| Title |
Water quality modeling in the Nakdong river (2) - A study on DO balance - |
| Authors |
송교욱 ; 안욱성 ; 박청길 ( Kyo Ook Song ; Ook Sung Ahn ; Chung Kil Park ) |
| Abstract |
The Nakdong river that was already over third grade in water quality criteria as BOD. The trophic state was over entrophic and the state of Do level was supersaturation inspite of high organic loads from the each tributary. It was the result of abnormal algal bloom according to the influent of each tributary which had high nutrient concentration. In all stations except Koryong, DO saturation level showed 114.4-160.9%. The model input parameters obtained by laboratory experiment were 0.11-0.49/d in deoxygenation rate(k-1) and 0.31-0.84g/㎡d in sediment oxygen demand(SOD). DO balance was conducted using the enhanced stream quality model(Qual 2E) which was developed by U. S. EPA. The Qual 2E model includes internal sources and sinks of oxygen. The major sources of oxygen, in addition to atmospheric reaeration, are the oxygen produced by photosynthesis and the oxygen contained in the incoming flow. The sinks of DO includes biochemical oxidation of carbonaceous and nitrogenous organic matter, benthic oxygen demand and the oxygen utilized by respiration. Based on the field data, the widely used Qual 2E model was calibrated and verified and then used to DO balance. The calibrated and verified results were in good agreement with measured value within relative error of 17%. In the result of DO balance, the major sources of DO were photosynthetic production and contribution rates of June and August were 71.47 and 48.02%, respectively. The major sinks of DO were biochemical oxidation of carbonaceous organic matter and the rates were 51.54 and 47.67%, respectively. |