초록
산림유역 조건에 따른 붕괴 토사량을 측정하여 사면 붕괴가능성을 평가하고 붕괴위험 지역에 대한 예지기술(豫知技術)을 개발함으로서 산지사면에서 발생하는 각종 재해에 대한 피해를 최소화 할 수 있는 산림유역 관리에 대한 기술적 기초 자료를 제공하고자 연구하였다. 붕괴 위험지역을 평가한 결과 I급지(매우 위험지역)는 화성암지 역으로 침엽수림이며 임령은 20년생 이하, 토심은 30cm 이하, 토성은 사질식양토(SCL), 석력함량은 $31{\sim}40%$, 사면방위는 남${\sim}$동$(S{\sim}E)$사면, 주하천길이는 $2,501{\sim}3,500m$, 총하천수는$26{\sim}30$개, 총하천길이는$5,501{\sim}10,000m$, 하천차수는 3차수, 일차하천수는 $11{\sim}15$개 또는 16개 이상, 사면경사는 $31^{\circ}$이상의 지역으로 평가되었고, II급지(위험지역)는 변성암지역으로 활엽수림이며 임령은 $21{\sim}24$년생, 토심은$31{\sim}40cm$, 토성은 미사질식양토(SiCL) 또는 사질식양토(SCL), 석력함량은 $11{\sim}20%$, 사면방위는 남${\sim}$서$(S{\sim}W)$사면, 주하천길이는 $1,501{\sim}2,500m$, 총하천수는 $6{\sim}10$개, 총하천길이는 $3,501{\sim}5,500m$, 하천차수는 2차수, 일차하천수는 $6{\sim}10$개, 사면경사는 $31^{\circ}$이상의 지역으로 평가되었으며, III급지(비 위험지역)는 퇴적암지역으로 임상은 혼효림, 임령은 25년생 이상, 토심은 $41{\sim}50cm$, 토성은 미사질식양토(SiCL), 석 력함량은 10% 이하, 사면방위는북${\sim}$서$(N{\sim}W)$사면, 주하천길이는 500m 이하, 총하천수는 5개 이하, 총하천길이는 1,000m 이하, 하천차수는 1차수, 일차하천수는 2개 이하, 사면경사는 $25^{\circ}$이하의 지역으로 평가되었다. 붕괴위험 예측치를 이용하여 붕괴위험지역을 예지한 결과 점수의 합계가 I급지는 4.8052점 이상이며 II급지는 4.8051점에서 2.5602점 사이에 해당하며 III급지는 2.5601점 이하의 지역으로 분석되었다.
This study was carried out to analyze the characteristics of forest watershed factors by using the quantification theory(I) for evaluation and prediction of the failure hazard area. Present $sediment(m^3/yr/ha)$ of erosion control dams were investigated in 95 sites of erosion control dam constructed during 1986 to 1999 in Gyeongnam province. The results obtained from this study were summarized as follows; General condition of class I(Very hazard area) were as follow; Igneous rock in parent rock, coniferous in forest type, below 20year in stand age, below 30cm in soil depth, SCL in soil texture, $31{\sim}40%$ in gravel contents, $S{\sim}E$ in aspect, $2,501{\sim}3,600m$ in length of main stream, $26{\sim}30$ in number of total streams, $6,601{\sim}10,000m$ in length of total streams, over 3 in stream order, over 16 in number of first streams order and over $31^{\circ}$ of slope gradient. General condition of class IIl(hazard area) were as follow; Metamorphic rock in parent rock, hardwood in forest type, over $21{\sim}24year$ in stand age, $31{\sim}40cm$ in soil depth, SiCL or SCL in soil texture, $11{\sim}20%$ in gravel contents, $S{\sim}W$ in aspect, $1,501{\sim}2,600m$ in length of main stream, $6{\sim}10$ in number of total streams, $3,501{\sim}5,500m$ in length of total streams, 2 in stream order, $6{\sim}10$ in number of first streams order and over $31^{\circ}$ of slope gradient. General condition of class III(Un hazard area) were as follow; Sedimentary rock in parent rock, mixed in forest type, over 25year in stand age, $41{\sim}50cm$ in soil depth, SiCL in soil texture, below 10% in gravel contents, $N{\sim}W$ in aspect, below 500m in length of main stream, below 5 in number of total streams, below 1,000m in length of total treams, below 1 in stream order, below 2 in number of first streams order and below $25^{\circ}$ of slope gradient. The prediction method of suitable for failure hazard area divided into class I, II, and III for the convenience of use. The score of class I evaluated as a very hazard area was over 4.8052. A score of class II was 4.8051 to 2.5602, it was evaluated as a hazard area, and class III was below 2.5601, it was evaluated as a un hazard area.
