Development of an Objective Procedure for Identifying Regions of Low Flow Homogeneity for the Specification of Environmental Flows

2002 ◽  
Vol 6 (1) ◽  
pp. 53-61
Author(s):  
R J Nathan ◽  
A Rahman ◽  
S Bagg ◽  
J H Green
Keyword(s):  
Environmental Flows ◽  
Low Flow ◽  
Objective Procedure

scholarly journals Water Temperature and Hydrological Modelling in the Context of Environmental Flows and Future Climate Change: Case Study of the Wilmot River (Canada)

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2101
Author(s):  
Christian Charron ◽  
André St-Hilaire ◽  
Taha B.M.J. Ouarda ◽  
Michael R. van den Heuvel
Keyword(s):  
Climate Change ◽  
Water Temperature ◽  
Environmental Flows ◽  
Low Flow ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Water Abstraction ◽  
Surface Water Flow ◽  
Modelling Studies ◽  
Rcp 8.5

Simulation of surface water flow and temperature under a non-stationary, anthropogenically impacted climate is critical for water resource decision makers, especially in the context of environmental flow determination. Two climate change scenarios were employed to predict streamflow and temperature: RCP 8.5, the most pessimistic with regards to climate change, and RCP 4.5, a more optimistic scenario where greenhouse gas emissions peak in 2040. Two periods, 2018–2050 and 2051–2100, were also evaluated. In Canada, a number of modelling studies have shown that many regions will likely be faced with higher winter flow and lower summer flows. The CEQUEAU hydrological and water temperature model was calibrated and validated for the Wilmot River, Canada, using historic data for flow and temperature. Total annual precipitation in the region was found to remain stable under RCP 4.5 and increase over time under RCP 8.5. Median stream flow was expected to increase over present levels in the low flow months of August and September. However, increased climate variability led to higher numbers of periodic extreme low flow events and little change to the frequency of extreme high flow events. The effective increase in water temperature was four-fold greater in winter with an approximate mean difference of 4 °C, while the change was only 1 °C in summer. Overall implications for native coldwater fishes and water abstraction are not severe, except for the potential for more variability, and hence periodic extreme low flow/high temperature events.

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).

Towards experimentally-based environmental flows for infrastructure management in high-altitude tropical streams

2020 ◽  
Author(s):  
Daniela Rosero-Lopez
Keyword(s):  
High Altitude ◽  
Environmental Flows ◽  
Benthic Fauna ◽  
Benthic Algae ◽  
Tropical Streams ◽  
Low Flow ◽  
Infrastructure Management ◽  
Temperature Conductivity ◽  
Stream Morphology ◽  
Flow Deviation

<p>Thresholds from flow–benthic fauna relationships in the light of data-scarce hydrosystems constitute an advance in implementing sustainable principles for water infrastructure management. To quantify thresholds the limits to the amount of water that can be withdrawn from Andean river networks before their natural functioning, biodiversity and ecosystem services become degraded, we conducted a whole-ecosystem experimental flow alteration. We reduced flow in the reach of a stream above a water intake from the supply system for the city of Quito, Ecuador. During the low-flow season, we diverted water using a system of weirs to accommodate streamflow in complementary percent (i.e., 90% flow deviation and 10% flow left in the stream). We performed seven reductions and kept them for seven days, during that time we sampled benthic algae chlorophyll-a concentration, flow, temperature, conductivity, light, and measured stream morphology. Our preliminary results indicate a high variability of ecological and physical responses to hydrological alterations in high-altitude tropical streams. A reduction to minimum flow similar to conditions observed for low-flows caused significant changes in stream morphology, and reductions above this threshold evidenced changes in the relative presence of major benthic algae groups.</p>

A Ramsar wetland in crisis - the Coorong, Lower Lakes and Murray Mouth, Australia

2011 ◽  
Vol 62 (3) ◽  
pp. 255 ◽  
Author(s):  
Richard T. Kingsford ◽  
Keith F. Walker ◽  
Rebecca E. Lester ◽  
William J. Young ◽  
Peter G. Fairweather ◽  
...  
Keyword(s):  
Environmental Flows ◽  
Large River ◽  
Freshwater Ecosystems ◽  
Water Levels ◽  
Environmental Benefits ◽  
Low Flow ◽  
Freshwater Turtles ◽  
Murray Darling Basin ◽  
High Conservation ◽  
Sulfate Soils

The state of global freshwater ecosystems is increasingly parlous with water resource development degrading high-conservation wetlands. Rehabilitation is challenging because necessary increases in environmental flows have concomitant social impacts, complicated because many rivers flow between jurisdictions or countries. Australia’s Murray–Darling Basin is a large river basin with such problems encapsulated in the crisis of its Ramsar-listed terminal wetland, the Coorong, Lower Lakes and Murray Mouth. Prolonged drought and upstream diversion of water dropped water levels in the Lakes below sea level (2009–2010), exposing hazardous acid sulfate soils. Salinities increased dramatically (e.g. South Lagoon of Coorong >200 g L–1, cf. modelled natural 80 g L–1), reducing populations of waterbirds, fish, macroinvertebrates and littoral plants. Calcareous masses of estuarine tubeworms (Ficopomatus enigmaticus) killed freshwater turtles (Chelidae) and other fauna. Management primarily focussed on treating symptoms (e.g. acidification), rather than reduced flows, at considerable expense (>AU$2 billion). We modelled a scenario that increased annual flows during low-flow periods from current levels up to one-third of what the natural flow would have been, potentially delivering substantial environmental benefits and avoiding future crises. Realisation of this outcome depends on increasing environmental flows and implementing sophisticated river management during dry periods, both highly contentious options.

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 The hydrological and environmental aspect of low flow assessment in ungauged basins - a case study in the Juzna Morava river basin

2021 ◽  
Vol 19 (3) ◽  
pp. 261-278
Author(s):  
Borislava Blagojevic ◽  
Vladislava Mihailovic ◽  
Jovan Blagojevic ◽  
Dragan Radivojevic
Keyword(s):  
Statistical Analysis ◽  
River Basin ◽  
Environmental Flows ◽  
Environmental Indicators ◽  
Low Flow ◽  
Ungauged Basins ◽  
Environmental Aspect ◽  
Morava River ◽  
Morava River Basin

Eighteen low flow indicators are considered in the research of sixteen hydrological stations in the Juzna Morava river basin. The indicators are estimated by statistical analysis and grouped as hydrological and environmental indicators. A crosscorrelation between all indicators is assessed. Environmental flows at hydrologic stations are obtained by the GEP method. The environmental low flow indicators are transferred to two small ungauged basins by regression with physiographic characteristics. The adjustment of environmental flows at ungauged basins is performed according to locations of the donor stations in the hydrogeological regions of the studied area.

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.

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.

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