학술논문
팔공산 산림소유역의 유출 특성 변화
Changes in Hydrological Characteristics of a Forested Watershed of Mt. Palgong
Changes in Hydrological Characteristics of a Forested Watershed of Mt. Palgong
Document Type
Article
Author
Source
한국산림과학회지(구 한국임학회지) / JOURNAL OF KOREAN FORESTRY SOCIETY. Dec 31, 2020 109(4):429
Subject
Language
Korean
ISSN
2586-6613
Abstract
본 연구는 산림 소유역에서 강우량에 대한 계류유출량의 장기적인 변화추이를 정량화하고, 임목의 생장이 산림소 유역의 유출변화에 어떠한 영향을 미치는지를 파악하기 위하여 실시했다. 연도별로 강우량과 유출량은 비례관계를 보였으며, 시간이 경과할수록 유출량은 점차 감소하는 것으로 나타났다. 월별 강우량과 유출량은 7월과 8월에 가장 높았으며, 유출률은 8월과 9월에 높은 값을 보여 강우량과 유출량, 유출률 변화가 반드시 일치하지는 않았다. 월별 변동계수(CV)는 강우량에 비해 유출량이 더 크게 나타났고, 강우량과 유출량 간의 편차는 점차 증가하였다. 강우량에 대한 총 유출량과 직접 유출량의 변화는 2011년∼2017년의 추세선의 기울기가 더 낮아졌고, 기저유출량의 기울기는 증가하였다. 산림토양이 발달하면서 토양층의 수분보유력이 증가하였기 때문으로 보여지며, 기저유출량의 증가는 팔공산 산림소유역의 유출수량 증가와 함께 지하수위 상승에 영향을 줄 것으로 판단된다. 감수곡선의 기울기는 2003년∼2010년에 비해 2011년∼2017년이 더 낮은 것으로 나타났고, 시간이 경과함에 따라 유출량의 감소가 완화되고 유출량이 일정하게 유지되었다. 따라서 팔공산 산림소유역은 임목의 생장에 따라 지표류의 유출이 감소하고 기저유량이 증가하는 것으로 나타나, 산림의 수원함양기능이 점차 증가하는 것으로 나타났다.
In this study we quantified the long-term change in discharge against precipitation in a forested watershed and investigated how the growth of forest trees influences these changes. We found a proportional relationship between precipitation and discharge for each year, and discharge decreased gradually with time. Precipitation and discharge were highest in July and August, and the changes in precipitation, discharge, and runoff rate did not always coincide, given that high runoff rate was shown in August and September. The monthly coefficient of variation (CV) for discharge was larger than that for precipitation, and the deviation between precipitation and discharge increased gradually. From 2011 to 2017, the gradient of the trend line for the change of total discharge and direct runoff against precipitation decreased, whereas the gradient of the base flow increased in this same time period. A possible explanation is that the water holding capacity of soil deposits increased as the forest soil of the Palgong Mountain watershed developed and the increase of base flow rose with groundwater level together with that of outflow quantity. The coefficient of flood recession was lower in the period 2011 to 2017 than in 2003 to 2010; thus, the reduction of discharge was mitigated and remained steady as time progressed. We conclude from these results that the discharge of surface runoff decreased as tree growth and base flow increased; however, the water yield function of the forest increased gradually.
In this study we quantified the long-term change in discharge against precipitation in a forested watershed and investigated how the growth of forest trees influences these changes. We found a proportional relationship between precipitation and discharge for each year, and discharge decreased gradually with time. Precipitation and discharge were highest in July and August, and the changes in precipitation, discharge, and runoff rate did not always coincide, given that high runoff rate was shown in August and September. The monthly coefficient of variation (CV) for discharge was larger than that for precipitation, and the deviation between precipitation and discharge increased gradually. From 2011 to 2017, the gradient of the trend line for the change of total discharge and direct runoff against precipitation decreased, whereas the gradient of the base flow increased in this same time period. A possible explanation is that the water holding capacity of soil deposits increased as the forest soil of the Palgong Mountain watershed developed and the increase of base flow rose with groundwater level together with that of outflow quantity. The coefficient of flood recession was lower in the period 2011 to 2017 than in 2003 to 2010; thus, the reduction of discharge was mitigated and remained steady as time progressed. We conclude from these results that the discharge of surface runoff decreased as tree growth and base flow increased; however, the water yield function of the forest increased gradually.