낙동강유역의 오염총량관리계획에 따른 환경회계

Abstract

낙동강유역의 오염총량관리계획에 대한 환경회계와 개선방안을 제안하기 위하여 emergy 분석을 실시하였다. 발생원 저감방안을 제안하기 위해 낙동강유역 전체의 emergy 분석결과 emergy 투자비는 17.50, 환경부하비는 30.82, 지속성 지수는 0.03으로 비교적 공업화가 집중되어 환경압박이 크고 지속성이 낮은 시스템으로 평가되었다. 낙동강 수자원의 실질적인 가치는 하류로 갈수록 190.9원, 190.1원, 188.9원으로 감소하고 상수원수 1㎥을 관리 및 처리하는데 드는 비용은 하류로 갈수록 372원, 392원, 406원으로 증가되는 것으로 평가되었다. 총량관리계획에 대한 환경회계 결과를 살펴보면 수질개선 효과를 위한 노력으로 수립전과 후 모두 편익이 발생하지만 수립 이후 추가 저감시설의 투자계획으로 편익/비용의 비율은 1.493에서 1.230으로 낮아졌다. 총량관리계획에 대한 개선방안으로 먼저 2차 처리된 유출수의 영양염 제거를 위해 고도처리시설을 확충하거나 신설하여 제거하는 고비용의 저감시설보다는 저비용의 습지조성으로 질소와 인을 제거하면 보다 자연친화적인 저감시설이 될 것이다. 질소와 인 1㎏를 제거하기 위해서 고도처리의 경우 각각 197,000￦과 2,390,000￦이며 인공습지의 경우 각각 118,000￦과 1,609,000￦의 비용이 소요되는 것으로 평가되었다. 낙동강유역의 지속적인 유역관리를 위해서는 유역내에서 발생되는 오염부하를 근원적으로 줄여야 하며 또한 산업활동이 지역 내의 영속성 에너지와 보유자원에 의존하여 이를 효율적으로 이용할 수 있는 자연친화적 산업구조로 재편성되어야 할 것이며 아울러 낙동강의 수자원도 지속적으로 이용할 수 있을 것이다. 또한 오염총량관리계획에 따른 낙동강수계의 수질개선을 위해서는 환경비용만을 유발하는 에너지 소모적인 고비용의 하수처리시설 확충에 의존한 수질관리보다는 시설투자비와 유지관리비가 적게 투자되고 보다 효율적인 자연환경자원을 이용하는 생태공학적인 처리시설로 점차 전환되어야 한다. 제1단계 오염총량관리계획의 대상물질은 BOD이지만, 제2단계 오염총량관리계획의 대상물질은 BOD뿐만 아니라 TP까지 포함되므로 비용절감차원에서의 인공습지조성과 비점오염원에 대한 저감관리 대책이 절실히 요구된다.

In present day, there is limited to accomplish environmental standards in the river by the concentration regulation of water quality, due to the high population growth, crowding and densely located industrial facilities on the middle and downstream area of Nakdong river. It is difficult to control increasing pollution load by only the concentration regulation of water quality focused on the standard of discharge permission. Therefore, the government should regulate the increase of pollution load by introduce Total Maximum Daily Loads(TMDL) Program to control pollutant load. Under this background, this study was carried out environmental accounting of the Total Maximum Daily Loads(TMDL) Program in the Nakdong river basin by emergy analysis which was evaluated both natural environment and human economic activity from the same measure. To evaluate the contribution for the economic systems and the essential value in the Nakdong river basin, this study is estimated by the emergy analysis prior to environmental accounting for the TMDL. Environmental accounting for TMDL is evaluated to separate the condition before and after TMDL program. This study discussed for the improvement countermeasure of TMDL is as below: First, emergy analysis of Nakdong river basin was carried out, the emergy input of whole Nakdong river basin was calculated 1.55E+23 sej/yr, and Emergy Yield Ratio and Emergy Investment Ratio were 1.06 and 17.50. In this result, it showed the local production contributes the main economy in Nakdong river basin and the area in Nakdong river basin has high environmental pressure. Emergy Sustainability Index was 0.03 which means sustainable development ability in this area is a little low. Second, emergy from the outside of goods and services after introduced with TMDL was calculated 7.90 E+20 sej/yr. Although river's real yield value after investment was still high(before : 9.7118E+20 sej/yr and after : 9.7224E+20 sej/yr) the real improvement effect is not great compared with the investment cost. Environmental Accounting result after TMDL shows us a decrease on benefit/cost ratio from 1.493 to 1.230 due to the cost on treatment facilities. Third, the input emergy of advanced treatment plant for N and P reduction by 1㎏ of N and P reduction were estimated 4.14E+14 sej, 5.02E+15 sej, and the imput emergy of wetland for the 1㎏ of N and P reduction were estimated 2.48E+14 sej, 3.38E+15 sej, respectively. To reduce 1㎏ of N and P, it costs 197,466 and 2,388,739 won by advanced treatment plant and 117,976 and 1,609,213 won by constructing artificial wetland. Fourth, In the case of wetland for reduction of non-point source, the share of renewable source showed 100%. According to the result of emergy analysis for the natural wetland, river was highest in the renewable resources by 2.92 E+19 sej /yr, and waterfowls was highest in the storages by 3.37 E+19 sej/yr. If we make efforts to use natural wetland with abundant natural resource or construct wetland for reduction facilities of non point source, the wetland will not provide only the effect of reduction of non point pollution source, but also flood control ability and habitat of animals or plants. In conclusion, it is necessary that ecological treatment facilities to use efficiently environmental resource with spending few cost of investment and management is suggested to the Total Maximum Daily Loads(TMDL) Program. If the structure of water management depending on expansion of the waste water treatment facilities to use high environmental cost should alternate with the efficient natural formation that is supported by the renewable source in the region, the system and water resource of Nakdong river basin will develop and be sustainable use of this structure.