IWC     Environmental Flows and Management                  Scenarios                                  December 2009      ...
Environmental Flows                                      Environmental flows describe                                     ...
Ecological Significance of Natural Flow Regime1. Poff et al. 1997. Natural Flow Regime Paradigm2. Bunn & Arthington 2002Ba...
Components of natural flow regimes     Natural Flow Regime Paradigm - Poff et al. (1997)     •    Magnitude of flow – disc...
Macro-scale                   Flow creates and maintains:         (channel form)                                          ...
Substrate composition                                  Frequency of use                                         30        ...
Impacts of water loss and habitat change        downstream of dams and weirs                Sudden loss of flow and water ...
Brisbane River d/s Wivenhoe Dam:                     Unregulated vs Regulated Flow                    180000              ...
Hydro-         Hydro-ecological relationships: riparian                      vegetation             Typical zonation of ri...
Principle 2                                    Life History Patterns                       Aquatic biodiversity and natura...
Flows trigger spawning in Clanwilliam Yellowfish                                                                  Spawnin...
Flow effects on different processes during a                  plant life cycleEcological responses to various temporal and...
Giant Mekong Catfish   (2.35 m and 260 kg)                                                            “Construction of    ...
Water flowing to sea                                                                                                      ...
Impoundments provide habitat for exotic  fish and plants (e.g. water hyacinth)                                          Mo...
Effects of weirs on                                               riparian & aquatic                                      ...
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Arthington iwc e flows principles handout

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  1. 1. IWC Environmental Flows and Management Scenarios December 2009 Prof. Angela Arthington Australian Rivers Institute, Griffith University Room 1.09C, Building N13 3735 7403 Rivers and floodplains are the world’s most threatened ecosystems Global declines in river health Loss of freshwater biodiversity Declining food fisheries Loss of human cultural values Impacts on river flow regimes surface and groundwater levee banks on floodplainst abstraction weirs impacts of water grids high value and IBTs free-flowing riversMinimal flow regime change dam release rules 1
  2. 2. Environmental Flows Environmental flows describe the quantity, timing and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well- being that depend upon th b i th t d d these systems Brisbane Declaration 2007 International Environmental Flows Conference, Brisbane, September 2007 750 delegates from over 50 countries Management Scenario 1 Determining e-flows for a new reservoir on a river like the Li Jiang• Rapid assessment, with limited resources and data DRIFT Methodology Downstream Response to Imposed Flow Transformation• Comprehensive assessment, with time to collect field data ELOHA Framework Ecological Limits of Hydrologic Alteration Management Scenario 2 Prioritising e-flows for multiple assets when there is limited water available because of other demands Which wetlands should be given water and how much, when,? g Water allocations to sustain commercial fisheries• Rapid assessment, with limited resources and data Flow Restoration Methodology• Comprehensive assessment, with time to collect field data ELOHA Framework 2
  3. 3. Ecological Significance of Natural Flow Regime1. Poff et al. 1997. Natural Flow Regime Paradigm2. Bunn & Arthington 2002Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity3. Nilsson & Svedmark 2002Basic principles and ecological consequences of changing water regimes: riparian plant communities4. Pinay et al. 2002Basic principles and ecological consequences of changing water regimes on nitrogen cycling in fluvial systems5. Naiman, Bunn et al. 2002Legitimising fluvial ecosystems as users of water: An overview Ecological Significance of Flow Natural Flow Regime Paradigm Poff et al. (1997)• The ecological structure and function of flowing water systems depends largely on their natural dynamic flow regime• Stream flow is a “master variable” that influences physical and chemical characteristics, e.g. - water quality - sediment regime and substrate characteristics - channel morphology, habitat structure and diversity - energy sources that fuel the aquatic food web• Stream flow characteristics influence the distribution, abundance and biotic interactions of river and floodplain species• Alteration of the natural flow regime of a river can have physical, chemical and ecological impacts Rivers differ in their natural flow regimes Mekong 0.8 Darling 30 0.6 20 0.4 10 0.2 0 0 6 8 Mississippi Murray 6 4 4 2 2 0 0 Columbia 8 Cooper Creek 20 6 4 10 2 0 0 3
  4. 4. Components of natural flow regimes Natural Flow Regime Paradigm - Poff et al. (1997) • Magnitude of flow – discharge Q • Frequency of occurrence – relates to a particular magnitude, e.g. e g zero flow, or 100 year flood etc flow flood, • Duration e.g. number of days of low flow, or number of days the floodplain is inundated, or composite values from flow duration curve • Timing, seasonality and predictability • Rate of change, or flashiness Bunn, S.E. and Arthington, A.H. (2002) Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environmental Management 30: 492-5071. Flow is a major determinant of physical habitat in streams, which in turn is a major determinant of biotic composition2. Aquatic Species have evolved life history strategies primarily in direct response to the natural flow regime3. Maintenance of natural patterns of longitudinal and lateral connectivity is essential to the viability of populations of many riverine species4. The invasion and success of exotic and introduced species in rivers is facilitated by the alteration of flow regimes Flow-ecology principles Bunn & Arthington (2002) Env. Management Aquatic biodiversity and natural flow regimes Principle 3 lateral connectivity Principle 1 longitudinal connectivity channel form habitat complexity biotic diversity patch disturbance access to spates floodplains variability Principle 2 dispersal Life history patterns Discharge triggers • spawning reproductive triggers • recruitment seasonality predictability stable baseflows drought Time Principle 4 natural regime discourages invasions 4
  5. 5. Macro-scale Flow creates and maintains: (channel form) •channel form - headwater tributaries, main channels, lowland floodplains •hydraulic habitat units - riffles, pools, floodplain wetlands Meso-scale (hydraulic units) Micro-scale (patches within hydraulic units)•patches of habitat - undercut banks, boulders - gravel & sand beds, - aquatic plants - woody debris – snags - leaf litter packs Images: Mark Kennard, Griffith University Fish habitat flow preferences in riffles, runs and pools run riffle • intermediate # species • streamlined body • few species pool • streamlined body form • many species • diverse body shapes Images: Mark Kennard & Brad Pusey, Griffith University Position in Rainbowfish Water Column (open water schooling species) Purple spotted gudgeon (benthic species)Water surface 0.2 0.4Relativewater 0.6depth 0.8 1 0 10 20 30Stream bed 0 20 40 60 Frequency (% of individuals) Images: Mark Kennard & Brad Pusey, Griffith University 5
  6. 6. Substrate composition Frequency of use 30 20 Availability 30 10 20 0 10 0 30 Substrate composition 20 10 0 Images: Mark Kennard & Brad Pusey, Griffith University Microhabitat structure Frequency of use Availability 20 Juveniles 15 Adults 10 15 5 10 0 5 0 Microhabitat structure Images: Mark Kennard & Brad Pusey, Griffith University Microhabitat structure Impacts of flow regime alterations that change habitat downstream of dams and g weirs 6
  7. 7. Impacts of water loss and habitat change downstream of dams and weirs Sudden loss of flow and water depth, fish stranding The Lower Murray – a River of Lakes Weir pools favour lentic Gastropods. River gastropods decline. Caused by loss of river habitat & food resources (biofilms) Blue-green algal blooms in the Darling River 1990-1991Caused by:• Stable low flows• Loss of flushing flows• Elevated nutrients• Ample light• Suitable water temps• Less grazing pressure 7
  8. 8. Brisbane River d/s Wivenhoe Dam: Unregulated vs Regulated Flow 180000 300 CV of monthly flow 160000 250 140000 Flow ML 120000 200 100000 150 80000 m 60000 100 40000 50 20000 0 0 MAR OCT AUG NOV APR JUN MAY FEB JAN JUL DEC Mean Monthly Unregulated SEP Mean Monthly Regulated Coefficient of Variation Unregulated Coefficient of Variation Regulated • Reduced mean monthly flows • Reduced flood peaks & “stepped” flow releases • Elevated & more stable low flows • Loss of flow variability at most flow magnitudesElevated, more stable low flows create habitat for dense, extensive aquatic plant beds Impacts: • altered water quality, e.g. DO Red water • habitat much less diverse milfoil • lower diversity of invertebrates and fish • reduced flood conveyance Effects of Natural Flow Regime on Riparian VegetationBefore Flow Regulation Lateral & longitudinalZonation of vegetation seed dispersal byby flood frequency & hydrochoryduratione.g. herbs, shrubs, trees Biologically active Usually diverse zone flora in comparison e.g. decomposition to surrounding terrestrial system Spatially and temporally heterogeneous plant community composition and structure 8
  9. 9. Hydro- Hydro-ecological relationships: riparian vegetation Typical zonation of riparian vegetation for SEQ Mature grassy open eucalypt (E. tereticornis) Tall She-oak (Casuarina & bloodwood (Corymbia Along the channel verge there is a cunninghamiana) riparian tessellaris) woodland stable band of reophytes such as bl b d f h h forest with mesic subcanopy Watergum (Tristaniopsis exilliflora), species on channel terraces Callistemon viminalis. & the Mat rush (Lomandra sp.) Effects of changing the Flow Regime on Riparian Vegetation After Flow Regulation by Dam Barriers to seed dispersal by hydrochory, particularlyStreamward migration affecting short-floating seedsof vegetation zones,i.e. replacement ofhydrophytic species by y p y p ymore mesic/ xeric species.e.g. encroachment of forest Decomposition rates decline with flood elimination Homogenisation of plant community composition & structure Severe effects of reduced flood frequency on floodplain wetlands and waterbirdsWetland loss in Australia:• 90 % loss in M-D Basin M-• 75 % loss on Swan Coastal Plain, WA• 50 % loss NSW coastal rivers 9
