How Everglades Restoration Can Mitigate Some Effects of Sea Level Rise in South Florida By the...
-
Upload
sheila-williams -
Category
Documents
-
view
213 -
download
0
Transcript of How Everglades Restoration Can Mitigate Some Effects of Sea Level Rise in South Florida By the...
How Everglades Restoration Can Mitigate Some
Effects of Sea Level Rise in South Florida
By the Arthur R Marshall 2013 Interns: Sarah Denisen, Casey Hickcox, Jessica
James, Tomena Scholze, and Kelsie Timpe
Climate Change and Sea Level Rise
Fig 1: NOAA, Climate.gov
Pre 1870s: 180-280 ppm
May 9, 2013: Mauna Loa above 400 ppm
• The US National Climate Assessment predicts with high confidence that the sea will rise at least 0.2 m (8 inches) and no more than 2 m (6.6 ft) by 2100 (NOAA 2012).
Climate Change and Sea Level Rise
Table 1: NOAA 2012
Threats to the urban environment• Saltwater Intrusion• Increased flooding• Infrastructure damage
Threats to the natural environment• Storm Surge• Saltwater Inundation• Mangrove Destruction• Habitat Conversion• Trophic Disruption
Outline of Sea Level Rise Threats
Threats to the Natural Environment: Storm Surge
http://www.disaster.qld.gov.au/getready/images/storm-surge.png
Physical Erosiono Sediment removalo Mangrove
destruction and removal
o Soil subsidence
Chemical Erosiono Saltwater inundation
Wetland Destructiono Almost 3100 acres in
S.Fla due to Hurricane Wilma
Healthy Ecosystems Provide Natural Protection
Mangroves - 'Natural wall'o Create peat dam o Increases drag on water
motiono Absorbs wave energyo Decreases fetch in wave
action
Inland plants o Prevent creation of waveso Increases drag on water
motiono Holds sediment in place
Peat decomposition
o Oxidative destruction
Nutrient Enrichment
o Phosphorus
Salinity increase
Threats to the Natural Environment: Saltwater Inundation
Seawater Okeechobee Everglades Goal
Mangrove Threatso Soil Erosiono Too fine sedimento Hypersalinity
Migration Capacity Limitedo SLR <9 cm/yr - Acceptableo SLR 9-12 cm/yr - Stressedo SLR >12 cm/yr - Threatened
Threats to the Natural Environment: Mangrove Destruction
• Salinity increases and reduced freshwater
-> vegetation community shiftso aquatic vegetation regime shiftso tidal marsh shifts and submergenceo buttonwood/coastal hammock loss
• Differing rates of migration -> elimination of some habitats
Threats to the Natural Environment:
Habitat Conversion
Total Ecosystem Value (TEV) Decreases as Habitats Shift
• TEV decreases to $5 billion with 5 ft. of SLR
• Losses occur as ecosystems degrade to less valuable habitats through salinity changes
• C sequestration values decreased from $32 million to $490 k due to mangrove loss
• TEV is $74 billion with no SLR effects in study area
• Biological effects of physical changes caused by SLR and flow alterations o disrupted trophic interactionso productivity effectso population/community structure
changes
• Examples:o coastal fish nurserieso wading bird nesting/feeding o periphyton composition
Threats to the Natural Environment:
Trophic Disruption
The Urban Side• 2010 population along the lower east coast was
approx. 5.6 million
• 2010 gross water demand of 1,775,000,000 gallons per day
• 2030 population projected to increase by 18% to approx. 6.6 million
• 2030 gross water demand for all uses is projected to increase by 213 million gallons per day (12%)
Climate Change Threatens Water Supply
• Warming will change in the rate of evapotranspiration
• Unpredictable weather patterns and rising temperatures may increase water demands
• Less frequent but more intense rainfall, with longer dry periods in between, may increase total annual rainfall but decrease total useable rainfall - more water may be lost to tide or runoff.
• This scenario increases the necessity for long term water storage for use during dry periods.
