Evaluation of environmental flow requirements using eco-hydrologic–hydraulic methods in perennial rivers

2015 ◽  
Vol 72 (3) ◽  
pp. 354-363 ◽  
Author(s):  
Reza Abdi ◽  
Mehdi Yasi
Keyword(s):  
Environmental Flows ◽  
Environmental Flow ◽  
Low Flow ◽  
Flow Duration Curve ◽  
North West ◽  
Flow Duration ◽  
Key Species ◽  
Habitat Simulation ◽  
Range Of Variability Approach ◽  
Ecological Methods

The assessment of environmental flows in rivers is of vital importance for preserving riverine ecosystem processes. This paper addresses the evaluation of environmental flow requirements in three reaches along a typical perennial river (the Zab transboundary river, in north-west Iran), using different hydraulic, hydrological and ecological methods. The main objective of this study came from the construction of three dams and inter-basin transfer of water from the Zab River to the Urmia Lake. Eight hydrological methods (i.e. Tennant, Tessman, flow duration curve analysis, range of variability approach, Smakhtin, flow duration curve shifting, desktop reserve and 7Q2&10 (7-day low flow with a 2- and 10-year return period)); two hydraulic methods (slope value and maximum curvature); and two habitat simulation methods (hydraulic–ecologic, and Q Equation based on water quality indices) were used. Ecological needs of the riverine key species (mainly Barbus capito fish), river geometries, natural flow regime and the environmental status of river management were the main indices for determining the minimum flow requirements. The results indicate that the order of 35%, 17% and 18% of the mean annual flow are to be maintained for the upper, middle and downstream river reaches, respectively. The allocated monthly flow rates in the three Dams steering program are not sufficient to preserve the Zab River life.

scholarly journals Environmental Flows Assessment in Nepal: The Case of Kaligandaki River

2020 ◽  
Vol 12 (21) ◽  
pp. 8766 ◽  
Author(s):  
Naresh Suwal ◽  
Alban Kuriqi ◽  
Xianfeng Huang ◽  
João Delgado ◽  
Dariusz Młyński ◽  
...  
Keyword(s):  
Environmental Flows ◽  
Environmental Flow ◽  
Trophic Levels ◽  
Flow Duration Curve ◽  
Small Hydropower ◽  
Distribution Method ◽  
Flow Duration ◽  
Hydropower Plants ◽  
Study Results ◽  
Annual Distribution

Environmental flow assessments (e-flows) are relatively new practices, especially in developing countries such as Nepal. This study presents a comprehensive analysis of the influence of hydrologically based e-flow methods in the natural flow regime. The study used different hydrological-based methods, namely, the Global Environmental Flow Calculator, the Tennant method, the flow duration curve method, the dynamic method, the mean annual flow method, and the annual distribution method to allocate e-flows in the Kaligandaki River. The most common practice for setting e-flows consists of allocating a specific percentage of mean annual flow or portion of flow derived from specific percentiles of the flow duration curve. However, e-flow releases should mimic the river’s intra-annual variability to meet the specific ecological function at different river trophic levels and in different periods over a year covering biotas life stages. The suitability of the methods was analyzed using the Indicators of Hydrological Alterations and e-flows components. The annual distribution method and the 30%Q-D (30% of daily discharge) methods showed a low alteration at the five global indexes for each group of Indicators of Hydrological Alterations and e-flows components, which allowed us to conclude that these methods are superior to the other methods. Hence, the study results concluded that 30%Q-D and annual distribution methods are more suitable for the e-flows implementation to meet the riverine ecosystem’s annual dynamic demand to maintain the river’s health. This case study can be used as a guideline to allocate e-flows in the Kaligandaki River, particularly for small hydropower plants.

scholarly journals Accounting for environmental flow requirements in global water assessments

2014 ◽  
Vol 18 (12) ◽  
pp. 5041-5059 ◽  
Author(s):  
A. V. Pastor ◽  
F. Ludwig ◽  
H. Biemans ◽  
H. Hoff ◽  
P. Kabat
Keyword(s):  
Flow Regime ◽  
Environmental Flows ◽  
Environmental Flow ◽  
Ecological Condition ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Human Needs ◽  
High Flows ◽  
The Mean ◽  
Global Vegetation

