review of tnc chapter 3 “climate and hydrology of the
TRANSCRIPT
Review of TNC Chapter 3 “Climate and Hydrology of the Upper Gila Basin"
(Garfin et al., Univ. of Arizona)
Reviewer: David S. Gutzler University of New Mexico
Garfin et al. estimate the effects of projected climate change on flows on the upper Gila and San Francisco Rivers Projected flows are derived from coupled climate and hydrologic models Global climate models Regional models Hydrologic model
General conclusion: Decreasing future flows due to climate change
This conclusion is qualitatively consistent with: * Previous projections by US Bureau of Reclamation * My related analysis of upper Gila flows commissioned by ISC
Garfin et al. modeling strategy
Strengths: State of the art models, competently utilized Daily output allows high-resolution analysis
Weaknesses: Known model limitations, e.g. summer precipitation Relatively few simulations (5, instead of dozens or hundreds) Little consideration given to future natural variability
Precipitation Climatologies Global climate models (CMIP3)
Regional atmospheric models (NARCCAP, UA)
Hydrologic model (VIC)
Simulate flows at gages in upper Gila basin: (Gila & Virden on Gila R, Clifton on S. Francisco R)
Garfin et al. principal results: Climate change
Temperature high 3-4°C/century
Snowpack high not shown, but huge decrease
Precipitation total low highly variable
Precipitation variability medium more extreme events
Confidence (my assessment)
Change by 2041-2070
Temperature Change Precipitation Change Wtr Spr Sum Aut Wtr Spr Sum Aut
Spring flow total high
Summer flow total low
Earlier Spring runoff high
Short-term peak flows medium ~10% increase of upper 10%
Garfin et al. principal results: Streamflow change
Average Monthly Flow Change Change in Distribution of Daily Flows
6-19% decrease annual flow }
Confidence (my assessment)
Change by 2041-2070
Low Flows
High Flows
0
CONCLUSIONS: TNC Chapter 3 "Climate and Hydrology of the Upper Gila Basin"
General conclusion: Decreasing future flows on the upper Gila River
Plan for: Significant decrease in average melt season flow .... superimposed on larger natural climatic variability
Uncertain change in average Summer flows
Increase in flow extrema associated with intense storms
Review of TNC Flow Needs Assessment, Chapter 5 and 7
Deborah L. Hathaway November 10, 2014
S.S. Papadopulos & Associates, Inc. www.sspa.com
Chapter 5:
Hydrologic Impacts of CUFA Diversions
• Review of TNC’s use of TNC IHA software to characterize flow under CUFA conditions
• IHA: “Indicators of Hydrologic Alteration”
• Provides descriptive and comparative statistics
• Compare TNC results to similar SSPA evaluation
• Review TNC chapter discussion
1. Set-up CUFA Diversion Model
• Inputs: • Historical daily gaged flows, • Storage assumptions, • CUFA diversion rules and constraints
• Results: Hypothetical daily flow record with CUFA diversions
• Spreadsheet model developed separately by TNC and NMISC
• Versions are different but are sufficiently similar for evaluating environmental impacts under CUFA
2. Analyze Differences in Flow Conditions under CUFA with IHA Model
• General agreement regarding impacts of CUFA (Scn 1):
• Decrease in median flow for March by about 15%, median flow is unchanged in other months
• Reduction of flow peaks in diversion months, typically late winter or spring
• No impact to lower flows, i.e., below 50th percentile (with 150 cfs bypass criteria)
Alternate Scenarios analyzed by TNC
• Scenario 2 – no bypass criteria, with CUFA
• Scenario 3 – climate change, not CUFA
• Scenario 4 – climate change, with CUFA
What does IHA analysis tell us about flow differences under CUFA?
• No change to extreme low flows (150 cfs criterion) • No change to low flows (150 cfs criterion) • CUFA does not dry up the river (low flows not diverted) • No change to median monthly flows except in March (March median flow: 189159 cfs) • High pulse events: median peak change 221205 cfs • Small floods: median peak change 28503072 cfs • Large floods: median peak change 12100 11930 cfs
Chapter 7:
Groundwater and Surface Water Interaction
• Review of contributing data – surface water, groundwater
• Review of TNC calculations and analyses
• Further exploration of data where relevant to analyses
• Review of TNC discussion
• Analysis of TNC concerns
TNC Concern: Increased Groundwater Rates of Recession will Impact Riparian Vegetation
• Concern based on opinion that surface water flow rates will fall more rapidly under CUFA conditions (Fall Rate)
IHA Analysis – Fall Rates decrease, not increase, under CUFA
• Concern that groundwater levels will drop too fast for vegetation under CUFA conditions (Recession Rate)
Groundwater levels won’t drop at faster rates under CUFA because surface flows don’t fall at faster rates
TNC’s calculated groundwater recession rates are generally not relevant because they isolate a portion of the hydrograph without considering impacts of the preceding peak:
TNC Concern: Reduction in flow will reduce seepage and recharge causing substantial declines
in groundwater levels
• Concern not supported by data:
Data show that extreme low flow and channel drying is the primary cause substantial declines
Data show that small increases in flow will initiate and sustain recharge
Effects of CUFA on Groundwater Levels
• CUFA diversions typically occur in periods where groundwater is rising, alluvial recharge continues to occur but at lower rate over period of diversion
• Groundwater rises less rapidly, and falls less rapidly
• CUFA effects on groundwater in range of 0 – 1 foot
• CUFA diversions will not occur under low flow conditions nor cause steep groundwater declines
TNC Concern: Rapid groundwater recession and steep groundwater declines will impact riparian
vegetation with cascading impacts to birds, mammals, etc.
Groundwater differences occur during higher water periods and do not constitute rapid or steep declines
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Chapter 6 Review
Gila River Flow Needs Assessment, TNC 2014
Andy McCoy, PhD, PE, HDR Jarvis Caldwell, HDR
Summary and critique Chapter 6 - Hydrodynamic Modeling and
Ecohydraulic Relationships by Dr. Mark Stone and Dr. Ryan Morrison. Primary Reviewers: Andy McCoy, PhD, PE, HDR. Jarvis Caldwell, Aquatic Sciences Manager, SW HDR
Expert Review - Purpose
The stated effect on riparian inundation is unreliable for the following reasons:
Summary
• Do not present relevant background information to support or document the development process, limitations or uncertainty of the: topographic surface, computational mesh or boundary conditions.
• Do not present calibration or validation methods or results
Summary cont. • Do not explain the significance of model
limitations regarding sediment movement.
• Do not provide adequate discussion on Bayesian Network model process, data inputs or how they relate to annual recruitment results.
• Do not provide scientific reference to explain whether reported changes in annual inundation is significant for seed recruitment.
Pg 141.Techniques were applied to correct inferior LiDAR data. Not described. No topography < 750 cfs.
there could be significant
error in the modeled channel, conveyance and results.
Topographic Uncertainty
No description or
quantification of computational mesh adequacy to the LiDAR resolution, areas of complex bathymetry, and high velocity gradients.
Computation Mesh
Accurate rating curve fundamental to simulation results oHEC-RAS 2010 o rating curves/boundary
conditions not presented o their development and
manipulations (Pg. 121) oSpatial relation to sites
Boundary Conditions
1397.50
1397.60
1397.70
1397.80
1397.90
1398.00
1398.10
1398.20
1398.30
0 200 400 600 800 1000
Wat
er S
urfa
ce E
levat
ion
(m)
Discharge (cfs)
There is no documentation
of the SRH2D model calibration or validation process. The degree of accuracy of
results cannot be placed into context.
Calibration & Validation Pg 121. Calibration was achieved by
making minor adjustments to Manning’s n values in order to more closely match observed water surface elevations during high flow events. Water surface elevations were estimated from piezometer data located at the TNC transects.
