Transcript of Tools and Research to Improve the Characterization of Drought and Understanding of Impacts on Water...
- Slide 1
- Tools and Research to Improve the Characterization of Drought
and Understanding of Impacts on Water and Ecological Resources
Ashley Brosius, Climate Outreach Specialist Carolinas Integrated
Sciences & Assessments, University of South Carolina CISA TEAM
Co-Pis: Greg Carbone, Kirstin Dow, Chip Konrad (Southeast Regional
Climate Center), Daniel Tufford, Jessica Whitehead (SC Sea Grant
Extension and NC Sea Grant) Research Associates: Kirsten Lackstrom,
Jinyoung Rhee Climate Outreach Specialist: Ashley BrosiusResearch
Assistants: Amanda Brennan, Ben Haywood, Peng Gao, Nate Kettle,
Aashka Patel Collaborators: Ryan Boyles (NC State Climatologist),
Paul Conrads (USGS), Art DeGaetano (NERCC), Hope Mizzell (SC State
Climatologist), Edwin Roehl and Ruby Daamen (Advanced Data Mining
International) Drought and Coastal Ecosystems State of Knowledge
Report Literature Gaps and Research Needs The most critical needs
include examining drought impacts in ecosystems not studied by
existing research, implementing long term studies to identify and
examine causal relationships, and developing a set of indicators
with which to monitor ecological change and impacts. More research
and information is needed regarding drought impacts on groundwater
resources, the significance of drought during different seasons,
the longevity of droughts in relation to long-term impacts and/or
length of recovery, and responses to potential future changes in
salinity regimes. NMAZ For more information about CISAs projects,
contact cisa@sc.educisa@sc.edu Background This State of Knowledge
Report provides a synthesis and analysis of the peer- reviewed
literature for the state of knowledge of drought impacts on coastal
ecosystems in the Carolinas. Its objective is to expand current,
limited understanding of drought impacts on coastal ecosystems, to
identify critical gaps, to inform future research efforts, and to
suggest measures to facilitate drought adaptation for ecosystems.
The report focuses on coastal ecosystems of North and South
Carolina and concentrates on the portion bordered inland by the
extent of tidal freshwater. Because there is significant ecological
continuity between extreme southeastern Virginia and northeastern
North Carolina and between coastal Georgia and the south coast of
South Carolina, work done in those parts of Virginia and Georgia
was included in the report. Review of Findings The research
reviewed for this report indicates that drought is discussed
primarily in terms of the hydrology-related impacts that affect
coastal ecosystems, such as changes to river discharge, freshwater
inflows, water level, and water table depth. The severity of these
effects depends upon the longevity and recurrence interval of
drought event(s) and may be compounded by other anthropogenic
stressors on the system. In addition, some drought-related research
considers how sea level interacts with freshwater precipitation and
runoff to influence the salinity levels experiences by these
systems. The review indicated that some ecoregions and locations
have been better studied and researched than others. Examples
include: Droughts represent an important stressor of estuarine
ecosystem functioning through their potential to reduce freshwater
delivery to estuaries. Effects may include changes in nutrient
loading, phytoplankton dynamics and primary productivity, resultant
changes in secondary production, food web dynamics, water quality,
and fish habitat. Although the literature is not conclusive about
drought as the single cause of salt marsh dieback in all
localities, it has been strongly implicated in concert with other
stressors. There is a clear relationship between decreased marsh
productivity and high pore water salinity to which drought can
contribute. Numerous authors reported on studies showing the
adverse effects of salinity intrusion into tidal freshwater
forests. There appears to be a consensus that any extended periods
of chronic or elevated exposure to saltwater intrusion without
freshwater recharge will ultimately lead to tree death and forest
dieback. Hydrology in non-alluvial wetland systems is largely
driven by rainwater making them particularly vulnerable to extended
droughts. Impacts include vegetation community shifts and invasion
by upland species. Next Steps CISA is partnering with the National
Integrated Drought Information System (NIDIS, www.drought.gov) to
develop a Carolinas pilot project in 2012, with a focus on coastal
ecosystems. Possible projects might include assessment of the most
appropriate and relevant drought indices for coastal ecosystems,
collaboration with resource managers to develop relevant drought
information for decision making, building or improving existing
regional communication networks to disseminate drought data and
information, or research to fill science gaps.www.drought.gov
Carolinas Integrated Sciences and Assessments (CISA) is part of the
NOAA Regional Integrated Sciences and Assessments (RISA) program.
