Hydropower project may bring with it social-economic profits as well as side effects.The built dam and reservoir often cause some problems to the surrounding areas,among which the ecological and environmental effects ...Hydropower project may bring with it social-economic profits as well as side effects.The built dam and reservoir often cause some problems to the surrounding areas,among which the ecological and environmental effects caused by hydropower projects are always concerned by the public.In this article,we take the Ertan reservoir catchment as the research area and try to quantitatively analyze the variation of vegetation cover and soil erosion by remote sensing technique,and to comprehensively assess the evolvement and development trend of reservoir catchment.Soil erosion,land use/cover are used as ecological and environmental indicators which reflect the changes before,after and in the period of the construction of Ertan hydropower station.Supported by the multi-source remote sensing data(from satellite Landsat and CBERS) and DEM data,the land use/cover is interpreted through RS images which are classified both by unsupervised and supervised method,and the driving factors of the ecological changes are also analyzed.At the same time,the changes of soil loss are also monitored and analyzed during flood seasons of Ertan reservoir area before and after reservoir impoundment(1995,2000 and 2005) using the revised universal soil loss equation(RUSLE) .The results show that during the recent 13 years the arable land area has decreased obviously,and construction area and water surface have increased slightly.The increase of vegetation cover has some relations with the implementation of local ecological projects,i.e.,de-farming to forestry and de-farming to pasture projects.At the same time,changes may also be caused by the climate adjustment in the reservoir area.In the ten years from 1995 to 2005,the high soil loss classes were transforming to lowly level classes continuously.All of these show that the soil loss of Ertan reservoir area is getting better.展开更多
This study evaluated the performance of rooftop catchment systems in securing non-potable water supply in Birjand, located in an arid area in southeastern Iran. The rooftop catchment systems at seven study sites of di...This study evaluated the performance of rooftop catchment systems in securing non-potable water supply in Birjand, located in an arid area in southeastern Iran. The rooftop catchment systems at seven study sites of different residential buildings were simulated for dry, normal, and wet water years, using 31-year rainfall records. The trial and error approach and mass diagram method were employed to optimize the volume of reservoirs in five different operation scenarios. Results showed that, during the dry water year from 2000 to 2001, for reservoirs with volumes of 200-20000 L, the proportion of days that could be secured for non-portable water supply was on average computed to be 16.4%-32.6% across all study sites. During the normal water year from 2009 to 2010 and the wet water year from 1995 to 1996, for reservoirs with volumes of 200-20000 L, the proportions were 20.8%-69.6% and 26.8%-80.3%, respectively. Therefore, a rooftop catchment system showed a high potential to meet a significant portion of non-potable water demand in the Birjand climatic region. Reservoir volume optimization using the mass diagram method produced results consistent with those obtained with the trial and error approach, except at sites #1, #2, and #5. At these sites, the trial and error approach performed better than the mass diagram method due to relatively high water consumption. It is concluded that the rooftop catchment system is applicable under the same climatic conditions as the study area, and it can be used as a drought mitigation strategy as well.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.50679096)
文摘Hydropower project may bring with it social-economic profits as well as side effects.The built dam and reservoir often cause some problems to the surrounding areas,among which the ecological and environmental effects caused by hydropower projects are always concerned by the public.In this article,we take the Ertan reservoir catchment as the research area and try to quantitatively analyze the variation of vegetation cover and soil erosion by remote sensing technique,and to comprehensively assess the evolvement and development trend of reservoir catchment.Soil erosion,land use/cover are used as ecological and environmental indicators which reflect the changes before,after and in the period of the construction of Ertan hydropower station.Supported by the multi-source remote sensing data(from satellite Landsat and CBERS) and DEM data,the land use/cover is interpreted through RS images which are classified both by unsupervised and supervised method,and the driving factors of the ecological changes are also analyzed.At the same time,the changes of soil loss are also monitored and analyzed during flood seasons of Ertan reservoir area before and after reservoir impoundment(1995,2000 and 2005) using the revised universal soil loss equation(RUSLE) .The results show that during the recent 13 years the arable land area has decreased obviously,and construction area and water surface have increased slightly.The increase of vegetation cover has some relations with the implementation of local ecological projects,i.e.,de-farming to forestry and de-farming to pasture projects.At the same time,changes may also be caused by the climate adjustment in the reservoir area.In the ten years from 1995 to 2005,the high soil loss classes were transforming to lowly level classes continuously.All of these show that the soil loss of Ertan reservoir area is getting better.
文摘This study evaluated the performance of rooftop catchment systems in securing non-potable water supply in Birjand, located in an arid area in southeastern Iran. The rooftop catchment systems at seven study sites of different residential buildings were simulated for dry, normal, and wet water years, using 31-year rainfall records. The trial and error approach and mass diagram method were employed to optimize the volume of reservoirs in five different operation scenarios. Results showed that, during the dry water year from 2000 to 2001, for reservoirs with volumes of 200-20000 L, the proportion of days that could be secured for non-portable water supply was on average computed to be 16.4%-32.6% across all study sites. During the normal water year from 2009 to 2010 and the wet water year from 1995 to 1996, for reservoirs with volumes of 200-20000 L, the proportions were 20.8%-69.6% and 26.8%-80.3%, respectively. Therefore, a rooftop catchment system showed a high potential to meet a significant portion of non-potable water demand in the Birjand climatic region. Reservoir volume optimization using the mass diagram method produced results consistent with those obtained with the trial and error approach, except at sites #1, #2, and #5. At these sites, the trial and error approach performed better than the mass diagram method due to relatively high water consumption. It is concluded that the rooftop catchment system is applicable under the same climatic conditions as the study area, and it can be used as a drought mitigation strategy as well.
