2011 Progress Report: Predicting Relative Risk of Invasion by Saltcedar and Mud Snails in River Networks Under Different Scenarios of Climate Change and Dam Operations in the Western United States
EPA Grant Number:
Predicting Relative Risk of Invasion by Saltcedar and Mud Snails in River Networks Under Different Scenarios of Climate Change and Dam Operations in the Western United States
Poff, N. LeRoy
, Auble, Gregor T.
, Bledsoe, Brian P.
, Friedman, Jonathan
, Lytle, David
, Merritt, David M.
, Purkey, David
, Raff, David A.
, Shafroth, Patrick B.
Colorado State University
Oregon State University
Stockholm Environmental Institute
U.S. Bureau of Reclamation
U.S. Forest Service
United States Geological Survey [USGS]
EPA Project Officer:
July 1, 2008 through
June 30, 2012
(Extended to June 30, 2013)
Project Period Covered by this Report:
July 1, 2010 through June 30,2011
Ecological Impacts from the Interactions of Climate Change, Land Use Change and Invasive Species: A Joint Research Solicitation - EPA, USDA (2007)
Global Climate Change
This project seeks to predict the establishment and spread of invasive species in rivers that are susceptible to changing climatic conditions. Changes in temperature and precipitation are expected to combine with increasing human water demands to modify flow regimes in many watersheds. Thermal shifts and altered snowmelt/rainfall will produce different discharge patterns, which may then influence population and community processes, potentially disfavoring native species while facilitating invasion by harmful non-natives. The approach consists of linking a hydrologic model, driven by regionally downscaled climate projection models, to biological response models representing invasive population growth as a function of discharge, air and water temperature, geomorphic setting and community interactions.
The project team completed the remainder of a geomorphic classification model of valley bottoms for the upper Green River basin, which generated a number of hydrogeomorphic classes of spatially explicit river–riparian habitat for tamarisk and New Zealand mud snail. The hydrologic process model for the upper Green River basin was further explored for implementation with data that will be obtained for a suite of future climate scenarios, and its structure was integrated with the hydrogeomorphic classes. An analysis of a multivariate biological response model was completed for riparian vegetation across the western United States. Furthermore, a more mechanistic biological response model for tamarisk has been progressing toward parameterization.
During this reporting period, the Geomorphic Valley Classification (GVC) model developed by the Bledsoe group was used to derive valley bottoms for the remaining watersheds in the upper Green River basin. The GVC, through a semi-automated procedure, applies Python scripting in ArcGIS to process DEMs at 10 m resolution into polygons of valley bottoms based on energy, coupling and confinement. Energy refers to the hydraulic power available to shape valley bottoms and the stream channels they contain, and is characterized by unit stream power or valley slope as its surrogate. Coupling refers to the proximity of hill slopes to the channel and the likelihood that debris flows on those slopes may move across the valley bottom into the stream channel. Confinement refers to constraints on the planform and lateral adjustability of stream channels.
During the prior reporting period, the Water Evaluation And Planning (WEAP) system developed by the Purkey group had been used to render hydrologic processes and water infrastructure in the upper Green River basin. WEAP, as an integrated watershed hydrology model and water resources analysis tool, applies a precipitation–runoff model using climatic (precipitation, temperature and wind), land cover/land use and soils data to generate water supply in the basin (i.e., streamflow, reservoir storage), which in turn is modified by water demand (e.g., agriculture, development).
Development of an agent-based model of western U.S. floodplains has been concurrent with these conditional inference analyses. The biological model component of the project attempts to synthesize the specific details of tamarisk life history with general principles of riparian ecology, suited to the spatiotemporal scale of input data for hydrology, climate and geomorphology (weekly flow time series, >2 km gridded temperatures, 10 m gridded elevations). An agent-based platform offers the ability to bridge these scales and provides flexibility in representing both spatial complexity within a floodplain and potentially significant biological interactions (i.e., herbivory by the tamarisk leaf beetle, Diorhabda).
The model is currently in the prototype stage, with development ongoing and a robust, basic version expected by the end of 2011. At the single floodplain scale, biological dynamics are subject to external forcing from the hydrogeomorphic template, ambient minimum temperatures and an assumption of tamarisk seeds reaching a site. The weekly sequence of flows from WEAP outputs associated with a particular location are translated into the inundation and drying conditions that drive tamarisk germination, establishment, growth, reproduction and mortality. These life history events update on weekly cycles embedded within the annual cycle to accommodate factors such as the timing of seed release relative to flooding (tamarisk seeds require bare, moist soils to establish and these conditions often follow high flows via mechanisms such as scour, avulsion and new sediment deposition). Mortality, either due to flooding or freezing, also feeds back into the establishment because germination is spatially constrained.
A testing and calibration phase will precede the evaluation of future climate and management scenarios. Meetings with the riparian ecology experts collaborating on the project will provide an initial screen to determine that the relevant processes have been incorporated as functions in the model. Throughout development, “stress tests” consisting of pathological parameterizations are combined with a variety of outputs (direct visualization of the invaded floodplain, sensitivity plots, etc.) to locate and correct coding errors. Finally, comparison with data regarding the presence and density of tamarisk occupying the study region during the period of historical record will help establish the model’s predictive strengths and weaknesses. Upon reaching a stable point in development, the model will be parameterized for runs using the range of GVC classes (e.g., moderate energy open, low energy floodplain) and a suite of downscaled climate scenarios from the Raff group’s Bias-Correction Constructed Analogs (BCCA) for phase three of the World Climate Research Programme’s (WCRP) Coupled Model Intercomparison Project (CMIP3).
During the next reporting period, the project team expects to obtain the latest suite of future climate scenarios for the BCCA of WCRP’s CMIP3 (and to determine the possible water management scenarios for the upper Green River basin) in order to implement WEAP model runs using these scenarios. WEAP outputs will be fully integrated with those of the GVC to provide the inputs for deploying the biological response models for tamarisk and New Zealand mud snail, which in turn will generate the predicted invasion risks throughout the upper Green River basin at several instances in the future.
on this Report
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River network, watershed, land use, invasive species, climate change, temperature, precipitation, flow regime, dams, disturbance, aquatic, habitat, stressor, risk assessment, vulnerability, decision support, conservation, ecology, hydrology, geomorphology, scaling, niche model, agent-based model, geographic information system, remote sensing, western, WY, CO, UT, EPA Region 8
, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Environmental Chemistry, climate change, Air Pollution Effects, Aquatic Ecosystem, Environmental Monitoring, Ecological Risk Assessment, Atmosphere, climatic influence, climate models, ecosystem indicators, aquatic ecosystems, coastal ecosystems, global climate models, invasive species, ecosystem stress, land and water resources, Global Climate Change, climate variability
Poff’s homepage (http://rydberg.biology.colostate.edu/poff/ Exit
Progress and Final Reports:
2009 Progress Report
2010 Progress Report
2012 Progress Report