한국농림기상학회지, 제 12권 제3호(2010) (pISSN 1229-5671, eISSN 2288-1859)
Korean Journal of Agricultural and Forest Meteorology, Vol. 12, No. 3, (2010), pp. 197~206
DOI: 10.5532/KJAFM.2010.12.3.197
ⓒ Author(s) 2014. CC Attribution 3.0 License.


토지이용이 다변화된 산림 유역의 수질에 미치는 몬순 강우의 영향

조경원(1), 이현주(1), 박지형(1), Jeffrey S. Owen(1),(2)
(1)강원대학교 산림환경과학대학 산림환경보호학과
(2)강원대학교 자연과학대학 환경과학과

(2010년 07월 01일 접수; 2010년 09월 26일 수정; 2010년 09월 27일 수락)

Effects of Monsoon Rainfalls on Surface Water Quality in a
Mountainous Watershed under Mixed Land Use

Kyeong-Won Jo(1), Hyun-Ju Lee(1), Ji-Hyung Park(1), Jeffrey S. Owen(1),(2)
(1)Department of Forest Environment Protection, College of Forest & Environmental Sciences, K
angwon National University, Chuncheon, 200-701, Korea
(2)Department of Environmental Science, College of Natural Sciences, Kangwon National University,
Chuncheon, 200-701, Korea

(Received July 01, 2010; Revised September 26, 2010; Accepted September 27, 2010)

ABSTRACT
To provide baseline information essential for assessing environmental impacts of monsoon rainfalls in a mountainous watershed under mixed land use, we investigated spatiotemporal variations in water quality using a combined approach of seasonal water quality survey and intensive storm samplings. Biannual water sampling at nine locations encompassing major land use types showed generally lower electrical conductivity and Cl- concentrations during the typical wet period compared to the dry period, indicating rainfall-induced dilution of dissolved ions. Total metal concentrations, however, were significantly higher during the monsoon period, probably associated with rainfall-induced increases in suspended sediments. Intensive storm sampling during a small monsoon rainfall event (18 mm) and an extreme event (452 mm) showed rapid changes in both suspended sediments and dissolved solutes in an agricultural stream draining the Haean Basin where arable lands have expanded rapidly over the recent decades. By contrast, a nearby forest stream derived from North Korea showed little responses to the small event compared to larges changes during the extreme event. In the agricultural stream total Pb concentrations showed significant positive relationships with suspended sediments. Although limited sampling frequency and locations require a cautious interpretation, the overall results suggest that expansion of agricultural fields in steep mountainous watersheds can increase the susceptibility of soil erosion and its off-site environmental impacts under increasing rainfall variability and extremes.

Keyword: Climate variability, Monsoon rainfalls, Mountainous watersheds, Surface water quality, Trace metals

MAIN

적요

토지 이용이 다변화된 산지 유역에서 몬순 강우에 의한 환경 영향을 평가하는데 필수적인 기초 자료를 확보하기 위해 수질의 계절간 비교와 강우사상 집중샘플링의 방법을 활용하여 지표수 수질의 시공간적 변이특성을 조사하였다. 유역 내 토지 이용을 반영하는 지표수 9개 지점을 대상으로 건·우기 수질의 계절적 차이를 비교하고, 2회의 강우사상에 대해 산림과 농경지하천 2개 지점에서 집중 샘플링을 실시하였다. 대부분의 지점에서 건기보다 우기에 전기전도도와 Cl−농도는 더 낮았으나, 총 금속 농도는 우기에 훨씬 더 높았다. 이는 우기에 늘어난 유량에 의해 용존 이온은 희석되고, 토양 침식량은 증가됐기 때문인 것으로 보인다. 한편 18mm의 적은 강우 시에 산림 하천의 수질에서는
거의 변화가 보이지 않은 데 반해, 농경지 하천에서는 부유토사와 용존 물질 농도가 모두 가파른 변화를 보였으며, 452mm의 많은 강우에 대해서는 농경지 하천은 물론 산림 하천에서도 큰 수질 변화를 관찰할 수 있었다. 농경지 하천의 Pb 농도는 부유토사 농도와 높은 양의 상관관계를 보였다. 제한된 샘플링 횟수와 조사지점으로 인해 결과 해석에 신중을 기해야 하겠지만, 전체 결과는 가파른 산지 유역에 농경지가 무분별하게 확장되면 강우의 변동폭과 극단화가 심해질 경우 토양 침식과 그에 따른 환경 영향의 취약도가 증가할 것임을 시사한다.

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