Susanna Glaze, Bobby Creel, and Christopher Brown New Mexico State University 2009 AWRA Spring Specialty Conference 4-6 May 2009 - Anchorage, Alaska

Susanna Glaze, Bobby Creel, and Christopher Brown
                      New Mexico State University

           2009 AWRA Spring Specialty Conference
                 4-6 May 2009 – Anchorage, Alaska

Outline

€   Introduction to general water resources issues
    in Las Cruces, NM
€   I f on climate
    Info     li t change
                     h      anddN
                                New MMexico
                                         i
€   Area of investigation and research questions
€   Data and methods
€   Anticipated results

Background
€   Water resources in
    the American
    Southwest
    y On the whole, an
      arid region
    y Sensitive to
      droughts and
      shortages
    y Water often over-
      allocated
    y Population growth
      creating further
      demand

Las Cruces,
    Cruces NM
€   Population
      p        86,268
                 ,    (as
                      ( of
    2006)
    y Increase of 17.3% since 2000
€   Arid – receiving only 8 -8
                             8 ½”
                               ½
    annually
    y Most precipitation occurring
      during summer monsoon
€   Prone to summer floods
    y Primary culprits:
      ○ Rio Grande (tamed by the Rio
        Grande Project of mid 1900s)
      ○ Side channels and arroyos

Climate Change
€   Increasing carbon dioxide
    levels are causing
    warming and drying in the
    A
    American
          i    S
               Southwest
                   h
    y Process is already
     underway
€ Added stress placed on
  water resources
€ Profound impacts will
  occur in manyy areas

Climate Change

        From the University
                          y of Arizona Department
                                         p        of
       Geosciences Environmental Studies Laboratory.

Climate Change

         From the University
                           y of Arizona Department
                                          p        of
        Geosciences Environmental Studies Laboratory

Climate Change in New Mexico
€   Rising temperatures
€   Changes in snowpack
€   Changes in water volume
€   Earlier peak flows
€   Warmer winters
€   Hotter summers
€   Increase in evaporation and
    evapotranspiration
€   More precipitation occurring as rain,
    less as snow
€   Increase in intensity of
    extreme weather events

Climate Change and Flooding
€   “When
     When it rains it pours!”
                      pours!

€   Increased frequency and
    intensity of summer
    monsoon storms
      ○ More precipitation falls in a
        shorter time span
      ○ Larger amounts of runoff
      ○ Flashier, more severe urban
        flooding

Climate Change and Flooding

                                  Hatch, NM
                                    2006

          From sarcher.nmsu.edu

Climate Change and Flooding
€   Compounding
    Factors
    y Urban Development
      ○ Impervious surface
      ○ Causes higher peak
        runoff
      ○ Higher volume of
        runoff
      ○ Faster
        F t flow
               fl
    y Aging Infrastructure
    y Sediment
                             From Leopold 1968

Climate Change and Flooding
€   100 year and 500-year
    100-year     500 year flood levels may
    need adjustment
    y Currently based on historic climate data
€   Flood control structures may require
    upgrade
    y Some already degraded due to age

From NM WRRI

From City of
 Las Cruces

Research Questions
€   How will rainfall intensity and periodicity change in Las
    Cr ces under
    Cruces   nder climate change?

€   If there is an increase in rainfall intensity, how will it affect
    flooding dynamics? Will we see more flood events events, higher
    stages, storm hydrographs exceeding channel capacity, or
    all of the above?

€   Can the current flood infrastructure accommodate
    potential future increases in runoff due to climate change
    and land-use change?

€   What changes or improvements should be made to allow
    infrastructure to accommodate projected future flood
    flows?

Methods & Data
€   Based on a framework created by
    Catherine Denault, Robert G. Millar, and
    Barbara J. Lence in 2006
    y “Assessment of Possible Impacts of Climate
     Change in an Urban Catchment.”
     ○ Journal of the American Water Resources
       Association 42(3): 685-697.

Methods & Data
€   Analyze
        y past
            p  rainfall intensity
                                y for
    trends
    y Data needed:
      ○ Rainfall
        R i f ll iintensity
                    t   it ddata
                              t ffor diff
                                     differentt
        durations (5min, 10min, 15min, 1hr,
        etc) for Las Cruces
      ○ Data
        D t should
               h ld cover enough     h titime tto
        ensure statistically significant results
      ○ Only summer monsoon data will be
        usedd
    y Linear regression will be used to
      test for trends

Methods & Data
€   Extrapolate to the future
    y Any trendlines of statistical
      significance will be used to create
      f t
      future  Intensity-Duration-
              I t   it D ti
      Frequency (IDF) curves
    y Linear regression will be used to
      extrapolate to two future years,
      2025 and 2050.
    y IDF curves willill b
                         be used
                               d tto create
                                         t
      future synthetic storms to be
      modeled in SWMM

Methods & Data
€   SWMM5
    y EPA’s StormWater Management Model
    y Used to model storm runoff in an urban
      setting
    y Uses topography,
                 g     y sewer system
                                 y      layout,
                                          y     soil
      attributes, slope, and land use change data
    y Can model single events or long term
      changes
       h

Methods & Data
€ Synthetic storms created from trendlines
  found will be used in SWMM
€ Simulations will be ran
€ SWMM will pinpoint which structures will
  be able to accommodate increases
                           increases,
  which will fail

Anticipated Outcomes
€ Trendlines of statistical significance are
  expected to be found
€ Future rainfall scenarios will cause
  “flashier” floods
€ Some structures will pass
                         pass, some will fail

Acknowledgements
 Funding provided by Vice President of
 Research, New Mexico State University
   Graduate Research Enhancement
                Program
  and NM Water Resources Research
                Institute

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