Environmental Flow Assessment Based on Different Metrics of Hydrological Alteration

To mitigate possible negative impacts of cascade dams in the Lower Jinsha River and maintain the natural flow regime of national natural reserve areas of rare and special fishes of the upper Yangtze River, environmental flow (e-flow) demands need to be considered in the cascade dams operation. Due to lack of regular ecological observation data, multiple hydrology-based e-flow methods including Tennant, minimum monthly flow, 7Q10 and Q90 are applied to provide specific e-flow prescripts to guide the reservoir release. A joint operation optimization model is developed for the cascade dams in the Lower Jinsha River for maximal hydropower generation under various e-flow constraints. The economic and ecological performances of cascade dams operation are evaluated by total hydropower outputs and hydrological alteration degree of downstream river individually. The operation results are analyzed and discussed, and some questions on the tradeoff relationship between ecology and hydropower generation, inherent relationship between ecological constrains and hydrological alteration, and rationality criteria of e-flow are further addressed. The conclusions indicate : (1) optimal operation for ecological considerations under e-flow constrains only reduce hydropower outputs slightly, no more than 2.4%; (2) e-flow constrains help lower hydrological alteration induced by hydropower dams, among the four e-flow methodologies Tennant is best in term of ecology; (3) there is a limitation for hydrology-based e-flow methodologies, and it is necessary to stress ecological foundation and ecological relevance for e-flow methodology. The paper will provide technical references for future ecological re-operation of the cascade dams.

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Assessment of hydrological alteration and environmental flow requirements for Srisailam dam on Krishna River, India

Water Policy ◽

10.2166/wp.2018.203 ◽

2018 ◽

Vol 20 (6) ◽

pp. 1176-1190 ◽

Cited By ~ 4

Author(s):

A. Uday Kumar ◽

K. V. Jayakumar

Keyword(s):

River Flow ◽

Environmental Flow ◽

Vital Role ◽

Low Risk ◽

Mean Flow ◽

Discharge Data ◽

Hydrological Alteration ◽

Seasonal Flow ◽

Biotic Diversity ◽

Medium Risk

Abstract Natural flow plays a vital role in forming biotic diversity by controlling essential environmental conditions within the river channel and floodplain. This paper assesses the changes in streamflow and ecology caused on Krishna River by Srisailam dam. Regulated and unregulated river flow discharge data were collected at Nagarjuna Sagar gauge station which is located downstream of Srisailam dam. Flow Health (FH) software developed by the International Water Centre, Brisbane is used to calculate the hydrological alteration and environmental flow requirements due to Srisailam dam. Results show that impoundment of the dam mainly decreases the high flows by storing flood flow for water supply, irrigation purposes, etc., and enhances low flows due to hydropower operation. Regulation of the dam significantly affected the mean flow in August, September, and October. Mean annual flow (MAF) decreased considerably and seasonal flow shifted. The minimum flow released from the dam to downstream was calculated by two options, namely, low risk and medium risk to the environment. Low risk achieved a score of 0.61 FH and 0.5 FH was achieved by high risk, with a MAF volume of 40% (i.e., 7,225 m3) and 30% (5,847 m3), respectively.

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Classifying Dams for Environmental Flow Implementation in China

Sustainability ◽

10.3390/su12010107 ◽

2019 ◽

Vol 12 (1) ◽

pp. 107 ◽

Cited By ~ 4

Author(s):

Ang Chen ◽

Miao Wu ◽

Michael E. McClain

Keyword(s):

Environmental Flows ◽

Flood Pulse ◽

Environmental Flow ◽

Future Research ◽

Endangered Fish ◽

Hydrological Alteration ◽

Fish Spawning ◽

Class 1 ◽

Rare And Endangered ◽

And Migration

The implementation of environmental flows is of the utmost importance for ecosystem protection and restoration in dammed rivers. A key challenge in optimizing dam regulation is the uncertainty of the ecohydrology relationship between flow release and ecological response. In the present paper, we develop a framework of dam classification to organize the categories of the ecohydrology relationship for implementing environmental flows. Dams are classified from three major categories that differ in dam properties, hydrological alteration, and downstream hydrobiological diversities based on the relationship of hydrology and ecology. Finally, 773 dams in China are screened and ranked into four classes involving a great diversity of environmental flow components. A classification of dams that utilizes the implementation of environmental flows is presented. (1) Class 1 includes dams with rare and endangered fish species in the downstream. It is the category with the highest priority for environmental flow releases and regulation, requiring continuous flow and flood pulse components for fish spawning and migration. (2) Class 2 includes dams with significant hydrological alteration in the downstream. It is the category with second priority for environmental flow releases and regulation, requiring natural hydrological regimes simulation or complete flow component recovery for optimizing the flow duration curve and mitigating adverse impacts of dam operation. (3) Class 3 includes dams with a high degree of regulation where there is urgency for environmental flow releases and regulation, requiring that minimum flow is guaranteed by cascade reservoir regulation. (4) Class 4 includes dams with a low degree of regulation where there is less urgency for environmental flow releases and regulation. This classification method is important for future research, including environmental flow release regulation and the effectiveness evaluation of environmental flow adaptive management. It will be useful for guiding the implementation of environmental flows.

