Flooding, storm surge, and sea level rise are serious threats to natural resources, infrastructure, and human communities along the coast. Changes to rainfall patterns could affect river flows and therefore flooding and sediment movement in the Santa Clara River basin. Many rivers are expected to become more “flashy,” with longer periods of drought followed by more intense periods of flooding. Rising sea levels are projected to inundate ground water supplies with salt water. Statewide, more precipitation is likely to fall as rain rather than snow, which will have serious consequences for fresh water management throughout California. Some threats are surely not yet known. What is clear is that habitats, key species, human communities, infrastructure, and livelihoods are all at stake.
Human Population: Sea level rise and the flooding that will come with climate change-driven coastal storms will impact human populations in a variety of ways, ranging from the displacement and disarray of evacuations to the tragedy of loss of human life. Studies have shown that not all populations are likely to be affected equally; as the California Climate Change Center’s seminal study, The Impacts of Sea-level Rise on the California Coast states, “While disasters do not discriminate, the existing societal and environmental conditions before, during, and after a disaster produce differences in vulnerability among groups within the population affected.” This phenomenon was fully evident in the aftermath of Hurricane Katrina on the Gulf coast. The California Climate Change Center estimates that 16,000 people in Ventura County would be vulnerable to the impacts of a 100-year flood coupled with a 1.4-m rise in sea level, a 120% increase over current vulnerability. The same study indicates that while the racial composition of the most vulnerable populations in Ventura County is no different from the county as a whole (meaning that no particular racial group will be disproportionately affected directly), there is a marked disparity with respect to income, with lower-income populations being disproportionately impacted. Other demographic factors also need to be explored, including distribution of non-English speaking populations and populations in particularly vulnerable age groups.
The mapping tool developed by the Coastal Resilience Ventura project allows users to visualize population density as well as other important demographic considerations such as distribution of population over the age of 64, under the age of 5, and under the poverty limit. These groups are likely to be at particular risk under various climatic scenarios.
Infrastructure: People often pay a premium to live along the coast, but more than residential buildings are at risk as sea level rises and inundation occurs. Commercial development, roads and other transportation infrastructure, ports and docks, and critical buildings like schools and hospitals in the coastal zone are all at risk. Statewide, the cost of replacing property that is at risk of inundation under a 1.4-meter (4.6 ft.) sea level rise scenario is estimated to be nearly $100 billion (in 2000 dollars), and $2.2 billion for Ventura County. Nearly 274 kilometers (170 miles) of roads and railways and three power plants are at risk in Ventura County under the 1.4-meter (4.6-ft.) sea level rise scenario, as well as a major military facility. Another concern is flooding of contaminated sites, which could lead to leaching of hazardous pollutants into the broader environment. In Ventura County, there are currently five EPA-regulated sites that are at risk of inundation by a 100-year flood. With a 1.4-m (4.6-ft.) rise in sea level, that number of sites increases to 13.
The distribution of these types of infrastructure along our coast can be mapped using the Coastal Resilience Ventura tool, and impacts to these resources can be determined under various sea level rise and storm surge scenarios.
Groundwater: A large portion of southern California’s drinking water and agricultural irrigation comes from groundwater. Like all sources of fresh water in southern California, groundwater is a precious and heavily utilized resource. Its managed use is already highly contentious and politicized, and is likely to become more so as aquifers are impacted by climate change and sea level rise.
Many of California’s aquifers have already experienced saltwater intrusion from overpumping, which occurs when groundwater is removed at such a rate that saltwater from the ocean is “sucked” into the aquifer as groundwater levels fall below sea level. For example, saltwater intrusion has already occurred in the deep aquifer system of the South Oxnard Plain. Rising sea levels could further exacerbate the problem by increasing the pressure from the rising elevation of saltwater. This process, combined with increased pumping to make up for changes in precipitation patterns as predicted, could result in significant, regional fresh water deficits.
Impacts of saltwater intrusion on human health and agriculture are well-documented. Saltwater intrusion into freshwater aquifers can eliminate drinking and irrigation water sources, with serious consequences for public health and the economy. Strategies for combating saltwater intrusion include “intrusion barriers” or “seawater barriers,” in which water is injected into an aquifer, building up pressure to combat the intrusion, but these solutions are expensive, and communities will need to assess a full range of response options. Coastal Resilience Ventura can help.