Abstract. As the water requirement for food production and other human needs grows, quantification of environmental flow requirements (EFRs) is necessary to assess the amount of water needed to sustain freshwater ecosystems. EFRs are the result of the quantification of water necessary to sustain the riverine ecosystem, which is calculated from the mean of an environmental flow (EF) method. In this study, five EF methods for calculating EFRs were compared with 11 case studies of locally assessed EFRs. We used three existing methods (Smakhtin, Tennant, and Tessmann) and two newly developed methods (the variable monthly flow method (VMF) and the Q90_Q50 method). All methods were compared globally and validated at local scales while mimicking the natural flow regime. The VMF and the Tessmann methods use algorithms to classify the flow regime into high, intermediate, and low-flow months and they take into account intra-annual variability by allocating EFRs with a percentage of mean monthly flow (MMF). The Q90_Q50 method allocates annual flow quantiles (Q90 and Q50) depending on the flow season. The results showed that, on average, 37% of annual discharge was required to sustain environmental flow requirement. More water is needed for environmental flows during low-flow periods (46–71% of average low-flows) compared to high-flow periods (17–45% of average high-flows). Environmental flow requirements estimates from the Tennant, Q90_Q50, and Smakhtin methods were higher than the locally calculated EFRs for river systems with relatively stable flows and were lower than the locally calculated EFRs for rivers with variable flows. The VMF and Tessmann methods showed the highest correlation with the locally calculated EFRs (R2=0.91). The main difference between the Tessmann and VMF methods is that the Tessmann method allocates all water to EFRs in low-flow periods while the VMF method allocates 60% of the flow in low-flow periods. Thus, other water sectors such as irrigation can withdraw up to 40% of the flow during the low-flow season and freshwater ecosystems can still be kept in reasonable ecological condition. The global applicability of the five methods was tested using the global vegetation and the Lund-Potsdam-Jena managed land (LPJmL) hydrological model. The calculated global annual EFRs for fair ecological conditions represent between 25 and 46% of mean annual flow (MAF). Variable flow regimes, such as the Nile, have lower EFRs (ranging from 12 to 48% of MAF) than stable tropical regimes such as the Amazon (which has EFRs ranging from 30 to 67% of MAF).

scholarly journals The Fate of Stationary Tools for Environmental Flow Determination in a Context of Climate Change

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1203
Author(s):  
André St-Hilaire ◽  
Habiba Ferchichi ◽  
Laureline Berthot ◽  
Daniel Caissie
Keyword(s):  
Aquatic Ecosystems ◽  
Environmental Flows ◽  
Flow Characteristics ◽  
Environmental Flow ◽  
Flow Time ◽  
Low Flow ◽  
Flow Alteration ◽  
Holistic Approaches ◽  
Simple Step ◽  
Flow Quality

Environmental flows (eflows) refer to the amount of water required to sustain aquatic ecosystems. In its formal definition, three flow characteristics need to be minimally maintained: quantity, timing and quality. This overview paper highlights the challenges of some of the current methods used for eflow determination in the context of an evolving climate. As hydrological methods remain popular, they are first analyzed by describing some of the potential caveats associated with their usage when flow time series are non-stationarity. The timing of low-flow events will likely change within a season but will also likely shift in seasonality in some regions. Flow quality is a multi-faceted concept. It is proposed that a first simple step to partly incorporate flow quality in future analyses is to include the water temperature as a covariate. Finally, holistic approaches are also critically revisited, and simple modifications to the Ecological Limits of Flow Alteration (ELOHA) framework are proposed.

scholarly journals Environmental flow assessment in the context of climate change: a case study in Southern Quebec (Canada)

