수생태계 보호를 위한 소하천 관리 방안 = A Small Stream Management Plan to Protect the Aquatic Ecosystem

다국어 초록 (Multilingual Abstract)

Small streams interconnect through the land between mountains, streams, and reservoirs. In general, small streams have diverse ecological and social characteristics because they are extensively formed across watersheds over time. According to statistical data, the total length of national and local streams, in Korea, is 26,841km and small streams run a total of 38,815km (1.2 times longer). The aquatic and terrestrial habitat structures around small streams are distinctly maintained based upon surrounding environments, such as landscape, soil, and land cover. Previous literature indicates that indigenous and endangered species in many countries are observed in conserved forested small streams. However, small streams in Korea have been significantly degraded primarily because of human disturbances including stream maintenance activities. Hydrologic alteration (e.g., channelization, dam construction) and landuse changes have deteriorated the functions of the aquatic ecosystems of small streams. Small streams are where runoff accumulates and flows downstream. In the context of the ``stream continuum concept``, small streams include areas of headwater where rivers originate. Therefore, the proper management of small streams to control the impact of flooding and pollutants is critical to protect the health of the upstream and downstream aquatic ecosystem. The main purpose of this study is to provide a management plan to protect the aquatic ecosystem of small streams. This paper reviewed the ecological roles of small streams documented in journals, field·survey reports, and interviews with ecologists. In addition, the limitations and shortcomings of current small stream management plans were analyzed from regulatory and field·conservation perspectives. In chapter 2, research regarding the ecological management of small streams and the theoretical background of the ecological role of small streams were reviewed. Chapter 3 summarized the laws, regulations, actual condition, management, and budget of small stream management and the problems caused by small stream maintenance that focuses largely on water control. In this regard, the ecological condition of nine small streams (seven streams applied with nature·friendly small stream maintenance methods) was quantified using the Stream Visual Assessment Protocol (SVAP). Chapter 4 included results of ecosystem health analysis in 28 small streams in the Han River Basin and analysis of land cover changes in the small stream riparian. In addition, the chapter examined the importance of riparian management in small streams through time·series analysis. The results were compared with both watershed· and stream reach·scales. In chapter 5 regulatory and research suggestions were included to improve the management and policies regarding the protection of the aquatic ecosystem in small streams. In addition, future studies regarding small stream management to respond to climate change were reviewed. The Appendix introduced cases of small stream recovery in other countries and provided a detailed explanation of the nature·friendly small stream maintenance method applied in Korea. The following includes brief suggestions and conclusions to protect small stream ecosystems through the review of theory, research report analysis, space analysis, laws, and regulations. 1. Standardization of (small) stream classification based on the characteristics of small streams to protect the ecosystem should be developed for efficient management. The current classification system was set up in an administrative manner, and although it considered the size of the stream (length and width), physical parameters such as stream order, water quality, and habitat characteristics, should be considered. This study reported that a majority of the small streams (88.8%) in Korea were included as first to third small streams at a scale of 1:25,000. 2. Better riparian management of small streams is required to protect ecological functions. Riparian conservation influences the health of an ecosystem by mitigating changes in ecosystem environments (i.e., water quality, temperature, habitat corridor, base flow). These factors are all related to upstream and downstream riparian conservancy and disturbance. Thus, riparian management for small streams is important to sustainably protect the ecosystem over a long·term period. 3. It is of the utmost importance to improve the strategies employed during maintenance work conducted by the federal and local governments on small streams. Concepts in the management plans should be revised to protect the ecosystem rather than focusing entirely on flood control and water use. 4. Research regarding a small stream management model will be needed in order to efficiently manage small stream ecosystems. The following research topics were summarized: 1) basic resources of small stream flux and water quality environment, 2) waste treatment system and water circulation studies to improve water quality, 3) research programs to develop small stream watershed adaptations, 4) expanding of eco·monitoring surveys to include small streams, and finally, 5) policy inducement of small stream management through local participation.