Agricultural Lands: Southern California’s mild Mediterranean climate and fertile river valleys foster an important agricultural industry. Strawberries, celery, nursery stock, lemons, raspberries, avocados – Ventura County, agriculturally the tenth most productive county in the country in terms of value, provides produce for much of the U.S. as well as Canada, the European Union, and China. The gross value of all crops grown in Ventura County in 2010 was $1.9 billion dollars. According to the Farm Bureau of Ventura County
Altogether, farming and farm-dependent businesses provide an estimated 31,000 jobs in Ventura County, more than any other sector of the economy except services. Agriculture and agriculture-related businesses account for about 4.4 percent of overall economic activity in Ventura County, generating $2.1 billion in revenue and $76 million in indirect business taxes annually. One in 10 county residents relies to some degree on income derived from farming.
Impacts of sea level rise on southern California agricultural lands are expected to be varied. While some agricultural lands are close enough to the coast or rivers to be flooded directly (such as portions of the Oxnard Plain), other indirect impacts are likely to be more significant. Changes in precipitation patterns in an already “flashy” system may affect delivery of water for agricultural uses. As stated in the 2009 California Climate Adaptation Strategy, “There will also be shifts in the type and location of agriculture as saltwater intrudes into coastal aquifers and natural recharge of groundwater resources decreases with the drying climate. Water transfer and management impacts may become increasingly complex, as there may be impacts to hydropower and hatchery project operations as well as water diversion projects.” Critical water resources within the state, such as the Sierra snowpack, as well as those outside the state but used by California, including the Colorado River, are predicted to decline. As water resources in southern California become even more scarce, agricultural uses may lose out to increasing urban demands. Changes in temperature and water availability may also have an impact on distribution of disease organisms, invasive species, and weeds.
The Coastal Resilience Ventura mapping tool can help visualize some of the impacts of coastal change on the agricultural resources of Ventura County.
Beaches and Dunes: Ninety-three percent of Ventura County’s shoreline consists of sandy beaches. More than a place to sunbathe and surf, these beaches provide critical habitat and a range of functions valued highly by people. One survey of biological communities of Southern California beaches found that species richness, organism abundance, and biomass are all higher here than similar beaches in other regions around the world. Two endangered shore birds, the California Least Tern and the Western Snowy Plover, nest and feed along these sandy beaches.
Beaches and dunes also protect the land, homes and infrastructure that lie shoreward of them from storm surge and flooding by dissipating wave energy. And the value of sandy beaches as economic resources should not be overlooked. By one estimate, California’s beaches generated $14 billion dollars in direct revenue for recreational uses in 1998.
Sandy beaches and dunes are at risk from inundation and erosion related to sea level rise and climate change-induced storms. A 2011study by Pendleton et al. states:
Climate change could substantially alter the width of beaches in Southern California. Climate-driven sea level rise will have at least two important impacts on beaches: (1) higher sea level will cause all beaches to become more narrow, all things being held constant, and (2) sea level rise may affect patterns of beach erosion and accretion when severe storms combine with higher tides.
These researchers expect the resulting economic impacts on Southern California beaches to be significant. Because the beaches will be less attractive to recreational users, estimated direct expenditures on beach-related activities are projected to decline by $10 to $15 million dollars annually.
The Coastal Resilience Ventura mapping tool clearly indicates the location of the shoreline under various inundation scenarios. Low-lying beaches are at particular risk of erosion and inundation. Narrower beaches will provide less space for recreation, and will probably result in more frequent encounters between people and nesting birds and other wildlife.
Coastal Wetlands: We have come a long way since the days of thinking of coastal wetlands as mosquito-infested swamps that must be filled or channelized in order to be of any use. Wetlands provide critical habitat for a range of organisms from the federally endangered Tidewater Goby to the Belding’s Savannah Sparrow, listed as endangered by the state of California. They also buffer coastal communities from storms and flooding, a function that will become even more important as sea level rises. And they filter contaminants from the water, helping to keep our beaches clean and swimmable.
The extensive wetlands of Ormond Beach, although much diminished from their historical extent, provide all of these benefits as well as serving as an important stopping point for migrating birds along the Pacific Flyway. In partnership with the California State Coastal Conservancy, The Nature Conservancy is working to acquire and restore the largest, and some experts say the most important, coastal wetlands in southern California at Ormond Beach. The goal of this ambitious project is to link together and restore 1,500 acres of wetlands to increase current wetland habitat and provide room for the wetlands to migrate as sea level rises.
In order to move landward to stay ahead of climate change, wetlands require adjacent space into which to move that is not obstructed by development. It will be critical to protect open spaces adjacent to coastal wetlands to allow for this marsh migration. Much of the Lower Santa Clara River watershed is in public ownership or privately conserved, but it will be important to vigilantly protect the areas where wetlands are headed in the future in order to continue to derive benefits from them.