2021 ◽  
Author(s):  
Laureline Berthot ◽  
André St-Hilaire ◽  
Daniel Caissie ◽  
Nassir El-Jabi ◽  
Judith Kirby ◽  
...  
Keyword(s):  
Climate Change ◽  
Environmental Flows ◽  
Environmental Flow ◽  
Low Flow ◽  
Physical Habitat ◽  
Climate Change Scenarios ◽  
Management Tools ◽  
Water Abstraction ◽  
The Impact

Abstract Through a case study in Southern Quebec (Canada), the assessment of environmental flows in light of the effects of climate change is investigated. Currently, the 7Q2 flow metric (7-day average flow with a 2-year return period) is used for water abstraction management. Several flow metrics were calculated using flow time series simulated by a deterministic hydrological model (HYDROTEL) and climate change scenarios as inputs. Results were compared within homogeneous low flow regions defined using ascendant hierarchical clustering, for the 1990, 2020 and 2050 horizons and annual, summer and winter periods. The impact of each flow metric on the potential availability of physical habitat was analyzed using the wetted perimeter as a proxy. Results indicated that: (1) the increasing non-stationarity of simulated flow data sets over time will complicate the use of frequency analysis to calculate the 7Q2 flow metric; (2) summer low flow values are expected to be lower than winter low flows; and (3) flow-duration curve metrics like the LQ50 (median discharge value of the month with the lowest flow) may become relevant environmental flow metrics by 2050. Results question current water abstraction management tools and permit to anticipate future local and regional issues during low flow periods.

scholarly journals Determination of Environmental Flows for the Barbuda Stream in the Municipality of Olaya, Antioquia, Colombia

2019 ◽  
Author(s):  
Juan Pablo Garcia Montoya ◽  
T Vanwalleghem ◽  
Juan V Giráldez ◽  
J Morató ◽  
Jorge Montoya
Keyword(s):  
Environmental Flows ◽  
Past Research ◽  
Environmental Flow ◽  
Morphometric Parameters ◽  
Rainfall Data ◽  
Water Harvesting ◽  
The Past ◽  
Weather Variation ◽  
Range Of Variability Approach

Environmental flow determination is important for the management of rivers and reservoirs. This parameter allows us to calculate the water supply of basins and minimize environmental impacts associated with water harvesting. In the past, research has been performed to determine environmental flows in rivers of Antioquia. However, the results did not include annual weather variation. Mean environmental flows, evapotranspiration and infiltration in the area have been calculated with the rainfall data registered in the Olaya station during 20 years and the basin morphometric parameters. The collected data were used to build a mathematical model in MATLAB and determine the environmental flows with the Range of Variability Approach (RVA) method for each month of the year and ENSO periods. The model can be used to determine environmental flows in similar basins using new rainfall data and morphometric parameters. 

Environmental Flow Estimation of Brunei River Based on Climate Change

2021 ◽  
pp. 097542532110472
Author(s):  
Shahriar Shams ◽  
Md Sumon Reza ◽  
Abul Kalam Azad ◽  
Rozeana Binti Hj. Md. Juani ◽  
Mohammad Abul Fazal
Keyword(s):  
Climate Change ◽  
Environmental Flows ◽  
Threshold Value ◽  
Environmental Flow ◽  
Planning System ◽  
Low Flow ◽  
Potential Growth ◽  
Flow Estimation ◽  
Brunei Darussalam ◽  
Main Challenge

The concept of environmental flows and its application and enforcement is a main challenge in several developing countries. The services and benefits derived from the ecosystem are indispensable for sustaining the livelihood of people particularly living in coastal areas. Decision-makers often ignore ecosystems when referring to water allocation, as the supporters of ecosystems are less vocal as compared to other stakeholders. This study focuses on establishing guidelines for maintaining the minimum amount of flow known as environmental flow of Brunei River in Brunei Darussalam for the sustainability of its rich ecosystem. In this study, the flow of the river was simulated based on land use, climate change, and potential growth of industries using a Water Evaluation and Planning System as a computing tool. The study finds that the months of March and June (1.48 and 3.92 m3/s) are more vulnerable to low flow. It recommends a threshold value of 2.7 m3/s for the environmental flow of Brunei River essential to preserve its rich and diversified ecosystem.

