Amongst the impacts of converting forest to agricultural activities are soil erosion and degradation of ecology service values and goods （ESVG）. The soil erosion can be seen as on-site impacts, such as the problems ...Amongst the impacts of converting forest to agricultural activities are soil erosion and degradation of ecology service values and goods （ESVG）. The soil erosion can be seen as on-site impacts, such as the problems of decreasing soil fertility and also its off-site impact such as the problems of sedimentation of the nearby rivers, whilst the degradation of ESVG are more holistie in nature, These impacts can be devastating in environmental, biological, and socio-economic manners. This paper reports the study undertaken on the impacts of agricultural development in 0.8 million ha of forest dominated landscape in Pasoh Forest Region （PFR）, Malaysia, within period of 8 years from 1995 to 2003. Three folds of impacts on agricultural development examined and analysed, are： （i） relationship of total soil loss and changes in land use pattern, （ii） mapping trends of ESVG for PFR in 1995 and 2003, and （iii） risk assessment of ESVG based on simulation of converting 339,630 ha of primary forest into mass-scale oil palm plantation. Results of this study indicated that although only minor changes of about 1464 ha （about 0.2% of PFR） of primary forest was converted to agricultural activities, it have significantly increased the total soil loss from 59 to 69 million ton/ha/yr. The mean rate of soil is loss for PFR is 0.8 mil ton/ha/yr and if translated into ESVG term, the soil loss costs about US$ 4.8mil/yr. However, majority of the soil loss within all land use classes are within range of very low-low risk categories （〈10 ton/ha/yr）. ESVG for PFR were costing US$ 179 millions in 1995, declined to US$114 millions in 2003 due to 0.2% reduction of forested land. The ESVG of converting 339,630 ha primary forest into mass plantation cost less than original forest within period of 20 years examined; the 20th year of conversion, the ESVG of plantation and to-remain as forest cost US$ 963 and US$ 575 millions, respectively. However, this difference is only marginal when full attributes of ESVG are considered.展开更多
Bangladesh is a south Asian Monsoonal Country and the recent precipitation pattern in the Cox’s Bazar area of Bangladesh is changing and increasing the number of monsoonal slope failures and landslide hazards in the ...Bangladesh is a south Asian Monsoonal Country and the recent precipitation pattern in the Cox’s Bazar area of Bangladesh is changing and increasing the number of monsoonal slope failures and landslide hazards in the Kutubpalong & Balukhali Rohingya camp area. An attempt has been made to see the influence of seasonal variation of ground water level (G.W.L.) fluctuations on the stability of the eco hills and forests of Ukhiya Teknaf region. Ukhiya hills are in great danger because of cutting trees from the hill slopes and it is well established that due to recent change of climate, short term rainfall for few consecutive days during monsoon might show an influence on the factor of safety (Fs) values of the camp hill slopes. A clear G.W.L. variation between dry and wet seasons has an influence on the stability (Fs) values indicating that climate has a strong influence on the stability and threatening sustainable development. A stable or marginally stable slope might be unstable during raining and show a variation of ground water level (G.W.L.). The generation of pore water pressure (P.W.P.) is also influenced by seasonal variation of ground water level. During wet season negative P.W.P. called suction plays an important role to occur slope failures in the Ukhiya hills. Based on all calculated factor of safety values (Fs) at different locations, four (4) susceptible landslide risk zones are identified. They are very high risk (Fs = 0.18 to 0.46), high risk (Fs = 0.56 to 0.75), medium risk (Fs = 0.76 to 1.0) and marginally stable areas (Fs ≈ 1). Proper geo-engineering measures must be taken by the concerned authorizes to reduce P.W.P. during monsoon by installing rain water harvesting system, allowing sufficient drainage & other geotechnical measures to reduce the risk of slope failures in the Ukhiya hills. Based on the stability factor (Fs) at different slope locations of the camp hills, a risk map of the investigated area has been produced for the local community for their safety and to build up awareness & to motivate them to evacuate the site during monsoonal slope failures. The established “Risk Maps” can be used for future geological engineering works as well as for sustainable planning, design and construction purposes relating to adaptation and mitigation of landslide risks in the investigated area.展开更多
