Impact of water runoff, storage
Water issues concern
farmers, cities, biologists
Bob
Krauter
Capital Press California
Editor
September 22, 2006
A meager winter snowpack, heightened risk of spring floods and greater competition among farmers, city dwellers and fish - those are some of the predicted effects associated with climate change in the century ahead.
Climate change is a recurring topic of discussion among climatologists, hydrologists and environmental engineers because it is vital to life and it is the lifeblood of farms and ranches - from Washington's Yakima Valley to the Imperial Valley of California.
Dire consequences are contained in California's Climate Action Team Report to Gov. Arnold Schwarzenegger in March. It estimates the Sierra snowpack, which accounts for approximately half of the surface water storage in the state, could decline by 70 percent to as much as 90 percent in the next century, threatening the state's water supply.
The report's analysis indicated that without significant reductions in greenhouse gas emissions, warming toward the end of this century will exceed 3 degrees F.
The report states, "Potential impacts from limited water storage, increasing temperatures and salt water in the Sacramento-San Joaquin Delta would pose challenges for the industry. Direct threats to the structural integrity of the state's levee and flood control systems would also have immense implications for the state's fresh water supply, food supply and overall economic prosperity."
Daniel Cayan, researcher at the Climate Research Division of Scripps Institute of Oceanography in La Jolla, Calif., said climate change could dramatically alter the Sierra landscape.
"It appears in the hydrological model explorations that have been done, we could easily lose a third of the present day spring snowpack by the end of the century if not considerably more at the upper range - perhaps 80 percent to 90 percent - of the April 1 snowpack would be gone," Cayan said.
Cayan said climate models show that there will be at least modest warming in the next several decades, "if not enormous amounts depending on the greenhouse gas loading of the atmosphere." He said the time is now to start calibrating and trying to understand how climate changes might affect water systems.
Maury Roos, who has been the state of California's hydrologist for nearly 20 years, has identified five areas of potential impact from climate change: a reduced snowpack, a rise in sea level, higher risk of spring flooding, higher evapotranspiration and having suitable cold water in rivers to support anadramous fish.
"If we get a warmer world, we will have less snowpack at a higher elevation and more runoff in the winter," Roos said. "Currently, the major foothill reservoirs are operated to maintain winter space for flood control, which is gradually filled during the spring snowmelt. We don't see less threat of floods; there may be more. So just changing the storage pattern won't help."
Rising sea level
If predictions come true, Central Valley residents will deal with greater flood risks during the spring and farmers in the Sacramento-San Joaquin Delta may feel the pressure from rising sea level. Roos said a gauge near the Golden Gate Bridge has documented a rise of7/10ths of a foot in the past century. A continued rise in the Pacific Ocean could threaten Delta farms, many of which are protected by an antiquated system of levees.
"The higher level of oceans has some impact on salinity intrusion because seawater intrusion is a function of the depth of the channels," Roos said. "The great fear is if you lost a large central Delta island to flooding during the summer dry season, you would get an inrush of water and so much saltwater in the Delta and it would take some time to get the pumps operating again."
The state of California operates a pumping plant at Tracy, which is the central fixture in the state's plumbing system. Water from Northern California courses through the Delta and is lifted by pumps into the California Aqueduct for transfer south into the San Joaquin Valley for crop irrigation and to Southern California for urban uses.
Sacramento Valley rice grower Al Montna, who has been involved in agricultural water issues for years and currently serves as president of the state Board of Food and Agriculture, said the time has come to develop more water storage for flood control and other benefits.
"We have to have the infra-structure for flood control for public safety. Many of the communities in Northern California are surrounded by levees. The storage issue is huge," Montna said. "We have to build some facilities, especially with climate change. It is real. The Delta is going to be threatened with rising tides and much more rainfall and we're going to have to store that water. We have to react."
Supply systems
Water for crop irrigation is already a critical issue as California has experienced two severe droughts in the past 30 years. Surface water supplies are oversubscribed in a state of 35 million people, which features millions of acres of irrigated farmland. Federally protected fish species must be considered in all actions. The California Climate Action report stated that "higher temperatures and reduced snowmelt will compound the problem of providing suitable cold water for salmon species."
Jay Lund, a UC Davis professor in the civil and environmental engineering department, has studied climate change. As an author of a June 2006 study, Climate Warming and Water Management Adaption for California, Lund and several colleagues examined the ability of California's water supply system to adapt to long-term climatic and demographic changes in 2100.
A conclusion of the study is California's water system can adapt to the fairly severe representations of population growth and climate warming. It also concluded that California's economy should weather the effects of these two forces, but major effects could hit agriculture and the environment.
Lund's report states, "Agricultural water users in the Central Valley are the most vulnerable to climate warming. While wetter hydrologies could increase water availability for agricultural users, the driest climate warming hydrology would reduce agricultural water deliveries in the Central Valley by about a third."
Rick Snyder, a UC Davis biometeorologist, offered some encouraging news about climate change and its effects on evapotranspiration, the sum of evaporation and plant transpiration.
"The effect on evapotranspiration is not expected to be too dramatic," Snyder said. "We have seen a significant increase in new irrigation advances with trend to micro-sprinklers and drip irrigation which will help farmers be more efficient in distributing water in the future."