  10. 10. Principle 2 Life History Patterns Aquatic biodiversity and natural flow regimes Principle 3 lateral connectivity Principle 1 longitudinal connectivity channel form habitat complexity biotic diversity patch disturbance access to spates floodplains variability Principle 2 dispersal Life history patterns Discharge triggers • spawning reproductive triggers • recruitment seasonality predictability stable baseflows drought Time Principle 4 natural regime discourages invasionsLife History and Recruitment Strategies Low flow recruitment Spawn during stable low flows in spring & summer, window of opportunity to access habitat/food for larval N. Armstrong fishesNo flow recruitment N. ArmstrongSpawning in standing water bodieswith no flow, e.g. river pools,waterholes on floodplains Merrick & Schmida Flow / flood pulse recruitment Spawn during rising water levels or floods in spring & summer, recruitment enhanced by backwater & floodplain inundationCatfish spawns into a ‘nest’ in well-oxygenated water,water level fluctuations can inhibit spawning Eel-tailed catfish R. Kuiter R. McDowall G. Schmida 10
  11. 11. Flows trigger spawning in Clanwilliam Yellowfish  Spawning stimulated by flow cues below dams  Larval growth requires warm water and diverse food items Skelton 1993Seasonal reproductive cycles of fish species in the Fitzroy River system, QLD A. ag A. per Ar. g. G. apr. p H. lep. Hyp. c. M. mog. N. ater Ox. lin. P. gr. Scl. l. Sc. h. T. tan. J A S O N D J F M A M J low & stable flows wet season Spring temps Summer temps Inversion of normal seasonal flow pattern below large dams Flow and temperature patterns no longer match Loss of fl d fl L f flood flows Fish spawning failure Loss of wetland biodiversity and functions Median monthly flows Murray River at Albury, NSW 11
  12. 12. Flow effects on different processes during a plant life cycleEcological responses to various temporal and spatial scale of flow disturbance Flowering, seed Adult set and release Growth and maturity y Seed Juvenile Dispersal Germination Establishment Seedling Predation, competition Principle 3 Movement and migration Aquatic biodiversity and natural flow regimes Principle 3 lateral connectivity Principle 1 longitudinal connectivity channel form habitat complexity biotic diversity patch disturbance access to spates floodplains variability Principle 2 dispersal Life history patterns Discharge triggers • spawning reproductive triggers • recruitment seasonality predictability stable baseflows drought Time Principle 4 natural regime discourages invasions Movement and Migration Merrick & Schmida 1984 Freshwater Fishes of North-Eastern Australia Pusey, Kennard & Arthington 2004 12
  13. 13. Giant Mekong Catfish (2.35 m and 260 kg) “Construction of mainstream dams that obstruct spawning migrations may seal its fate” Dudgeon, 2001 Overfishing has caused failure of the fishery • Fish return to Flood March 2000 waterholes Importance of 13,471 km2 connectivity Bust • Drying waterhole • Fish mortality 93% Connectivity Connectivity Boom• Floodplain inundation Channel flows• Fish breeding • Connectivity• Movement of all life stages • Movement to floodplain• Growth and juvenile • Fish breeding recruitment11/12 native species move from river to inundatedfloodplains to feed and grow 13
  14. 14. Water flowing to sea is not “wasted” 1600 1400 Total fish catch 1200Total catch (tonnes) Annual flow (GL) 1000 Fish catch in Moreton 800 Bay vs Logan River 600 400 flow 200 Total flow 0 Loneragan & Bunn 1999 1945 1950 1955 1960 1965 1970 1975 Aust. J. Ecol. 24: 431-440 Year total Prawn catch in Logan 100 estuary vs total summer Catch (tonnes) kings flow 10 Mechanisms: 0 • catchability 10 000 100 000 1 000 000 • habitat & food resources Summer flow (ML) • life history Principle 4 Alien and translocated species Aquatic biodiversity and natural flow regimes Principle 3 lateral connectivity Principle 1 longitudinal connectivity channel form habitat complexity biotic diversity patch disturbance access to spates floodplains variability Principle 2 dispersal Life history patterns Discharge triggers • spawning reproductive triggers • recruitment seasonality predictability stable baseflows drought Time Principle 4 natural regime discourages invasions 14
  15. 15. Impoundments provide habitat for exotic fish and plants (e.g. water hyacinth) Mozambique tilapia has established self- maintaining populations n Wivenhoe and North Pine Dams Y e Fish species diversity has declined with increasing degree of flow regulation in the Murray-Darling Basin - more stable flows, - less frequent flooding - modified habitat, food, spawning conditions - native fish have declined - exotic species dominate, especially carp Annual proportional flow deviation Water fern – Salvinia - covering a riverine impoundment 15
  16. 16. Effects of weirs on riparian & aquatic vegetationReach with natural flows Between Marian and Dumbleton Weir Pools - Pioneer R (Site 5) Weir pool more stable water levels few native aquatic plants Weir pool exotic species proliferate Environmental Flows Environmental flows describe the quantity, timing and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well- being that depend upon th b i th t d d these systems Brisbane Declaration 2007 International Environmental Flows Conference, Brisbane, September 2007 750 delegates from over 50 countries 16

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