Salt Water Intrusion Threatens Water Supply
• The majority of public water supply is pumped from shallow wells
• Salt water contaminates shallow well fields, making them unusable
• Many coastal well fields are already experiencing salt water intrusion and must be abandoned
• Utilities at risk - Lake Worth, Lantana, Hillsboro Beach, Dania Beach, Hallendale Beach, Miami-Dade south wellfields, Florida City, Homestead, and the Florida Keys Aqueduct Authority.
The Aquifer Systems under South Florida
• Surficial Aquifer System (SAS)
• Floridan Aquifer System (FAS)
• SAS holds freshwater from surface level to about 200 ft in depth
• FAS holds brackish water in several layers
Photo Credit: SFWMD
How Saltwater Intrusion Works
• When water is withdrawn faster than it is recharged, seawater moves in
• With SLR, pressure from the a growing ocean will push more saltwater inland.
Photo Credit: USGS
Connection between Water Supply and the Greater Everglades
Water from Lake Okeechobee, the Water Catchment Areas (WCAs) and the C&SF Canals recharge the SAS and Biscayne
Aquifer
Photo Credit: SFWMD Photo Credit: SFWMD
How can we meet future water supply demand?
• Diversify our water sources
• Increase surface water storage
• Use reclaimed water and rain for non-potable uses
• Increase water conservation
• Restore the Everglades Photo Credit Ken Kaye
Alternative Water Supply Options
• Temporary fix - move Biscayne and surficial aquifer system (SAS) wells inland.
• Desalinize brackish water from the Floridan Aquifer System (FAS).
• Desalinize saltwater from the ocean.
SAS and the Biscayne Aquifer
• Salt water intrusion necessitates abandoning wells or moving them further inland.
• Moving wells is costly - Earl King, assistant director of utilities for the City of Hallendale Beach, estimates moving a small wellfield inland will cost $8,500,000.
• Only a temporary fix.
• Relying exclusively on the SAS and the Biscayne is not a viable option to meet future water demand.
• Other water sources must be explored.
Floridan Aquifer System - FAS
• FAS is brackish – requires treatment (RO)
• Construction is costly.
• RO highly energy intensive. • Deep injection wells (DIWs) are
necessary
Seawater Desalinization• Unlimited, drought-proof source of water
• RO is highly energy intensive and expensive
• Brine byproduct of RO can be damaging to marine ecosystems.
• Advances technology reducing cost
• Co-location of desal facilities and coastal power plants
Ten SAS Wells & One 20 mgd
Treatment Plant
Ten FAS Wells, Two DIWs, & One 20
mgd RO Treatment plant
One Seawater 20 mgd RO Treatment Plant & Two DIWs
0
20000000
40000000
60000000
80000000
100000000
120000000
140000000
160000000
Cost Comparison of Urban Water Supply Options for the Lower East Coast
Capital Costs Annual Maintnence and Operation Costs
20
13
US
D
*These costs do not include land, water mains, or pumps .
FAS
DESAL
SAS
Supplemental Sources and Conservation Measures
Rainwater harvesting, use of reclaimed water and water conservation practices will help reduce water supply demands
Photo Credit: EPA
Reclaimed Water• Used for irrigation, agricultural
and industrial uses• Reduces pumping from
groundwater• Reduces quantity of
wastewater disposed of via ocean outfalls and deep injection wells
• Reduces need for fertilizer• Wastewater flows predicted to
increase from 636 MGD in 2010 to 832 MDG by 2030
• Is no more dirty than ocean water!
Photo Credit: SunSentinel
Rainwater Harvesting
• Inexpensive• Reduces stress on water supplies• Reduces stormwater runoff,
pollution and flooding
Photo Credit: EcoFriend Photo Credit: SunSentinal
• Help recharge the shallow Biscayne Aquifer
• Provide more surface water storage
• Prevent peat degradation
• Push back saltwater intrusion
• Reduce nutrient enrichment
• Maintain freshwater habitats for plants and wildlife.
• Maintain the coastal mangrove storm barriers
The Solution: Everglades Restoration
More water in the Everglades ecosystem will: