In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a conce...In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a concept of regional water demand for minimum instream flow have been developed. The concept was used in the process of determining river functions and calculating ecological water demand for a river. The Yellow River watershed was used to validate the calculation methodology for regional water demand. CaIculation results indicate that there are significant differences in water demands among the different regions. The regional water demand at the downstream of the Yellow River is the largest about 14.893 × 10^9 m^3/a. The regional water demand of upstream, Lanzhou-Hekou section is the smallest about -5.012 × 10^9 m^3/a. The total ecological water demand of the Yellow River Basin is 23.06 × 10^9 m^3/a, about the 39% of surface water resources of the water resources should not exceed 61% in the Yellow River Basin. Yellow River Basin. That means the maximum available surface The regional river ecological water demands at the Lower Section of the Yellow River and Longyangxia-Lanzhou Section exceed the surface water resources produced in its region and need to be supplemented from other regions through the water rational planning of watershed water resources. These results provides technical basis for rational plan of water resources of the Yellow River Basin.展开更多
Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sedimen...Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sediment (IFRTS). We defined the permitting flow velocity by the conception of IFRTS, and also put forward the ecological hydraulic radius model (EHRM) to estimate IFRTS. The calculating process of EHRM is explained by the example of Daofu Hydrological Station on Xianshui branch of Yalong River in the west line first-stage construction of South-North Water Transfer Project. The result shows that the IFRTS occupied 29.7%―59.5% of annual mean discharge in flood season, the average of IFRTS was about 100.2 m3/s during 1966―1987, it is close to the IFRTS 90 m3/s calculated by IFRTS conception. Hence, it is feasible to use EHRM to calculate IFRTS.展开更多
Instream aeration has been used as a supplement to secondary treatment or a substitute for tertiary treatment for meeting dissolved oxygen （DO） standards in rivers. Many studies have used water quality models to det...Instream aeration has been used as a supplement to secondary treatment or a substitute for tertiary treatment for meeting dissolved oxygen （DO） standards in rivers. Many studies have used water quality models to determine the number, location, and capacity of instream aeration stations （IASs） needed to meet DO standards in combination with other pollution control measures. DO concentrations have been improved in the North Shore Channel and North Branch Chicago River by the Devon Avenue IAS for more than 35 years. A study was initiated to determine whether it was better to rehabilitate or relocate this station and to determine appropriate operational guidance for the IAS at the selected location. A water quality model capable of simulating DO concentrations during unsteady flow was used to evaluate the proper location for an IAS and operational guidance for this IAS. Three test years, a dry year, a wet year, and an extreme year, were considered in the evaluation. The study found that the Devon Avenue IAS should be rehabilitated as this location performed as well as or better than any of 10 alternative locations. According to the new operational guidance for this IAS, the amount of time with blowers operating could be substantially reduced compared to traditional operations while at the same time the attainment of the DO standards could be increased. This study shows that a carefully designed modeling study is key to effective selection, location, and operation of IASs such that attainment of DO standards can be maximized while operation hours of blowers can be minimized.展开更多
Research on macroinvertebrate community structure in Andean rivers has been oriented towards describing patterns of alpha and gamma diversity by taking into account environmental predictors at local spatial scales(e.g...Research on macroinvertebrate community structure in Andean rivers has been oriented towards describing patterns of alpha and gamma diversity by taking into account environmental predictors at local spatial scales(e.g.,micro-and mesohabitats).However,the patterns of beta diversity and the importance of landscape-scale variables have been evaluated to a lesser extent.The objective of this study was to describe the patterns of alpha and beta diversity of benthic macroinvertebrates in the Andean rivers of the Orinoco basin and their relationship with local and landscape environmental variation.A stratified random sampling of macroinvertebrates was carried out at 40 sites(comprising an altitudinal range of between 500 and 2900 m.a.s.l.),local and landscape variables were measured.Our results showed that the variation of alpha