Environmental Flows: Ecological Limits of Hydrologic Alteration (ELOHA)

The science needed to inform management of environmental flows to temporarily closed estuaries and coastal lagoons is decades behind the state of knowledge for rivers and large embayments. These globally ubiquitous small systems, which are often seasonally closed to the ocean’s influence, are under particular threat associated with hydrologic alteration because of changes in atershed land use, water use practices, and climate change. Managing environmental flows in these systems is complicated by their tight coupling with watershed processes, variable states because of intermittently closing mouths, and reliance on regional scale sediment transport and littoral processes. Here we synthesize our current understanding of ecohydrology in temporarily closed estuaries (TCEs) and coastal lagoons and propose a prioritized research agenda aimed at advancing understanding of ecological responses to altered flow regimes in TCEs. Key research needs include agreeing on a consistent typology, improving models that couple watershed and ocean forcing at appropriate spatial and temporal scales, quantifying stress–response relationships associated with hydrologic alteration, improving tools to establish desired conditions that account for climate change and consider cultural/indigenous objectives, improving tools to measure ecosystem function and social/cultural values, and developing monitoring and adaptive management programs that can inform environmental flow management in consideration of other stressors and across different habitat types. Coordinated global efforts to address the identified research gaps can help guide management actions aimed at reducing or mitigating potential impacts of hydrologic alteration and climate change through informed management of freshwater inflows.

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Environmental Flows: Ecological Limits of Hydrologic Alteration (ELOHA)

The Wetland Book ◽

10.1007/978-94-007-6172-8_348-1 ◽

2016 ◽

pp. 1-5

Author(s):

Angela H. Arthington

Keyword(s):

Environmental Flows ◽

Hydrologic Alteration

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Implementing Environmental Flows: Lessons for Policy and Practice

10.3389/978-2-88966-039-1 ◽

2020 ◽

Keyword(s):

Environmental Flows ◽

Policy And Practice

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Environmental Flows

10.1525/9780520953451 ◽

2012 ◽

Cited By ~ 4

Author(s):

Angela Arthington

Keyword(s):

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

Water ◽

10.3390/w13152101 ◽

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.

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The Influence of Flow Regime on Ecological Quality, Bird Diversity, and Shellfish Fisheries in a Lowland Mediterranean River and Its Coastal Area

Water ◽

10.3390/w11050918 ◽

2019 ◽

Vol 11 (5) ◽

pp. 918 ◽

Cited By ~ 6

Author(s):

Oscar Belmar ◽

Carles Ibáñez ◽

Ana Forner ◽

Nuno Caiola

Keyword(s):

Aquatic Vegetation ◽

Environmental Flows ◽

Ecological Status ◽

Model Performance ◽

Habitat Characteristics ◽

Bird Diversity ◽

Ecological Quality ◽

Anthropogenic Pressures ◽

Discharge Data ◽

Mantis Shrimp

Designing environmental flows in lowland river sections and estuaries is a challenge for researchers and managers, given their complexity and their importance, both for nature conservation and economy. The Ebro River and its delta belong to a Mediterranean area with marked anthropogenic pressures. This study presents an assessment of the relationships between mean flows (discharges) computed at different time scales and (i) ecological quality based on fish populations in the lower Ebro, (ii) bird populations, and (iii) two shellfish fishery species of socioeconomic importance (prawn, or Penaeus kerathurus, and mantis shrimp, or Squilla mantis). Daily discharge data from 2000 to 2015 were used for analyses. Mean annual discharge was able to explain the variation in fish-based ecological quality, and model performance increased when aquatic vegetation was incorporated. Our results indicate that a good ecological status cannot be reached only through changes on discharge, and that habitat characteristics, such as the coverage of macrophytes, must be taken into account. In addition, among the different bird groups identified in our study area, predators were related to river discharge. This was likely due to its influence on available resources. Finally, prawn and mantis shrimp productivity were influenced up to a certain degree by discharge and physicochemical variables, as inputs from rivers constitute major sources of nutrients in oligotrophic environments such as the Mediterranean Sea. Such outcomes allowed revisiting the environmental flow regimes designed for the study area, which provides information for water management in this or in other similar Mediterranean zones.

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