文摘Amongst the impacts of converting forest to agricultural activities are soil erosion and degradation of ecology service values and goods （ESVG）. The soil erosion can be seen as on-site impacts, such as the problems of decreasing soil fertility and also its off-site impact such as the problems of sedimentation of the nearby rivers, whilst the degradation of ESVG are more holistie in nature, These impacts can be devastating in environmental, biological, and socio-economic manners. This paper reports the study undertaken on the impacts of agricultural development in 0.8 million ha of forest dominated landscape in Pasoh Forest Region （PFR）, Malaysia, within period of 8 years from 1995 to 2003. Three folds of impacts on agricultural development examined and analysed, are： （i） relationship of total soil loss and changes in land use pattern, （ii） mapping trends of ESVG for PFR in 1995 and 2003, and （iii） risk assessment of ESVG based on simulation of converting 339,630 ha of primary forest into mass-scale oil palm plantation. Results of this study indicated that although only minor changes of about 1464 ha （about 0.2% of PFR） of primary forest was converted to agricultural activities, it have significantly increased the total soil loss from 59 to 69 million ton/ha/yr. The mean rate of soil is loss for PFR is 0.8 mil ton/ha/yr and if translated into ESVG term, the soil loss costs about US$ 4.8mil/yr. However, majority of the soil loss within all land use classes are within range of very low-low risk categories （〈10 ton/ha/yr）. ESVG for PFR were costing US$ 179 millions in 1995, declined to US$114 millions in 2003 due to 0.2% reduction of forested land. The ESVG of converting 339,630 ha primary forest into mass plantation cost less than original forest within period of 20 years examined; the 20th year of conversion, the ESVG of plantation and to-remain as forest cost US$ 963 and US$ 575 millions, respectively. However, this difference is only marginal when full attributes of ESVG are considered.
文摘Bangladesh is a south Asian Monsoonal Country and the recent precipitation pattern in the Cox’s Bazar area of Bangladesh is changing and increasing the number of monsoonal slope failures and landslide hazards in the Kutubpalong & Balukhali Rohingya camp area. An attempt has been made to see the influence of seasonal variation of ground water level (G.W.L.) fluctuations on the stability of the eco hills and forests of Ukhiya Teknaf region. Ukhiya hills are in great danger because of cutting trees from the hill slopes and it is well established that due to recent change of climate, short term rainfall for few consecutive days during monsoon might show an influence on the factor of safety (Fs) values of the camp hill slopes. A clear G.W.L. variation between dry and wet seasons has an influence on the stability (Fs) values indicating that climate has a strong influence on the stability and threatening sustainable development. A stable or marginally stable slope might be unstable during raining and show a variation of ground water level (G.W.L.). The generation of pore water pressure (P.W.P.) is also influenced by seasonal variation of ground water level. During wet season negative P.W.P. called suction plays an important role to occur slope failures in the Ukhiya hills. Based on all calculated factor of safety values (Fs) at different locations, four (4) susceptible landslide risk zones are identified. They are very high risk (Fs = 0.18 to 0.46), high risk (Fs = 0.56 to 0.75), medium risk (Fs = 0.76 to 1.0) and marginally stable areas (Fs ≈ 1). Proper geo-engineering measures must be taken by the concerned authorizes to reduce P.W.P. during monsoon by installing rain water harvesting system, allowing sufficient drainage & other geotechnical measures to reduce the risk of slope failures in the Ukhiya hills. Based on the stability factor (Fs) at different slope locations of the camp hills, a risk map of the investigated area has been produced for the local community for their safety and to build up awareness & to motivate them to evacuate the site during monsoonal slope failures. The established “Risk Maps” can be used for future geological engineering works as well as for sustainable planning, design and construction purposes relating to adaptation and mitigation of landslide risks in the investigated area.
