The current environmental flow assessment of Chinese rivers is thought to have three shortcomings: The first is that environmental flow requirements of reservoirs in dammed rivers are usually not explicitly considered...The current environmental flow assessment of Chinese rivers is thought to have three shortcomings: The first is that environmental flow requirements of reservoirs in dammed rivers are usually not explicitly considered; the second is that enough attentions have not been paid to the inherent links between flow regime and ecological processes; the third is that most studies focus on the variable range of merely one hydrological element such as discharge needed by riverine ecosystems. Here, first proposed is a holistic method for environmental flow assessment, the flow-ecological response relationship method that is suitable for large rivers with relatively abundant ecological data. Based on the conceptual models and quantitative relationships between flow and ecological response, this method comprehensively considers the ecological conservation requirements of both reservoir and its downstream reach. Then, it is applied to assessing the environmental flows of the Three Gorges Reservoir and its downstream reach by the following steps: 1) Construction of conceptual models of flow-ecological response; 2) identification of ecological targets of environmental flows and their key periods; 3) development of the quantitative relationships between hydrological indicators and ecological indictors; 4) preliminary assessment of environmental flow according to the tradeoff between ecological targets and water demands of human. The environmental flow hydrographs obtained have explicit ecological conservation targets, time schedule of achieving each target, and characteristics of multiple hydrological elements such as flow, water level, frequency, timing, duration and rate of change. The case study has tested the reasonability and feasibility of this method, and the results of this study are expected to provide technical support and decision reference for improving the operation of the Three Gorges-Gezhouba cascade reservoirs.展开更多
River classification has emerged as a major application of environmental science, which can overcome the deficcts of tradition- al methods in focusing on the single objective of maintaining specified, valued features ...River classification has emerged as a major application of environmental science, which can overcome the deficcts of tradition- al methods in focusing on the single objective of maintaining specified, valued features of ecosystems. However, current ef- forts to classify rivers by hydrologic processes may result in a growing temptation to ignore ecological variability across basins Thus, an eco-functional classification is proposed for river management in the Pearl River Basin. This method riews ecological functions as fundamental characteristics of riverine systems and provides a framework for dividing a basin iato eco-specific categories according to the heterogeneity of the primary ecological functions. In addition, we proposed specific environmental flow methodologies corresponding to three typical river reaches of the basin by perceiving the key attributes of flow variability In the upstream region of the West River, flow velocity and wetted perimeter are considered as the key attributes of maintain- ing fish habitat; in a small-sized mountainous tributary of the North river, we choose water surface area to maintain the conti- nuity and biodiversity of the river; while for the aspect of river landscape in the midstream reach of the East R vet, water level is crucial for maintaining the aesthetic value. This research highlights the ecologically relevant heterogeneity that occurs within and among regions of a basin, and is expected to contribute to a simpler and more comprehensive river manage：nent.展开更多
基金supported by the Ministry of Science and Technology of China (Grant Nos. 2012BAC06B01, 2012BAC06B04)
文摘The current environmental flow assessment of Chinese rivers is thought to have three shortcomings: The first is that environmental flow requirements of reservoirs in dammed rivers are usually not explicitly considered; the second is that enough attentions have not been paid to the inherent links between flow regime and ecological processes; the third is that most studies focus on the variable range of merely one hydrological element such as discharge needed by riverine ecosystems. Here, first proposed is a holistic method for environmental flow assessment, the flow-ecological response relationship method that is suitable for large rivers with relatively abundant ecological data. Based on the conceptual models and quantitative relationships between flow and ecological response, this method comprehensively considers the ecological conservation requirements of both reservoir and its downstream reach. Then, it is applied to assessing the environmental flows of the Three Gorges Reservoir and its downstream reach by the following steps: 1) Construction of conceptual models of flow-ecological response; 2) identification of ecological targets of environmental flows and their key periods; 3) development of the quantitative relationships between hydrological indicators and ecological indictors; 4) preliminary assessment of environmental flow according to the tradeoff between ecological targets and water demands of human. The environmental flow hydrographs obtained have explicit ecological conservation targets, time schedule of achieving each target, and characteristics of multiple hydrological elements such as flow, water level, frequency, timing, duration and rate of change. The case study has tested the reasonability and feasibility of this method, and the results of this study are expected to provide technical support and decision reference for improving the operation of the Three Gorges-Gezhouba cascade reservoirs.
基金supported by the Surface Project of the National Natural Science Foundation of China(Grant No.51379150)Key Project of the National Natural Science Foundation of China(Grant No.51439006)
文摘River classification has emerged as a major application of environmental science, which can overcome the deficcts of tradition- al methods in focusing on the single objective of maintaining specified, valued features of ecosystems. However, current ef- forts to classify rivers by hydrologic processes may result in a growing temptation to ignore ecological variability across basins Thus, an eco-functional classification is proposed for river management in the Pearl River Basin. This method riews ecological functions as fundamental characteristics of riverine systems and provides a framework for dividing a basin iato eco-specific categories according to the heterogeneity of the primary ecological functions. In addition, we proposed specific environmental flow methodologies corresponding to three typical river reaches of the basin by perceiving the key attributes of flow variability In the upstream region of the West River, flow velocity and wetted perimeter are considered as the key attributes of maintain- ing fish habitat; in a small-sized mountainous tributary of the North river, we choose water surface area to maintain the conti- nuity and biodiversity of the river; while for the aspect of river landscape in the midstream reach of the East R vet, water level is crucial for maintaining the aesthetic value. This research highlights the ecologically relevant heterogeneity that occurs within and among regions of a basin, and is expected to contribute to a simpler and more comprehensive river manage：nent.