CISA conducts research in collaboration with water and coastal
stakeholders across the Carolinas to produce usable, useful, and
accessible climate information for decision making. The potential
users of this information cover a broad range of interests
including municipal water supply planners, natural area/refuge
managers, regulatory staff involved in mitigation or restoration
activities, and coastal emergency planning staff. Focus areas
include drought, watershed and climate modeling, coastal climate,
health, and adaptation. CISAs drought work seeks to improve
monitoring methods, to develop a more comprehensive understanding
of regional impacts, and to assess drought planning and early
warning needs. CISA has initiated several projects to advance
regional and local capacity to cope with drought and to improve
understanding of drought impacts on social and environmental
systems. This poster highlights three projects. First, the Dynamic
Drought Index Tool (DDIT) provides a web based drought mapping tool
that displays multiple drought indices for different time scales
and across user-specified regions. Second, with other scientists
and water suppliers in the Carolinas, CISA developed a decision
support tool that allows resource managers to assess the effects of
salinity intrusion on surface water resources in coastal areas.
Third, we are investigating drought impacts on coastal
environments, an area currently under- represented in regional
drought assessments. CISA produced a state of knowledge report that
synthesizes and analyzes the peer reviewed literature regarding
drought impacts on coastal ecosystems in the Carolinas. Findings
from this report will help inform CISAs collaboration with the
National Integrated Drought Information System (NIDIS) to develop a
drought early warning system pilot project in the Carolinas.
Introduction Background The ability of water-resource managers to
adapt to future climatic change is especially challenging in
coastal regions of the world. There are many municipal water
intakes along the South Atlantic coast that are proximal to the
saltwater-freshwater interface of tidal rivers. An increase in the
extent of saltwater intrusion along the coast due to climate
changes could threaten freshwater intakes for several major cities
along the coast. Water-resource managers need estimates of the
change in the frequency, duration, and magnitude of salinity
intrusion near their water intakes that may occur as a result of
climate change. Methods Salinity intrusion results from the
interaction of three different forces: streamflow, mean tidal water
levels, and tidal range. To analyze, model, and simulate
hydrodynamic behaviors at critical coastal gage locations along the
Atlantic Intracoastal Waterway and Waccamaw River near Myrtle
Beach, SC, data-mining techniques were applied to over twenty years
of hourly streamflow, coastal water-quality, and water-level data.
Artificial neural network (ANN) models were trained to learn the
specific variable interactions that cause salinity intrusions.
Streamflows into the estuarine systems are input to the models as
time-delayed variables and accumulated tributary inflows. Tidal
inputs to the models were obtained by decomposing tidal water-level
data into a periodic signal of tidal range and a chaotic signal of
mean water levels. The ANN models were able to convincingly
reproduce historical salinity dynamic behaviors in both systems.
User-defined hydrologic and coastal water-level inputs from
down-scaling of regional climate models can be simulated in the
salinity intrusion models to evaluate various climate-change
scenarios. Assessing the Impact of Salt-Water Intrusion in the
Carolinas Under Future Climatic and Sea-Level Conditions Results
Artificial Neural Network models were trained to learn the variable
interactions that cause these salinity events. Model results from
Pawleys Island stream gage (USGS station 02110125), near a
municipal freshwater intake, indicate that 1 foot (30 cm) of SLR
would double the number of days the municipal intake is unavailable
to 400 days and a 2-ft rise increases the unavailability to nearly
2 years (700 days). (Conrads et al. 2010). Changes in precipitation
patterns due to changes in the climate have the potential of
decreasing streamflow to the coast. Salinity intrusion in coastal
rivers during low streamflow periods and a decrease in streamflow
combined with a sea-level rise could increase the duration of
salinity intrusion along the coast. A 1-ft sea-level rise combined
with a 25-percent decrease in historical streamflow would increase
the days the intake is unavailable to over 700 days. Water-resource
managers can use this information to plan mitigation efforts to
adapt to potential effects from climate change. The project team
developed a new, web-based Decision Support System (DSS) PRISM2
(Pee Dee River and Atlantic Intracoastal Waterway Salinity
Intrusion Model) for stakeholder and government agency use in
evaluating potential changes in the hydrologic system of the Pee
Dee River under different climatic regimes. In December 2011 the
CISA team conducted a workshop in Georgetown, SC, with resource
managers, water/utility managers, and applied researchers to
provide information about the PRISM2 DSS and to gather feedback
about the potential impacts of sea level rise and salinity
intrusion on existing ecological and infrastructure systems and
about the models applicability for decision making. Insights from
the workshop will be used to enhance the DSS. Reference Conrads, P.
et al. 2010. Estimating Salinity Intrusion Effects Due to Climate
Change Along the Grand Strand of the South Carolina Coast. In:
Proceedings Paper for the 4th Federal Interagency Hydrologic
Modeling Conference. June 27- July 1, Las Vegas, Nevada..