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U.S. Department of the Interior
U.S. Geological Survey
Mapping Instream Riverine Habitat Using High-
Precision GPS
A Project in Support of the Experimental Introduction of the Federally Endangered
Rio Grande Silvery Minnow (Hybognathus amarus) into the
Big Bend Reach of the Rio Grande
Bruce Moring
Senior Biologist
USGS Texas Water Science Center
Austin, Texas
512.927.3585
Daniel K. Pearson
Geographer/GIS Specialist
USGS Texas Water Science Center
Austin, Texas
512.927.3561
Overview
Background on Rio Grande silvery minnow
introduction
Rationale and approach to river mapping
GPS Data Collection
Methods, equipment and musings
Results and Data products
Project Support
Funding for study USGS SSP, USFWS, MRGESP
Collaborative
Key Contacts –
Aimee Roberson, Fish and Wildlife Biologist, Project
Lead, USFWS, Alpine, TX
Jason Remshardt and staff, support for fish assemblage
survey, USFWS, Albuquerque, NM
Rio Grande Silvery Minnow Technical Advisory Team
(USFWS, Texas Parks and Wildlife Service, UT-Pan
American University, Big Bend National Park, and USGS)
Mickey Porter, Sarah Beck, USACE, Albuquerque, NM
Biology of Hybognathus amarus
Historically found throughout the Rio Grande
and Pecos Basins. Population numbers
dropped after 1950s. Sustained population in
Middle Rio Grande, New Mexico
Pelagic spawners, produce large numbers of
semi-buoyant eggs
Prefer low-velocity habitat with sandy or silty
substrates
Preferred habitats including side channels,
backwaters, and oxbows associated with a
meandering channel. Algal grazers.
Historical Change to Rio Grande
Drivers of change
Altered flow, peak flows and
sediment transport
Aggrading and narrowing
channel
Invasives (Salt cedar, exotic
river cane)
Changes to flow contribution
from Rio Conchos
Images: Taken near Black
Dike (Big Bend NP)
Dean and Schmidt, Role of feedback mechanisms in historic channel changes of the lower
Rio Grande in the Big Bend region., Geomorphology, 2010
RGSM Re-introduction to BBNP
December 2008, silvery minnows were re-
introduced in the Rio Grande as a non-
essential experimental population under
section 10(j) of the Endangered Species Act
1.43 million minnows released to date with 4
releases (2008-11), one additional release
(2012)
Release sites – 1. Contrabando, 2. Santa
Elena (Terlingua Creek), 3. Rio Grande
Village, 4. Stillwell Crossing (Adam’s Ranch)
Release Sites/Study Area
Project Objectives
River mapping and fish assemblage collocated with
release sites to understand variability among release
sites
Determine the area, frequency, and physical
characteristics of in-channel river habitats at the
mesohabitat scale over a range of river flows.
Determine how fish assemblage varies (composition
and distribution) among mesohabitat types and
between reaches over a range of river flows with
focus on Rio Grande silvery minnow population
Rationale for Mesohabitat Approach
USFWS wanted a habitat component and fish assemblage
survey in the early stages of the introduction and in the context
of river flow!
“.…interest has grown in testing the hypothesis that significant
variation in assemblage among streams is explicable in terms of
hydrological patterns, which can vary substantially over short
geographic distances (Poff and Allen, 1995).”
River
Channel
Geomorph.
Eco
-hyd
rau
lic
Me
so
ha
bita
t
Distribution
of
Aquatic
Biota
Mesohabitat
Our Mesohabitat Scheme: A priori classification of “eco-
hydraulic” habitats biased towards including more backwater
and slack-water habitats important for Rio Grande silvery
minnows and similar species.
Mesohabitats used in this study include: backwater, forewater,
embayment, rapid, riffle, run/glide, pool (eddy, main channel and
isolated), submerged channel and point bars.