diversity was influenced by local and landscape variables,which are directly and indirectly related to the contribution of sediments,substrate composition and flow velocity,providing a heterogeneity of habitats.Global beta diversity was explained by the combined effect of local and landscape variables.Regarding the beta diversity phenomena,turnover was predominant while nestedness presented a minor contribution and both were explained in greater proportion by local descriptors and some landscape variables,specifically those of a geomorphological nature.Our results concur with the view of an environmental and spatial hierarchy within the river habitat and highlight the influence of multiple scales on macroinvertebrate diversity.The above suggests that both local and landscape scales must necessarily be considered for environmental management and the conservation of Andean lotic ecosystems.展开更多
The Holtemme is a small headwater stream in North Germany＇s Elbe River Basin. According to German and European legislation, hygienic monitoring is not mandatory for such water bodies which are neither drinking water ...The Holtemme is a small headwater stream in North Germany＇s Elbe River Basin. According to German and European legislation, hygienic monitoring is not mandatory for such water bodies which are neither drinking water sources nor categorized as bathing waters. Consequently, relatively little is known about the occur- rence of-potentially pathogenic- bacteria and viruses in Germany＇s streams and rivers. The Holtemme was selected for a case study because it is relatively well monitored for both chemical water quality and aquatic ecology, but not for hygiene. Originating in the mountains of Harz Nature Park, the 47 km long Holtemme is characterized by a strong longitudinal gradient in chemical water quality, which is related to different land uses and the influx of treated wastewater from two urban areas （Wernigerode and Halberstadt）. Waste water loads received by the Holtemme are comparatively high when compared to similarly small streams. In 2015, total coliform concentrations between more than 200 and 77,010 bacteria per 100 mL, and fecal coliform concentrations between 5 and 24,060 bacteria per I00 mL were observed in the Holtemme＇s main channel. The highest concentrations were typically found below the outlets of the two wastewater treatment plants. The treated wastewater contained total and fecal coliform concentra- tions of up to 200,500 and 83,100 per 100 mL, respectively; however, there were significant temporal variations. While the observed concentrations are unpro- blematic from a legal perspective （because no maximum permissible limits are defined for streams in Germany）, they would exceed the tolerable limits for bathing waters in the EU, indicating moderate to critical pollution limits.展开更多
基金The National Natural Sciences Foundation of China (No. 50239020)
文摘In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a concept of regional water demand for minimum instream flow have been developed. The concept was used in the process of determining river functions and calculating ecological water demand for a river. The Yellow River watershed was used to validate the calculation methodology for regional water demand. CaIculation results indicate that there are significant differences in water demands among the different regions. The regional water demand at the downstream of the Yellow River is the largest about 14.893 × 10^9 m^3/a. The regional water demand of upstream, Lanzhou-Hekou section is the smallest about -5.012 × 10^9 m^3/a. The total ecological water demand of the Yellow River Basin is 23.06 × 10^9 m^3/a, about the 39% of surface water resources of the water resources should not exceed 61% in the Yellow River Basin. Yellow River Basin. That means the maximum available surface The regional river ecological water demands at the Lower Section of the Yellow River and Longyangxia-Lanzhou Section exceed the surface water resources produced in its region and need to be supplemented from other regions through the water rational planning of watershed water resources. These results provides technical basis for rational plan of water resources of the Yellow River Basin.
基金Supported by the National Natural Science Foundation of China (Grant No. 50809027)
文摘Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sediment (IFRTS). We defined the permitting flow velocity by the conception of IFRTS, and also put forward the ecological hydraulic radius model (EHRM) to estimate IFRTS. The calculating process of EHRM is explained by the example of Daofu Hydrological Station on Xianshui branch of Yalong River in the west line first-stage construction of South-North Water Transfer Project. The result shows that the IFRTS occupied 29.7%―59.5% of annual mean discharge in flood season, the average of IFRTS was about 100.2 m3/s during 1966―1987, it is close to the IFRTS 90 m3/s calculated by IFRTS conception. Hence, it is feasible to use EHRM to calculate IFRTS.
