Energy Conservation Model for Surface Runoff and Soil Erosion on Mountain Slopes
산지사면의 지표유출 및 토양침식에 대한 에너지보존 모형
- 주제(키워드) Energy Conservation , Surface Runoff , Soil Erosion , Mountain Slope , Work , Energy Loss , 에너지보존 , 지표유출 , 토양침식 , 산지사면 , 일 , 에너지손실
- 발행기관 강릉대학교 대학원
- 지도교수 朴相德
- 발행년도 2008
- 학위수여년월 2008. 8
- 학위명 박사
- 학과 및 전공 토목공학과
- 원문페이지 xxiii, 131 p.
- 본문언어 영어
초록/요약
The surface runoff and soil erosion on steep slopes which have high potential of sediment disaster depends on kinetic energy of rainfall. Kinetic energy of raindrop and potential energy of surface runoff conduct work to transport soil from upslope to slope down. High potential energy on mountain slopes processes as source of main energy to transport of water and soil. Frictional energy loss for a movable bed is usually larger than that on rigid bed and total energy loss increase with work to transport sediment. The most governing equation of physically?uprocess model in hillslope was developed to account conservation of soil mass and water mass and energy of water flow. In this study, energy conservation equation of surface runoff and soil erosion is derived to apply on real areas. Data of forty two plots established on mountain slopes in the eastern coastal region of Gangwon and operated from 2001~2004 are analyzed to estimate the energy conservation model for movement of water and soil on mountain slope system. Rainfall energy, the input energy, consisted of kinetic and potential energy and was calculated as considering effect of vegetation coverage, heights, structures, species, and litter layer coverage on forested land. Output energy was determined by the kinetic energy of overland flow at the outlet of the hillslope. Work by friction was equal to weigh of discharge and sediment yield times average moving distance of soil and water. Total energy loss except work was calculated by energy loss by mass disappearance such as interception, evapotranspiration and infiltration and due to physical process such as vegetation disturbance and impact with soil surface. Infiltration was important in determining the hydraulic conductivity which is influenced by kinetic energy of rainfall. Impact energy correlated most strongly with the kinetic energy of rainfall through vegetation and litter coverage, and the ratio of input energy to impact energy loss depended on the conditions of ground cover. The dimensionless energy coefficient was defined as the ratio of input rainfall energy to work of discharge and sediment. The energy coefficient and runoff coefficient showed the strongest correlation with vegetation coverage, with maximum coefficients of 0.45 and 0.76, respectively. Analysis between work and loss energy versus rainfall energy shows high correlation. The input energy of freefall was assigned to energy loss by vegetation and litter layer (37%), energy of infiltration (34%), impact energy (17%), energy of evapotranspiration (7%), and work by friction of discharge and sediment (5%) on mountain slopes. As a result, energy conservation model of soil erosion was presented simply as function of rainfall energy acting on soil surface, energy loss by impact of rainfall on soil surface, and kinetic energy at outlet. To estimate soil erosion exactly on a mountain slope demands examination of impact energy due to detachment and transport of soil particles by the action of rainfall.
more목차
Chapter I Introduction = 1
1.1 Background of the Study = 2
1.2 Research Objectives = 4
Chapter II Literature Review = 5
2.1 Rainfall Energy = 6
2.2 Processes of Soil Erosion = 11
2.3 Hydrological Effects on Erosion = 14
2.3.1 Effect of vegetation cover = 14
2.3.2 Infiltration = 15
2.4 Equations of Surface Runoff and Soil Erosion = 18
2.4.1 Continuity equation of unsteady surface runoff = 18
2.4.2 Continuity equation of soil erosion = 18
2.5 Models of Soil Erosion = 20
2.5.1 Empirical models = 20
2.5.2 Physically?based models = 23
Chapter III Energy Conservation for Soil Erosion = 29
3.1 Derivation of General Equation for Energy Conservation = 30
3.1.1 Reynolds transport theorem of the first law of thermodynamics = 30
3.1.2 Energy equation of surface runoff and soil erosion = 32
3.2 Derivation of Energy Conservation of Surface Runoff and Soil = 36
Chapter IV Model Components = 43
4.1 Input Energy of Rainfall = 44
4.1.1 Bare land = 45
4.1.2 Forested land = 49
4.1.3 Case of being litter layer = 56
4.2 Output Energy = 57
4.3 Energy Loss = 61
4.3.1 Evapotranspiration = 61
4.3.2 Infiltration = 62
4.3.3 Work by friction force of surface runoff and sediment = 64
4.3.4 Impact of rainfall = 65
4.4 Soil Erosion Model = 67
Chapter V Materials and Methods = 69
5.1 Site Description = 70
5.2 Field Experiments and Data Collection = 72
5.3 Surface Runoff and Soil Erosion = 83
Chapter VI Results and Discussions = 85
6.1 Input Energy = 86
6.2 Output Energy = 90
6.3 Energy Loss = 91
6.3.1 Evapotranspiration = 91
6.3.2 Infiltration = 92
6.3.3 Work of surface runoff and soil erosion = 95
6.3.4 Impact of rainfall = 97
6.4 Energy Distribution = 103
6.4.1 Energy coefficient = 103
6.4.2 Distribution of energy = 106
6.5 Establishment of Energy Conservation Model = 110
Chapter VII Conclusions = 114
References = 118
국문요약 = 130