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ASSESSMENT OF HYDROLOGICAL CHANGES IN THE ŠUŠVĖ RIVER

Proceedings of the 7th International Scientific Conference Rural Development 2015 ◽

10.15544/rd.2015.035 ◽

2015 ◽

Author(s):

Gražina ŽIBIENĖ ◽

Alvydas ŽIBAS ◽

Goda BLAŽAITYTĖ

Keyword(s):

Hydrological Regime ◽

Maximum Flow ◽

Environmental Flow ◽

Physical Structure ◽

River Channels ◽

Hydrologic Alteration ◽

Water Conditions ◽

Flow Components ◽

The Impact ◽

Large Floods

The construction of dams in rivers negatively affects ecosystems because dams violate the continuity of rivers, transform the biological and physical structure of the river channels, and the most importantly – alter the hydrological regime. The impact on the hydrology of the river can occur through reducing or increasing flows, altering seasonality of flows, changing the frequency, duration and timing of flow events, etc. In order to determine the extent of the mentioned changes, The Indicators of Hydrologic Alteration (IHA) software was used in this paper. The results showed that after the construction of Angiriai dam, such changes occurred in IHA Parameters group as: the water conditions of April month decreased by 31 %; 1-day, 3-days, 7-days and 30-days maximum flow decreased; the date of minimum flow occurred 21 days later; duration of high and low pulses and the frequency of low pulses decreased, but the frequency of high pulses increased, etc. The analysis of the Environmental Flow Components showed, that the essential differences were recorded in groups of the small and large floods, when, after the establishment of the Šušvė Reservoir, the large floods no longer took place and the probability of frequency of the small floods didn’t exceed 1 time per year.

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Koyunbaba Barajı’ndan akış aşağıya bırakılması gereken çevresel akış miktarının değerlendirilmesi (Environmental Flow Assessment for Downstream of Koyunbaba Dam)

SSRN Electronic Journal ◽

10.2139/ssrn.3417327 ◽

2014 ◽

Author(s):

Murat M. Köle

Keyword(s):

Environmental Flow

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GLOBAL MONTHLY ENVIRONMENTAL FLOW REQUIREMENT BASED ON THE NET PRIMARY PRODUCTIVITY OF RIVERS

Journal of Japan Society of Civil Engineers Ser G (Environmental Research) ◽

10.2208/jscejer.74.ii_85 ◽

2018 ◽

Vol 74 (6) ◽

pp. II_85-II_92

Author(s):

Yui SHINOZAKI ◽

Masashi FUJIWARA ◽

Naoki SHIRAKAWA

Keyword(s):

Primary Productivity ◽

Net Primary Productivity ◽

Environmental Flow ◽

Flow Requirement

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Environmental Flow Assessment Considering Inter- and Intra-Annual Streamflow Variability under the Context of Non-Stationarity

Water ◽

10.3390/w10121737 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1737 ◽

Cited By ~ 3

Author(s):

Kang Ren ◽

Shengzhi Huang ◽

Qiang Huang ◽

Hao Wang ◽

Guoyong Leng

Keyword(s):

Kendall Test ◽

Environmental Flow ◽

Mean Value ◽

Test Method ◽

Stationary Condition ◽

Annual Streamflow ◽

Riverine Ecosystems ◽

Study Results ◽

Wide Range ◽

Streamflow Variability

A key challenge to environmental flow assessment in many rivers is to evaluate how much of the discharge flow should be retained in the river in order to maintain the integrity and valued features of riverine ecosystems. With the increasing impact of climate change and human activities on riverine ecosystems, the natural flow regime paradigm in many rivers has become non-stationary conditions, which is a new challenge to the assessment of environmental flow. This study presents a useful framework to (1) detect change points in runoff time series using two statistical methods (Mann-Kendall test method and heuristic segmentation method), (2) adjust data of the changed period against the original flow series into a stationary condition using a procedure of reconstruction; and (3) incorporate inter- and intra-annual streamflow variability with adjusted streamflow to evaluate environmental flow. The Jialing to Han inter-basin water transfer project was selected as the case study. Results indicate that a change point of 1994 was identified, revealing that the stationarity of annual streamflow series is invalid. The variations of reconstructed streamflow series are roughly consistent with original streamflow series, especially in the maximum/minimum values and rise/fall rates, but the mean value of reconstructed streamflow series is increased. The reconstructed streamflow series would further serve to eliminate the non-stationary of original streamflow, and incorporating the inter- and intra-annual variability would upgrade the ecosystem fitness. Selecting different criteria for the conservation of riverine ecosystems can have significantly different consequences, and we should not focus on the protection of specific objectives that will inevitably affect other aspects. This study provides a useful framework for environmental flow assessment and can be applied to a wide range of instream flow management approaches to protect the riverine ecosystem.

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