Riffle
Point bar
Eddy Pool
Run`Inundated point bar
Selected River Flows
Used IHA to determine target flows (Nature
Conservancy)
Winter to spring low-flow target = 200 – 400
cfs
Late spring to mid summer within-bank high
pulse = 500 – 1500 cfs
Overbank flooding
flow = using peak of
fall 2008 event
(ca. 50,000 cfs)
GPS Data Collection
Map and characterize instream habitat
(mesohabitat-scale approach)
Create a detailed reach map at each targeted
flows using high-performance GPS receiver
in conjunction with high-resolution remotely
sensed imagery
Create spatially enabled database to capture
geographic (map), physical habitat, fish
assemble and
Equipment
Trimble® DSM™ 232 modular GPS receiver
Omnistar Subcription (XP) - offers GPS correction
services that improves the accuracy of a GPS
receiver, allows sub-foot realtime positioning
Fed directly in GIS (no post-processing)
Panasonic Toughbook CF-19
Hi Capacity External Laptop Battery
Mapping Methods
Capture water’s edge on both banks was
mapped first creating a boundary for each site
Next, each mesohabitat was mapped by
delineating its perimeter with the GPS receiver
mounted in a boat or in a backpack by wading
Each mesohabitat (e.g., rapid, riffle, run, pool,
glide, embayment, backwater) edited and
stored on a field laptop as geo-referenced
polygons using ArcGIS
GPS used to capture water’s edge
Rio Grande @ Terlingua Creek
Run
Run
Pool
SCB
Complete delineations and attribute
Rio Grande @ Terlingua Creek
Results – Data Collection/Mapping
FY 2010 Sampling
low-flow target (200-400cfs)
high-pulse flow target (500-1500cfs)
Low-flow sampling divided by flash flood
event ~10,000cfs
High-pulse flow mapping possible due to
sustained release from Rio Conchos dams
(MX)
More Results – Extreme low-flow
FY 2011 Sampling
West Texas and throughout under “Extreme
Drought”
Capture “bottom out” flows – May 2011
Historically low flows – 1st Qtr 2011
No measureable rainfall since September 2010
Full habitat assessment, mapping study
reaches and fish assemblage data
Low flows - May 2011
RAPID
RIFFLE
RUN
POOL
FOREWATER
BACKWATER
EMBAYMENT
SUBMERGED BAR
Lessons learned…
Requires use of multiple flotation devices –
Canoe/Kayak, Zodiac, Human
Effort to limit impact of our presence on
habitat
Low flow mapping much easier than high-
pulse (wadeable)
Putting equipment in harm’s way
GPS – Marine unit
Panasonic laptop – Water “resistant”
More…
Laptop battery good for about 4 hours
External gives us +6 hours
Considered use of PDA but opted for
Toughbook for larger screen size
Other GPS units would get us better accuracy
but drawbacks
Cost/Time
Post-processing/Direct feed into ArcGIS
Current imagery source
Maps exported to GeoPDF (iPad)
Physical Characterization - Habitat
•Depth, velocity, substrate, at
3 to 5 points in each
mesohabitat.
•Fish cover along 1-meter
wide bank-to-bank transect at
each point.
•Margin or near-shore habitat
at mid-point transect
evaluated for percent
periphyton cover and
dominant substrate using .25
m2 quadrat
Mesohabitat
Right bankLeft bank
Fish Assemblage – (Wadeable)
One seine haul per mesohabitat randomly
selected from nine possible locations.
Two or more seine hauls in some very large runs.
Per seine haul
Length, depth and velocity (center point),
dominant substrate, and counts per species
recorded.
H. amarus
N. braytoni
Guild Association – Velocity
Project Data Model
Geographic Data (GPS)
Polygons
Low-pulse
High-pulse
Extreme low-pulse
Points
Sampling
Lines
ADCP
Electrofishing
Tabular Data
Site information
Physical Measures
Margin
Fish
Fish cover
Fish habitat
Water quality
Relationship Class
For RGSM Project:
Project management of data resources
Answer complex spatial queries
Using GIS or via MS Access
Data can be exported to other formats as needed
for analysis
Web application development
Online access
Mapping components
How do we use this technology?
Next Steps
Complete data analysis and writing of USGS
Scientific Investigation Report and a journal
article this summer
Online publication of project database
In first year of similar study in Middle Rio
Grande (Albuq – Elephant Butte Reservoir) in
New Mexico
Questions?
http://tx.usgs.gov/projects/bigbend/mapping
SMhabitat.html
Daniel Pearson – [email protected]
Bruce Moring – [email protected]