There was no attempt to quantify the types and numbers of areas that will be overpredicted or underpredicted soley because of the assumptions Riparian vegetation Single substrate grain size
used for each study subreach – size not stated, significance not stated
Sediment Motion
Authors state that changes
in inundation frequency (<750 cfs) are not shown due to poor topography Authors state some areas
reduced inundation up to 50%
Inundation Frequency
Pg 133. In the spring (b), much of the intermediate zones are expected to be inundated between 20% and 40 % less frequently
Bayesian network input parameters – compounded errors and uncertainty Figure 10 – 50% of area,
inundated 0.2% annually – 18 hrs inundation frequency
changes is on order of 2 to 9 total hours in a year. Is two to nine hours is
significant?
Recruitment
Conclusion • There are serious shortcomings in model development
documentation, background information and assumptions.
• This lack of transparency undermines confidence in reported results used to develop the conclusions.
• To qualify results, many of the real or perceived model shortcomings should be cleared up with a comprehensive model development report.
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Chapter 10 Review
Gila River Flow Needs Assessment, TNC 2014
Dave Ward, HDR Jarvis Caldwell, HDR
Summarize and critique Chapter 10 – Effects of Altered Flow Regimes and habitat Fragmentation on Gila River Fishes by Dr. David Propst and Dr. Thomas Turner Primary Reviewer:
Dave Ward, National Fisheries Science Lead, HDR
Expert Review - Purpose
Magnitude of effect of diversion project overstated because the authors:
Summary
• Infer too much from analyses with limited predictive value
• Imply relationships between fish density and discharge for which no analyses are presented
• Provide contradictory statements regarding fish life history and effects of withdrawal
• Rely on data from only one site to represent fish populations for the entire reach
• Incorrectly imply reach is presently un-altered from “natural” state
Characterization of reach as ‘un-altered’ is misleading. Native fish have been
extirpated, and non-native species have been introduced. Water diverted from river
Upstream and Downstream
Mischaracterization of Cliff-Gila Valley
Page 233 – Gila chub was extirpated from New Mexico by the 1950s and roundtail chub has not been found in the Cliff-Gila Valley reach since 1991.
Reliance on data from one site to characterize entire reach imprudent and not reliable for broad-scale implications. Lack of recognition that
existing diversions have historically reduced river flow to near no-flow conditions just upstream of study site.
One Study Site – Limited Sample Size
Page 255 – At Riverside, most Sonora suckers collected in autumn were age-0 individuals and adults were uncommon.
Coefficients of determination (r2) are consistently low o1.0 - 0.0 oEg. 0.25 – explains 25% of
the variation
Low values for r2 limit the predictive value of the models
Limited Predictive Value
Page 243 – Table 5. Regression Analysis.
No statistical analyses presented for relationships between fish density and flows less than and greater than 185 cfs. Contrary to what the authors
state or imply, Figures 12 (spikedace) and 20 (loach minnow) indicate that the relationship between spring discharge and fish density may be negative or non-existent at flows >185 cfs.
Fish Density and Flow
Page 257 – Among the flow attributes considered, both spikedace and loach minnow responded positively to increasing spring mean daily discharge through about 300 cfs, indicating this spring discharge level represents a threshold.
Figure 12 - Spikedace
Authors often imply that a new obstacle to upstream migration will fragment fish populations. To the contrary, Figure 31
shows that for spikedace, allelic richness already decreases in an upstream direction, indicating upstream movement limited.
Upstream Migration Support limited upstream movement on Page 257 – While drift contributes to maintenance of downstream populations, it cannot be so massive that it depopulates source reaches.
Authors state that there was no relation between monsoon flows and fish density, but later claim that withdrawals during monsoon season under climate change scenario would further compromise conditions for native fishes.
Monsoon Season Page 258 – By and large, there was no relation between monsoon or winter flows and autumn density of Cliff-Gila Valley native fishes.
Page 276 - Because sufficient water cannot be diverted during spring, water is also withdrawn during the monsoon season, further compromising conditions for native fishes.
Misunderstanding of AWSA diversion proposal. Authors imply that proposed
diversion and storage project control or even release “multiple flow pulses”.
Flow Pulses Page 276 – The most troublesome attribute of the projected flow regime with CUFA diversion is the effect of multiple flow pulses during spawning and early ontogeny..
Conclusion
• Chapter provides useful information on status and ecology of fishes in the Cliff-Gila Valley, and effectively describes the types of effects that a new diversion may have.
• However, authors infer too much from analyses of limited predictive value and sometimes use artificial discharge “thresholds” to enforce questionable points.
• Authors provide contradictory statements regarding the effects of withdrawals and rely on a single site to characterize the entire reach.
• Authors imply throughout the report that a diversion would alter the Gila from its “natural” state, although the river has undergone substantial changes already.
Report Reviewer: Michael Hatch
SWCA Environmental Consultants
November 10, 2014
Report Review “Effects of Altered Flow Regimes and Habitat
Fragmentation on Gila Fishes” by Thomas F. Turner and David L. Propst
University of New Mexico
A July 2014 publication of the Nature Conservancy
Purpose of this Review
Advise ISC of significant findings,
Identify problematic elements of study design and execution,
Identify problematic elements of study analysis and conclusions,
Identify measures needed to rectify problematic elements of experimental protocol,
Offer alternative conclusions if warranted.
Turner-Propst Study Scope
Study focus − effects of altered flow under AWSA: community composition, trends in abundance, density effects, and age-specific effects.
An additional study topic concerns the effects of river fragmentation.
Problematic Elements of Turner-Propst Study Design and Execution
Lack of fidelity between remotely measured hydrologic predictor values with conditions at the fish sampling site.
Investigated “averaged” hydrologic variables do not adequately represent regional environmental extremes.
Response variables are poorly suited for a hydrology-based effects analysis.
Problems that stem from small biased samples.
Flawed procedures of age determinations.
Failures to meet underlying assumptions of statistical analyses.
Problematic Elements of Turner-Propst Analysis and Conclusions
Only a small portion of the total variation in species density is explained by its linear relationship with the individual flow attributes that were studied.
Site conditions vary over time so it is unclear which factors are responsible for any perceived patterns.
Relationships between environmental and response variables may only be valid over the range of values found at the surveyed site.
Some analyses comingle categorical and continuous variables.
Regression analyses rely on static measures and are poor at elucidating dynamic relationships between factors (e.g., those involving feedbacks and time lags).
Review Findings
Age-specific Effects Linked to Flow Flawed basis for interpreting and modeling species
growth with advancing age.
0
50
100
150
200
250
300
350
400
38 42 46 50 54 58 62 66 70 74 78 82 86
Nu
mbe
r of
Fis
h
Standard Length (2 mm intervals)
Age (year class)
1 2 3 4 5 6 7
Stan
dard
Len
gth
(mm
)
20
30
40
50
60
70
Observedvon Bertalanffy modeled lengths-at-age
(2008) (2007) (2006) (2005) (2004) (2003) (2002)
lt= 80.1699 (1-EXP(-0.1989 (Age - -1.5029)))
Findings − Effects of River Fragmentation
Whereas the discussion of river fragmentation is important to the aquatic species conservation, it is not specifically relevant to an effects assessment for current AWSA proposals. Current AWSA proposals − avoid impediments to fish movement, avoid depletions of flow that fragment
aquatic habitats, restrict water storage facilities to off-channel
catchments, and preserves ecological functionality.
Summary and Conclusions
The study design and statistical analyses are flawed.
Evidence is lacking to affirm or refute assertions of flow effects on fish in the Gila River Basin of New Mexico.
The discussion of river fragmentation is considered important and generally relevant to the management of all natural resources in the Gila River Basin that may directly or indirectly affect aquatic habitats in the Gila River Basin. Certainly this section of the report is relevant to endangered species recovery planning and the formulation of management policy.