DSD-INT 2016 Assessment of hydrologic alterations using floodplain connectivity metrics - Stone
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Transcript of DSD-INT 2016 Assessment of hydrologic alterations using floodplain connectivity metrics - Stone
Assessment of Hydrologic and Geomorphic Alterations Using
Floodplain Connectivity Metrics
Mark Stone, PhD, PE
Colin Byrne
University of New Mexico
Ryan Morrison, PhD, PE Colorado State University
Overarching Research Themes
(2) Resilience of Socio-Ecological Systems
(1) Hydro-Geo-Ecological Processes
Channel-Floodplain Interface
Interactions of Flow and Vegetation
Floodwave Attenuation
Fish Passage
Environmental Flow Assessments
Resilience to Natural Disasters Floods – Wildfires – Earthquakes
Endangered Species Recovery and Restoration
Vulnerability
Ecosystem Services & System Resilience
Watershed and Floodplain Development & Narrowly Focused Resource Management
Watershed and River Restoration & Holistic Resource Management
As natural systems are degraded, ecosystem services are diminished and system resilience is lost.
Floods, Droughts, Wildfires, Loss of Biodiversity, etc.
Investigate the impacts of flow modifications, historical channel and floodplain modifications, and river restoration on channel/floodplain processes in the Middle Rio Grande.
Study Objectives
An example of efforts to manage rivers more holistically
is through the practice of environmental flows.
5 kilometers
Historical RG Floodplain
Modern RG Floodplain
Modified structure and function of riparian vegetation
Interrupted energy and nutrient fluxes
Lost maintenance of geomorphic processes and features
Lost dissipation of hydraulic energy and momentum
Reduction in floodwave attenuation
Reduction in groundwater recharge
Modified hyporheic exchange and bank storage
The Impacts
Rio Grande Silvery Minnow - Southwestern Willow Flycatcher - Yellow Billed Cuckoo
Legal Impacts -Three Federally Listed Endangered Species
Methods Applied D-Flow FM 35 km reach – Albuquerque MRG Multiple physical configurations - historical - modern - “restored” Multiple flood conditions - stead state (e.g. 100-yr) - multiple synthetic and gauged floods
D-Flow Model • Unstructured mesh with a
resolution of around 5 to 10 m • Lidar, maps, and survey data were
used to define the topography • Simulations completed at the UNM
Center for Advanced Research Computing using a Linux cluster
• Extensive benchmarking to determine “optimal” number of partitions
Spatial Rating Curves
Water depth
Velocity
Shear Stress
as a function of Q
for every grid point
100
1000
Dis
char
ge (
cms)
Spatial Metrics
Stre
amfl
ow
In
un
dat
ion
D
epth
V
elo
city
Hence we can build a time series of hydraulic characteristics for each grid point in the domain; run stats on each point; and create maps of those stats.
She
ar
Stre
ss
D-Flow FM mesh element boundaries
Digitized boundary of interest
D-Flow FM observation point with temporal output data
MATLAB calculated boundary element with averaged depth-velocity information
Unit flux vectors used to calculate dynamic fluxes across boundaries
Boundary Flux Calculations
Hence, we can investigate spatial and temporally varying fluxes of mass, momentum, and other constituents moving across the channel/floodplain boundary.
Percentage of time inundated Percentage change in inundation
0.01
3
-100
0
Impacts of Cochiti Dam on Inundation Patterns
Hydrodynamics
Hydrology for each scenario
Evidence
Time Dis
char
ge
Bayesian Network Model for Riparian Recruitment
Site Condition
Morrison and Stone. 2014. Water Resources Research.
0 10 20 30 40 50 60 70 80 90 100
Time (hrs)
-4
-2
0
2
4
6
8M
ass tra
nsfe
r acro
ss b
ou
nda
ry (
kg
)
# 104
Right CH-FP
Left CH-FP
RS 1
RS 2
RS 3
RS 4
RS 5
RS 6
RS Total
Flood peak leaves reach
Simulated flood peak of 300 cms
Discussion and Conclusion
Historical channel, floodplain, and hydrologic modifications have profoundly impacted floodplain processes in places like the Rio Grande.
The spatial assessments of inundation frequency, water fluxes, riparian recruitment, and floodwave attenuation (etc.) provide insights into the roles and significance of various stressors on ecosystem processes and to identify methods to address their impacts.
The temporal assessments provide insights for comparing overall impacts of streamflow and geomorphic modifications between sites or scenarios over an extended period of time.
Boundary flux assessments provide greater insights into underlying physical processes at the floodplain/channel interface.