Environmental Flow Regimes. Joe Trungale s presentation to the Science Advisory Committee March 4, 2009

Transcription

1 Overlays to Hydrology-Based Environmental Flow Regimes Joe Trungale s presentation to the Science Advisory Committee March 4, 2009

2 Overlays - Definition Application of analysis to validate or refine flow estimates derived from hydrologic analysis Not limited to quantitative adjustments Expected ecological response -> research priorities and indicators

3 Overlays - Examples Literature Survey and Summary Report Subsistence Flow Water Quality Standards Longitudinal Connectivity i Water Quality Models Base Flow Analysis of Fish Assemblage Hydraulic-Habitat Models High Flow Pulse Effective Discharge Estimate Spawning/Migratory Cues Riparian/Oxbow Connection Points Sediment Transport Model Overbank Flow Bankfull Discharge Estimate High Flow Rating Curves HEC-RAS Water Surface Model GIS Analysis of Inundated Areas

4 Subsistence Flows Ecological Response Maintain water quality criteria Provide life cycle cues Provide refuge habitat Overlays Water Quality Standards Longitudinal Connectivity i Water Quality Models

5 Longitudinal Connectivity Good agreement between surveyed channel features and the flow prescriptions chosen to maintain longitudinal connectivity from dry (6-90 cfs) through wet year ( cfs) 536 cfs 90 cfs 40 cfs 6 cfs Pool Riffle Cypress knees are important structure for aquatic biota Reach Length (ft)

6 Base Flows Ecological Response Ensure adequate habitat conditions, including variability Overlays Analysis of Fish Assemblage Hydraulic-Habitat Model Stream Survey & Discharge Rating Curve Habitat Suitability Criteria

7 Analysis of Fish Assemblage Literature Review Life history summaries of select species representing various flow dependencies (i.e. dependent on flowing channel habitats, backwater habitats) The ichthyofauna of the Cypress Bayou basin appears to have shifted from assemblages dominated by cyprinids, percids, and cyprinidontids in the 1950 s to assemblages dominated by centrachids, other cyprinids, clupeids, and atherinids in the 1980 s. Hoover et al. Fishes of the Cypress Bayou System in Northeast Texas and Northwest Louisinana. Unpublished manuscript 1989.

8 Analysis of Fish Assemblage Museum Study Reproductive Guild Non guarders Open Substratum Pelagophils Guarders Nest Spawners Lithophils Pelagophils : Obligate riverine species, broadcastspawn buoyant eggs within current Lithophils : Includes most Centrarchidae, spawn elliptical egg envelopes over rock or gravel nests

9 Hydraulic-Habitat Model Hydraulic Model Habitat Area Flow vs. Habitat Preference e / Utilization Habita at Quantitiy/Quality Flow Habitat Parameter Habitat Suitability

10 Existing Data

11 Habitat Suitability Criteria

12 Ecological Response Curves Flow vs. WUA Weighted Usable Area versus Simulated Discharge SPOTTED SUCKER SPOTTED BASS PICKEREL BlUNTNOSE DARTER FLATHEAD CATFISH IRONCOLOR SHINER BLACKSIDE DARTER BLACKTAIL SHINER Habitat (ft 2 /100 00ft) Discharge (cfs)

13 High Flow Pulses Ecological Responses Maintain important physical habitat features Longitudinal connectivity Overlays Effective Discharge Estimate Spawning/Migratory Cues Riparian/Oxbow Connection Points Sediment Transport Models

14 Overbank Flows Ecological Responses Maintain riparian areas Provide lateral connectivity between the river channel and active floodplain Overlays Bankfull Discharge Estimate High Flow Rating Curves HEC-RAS Water Surface Model GIS Analysis of Inundated Areas

15 Bankfull discharge (X = 1687 cfs) in upstream reach is much less than the 2 to 3-year recurrence discharge of 6,000 cfs that was prescribed. Equal to surveyed bankfull discharge Stag ge Riffle Pool Riffle Pool Reach Length (ft)

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17 Instream Flow Building Blocks Big Cypress Creek Hydrology based only 20,000 cfs for 2-3 days Every 10 years PeakFQ(10) = 23,300 Floods 6,000-10,000 cfs for 2-3 days Every 3-5 years PeakFQ(2-3) = 6,485-9,956 High Flow Pulses 6,000 cfs for 2-3 days Every 2 years PeakFQ(2) = 6,485 1,500 cfs for 11 days 7X a year every year Low Flows Key Wet Year Avg Year Dry Year JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

18 Instream Flow Building Blocks Big Cypress Creek Floods High Flow Pulses 20,000 cfs for 2-3 days Every 10 years *For channel migration 3,000-10,000 cfs for 2-3 days Every 3-5 years *Maintain aquatic habitat in floodplain * Riparian seed dispersal * Inhibition of upland vegetation ti for both creek & lake *Seed dispersal * Vegetation removal 2,500 cfs for 2-3 days Every 2 years * For channel maintenance * Oxbow connectivity 1,500 cfs for 2-3 days 3-5X a year every year * 1 occurring in March for Paddlefish * Sediment transport Waterfowl habitat flushing (Includes December) 3000 = flow that connects to oxbows and other off-channel wetlands upstream of Jefferson. 2,500 = about mean bankfull over the reach studied. 2-3 days = peak period for high-flow and dfloods. Low Flows Maintain biodiversity and connectivity (backwater & oxbows) Pre-dam median Benthic drift & dispersal, fish spawning Fish habitat Pre-dam median Key Fish habitat Spawning habitat Maintain aquatic diversity Fish habitat Wet Year Avg Year Dry Year JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

19 Sabine/Neches Biological Overlay Effort Literature Review: Information was sought for: a handful of indicator species & information about species needs with regard to low flow, high pulse & flood conditions seasonal & inter-annual variation (dry, ave., wet years) habitat use (abiotic conditions, spatial extent, connectivity, etc.) reproduction, life stages feeding & food resources rces population trends within the basins that might be informative response to salinity and freshwater inflows (estuarine species)

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24 Unionid Mussels (33 spp. in Sabine/Neches basins) C.C. Vaughn & C.M. Taylor Impoundments and the decline of freshwater mussels: a case study of an extinction gradient. Conservation Biology 13(4): Little River, SE Oklahoma

25 Unionid Mussels A.L. Rypel, W.R. Haag & R.H. Findlay. Pervasive hydrologic effects on freshwater mussels and riparian trees in southeastern floodplain ecosystems. Wetlands 29(2): Sipsey River, Alabama St. Francis River, Arkansas Little Tallahatchie River, Mississippi Growth of mussels in unregulated rivers was negatively correlated with annual flood pulse count and May-June discharge, but positively correlated with annual low pulse count and annual number of hydrographic reversals. Baldcypress growth in unregulated rivers was positively correlated with May-June Baldcypress growth in unregulated rivers was positively correlated with May-June discharge, and negatively correlated with annual low pulse count.

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33 Oysters, Freshwater Inflows & Salinity D. Buzan et al Positive relationship between freshwater inflow and oyster abundance in Galveston Bay, Texas. Estuaries and Coasts 32: found increased abundance of market-sized oysters in Galveston Bay 1-2 years after years with increased freshwater inflow and decreased salinity (fisheries-independent data) R.E. Turner (2006, Estuaries and Coasts 29: ) reported an inverse relationship between freshwater inflow and commercial harvest with low harvest during years of high inflow and increased harvest during low flow years. high mortality during extended periods of high inflow and sustained low salinities populations may be decimated during prolonged episodes of low flow when conditions favor oyster predators, parasites, and diseases See also: La Peyre et al Estuaries and Coasts 32: