water supply analysis lindsay carr, joey kleiner, kinsey hoffman
TRANSCRIPT
Water Supply Analysis Lindsay Carr, Joey Kleiner, Kinsey Hoffman
7Q10
7Q10
average 7 day annual low flow with a 10 year return period
Consider 1 year of flow dataAverage over 7 consecutive days
Consider the 7 day averagesTake the lowest 7-day average for each year
Consider lowest flows for every yearFind annual low flow with a chance of occurring once
every 10 years
Importance in Water Supply Management
•Describes characteristics of a watershed
•Often used to regulate withdrawals• Amount of flow needed for water quality
standards• Amount of flow needed for habitat stability
Calculation Methods and Tools
DFLOW• EPA’s program for determining 7Q10
values
Matlab• Adapted a version from the University
of Georgia
R• Converted to R language from our
Matlab version
Log-
Pearson
Type III
Distribution
Log-Pearson Type III Distribution
Type of curve fitting for a frequency distribution common to hydrology
Log-Pearson Type III Distribution
DFLOW: Simplified version of the Log-Pearson III calculation within the program
Matlab: Calculates Log-Pearson III using multiple steps in the code
R: Uses a Log-Pearson III function within the code
Type of curve fitting for a frequency distribution common to hydrology
Add historic data
Specify flow averaging period
Specify the return period
Then calculate
DFLOW Interface
DFLOW Constraints• Requires user to download files from WOOOMM
• Find specific segment in WOOOMM• Export flow data as a text file
• User must alter the text file before importing to DFLOW• Header/footer of the exported results must be deleted
• Only a few segments can be calculated at a time
• Gives more than just 7Q10 value• Once calculated, users must separate the 7Q10 values
from the other calculations in the resulting table
Matlab Code
Specify query types within code rather than on WOOOMM
Automatically enters login information to access WOOOMM
Accesses data online rather than having to manually save it as a .txt file
Builds WOOOMM url to access data based on specified parameters
R Code
Specify query types within code
Build url to access data automatically
Can do multiple runs and segments at a time
Matlab and R Advantages• Automated data entry from WOOOMM
• Only a few specifications before running the code
• Results are automatically saved and returned to the WOOOMM database
• More detailed Log-Pearson Type III distribution is used
• Multiple segments and runs can be done all at the same time
Matlab
Current Work – Handling Zeroes
Large sections of 0.0 cfs values in the flow data
7 day average of 0.0 cfs
Annual low flow of 0.0 cfs log ( 0 ) = undefined
Current Work – Handling Zeroes
Conditional distribution – all values must remain non-zero
Unconditional distribution – accounts for zero flows
2. Frequency factor, K, is adjusted
1. Mean (x@) and standard deviation (S) is calculated with
all non-zero values
Current Work – Handling Zeroes
adjusted p
mean & standard deviation without
zeroes
𝑧=4 .91 [ (𝑃𝑎𝑑𝑗 )0 . 14− (1−𝑃𝑎𝑑𝑗 )
0 .14 ]
𝐾=( 2𝑔 )[(1+𝑔𝑧6 − 𝑔236 )3
−1]
𝑃𝑎𝑑𝑗=(𝑝 ∙𝑁𝑛 )−(𝑁−𝑛𝑁 )Vector without zeroes
z with adjusted p
Instream Flow Incremental Methodology (IFIM)
IFIM: Instream Flow Incremental Methodology • The goal of an IFIM study is to show
the relationship between stream flows and available aquatic habitat • This Flow:Habitat relationship is
necessary for assessing potential downstream impacts on habitat resulting from upstream flow alterations
• A main product of an IFIM study is the Weighted Usable Area (WUA) table- an index showing habitat suitability for a given species over a range of flows
Steps in the IFIM Process
1) Habitat identification 2) Transect selection 3) Species selection, habitat suitability criteria (HSC) compilation 4) Collection of field hydraulic and habitat data 5) Physical Habitat Simulation System (PHABSIM) model 6) PHABSIM output of “Weighted Usable Area” (WUA)
The Formation of Fish Habitat
• Fish habitat is dependent on:• Depth • Velocity • River bottom conditions
(substrate/cover)
• Depth and velocity conditions change with increasing flow
• Example: Riffles, runs, pools
The Mapping of Fish Habitat
• The first step in an IFIM study is the identification of aquatic habitats within the study area
• The stream is divided into “study reaches” at points where significant changes in channel morphology or flow occur • The primary types of
mesohabitats within these reaches need to be identified to facilitate transect site selection
The Mapping of Fish Habitat (cont.)
• Habitat mapping is achieved through the use of existing institutional knowledge, aerial photographs, GIS, GPS, and site-specific data obtained through “float trips”
Transect Locations
• Once the river reaches and habitat types are identified and mapped, transect locations for the collection of field hydraulic data are determined • Transects are located in areas
representative of the hydraulic/habitat conditions observed in that reach
Field Data Collection
• Physical Habitat Simulation (PHABSIM) software is used to simulate the relationship between streamflow and habitat for various species and life stages of fish • Data collected in the field at each transect location is used to calibrate
PHABSIM for the study reach of interest • Data is collected at sampling stations/cells equally spaced along each
transect • Data collected at each cell include: • Water surface elevation (WSE) • Water velocity • Substrate/cover
Field Data Collection (Cont.)
• WSE and velocity data are typically collected at each transect under 3 different “target flows” (low flow, medium flow, high flow) • The target flows observed at the transects are achieved by altering dam releases upstream • Example of target flows: 50, 150, and 300 cfs (measured by a USGS gage within the study reach)
• By entering the measurements taken at 3 flows, PHABSIM is able to interpolate WSE and velocity values for flows other than the 3 observed in the field
Field Data Collection (Cont.)
• Cover/substrate measurements are taken during the lowest target flow• Codes for cover/substrate are
assigned to each cell along a transect
Species Selection and HSC
• A set of fish species needs to be selected for Flow:Habitat analysis • The species selected must be present within the
study reach
• The species chosen are usually the ones most affected by changes in flow
• Each species has corresponding Habitat Suitability Criteria (HSC) that can be gathered from existing sources• HSC quantify habitat quality for each species/life
stage based on flow velocity, depth of the water column and substrate/cover
• HSC utilize a preference index ranging from 0 (least preferred) to 1 (most preferred)
PHABSIM Development
• A hydraulic model within PHABSIM is created for each study transect • The hydraulic model consists of a water surface model and a velocity model
• The water surface and velocity models are developed and calibrated using the 3 data sets obtained in the field (1 data set from each of the 3 target flows)
• The calibrated hydraulic model is able to simulate WSE and velocity values at each cell along the transect for any flow value• The hydraulic model at each transect is
combined with the HSC to produce a WUA table showing the Flow:Habitat relationship at that transect
PHABSIM Development (Cont.)
• HSC for water depths, water velocities and substrate/cover are used to rank the suitability of each model cell in a transect• This uses a multiplicative approach where suitability indexes (on a scale from 0.0 to 1.0) for a single
cell in a transect are multiplied together (depth*velocity*substrate) to produce a composite suitability score for that cell (0.0 to 1.0)
• The suitability score of a cell is used to weight the area of that cell to produce a “Weighted usable area” (WUA) value for that cell
• The weighted values for all cells in a transect are summed to produce a total WUA for that transect
WUA = suitability-weighted samples of area • WUA is an index to the microhabitat availability
WUA Development within PHABSIM
• By repeating this process for multiple species/lifestages over an entire range of flows, a WUA table can be produced for each transect displaying the flow:habitat relationship for each species/lifestage of interest
• The WUA tables from each transect in a reach can be averaged together using weighting factors to produce a single WUA table representative of the entire reach • WUA tables from each transect are weighted so that each transect's
contribution to the reach-WUA is indicative of the amount of each habitat type (% area) present in the reach • Area weighting factors are determined during the development of the habitat
maps
WUA Development within PHABSIM (Cont.) • Weighting transect-WUAs to produce a single reach-WUA table:
% of each habitat type present in a single reach
Weighting factors for each transect in the reach
WUA Example
WUA ExampleRedBSun
Juvenile Adult Spawning Adult Spawning Spawning Slow Fast Slow Fast10 8,650 4,062 18,545 1,585 112 19,431 8,020 288 17,310 1,17220 13,381 8,447 18,820 2,071 176 19,960 4,740 693 18,889 2,53640 22,200 16,204 18,799 3,537 293 19,972 2,488 1,137 21,407 5,26160 28,774 20,791 18,726 5,323 394 19,880 1,643 1,964 23,420 7,96980 32,940 22,872 18,496 7,642 482 19,876 1,532 2,631 25,292 10,168
100 36,522 24,433 17,592 10,083 574 19,626 1,479 2,807 26,489 12,558120 39,761 25,291 16,474 13,036 684 19,183 1,644 3,136 27,450 15,079160 44,456 26,838 13,635 19,659 893 16,465 1,062 3,354 28,132 20,133200 47,555 27,499 9,493 26,700 1,096 13,042 667 2,065 27,429 24,033250 49,959 28,079 7,368 33,427 1,247 11,139 615 1,564 26,722 27,576300 51,581 28,710 6,000 39,508 1,379 9,454 430 1,071 25,607 30,227350 52,257 28,869 4,792 44,866 1,456 7,854 486 737 24,197 30,935400 51,643 28,429 3,887 49,235 1,498 6,617 546 611 22,672 30,704450 50,249 27,458 3,261 52,640 1,477 5,411 645 517 20,851 29,608500 48,364 26,438 2,821 55,144 1,407 4,514 484 413 19,294 28,123550 46,047 25,640 2,554 56,623 1,322 3,889 334 333 17,737 26,710600 44,087 24,248 2,144 57,514 1,201 3,229 189 279 16,570 25,499650 42,233 23,011 1,925 58,020 1,099 2,898 155 197 15,305 23,741700 40,196 22,018 1,769 58,065 976 2,565 173 154 14,093 22,428750 38,186 20,711 1,503 57,884 831 2,121 196 125 12,972 20,835800 36,218 19,469 1,392 57,521 661 1,875 216 84 12,034 19,426900 33,366 17,012 1,114 56,349 469 1,557 186 51 10,274 16,857
1,000 29,379 14,898 962 54,663 329 1,339 122 31 8,706 14,5191,100 26,655 13,299 793 52,923 197 1,178 89 24 7,588 12,331
Smallmouth Bass N Hogsucker Shallow Guild Deep GuildWUA (ft²/1,000 ft stream)
Flow(cfs)
WUA ExampleRedBSun
Juvenile Adult Spawning Adult Spawning Spawning Slow Fast Slow Fast10 8,650 4,062 18,545 1,585 112 19,431 8,020 288 17,310 1,17220 13,381 8,447 18,820 2,071 176 19,960 4,740 693 18,889 2,53640 22,200 16,204 18,799 3,537 293 19,972 2,488 1,137 21,407 5,26160 28,774 20,791 18,726 5,323 394 19,880 1,643 1,964 23,420 7,96980 32,940 22,872 18,496 7,642 482 19,876 1,532 2,631 25,292 10,168
100 36,522 24,433 17,592 10,083 574 19,626 1,479 2,807 26,489 12,558120 39,761 25,291 16,474 13,036 684 19,183 1,644 3,136 27,450 15,079160 44,456 26,838 13,635 19,659 893 16,465 1,062 3,354 28,132 20,133200 47,555 27,499 9,493 26,700 1,096 13,042 667 2,065 27,429 24,033250 49,959 28,079 7,368 33,427 1,247 11,139 615 1,564 26,722 27,576300 51,581 28,710 6,000 39,508 1,379 9,454 430 1,071 25,607 30,227350 52,257 28,869 4,792 44,866 1,456 7,854 486 737 24,197 30,935400 51,643 28,429 3,887 49,235 1,498 6,617 546 611 22,672 30,704450 50,249 27,458 3,261 52,640 1,477 5,411 645 517 20,851 29,608500 48,364 26,438 2,821 55,144 1,407 4,514 484 413 19,294 28,123550 46,047 25,640 2,554 56,623 1,322 3,889 334 333 17,737 26,710600 44,087 24,248 2,144 57,514 1,201 3,229 189 279 16,570 25,499650 42,233 23,011 1,925 58,020 1,099 2,898 155 197 15,305 23,741700 40,196 22,018 1,769 58,065 976 2,565 173 154 14,093 22,428750 38,186 20,711 1,503 57,884 831 2,121 196 125 12,972 20,835800 36,218 19,469 1,392 57,521 661 1,875 216 84 12,034 19,426900 33,366 17,012 1,114 56,349 469 1,557 186 51 10,274 16,857
1,000 29,379 14,898 962 54,663 329 1,339 122 31 8,706 14,5191,100 26,655 13,299 793 52,923 197 1,178 89 24 7,588 12,331
Smallmouth Bass N Hogsucker Shallow Guild Deep GuildWUA (ft²/1,000 ft stream)
Flow(cfs)
Flow Statistics
Habitat Peaks (WUA)
Maximum Flow at Habitat Peaks
Median Flow at Habitat Peaks
Minimum Flow at Habitat Peaks
• Determine flow values at peak WUA values
August Low Flow (ALF)
• Median of the minimum flows on record in month of August• Used more for biological purposes • Is there enough water for
necessary biological functions in this late summer time period?• Calculated with R, stored in
WOOOMM• WOOOMM Comparison Link
Calculate median of the minimum flows
Percentile Flows
• Percent non-exceedance flows over a long period of recorded flow data• Ex: Flow on any given day is less than the long-term median flow (50th
percentile) only 50% of the time on record
• USGS calculates stats for their long-term gages • We can also calculate in WOOOMM
looking at August flow statistics
Flow Statistics Analysis Table
• Compare August Low Flow, percentile flows, and flows at habitat peaks for existing IFIM studies• See where flows at habitat peaks fall in relation to August Low Flow
and certain percentile flows
Flow-Habitat vs. Flow-Ecology
Old Science of Flow-Habitat Relationship• Observe changes in flow regime and
habitat structure• Flow regime: discharge, depth, velocity, flood
frequency/magnitude, drought frequency/magnitude• Habitat structure: biodiversity, bank stability,
streambed cover, riparian vegetation
• Create X-Y plot that shows how habitat varies with flow (IFIM & WUA)
Bovee et. al, 1998
FLOW
HAB
ITAT
Transition to Flow-Ecology
• Historically, find a single flow to maximize microhabitat for a life stage of high-profile fish species• Now widely accepted that a naturally variable
regime of flow, rather than just a single flow, is required to sustain freshwater ecosystems• Natural flow regime = range and variation of
flows over recent historical time • No single flow value will conserve an
ecosystem, or is optimal for all organisms and life cycles
Bovee et. al, 1998; Poff, 2010; Ahmadi-Nedushan et. al, 2006; Poff and Zimmerman, 2010
New Science of Flow-Ecology Relationship• Dubbed “flow alteration-ecological response
relationships”• Relate measures of ecological condition to
metrics of flow alteration• Ecological indicators: fish, macroinvertebrates,
algae and vegetation, riparian vegetation, wildlife, organic matter, nutrients, sediment
• Indicators of Hydrologic Alteration (IHA): 7Q10, August low flow, number of flood flow events, etc.
• Assess how flow regimes have been affected by human activities over time observe how ecosystem responds
Poff et. al, 2010;
Examples of Flow-Ecology
1. Flow Analysis table2. Comparison of flow metrics3. Percent changes in flow metrics4. When 7-day minimum flow occurs
Percent Change in 7Q10
August Low Flow
7Q10 Sept. Drought Warning
Month in which 7-day Min Occurs
Implications of Flow-Ecology
Strengths• Ecological condition can be
difficult to manage directly, but streamflow conditions can be managed through water-use strategies and policies • Use flow metrics as surrogate to
collecting habitat data• Expensive, time-consuming
Weaknesses• Rely too much on assumptions
between flow-ecology connections?• Are changes in flow regimes (and
thus changes in ecology) natural or anthropogenic?
Ahmadi-Nedushan et. al, 2006