Effects on ecosystems and biodiversity. Environmental flows
Fernando Magdaleno Mas Area of Environmental Engineering CEDEX (Ministry of Public Works – Ministry of the Environment and Rural and Marine Affairs) Legal framework in water planning and management
• New legal context in Europe: – Water Framework Directive (2000/60/EC) – Flood Risk Directive (2007/60/EC) – Habitats Directive (92/43/EEC) – Directive on Environmental Quality Standards (2008/105/EC) – Freshwater Fish Directive, Groundwater Directive,...
• New legal context in Spain: – Water Law amendments (R.D.L. 1/2001) – Modifications of the National Hydrological Plan (Law 11/2005) – Hydrological Planning Act (R.D. 907/2007) – Specifications of the Hydrological Planning Act (OM ARM/2656/2008) – Public Hydraulic Domain Act (R.D. 9/2008) – Transposition of European Directives Legal framework in water planning and management
1.1. Quality elements for the classification of ecological status 1.1.1. Rivers Biological elements Composition and abundance of aquatic flora Composition and abundance of benthic invertebrate fauna Composition, abundance and age structure of fish fauna Hydromorphological elements supporting the biological elements Hydrological regime quantity and dynamics of water flow connection to groundwater bodies River continuity Morphological conditions river depth and width variation structure and substrate of the river bed structure of the riparian zone Chemical and physico-chemical elements supporting the biological elements General Thermal conditions Oxygenation conditions Salinity Acidification status Nutrient conditions Specific pollutants Pollution by all priority substances identified as being discharged into the body of water Pollution by other substances identified as being discharged in significant quantities (...) Effects on ecosystems and biodiversity
• Direct connection between hydrological and ecological processes Effects on ecosystems and biodiversity
• Direct connection between hydrological and ecological processes
(Fernández Yuste & Martínez Santa-María, 2006) Effects on ecosystems and biodiversity
1. River continuum concept 2. Serial discontinuity concept 3. Natural flow regime paradigm (predictable diversity) 4. Intermediate disturbance hypothesis in rivers 5. Flood pulse concept 6. Hierarchical organization of river systems 7. Hyporheic corridor concept 8. Channel-basin interactions
(Poole, 2002) Effects on ecosystems and biodiversity
Main effects of losing a natural or a well-balanced flow regime:
1. Decrease of number and extension of wetlands; 2. Reduction (quantitative and qualitative) of aquatic and riparian habitats; 3. Substantial modification of the structure and composition of vegetation stands; 4. Difficulties in the development of the vital cycles of a wide range of aquatic organisms (benthic micro-organisms, phytoplankton, zooplankton, fishes,...); 5. Loss or decrease in the diversity and abundance of migrating species; Effects on ecosystems and biodiversity
Main effects of losing a natural or a well-balanced flow regime:
6. Colonization of habitats by alien species; 7. Reduction of the ecological function of the river system as a corridor and ecosystems connector; 8. Loss of cultural and recreational values; 9. Reduction of economic fluxes associated to the river systems, specially for riverine communities; 10. In developing regions, decrease of role as a basic resources supplier for a large amount of rural communities; Effects on ecosystems and biodiversity
Map of hydro-regions for the Spanish implementation of environmental flows (CEDEX-INDEGIS)
Flow regime protection in Spain
Water Laws: RDL 1/2001; L 11/2005
(...) It is considered compulsory to assure:
Environmental flows, understood as those that maintain, at least, the fish assemblages that naturally inhabit or would inhabit the river, and its riparian vegetation.
The natural river reserves, in order to preserve, without further disturbance, those river reaches scarcely or not at all altered by human uses. General procedure of analysis and establishment
• The establishment of environmental flow regimes will be fulfilled in a three- fold process:
a) An initial phase of development of technical analyses, in order to determine the whole range of environmental flow components in all the water bodies.
b) A second phase, based on the public concertation of the former results, and defined by different levels of action (information, public consultation and active participation).
c) A third phase, based on the establishment of all the environmental flow components, and on its adaptative management.
• The Management Plans of each Basin will include a synthesis of the afore- mentioned tasks. Objectives
• The environmental flow regimes will be determined and managed in the most convenient manner to maintain, in a sustainable way, the functionality and structure of the aquatic ecosystems and their associated terrestrial ecosystems, contributing to reach the good ecological status or potential status in the different water bodies.
• Protected areas will be given priority, after those, natural water bodies, and then, heavily modified water bodies (HMWB).
• The determination and management of environmental flows in protected areas will also include other associated water bodies and wetlands. Characterization in perennial rivers
• Environmental flow regimes will define, at least, the following attributes:
a) Temporal distribution of minimum flows.
b) Temporal distribution of maximum flows.
c) Maximum rates of change.
d) Flood regime, including peak flow, duration, frequency, seasonality and rate of change. Seasonal distribution of minimum flows
• Seasonal distribution of minimum flows will be determined through hydrological methods. Results will be adjusted through hydrobiological methods in representative reaches in all types of rivers.