文摘Instream aeration has been used as a supplement to secondary treatment or a substitute for tertiary treatment for meeting dissolved oxygen （DO） standards in rivers. Many studies have used water quality models to determine the number, location, and capacity of instream aeration stations （IASs） needed to meet DO standards in combination with other pollution control measures. DO concentrations have been improved in the North Shore Channel and North Branch Chicago River by the Devon Avenue IAS for more than 35 years. A study was initiated to determine whether it was better to rehabilitate or relocate this station and to determine appropriate operational guidance for the IAS at the selected location. A water quality model capable of simulating DO concentrations during unsteady flow was used to evaluate the proper location for an IAS and operational guidance for this IAS. Three test years, a dry year, a wet year, and an extreme year, were considered in the evaluation. The study found that the Devon Avenue IAS should be rehabilitated as this location performed as well as or better than any of 10 alternative locations. According to the new operational guidance for this IAS, the amount of time with blowers operating could be substantially reduced compared to traditional operations while at the same time the attainment of the DO standards could be increased. This study shows that a carefully designed modeling study is key to effective selection, location, and operation of IASs such that attainment of DO standards can be maximized while operation hours of blowers can be minimized.
基金part the research project"Importancia de las variables locales y de paisaje sobre las comunidades de peces y macroinvertebrados bentónicos de sistemas lóticos andinos"(SGI 2955)financed by the Ministry of Science,Technology and Innovation of Colombia(MINCIENCIAS)with resources from the Fondo Nacional de Patrimonio Autónomo para el Financiamiento de la Cienciaendorsed by the Universidad Pedagógica y Tecnológica de Colombia ethics committee(Acta No 06 del 12 de agosto de 2019)。
文摘Research on macroinvertebrate community structure in Andean rivers has been oriented towards describing patterns of alpha and gamma diversity by taking into account environmental predictors at local spatial scales(e.g.,micro-and mesohabitats).However,the patterns of beta diversity and the importance of landscape-scale variables have been evaluated to a lesser extent.The objective of this study was to describe the patterns of alpha and beta diversity of benthic macroinvertebrates in the Andean rivers of the Orinoco basin and their relationship with local and landscape environmental variation.A stratified random sampling of macroinvertebrates was carried out at 40 sites(comprising an altitudinal range of between 500 and 2900 m.a.s.l.),local and landscape variables were measured.Our results showed that the variation of alpha diversity was influenced by local and landscape variables,which are directly and indirectly related to the contribution of sediments,substrate composition and flow velocity,providing a heterogeneity of habitats.Global beta diversity was explained by the combined effect of local and landscape variables.Regarding the beta diversity phenomena,turnover was predominant while nestedness presented a minor contribution and both were explained in greater proportion by local descriptors and some landscape variables,specifically those of a geomorphological nature.Our results concur with the view of an environmental and spatial hierarchy within the river habitat and highlight the influence of multiple scales on macroinvertebrate diversity.The above suggests that both local and landscape scales must necessarily be considered for environmental management and the conservation of Andean lotic ecosystems.
文摘The Holtemme is a small headwater stream in North Germany＇s Elbe River Basin. According to German and European legislation, hygienic monitoring is not mandatory for such water bodies which are neither drinking water sources nor categorized as bathing waters. Consequently, relatively little is known about the occur- rence of-potentially pathogenic- bacteria and viruses in Germany＇s streams and rivers. The Holtemme was selected for a case study because it is relatively well monitored for both chemical water quality and aquatic ecology, but not for hygiene. Originating in the mountains of Harz Nature Park, the 47 km long Holtemme is characterized by a strong longitudinal gradient in chemical water quality, which is related to different land uses and the influx of treated wastewater from two urban areas （Wernigerode and Halberstadt）. Waste water loads received by the Holtemme are comparatively high when compared to similarly small streams. In 2015, total coliform concentrations between more than 200 and 77,010 bacteria per 100 mL, and fecal coliform concentrations between 5 and 24,060 bacteria per I00 mL were observed in the Holtemme＇s main channel. The highest concentrations were typically found below the outlets of the two wastewater treatment plants. The treated wastewater contained total and fecal coliform concentra- tions of up to 200,500 and 83,100 per 100 mL, respectively; however, there were significant temporal variations. While the observed concentrations are unpro- blematic from a legal perspective （because no maximum permissible limits are defined for streams in Germany）, they would exceed the tolerable limits for bathing waters in the EU, indicating moderate to critical pollution limits.
