the whole, pan evaporation tended to decrease in January, July, and annual basis. On the other hand, pan evaporation tended to increase in April and October. Furthermore, pan evaporation trend in each individual region shows also different trend even though the region is located nearby, indicating that there are geographical and topographical effects on pan evaporation trend. Pan evaporation data and climatic data from 1973 to 2006 for 11 climatological stations were used for trend analysis. Climatic variables such as temperature, relative humidity and wind speed show same or opposite trend direction compared with pan evaporation in annual or monthly basis. Annual and monthly solar radiation trends show the same direction compared with pan evaporation; however, annual and monthly precipitation trends show the opposite direction compared with pan evaporation.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.302-313
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• 2012

Long-term trends (e.g. 1997~2010) of chlorophyll a and water quality properties of the Yeongsan River were analyzed by using water quality monitoring data collected by the water information system, ministry of environment. Nine monitoring stations were selected along the main channel of the river, and parameters of BOD, COD, TN, TP, conductivity, TSS and chlorophyll a were collected for surface water monthly through the monitoring system. Trends of water quality and chlorophyll a were analyzed by the Seasonal Mann-Kendall Test and LOWESS (Locally Weighted Scatter-plot Smoother). The results showed that the water quality parameters, including chlorophyll a, were improved in all stations except Station WC in the most-upper region, where water quality data for the determined parameters were increased, indicating a reduction in water quality. Based on the results from LOWESS analysis, chlorophyll a (algal blooms), BOD and COD recently began to increase after 2007 suggesting that an additional study on the cause of these increases in organic pollution, as well as a better management system for the region are required.