The purpose of this study is to evaluate and to predict of eutrophication in lakes by using Vollenweider-OECD model and total phosphorus concentration and inflow rate which were measurded in 1993-1996. The results of study was as follows.
The annual total phosphorus loading from the watershed was calculated to be 181∼195tP/yr at lake Soyang, 591∼680tP/yr at lake Chungju, 420∼466tP/yr at lake Taechong, 229∼278tP/yr at lake Andong, 103∼106tP/yr at lake Hapchon, 57∼59tP/yr at lake Imha, 194∼244tP/yr at lake Namgang, 83∼86tP/yr at lake Chuam, 99∼109tP/yr at lake Somjin. These are discharged, for the most parts, from population and fishfarm facility.
TP loading on the surface area at lake Soyang was 3.01gP/㎡/yr, 2.82gP/㎡/yr, 2.84gP/㎡/yr. 3.03gP/㎡/yr, at lake Chungju 7.9lgP/㎡/yr, 6.87gP/㎡/yr, 7.38gP/㎡/yr, 7.18gP/㎡/yr, at lake Taechong 6.7lgP/㎡/yr, 7.25gP/㎡/yr, 7.24gP/㎡/yr, 6.53gP/㎡/yr and TP loading on the surface area of Nakdong river basin, that is, lake Andong, Imha, Hapchon and Namgang were 5.39gP/㎡/yr, 4.47gP/㎡/yr, 4.56gP/㎡/yr, 4.45gP/㎡/yr and 2.20gP/㎡/yr, 2.23gP/㎡/yr, 2.24gP/㎡/yr, 2.17gP/㎡/yr and 4.50gP/㎡/ yr, 4.50gP/㎡/yr, 4.54gP/㎡/yr, 4.43gP/㎡/yr and 8.25gP/㎡/yr, 8.48gP/㎡/yr, 8.48gP/㎡/yr, 10. 39gP/㎡/yr respectively. Also those of lake Chuam was 2.51gP/㎡/yr, 2.61gP/㎡/yr, 2.52gP/㎡/yr, 2.54gP/㎡/yr and TP loading on the surface area at lake Somjin was analysed 4.09gP/㎡ /yr, 4.10gP/㎡/yr, 3.98gP/㎡/yr, 3.73gP/㎡/yr.
The tropic states of nine lakes can be assessed as eutrophy because phosphorus loading exceeds the critical phosphorus loading by Vollenweider-OECD model.

• 김재윤(한국수자원공사) | Jae-Yun Kim (Korea Water Resources Corporation)