• In case of meaningful differences, complementary analyses and monitoring programmes will be fulfilled. Analysis and establishment of environmental flows
Ca. 500 water bodies Seasonal distribution of minimum flows
• Hydrological methods Hydrological methods will be based on the analysis of monthly minimum flows, using one of the following criteria:
a) Definition of annual mobile averaging values. Unique (e.g., 25 consecutive days) or variable order will be used, with the aim of determining discontinuities in the hydrological balance. b) Definition of percentiles between 5 and 15%, on the basis of classified flows curves, with the aim of determining the minimum threshold. Seasonal distribution of minimum flows
• Hydrobiological methods
Habitat suitability modeling will be based on hydraulic simulation techniques combined with habitat preference curves for target species, which will drive to curves relating weighted usable habitat and flow.
Hábitat Real Útil - Comparativa
500 Barbo-adulto 450 Cacho-adulto 400 Boga-adulto
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300
250
200
Hábitat Real Útil (m2 Útil Real Hábitat 150
100
50
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Caudal (m3/s)
Simulation models: River2D, RHABSIM, RHYHABSIM,... Selection of target species
Chondrostoma polylepis(JUVENIL)
1, 0
0,5
0,0 0 0,3 0,6 0,9 1,2 1,5 1,8 2,1
Velocidad (m/s) Luciobarbus sclateri. Adulto
1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 0 20 40 60 80 100 120 140
Calado (m)
Gobio lozanoi . Juvenil
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Sustrato Seasonal distribution of minimum flows • Hydrobiological methods
• Species selection will give priority to those in peril of extinction, sensitive to habitat alteration, vulnerable or of special interest, included in lists of species in danger, or included in annexes II and IV of Directive 92/43/EEC. Rate of change
• Determination of the rate of change.
• The maximum rate of change will be determined on the basis of the natural distribution of consecutive temporal variations in the flow series. • This analysis will be performed on average diary flow series, or in a hourly scale, when this is necessary and the required data is ready. Flood regime characterization
• Determination of the flood environmental regime
• In reaches downstream of hard regulations, it should be determined, at least, the bankfull discharge (magnitude, frequency, duration, season and maximum rate of change in both branches of the hydrograph). Temporary, intermittent and ephemeral rivers
• Temporary, intermittent and ephemeral rivers
a) Temporary rivers: Same criteria as in perennial rivers.
b) Intermittent rivers: - connectivity with subterranean waters, defining the required minimum water volumes to protect the hyporheic flow, core for ecological purposes. - flood magnitude and time to reach the base flow. - bankfull discharge.
c) Ephemeral rivers: - time to reach the base flow. - bankfull discharge. Estuaries and coastal waters
• EFRs determination in estuaries and coastal waters.
• In general terms, results for rivers will be applicable to estuaries and coastal waters. In all cases, the EFRs will be tested on environmental variables and on salinity modeling.
• If the fluvial dynamics controls the salt intrusion, the environmental flow regime will be adjusted to avoid anoxic conditions in the river bed and an increase in the frequency and intensity of algae blooms.
• Special focus will be driven in nutrient and sediment fluxes. Highly Modified Water Bodies (HMWB)
• In Highly Modified Water Bodies (HMWB), hydrologic alteration will be calculated through IHA techniques.
• Those indicators use a set of parameters to characterize statistically the inter and intra-annual hydrological variability, both in the natural and the regulated flow regime.
• Indicators of Hydrologic Alteration must focus on the main characteristics of the flow regimes, such as magnitude, duration, frequency, season and rate of change.
• EFRs estimate will follow the general recommendations. As a first approximation, threshold for minimum and maximum flows will be in the range 30-80% of the maximum WUH for the target species. Utilization of IAHs
(Fernández Yuste & Martínez Santa- María, 2006) - CEDEX Environmental Flow Assessment in lakes and wetlands
• Environmental water requirements of lakes and wetlands will consider the following topics:
a) Lake type, b) Area and depth. c) Water chemicals (composition and concentration). d) Hydrologic functioning (sp., inflows and outflows). e) Composition and structure of biological communities.
• Best available techniques (BATs) will be used (e.g., remote sensing).
• Water requirements of wetlands included in network Natura 2000 or Ramsar Areas, but not identified as water bodies, will be determined with the afore- mentioned procedure. EFRs in extreme drougths
• In extreme droughts, some changes in the environmental flow regime will be accepted. However, this occasional management must: – Avoid any unrecoverable alteration of the fluvial ecosystems. – Follow the procedure included in the Drought Plans existing in all Basins.
• No modification from the environmental flow regime can be done in Natura 2000 or Ramsar Areas, except when human supply is in risk.
• Implementation of EFRs in drougth situations must be developed progressively.
• Habitat suitability and minimum monthly flows must be considered. In a first approx., at least 25% of maximum WUH must be maintained. Spanish strategy for the improvement of river systems
• National Strategy for River Restoration
• National Plan of Water Quality
• Basin Management Plans – Instream flows – Improvement of ecological status – Creation of a network of protected rivers
• National Plan for Wetlands conservation Restoration of aquatic and riparian ecosystems Restoration of aquatic and riparian ecosystems Reduction of river fragmentation National network of protected rivers [email protected]