A meager winter snowpack, heightened risk of spring floods and greater competition among farmers, city dwellers and fish - those are some of the predicted effects associated with climate change in the century ahead.
Climate change is a recurring topic of discussion among climatologists, hydrologists and environmental engineers because it is vital to life and it is the lifeblood of farms and ranches - from Washington's Yakima Valley to the Imperial Valley of California.
Dire consequences are contained in California's Climate Action Team Report to Gov. Arnold Schwarzenegger in March. It estimates the Sierra snowpack, which accounts for approximately half of the surface water storage in the state, could decline by 70 percent to as much as 90 percent in the next century, threatening the state's water supply.
The report's analysis indicated that without significant reductions in greenhouse gas emissions, warming toward the end of this century will exceed 3 degrees F.
The report states, "Potential impacts from limited water storage, increasing temperatures and salt water in the Sacramento-San Joaquin Delta would pose challenges for the industry. Direct threats to the structural integrity of the state's levee and flood control systems would also have immense implications for the state's fresh water supply, food supply and overall economic prosperity."
Daniel Cayan, researcher at the Climate Research Division of Scripps Institute of Oceanography in La Jolla, Calif., said climate change could dramatically alter the Sierra landscape.
"It appears in the hydrological model explorations that have been done, we could easily lose a third of the present day spring snowpack by the end of the century if not considerably more at the upper range - perhaps 80 percent to 90 percent - of the April 1 snowpack would be gone," Cayan said.
Cayan said climate models show that there will be at least modest warming in the next several decades, "if not enormous amounts depending on the greenhouse gas loading of the atmosphere." He said the time is now to start calibrating and trying to understand how climate changes might affect water systems.
Maury Roos, who has been the state of California's hydrologist for nearly 20 years, has identified five areas of potential impact from climate change: a reduced snowpack, a rise in sea level, higher risk of spring flooding, higher evapotranspiration and having suitable cold water in rivers to support anadramous fish.
"If we get a warmer world, we will have less snowpack at a higher elevation and more runoff in the winter," Roos said. "Currently, the major foothill reservoirs are operated to maintain winter space for flood control, which is gradually filled during the spring snowmelt. We don't see less threat of floods; there may be more. So just changing the storage pattern won't help."
Rising sea level
If predictions come true, Central Valley residents will deal with greater flood risks during the spring and farmers in the Sacramento-San Joaquin Delta may feel the pressure from rising sea level. Roos said a gauge near the Golden Gate Bridge has documented a rise of7/10ths of a foot in the past century. A continued rise in the Pacific Ocean could threaten Delta farms, many of which are protected by an antiquated system of levees.
"The higher level of oceans has some impact on salinity intrusion because seawater intrusion is a function of the depth of the channels," Roos said. "The great fear is if you lost a large central Delta island to flooding during the summer dry season, you would get an inrush of water and so much saltwater in the Delta and it would take some time to get the pumps operating again."
The state of California operates a pumping plant at Tracy, which is the central fixture in the state's plumbing system. Water from Northern California courses through the Delta and is lifted by pumps into the California Aqueduct for transfer south into the San Joaquin Valley for crop irrigation and to Southern California for urban uses.
Sacramento Valley rice grower Al Montna, who has been involved in agricultural water issues for years and currently serves as president of the state Board of Food and Agriculture, said the time has come to develop more water storage for flood control and other benefits.
"We have to have the infra-structure for flood control for public safety. Many of the communities in Northern California are surrounded by levees. The storage issue is huge," Montna said. "We have to build some facilities, especially with climate change. It is real. The Delta is going to be threatened with rising tides and much more rainfall and we're going to have to store that water. We have to react."
Supply systems
Water for crop irrigation is already a critical issue as California has experienced two severe droughts in the past 30 years. Surface water supplies are oversubscribed in a state of 35 million people, which features millions of acres of irrigated farmland. Federally protected fish species must be considered in all actions. The California Climate Action report stated that "higher temperatures and reduced snowmelt will compound the problem of providing suitable cold water for salmon species."
Jay Lund, a UC Davis professor in the civil and environmental engineering department, has studied climate change. As an author of a June 2006 study, Climate Warming and Water Management Adaption for California, Lund and several colleagues examined the ability of California's water supply system to adapt to long-term climatic and demographic changes in 2100.
A conclusion of the study is California's water system can adapt to the fairly severe representations of population growth and climate warming. It also concluded that California's economy should weather the effects of these two forces, but major effects could hit agriculture and the environment.
Lund's report states, "Agricultural water users in the Central Valley are the most vulnerable to climate warming. While wetter hydrologies could increase water availability for agricultural users, the driest climate warming hydrology would reduce agricultural water deliveries in the Central Valley by about a third."
Rick Snyder, a UC Davis biometeorologist, offered some encouraging news about climate change and its effects on evapotranspiration, the sum of evaporation and plant transpiration.
"The effect on evapotranspiration is not expected to be too dramatic," Snyder said. "We have seen a significant increase in new irrigation advances with trend to micro-sprinklers and drip irrigation which will help farmers be more efficient in distributing water in the future."