The mapping tool on this site allows users to examine the extent of tidal marsh in the Coastal Resilience Ventura study area as well as to visualize both inundation impacts to marshes in their current locations and potential future locations of marshes.
Critical Species: Warming temperatures, sea level rise, and changes in precipitation patterns put many species at risk, including a number of key species along the southern California coast. The lower Santa Clara River basin is home to 18 state and/or federally listed threatened or endangered species, ranging from fish (steelhead, tidewater goby) to birds (California Condor, California Least Tern) to plants (Ventura marsh milkvetch, salt marsh bird’s beak). Information about a few of these species, and how they are likely to be affected by climate change, is included here.
Steelhead trout (Oncorhynchus mykiss) are in the salmonid family, and do as almost all salmon do: they spawn in their natal rivers and streams, where the young hatch and begin their life. Then the young steelhead migrate out to the ocean to live out most of their lifecycle. The adults then return to the streams to spawn. On the West Coast, steelhead range from Alaska to the northern Baja Peninsula. In the Santa Clara River, the steelhead run is federally listed as endangered, and is included in the Southern California steelhead Distinct Population Segment (DPS; the smallest unit that can be treated as endangered under the Endangered Species Act).
Climate change might impact southern steelhead in a number of ways. First, according to the City of Ventura’s Year One Data Summary and Assessment for its Estuary Subwatershed Study, “The life history patterns of southern California steelhead depend more strongly on rainfall and flow than steelhead populations found further north.” Rainfall is already highly variable in southern California, and is expected to become more so. Second, habitats such as wetlands could move or change in response to climate change and sea level rise; steelhead smolts spend a critical portion of their outmigration in estuaries, and changes there could impact estuarine survival. Finally, water temperatures are expected to increase, perhaps outside of the species’ tolerance range. El Niño conditions, which are expected to occur more frequently, have already been observed to affect West Coast salmon populations.
The tidewater goby, Eucyclogobius newberryi, is a small, bottom-dwelling, annual fish (generally only living one year) endemic to the state of California. Listed as federally endangered, tidewater gobies are found in brackish waters, chiefly estuaries and lagoons, along much of the California coast. They are found in the Santa Clara River as far as three miles from the estuary. This little fish is an important link in California’s estuarine food webs, serving as prey for many larger fish and bird species, including steelhead. Despite federal protection, many threats remain to tidewater goby populations, including loss of estuarine habitat resulting from coastal development, alteration of freshwater flows, and introduction of non-native species, especially predatory fish and amphibians.
Tidewater goby populations, already at risk throughout their small range, could be seriously impacted by climate change. The biggest threat is inundation of existing habitat by rising seas, which would flood existing goby habitat with higher-salinity water. For this reason, in response to a lawsuit brought by the Natural Resources Defense Council in 2011, the U.S. Fish and Wildlife Service extended the definition of critical habitat for tidewater goby to areas that are currently appropriate for tidewater gobies, but as yet unoccupied by the species. This ruling increases the likelihood that appropriate goby habitat will be available even when current habitats are rendered unsuitable by rising sea levels.
The California Least Tern (Sterna antillerum browni), a subspecies of the smallest variety of North American Tern, is listed by both the state and federal governments as endangered. This small seabird nests and forages on sand or gravel beaches during the summer breeding season, migrating to overwintering grounds in Central America in July or August. There are four major nesting sites for California Least Terns found within the Coastal Resilience Ventura study area. Eggs are laid in bowl-shaped indentations in the sand, sometimes near sparse protective vegetation. The birds feed in shallow estuaries, lagoons, coastal ponds, or near shore waters where they pursue small bait fish as prey.
The Western Snowy Plover (Charadrius alexandrinus nivosus), another small shorebird species, is found from Washington State to the Baja Peninsula. Coastal populations of Western Snowy Plovers are federally listed as endangered, while inland populations are considered a species of special concern by the state of California. This species also nests and forages in the summertime on exposed sand and gravel beaches, but does not migrate (although there is evidence that inland birds overwinter in coastal areas).
Because the nests of both bird species are so exposed, they are particularly vulnerable to threats from terrestrial predators and human disturbance. As sea level rise inundates beaches, critical habitat for California Least Terns and Western Snowy Plovers will be eaten away. Pressure on beach-nesting bird populations will mount as beaches become narrower and multiple uses of the shore compete for space.
The mapping tool developed by the Coastal Resilience Ventura project allows users to visualize how climate change may impact the extent and quality of coastal habitats upon which critical species depend.