Background:Population growth and intensified human activities in conjunction with climate variability continue to affect the hydrologic cycle,aquatic and terrestrial flora and fauna.In this regard,understanding intera...Background:Population growth and intensified human activities in conjunction with climate variability continue to affect the hydrologic cycle,aquatic and terrestrial flora and fauna.In this regard,understanding interactions among ecosystem functions,impacts of anthropogenic interventions and those of climate variability is vital for projecting future ecosystem responses to human activities and climate forcing.The objectives of this study are to determine the ecological flow state via eco-flow index based on discharge hydrograph,to model the ecological diversity through the Shannon diversity index,and to assess the degree of hydrologic alteration using indicators of hydrologic alteration and range of variability approach in six hydrometric stations along the Zayandeh-Rud River in central Iran.The river drains into Gavkhuni Marsh.Also,the streamflow-induced potential changes for Capoeta damascina(a cyprinid fish species of the genus Capoeta),Petroleuciscus esfahani(a small cyprinid fish)and Aphanius isfahanensis(a Cyprinodontid fish)are evaluated.The outcome is expected to assist managers with understanding the effects of anthropogenic activities and climate variability on Gavkhuni aquatic ecosystems so that management options that enhance species resilience and adaptability are outlined.Results:Human activities,a primary factor influencing the natural flow regime,caused a significant increase in the minimum flow,July to March streamflow,low pulse number,and the number of reversals in most studied stations.On the contrary,some other hydrologic indices declined in value.Reservoir impoundment,the most prominent factor among human interventions,resulted in an overall alteration degree of 74.8%in streamflow.Climate variability impacted the natural flow regime in the range of low degree hydrologic alteration(27.3%).In addition,the biodiversity of the study basin,as modeled by the Shannon diversity index,had strong relevance to the annual eco-surplus and was more sensitive to summer floods and autumn hydrological droughts than other factors.Conclusions:This study corroborates the effectiveness of scenario-based hydrological modeling framework in evaluating the impacts of climate variability and human activities imposed on natural flow metrics.Additionally,the recently introduced eco-flow metrics based on discharge hydrographs and the Shannon diversity index based on indicators of hydrological alteration may be adopted in basins lacking ecological data.These two indices can effectively identify the most prominent factors in hydrological alteration and biodiversity change through a river network and may provide scientific decision-making support for water resource management in the study area.展开更多
选择信江下游梅港站1950~2010年日径流量,根据流域大型水库界牌枢纽运行时间将梅港站径流序列分为建库前（1953~2001）和建库后（2002~2010）两个时段。采用变动范围法（Range of Variability Approach,简称：RVA）分析水库运行对下游...选择信江下游梅港站1950~2010年日径流量,根据流域大型水库界牌枢纽运行时间将梅港站径流序列分为建库前（1953~2001）和建库后（2002~2010）两个时段。采用变动范围法（Range of Variability Approach,简称：RVA）分析水库运行对下游梅港站流域生态水文指标改变度,并分析了信江下游生态流量。研究表明：33个水文指标有22个发生中高度改变,11个指标发生低度改变,其水文综合改变度为0.51,属于中度改变;梅港站生态流量值均在RVA阈值内,基本能够保持河流稳定流量,但2月、7~9月及12月河道生态流量大于RVA下限。可适量增大水库下泄水量,降低对下游河段生态系统的威胁。展开更多
文摘Background:Population growth and intensified human activities in conjunction with climate variability continue to affect the hydrologic cycle,aquatic and terrestrial flora and fauna.In this regard,understanding interactions among ecosystem functions,impacts of anthropogenic interventions and those of climate variability is vital for projecting future ecosystem responses to human activities and climate forcing.The objectives of this study are to determine the ecological flow state via eco-flow index based on discharge hydrograph,to model the ecological diversity through the Shannon diversity index,and to assess the degree of hydrologic alteration using indicators of hydrologic alteration and range of variability approach in six hydrometric stations along the Zayandeh-Rud River in central Iran.The river drains into Gavkhuni Marsh.Also,the streamflow-induced potential changes for Capoeta damascina(a cyprinid fish species of the genus Capoeta),Petroleuciscus esfahani(a small cyprinid fish)and Aphanius isfahanensis(a Cyprinodontid fish)are evaluated.The outcome is expected to assist managers with understanding the effects of anthropogenic activities and climate variability on Gavkhuni aquatic ecosystems so that management options that enhance species resilience and adaptability are outlined.Results:Human activities,a primary factor influencing the natural flow regime,caused a significant increase in the minimum flow,July to March streamflow,low pulse number,and the number of reversals in most studied stations.On the contrary,some other hydrologic indices declined in value.Reservoir impoundment,the most prominent factor among human interventions,resulted in an overall alteration degree of 74.8%in streamflow.Climate variability impacted the natural flow regime in the range of low degree hydrologic alteration(27.3%).In addition,the biodiversity of the study basin,as modeled by the Shannon diversity index,had strong relevance to the annual eco-surplus and was more sensitive to summer floods and autumn hydrological droughts than other factors.Conclusions:This study corroborates the effectiveness of scenario-based hydrological modeling framework in evaluating the impacts of climate variability and human activities imposed on natural flow metrics.Additionally,the recently introduced eco-flow metrics based on discharge hydrographs and the Shannon diversity index based on indicators of hydrological alteration may be adopted in basins lacking ecological data.These two indices can effectively identify the most prominent factors in hydrological alteration and biodiversity change through a river network and may provide scientific decision-making support for water resource management in the study area.
文摘选择信江下游梅港站1950~2010年日径流量,根据流域大型水库界牌枢纽运行时间将梅港站径流序列分为建库前（1953~2001）和建库后（2002~2010）两个时段。采用变动范围法（Range of Variability Approach,简称：RVA）分析水库运行对下游梅港站流域生态水文指标改变度,并分析了信江下游生态流量。研究表明：33个水文指标有22个发生中高度改变,11个指标发生低度改变,其水文综合改变度为0.51,属于中度改变;梅港站生态流量值均在RVA阈值内,基本能够保持河流稳定流量,但2月、7~9月及12月河道生态流量大于RVA下限。可适量增大水库下泄水量,降低对下游河段生态系统的威胁。
