Water-sediment regulation of the Yellow River is to regulate and control the flow and sediment transport relationship of the lower reaches through reservoirs on the main streams and tributaries to create balance betwe...Water-sediment regulation of the Yellow River is to regulate and control the flow and sediment transport relationship of the lower reaches through reservoirs on the main streams and tributaries to create balance between water and sediment so that sediment transport capacity of the downstream channels can be maximized,shrinking of channels be contained,and medium flood channel be restored and maintained.Many years' research by the Yellow River Conservancy Commission(YRCC) reveals the water and sediment transport relationship that will prevent sedimentation at the downstream river channels.Based on this relationship and coming sediment and water conditions in the Yellow River basin,the YRCC,with maximized use of reservoirs on the main streams and tributaries,has developed three models of water-sediment regulation:single Xiaolangdi Reservoir-dominated regulation,space scale water-sediment match,and mainstream reservoirs joint operation.Ten water-sediment regulations based on these three models have resulted in an average drop of 1.5 m in the main channel of the downstream 800 km river and an increase of carrying capacity from 1800 to 4000 m3/s.Besides,the wetland ecosystems of estuarine delta has also been improved and restored significantly.展开更多
Biosolids application in periurban agroecosystems could mitigate climate change by sequestering C, while improving plant net primary production(NPP). Monitoring NPP is useful for studying ecological responses to human...Biosolids application in periurban agroecosystems could mitigate climate change by sequestering C, while improving plant net primary production(NPP). Monitoring NPP is useful for studying ecological responses to human management. The values of NPP and C input in periurban agroecosystems are insufficient or missing. The objective was to use local databases to estimate NPP and C input in periurban areas(south, north and west) of Buenos Aires City, Argentina, using different biosolids application scenarios(low and high effects). The NPP varied with crop and vegetable types(P < 0.05), with maize(Zea mays) and wheat(Triticum aestivum) presenting the highest production, soybean(Glycine max) medium and sunflower(Helianthus annuus) the lowest. Tomato(Lycopersicon esculentum Mill.) presented the highest production in the south area(La Plata). West and north areas, where Vertic and Typic Argiudolls are the main soils, presented the lowest NPP and C input. According to the low and high effect scenarios,only vegetables presented significant differences(P < 0.05) in average and cumulative NPP and C input between areas. Vegetables contributed with the highest proportion(> 70%) to NPP in both projected scenarios. For both scenarios, average C input by crops and vegetables presented similar proportions. Biosolids addition in periurban agroecosystems could be a viable practice to elevate NPP and C input.展开更多
文摘Water-sediment regulation of the Yellow River is to regulate and control the flow and sediment transport relationship of the lower reaches through reservoirs on the main streams and tributaries to create balance between water and sediment so that sediment transport capacity of the downstream channels can be maximized,shrinking of channels be contained,and medium flood channel be restored and maintained.Many years' research by the Yellow River Conservancy Commission(YRCC) reveals the water and sediment transport relationship that will prevent sedimentation at the downstream river channels.Based on this relationship and coming sediment and water conditions in the Yellow River basin,the YRCC,with maximized use of reservoirs on the main streams and tributaries,has developed three models of water-sediment regulation:single Xiaolangdi Reservoir-dominated regulation,space scale water-sediment match,and mainstream reservoirs joint operation.Ten water-sediment regulations based on these three models have resulted in an average drop of 1.5 m in the main channel of the downstream 800 km river and an increase of carrying capacity from 1800 to 4000 m3/s.Besides,the wetland ecosystems of estuarine delta has also been improved and restored significantly.
文摘Biosolids application in periurban agroecosystems could mitigate climate change by sequestering C, while improving plant net primary production(NPP). Monitoring NPP is useful for studying ecological responses to human management. The values of NPP and C input in periurban agroecosystems are insufficient or missing. The objective was to use local databases to estimate NPP and C input in periurban areas(south, north and west) of Buenos Aires City, Argentina, using different biosolids application scenarios(low and high effects). The NPP varied with crop and vegetable types(P < 0.05), with maize(Zea mays) and wheat(Triticum aestivum) presenting the highest production, soybean(Glycine max) medium and sunflower(Helianthus annuus) the lowest. Tomato(Lycopersicon esculentum Mill.) presented the highest production in the south area(La Plata). West and north areas, where Vertic and Typic Argiudolls are the main soils, presented the lowest NPP and C input. According to the low and high effect scenarios,only vegetables presented significant differences(P < 0.05) in average and cumulative NPP and C input between areas. Vegetables contributed with the highest proportion(> 70%) to NPP in both projected scenarios. For both scenarios, average C input by crops and vegetables presented similar proportions. Biosolids addition in periurban agroecosystems could be a viable practice to elevate NPP and C input.