scholarly journals “E = mc2” of Environmental Flows: A Conceptual Framework for Establishing a Fish-Biological Foundation for a Regionally Applicable Environmental Low-Flow Formula

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1501 ◽  
Author(s):  
Piotr Parasiewicz ◽  
Paweł Prus ◽  
Katarzyna Suska ◽  
Paweł Marcinkowski
Keyword(s):  
Environmental Flows ◽  
Regional Scale ◽  
Biological Significance ◽  
Aquatic Organisms ◽  
Pilot Project ◽  
Standard Setting ◽  
Environmental Flow ◽  
Low Flow ◽  
Fish Community Structure ◽  
Body Type

Determination of environmental flows at the regional scale has been complicated by the fine-scale variability of the needs of aquatic organisms. Therefore, most regional methods are based on observation of hydrological patterns and lack evidence of connection to biological responses. In contrast, biologically sound methods are too detailed and resource-consuming for applications on larger scales. The purpose of this pilot project was to develop an approach that would breach this gap and provide biologically sound rules for environmental flow (eflow) estimation for the region of Poland. The concept was developed using seven river sites, which represent the four of six fish-ecological freshwater body types common in Poland. Each of these types was distinguished based on a specific fish community structure, composed of habitat-use guilds. The environmental significance of the flows for these communities was established with help of the habitat simulation model MesoHABSIM computed for each of the seven sites. The established seasonal environmental flow thresholds were standardized to the watershed area and assigned to the corresponding water body type. With these obtained environmental flow coefficients, a standard-setting formula was created, which is compatible with existing standard-setting approaches while maintaining biological significance. The proposed approach is a first attempt to use habitat suitability models to justify a desktop formula for the regional scale eflow criteria.

scholarly journals Quantification of Environmental Flow Requirement of the Khun Dan Prakan Chon Dam Using Hydrological-Hydraulic-Habitat Simulation Methods

2018 ◽  
pp. 76-90
Author(s):  
Penpicha Nakvachara ◽  
Areeya Rittima ◽  
Yutthana Talaluxmana
Keyword(s):  
Aquatic Organisms ◽  
Environmental Flow ◽  
Habitat Conservation ◽  
Low Flow ◽  
Physical Habitat ◽  
Flow Rates ◽  
Habitat Simulation ◽  
Water Resources Projects ◽  
Naturalized Flow ◽  
Flow Requirement

With increased water demand, reservoir operation has become more complex with the need to quantify the exact amount of water needed for each demand sector. The environmental flow requirement, also known as instream flow is regarded as the first-prioritized objective of the multipurpose water resources projects in Thailand. The capability of reservoirs in Thailand to allocate water for environmental needs depends on available supply, strategies and operating policy. Therefore, this study aims to assess the environmental flow requirements of Khun Dan PrakanChon Dam using three methods; 1) the hydrological method (Tennant, Tessmann, 7Q10, FDC, and VMF), 2) hydraulic method (R2CROSS and wetted perimeter) and 3) habitat simu-lationmethod, using the PHABSIM model for physical habitat simulation of aquatic organisms in the Nakhon Nayok River. The hydrological approach was performed under the historically-naturalized flow data of the NY.1B station and established hydrologic flow regime during low flow and high flow months. The environmental flow rates obtained from two hydraulic methods were based upon field observations at the NY.1B station significantly. However, the biological conditions and interactions of aquatic organisms in the river were not principally characterized in hydrologic and hydraulic approaches. In addition, the estimated results performed by habitat simulation model gave an additional meaning of ecological flow needs mainly for aquatic habitat conservation in the river. By integrating the conditions of hydrologic and hydraulic flow regimes as well as the habitat conservation objectives, environmental flow rates of 8-10 cm were recommended to determine the downstream release of Khun Dan Prakan Chon Dam; these recommendations were very close to those derived using the Tessmann, 7Q10 and PHABSIM methods-Tennant and flow duration curve methods.

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