Changes in the Water Environment Based on the Statistical Data in the Lake Paldang

통계로 보는 팔당호 물환경 변화

Abstract

Since the 1970s regulations against the pollution of drinking water have been introduced in Lake Paldang watershed area. To understand the effects of water environment management policies and the impacts of climate changes on Lake Paldang, a long-term comprehensive study of this watershed and the changes in its water environment is required. In this study, we analyzed changes in the weather, hydrology, sources of pollution, water quality, and algal development from 2000 to 2015 year based on the statistical data provided by several national information systems. While the population and amount of sewage in the Lake Paldang watershed increased by about 1.5 times, the amount of animal manure showed a decreasing trend during the same period. The wastewater also increased by about 1.5 times while the amount of water intakes rose by about 1.14 times. The water quality in front of the Paldang Dam, which is the representative monitoring site of the Lake Paldang, was stable. The annual average BOD concentration remained within 2 mg/L, which is a "Good (lb)" level according to the environment standards of Republic of Korea. The development of phytoplankton and harmful cyanobacteria were largely influenced by meteorological factors.

Fig. 1. Hydraulic structures, weather stations, water gauging stations and monitoring points around the Lake Paldang.

Fig. 2. Special measures areas for the preservation of water quality in the Lake Paldang.

Fig. 3. Mean annual temperature change in the Yangpyeong weather station.

Table 1. Location of water quality measuring network and algae alert system in the Lake Paldang

Table 2. Annual temperature status at the Yangpyeong weather station

Table 3. Average monthly temperature at the Yangpyeong weather station

Table 4. Monthly precipitation at the Yangpyeong weather station

Table 5. Annual precipitation status at the Yangpyeong weather station

Table 6. Mean annual inflow, outflow and flow duration in the Lake Paldang

Table 7. Inflow ratio of Namhan river to Bukhan river

Table 8. Status of the special measures areas in the Paldang watershed

Table 9. Population and density in the special measures areas of the Paldang watershed (2015)

Table 10. Variation of population and sewage flow in the special measures areas of the Paldang watershed

Table 11. Variation of livestock population and manure in the special measures areas of the Paldang watershed

Table 12. Variation of number and flow of wastewater facility in special measures areas of the Paldang watershed

Table 13. Wastewater facility and flow in the special measures areas of the Paldang watershed (2015)

Table 14. Water intake and purification station (as of Dec. 2015)

Table 14. Water intake and purification station (as of Dec. 2015) (continued)

Table 14. Water intake and purification station (as of Dec. 2015) (continued)

Table 15. Annual averaged water quality in the Lake Paldang

Table 16. The change of annual flow rate, water quality, and inflow load in the Lake Paldang

Table 17. Comparison of annual discharge and inflow load by river

Table 18. Variation of phytoplankton taxa with harmful cyanobacteria in 2002 ~ 2015