Yolo Bypass: the inland sea of Sacramento

A very flooded Yolo Bypass. Photo taken by Carson Jeffres on January 26, 2017. (In view is looking south at Interstate 5 just west of Woodland, in the distance is Interstate 80 between Davis and Sacramento)

A flooded Yolo Bypass, flowing much less than capacity. Photo taken by Carson Jeffres on January 26, 2017. (View looking south at Interstate 5 west of Woodland, in the distance is Interstate 80 between Davis and Sacramento)

By Megan Nguyen

Land or Sea? The recent rains early this year brought much needed relief from the five-year drought in California. Reservoirs are full, mountains are covered with snow, and flood control structures are being used, some for the first time since 2006. Interstate 80 causeway commuters frequently, though perhaps unknowingly, witness one of the most important floodplains in California – the Yolo Bypass is now filled with water as far as the eye can see.

The recent events at Oroville Dam help highlight the Yolo Bypass’ vital role in flood protection for the Sacramento area. Despite the risk of flooding from the potential failure of Oroville Dam’s emergency spillway last week, flood control managers and experts emphasized the limited risk to the Sacramento area. The Bypass was a big reason why communities near Sacramento didn’t experience the same risk as those closer to the dam. Understanding the Bypass helps explain why it functions so well in our regional flood control strategy. But it also emphasizes the scale of protection needed for a low-lying area like Sacramento.

Sacramento Valley and San Joaquin Valley historically flooded from major rainstorms or snowmelt. Most major floods in California are caused by “atmospheric rivers” from the Pacific Ocean.  Atmospheric rivers are warm, intense streams of tropical moisture that often produce several days of heavy precipitation in the Central Valley and over the mountains of California. By the time this blog is posted, forecasts say we will be drenched by one.

Prior to construction of large flood infrastructure and coordinated flood management, seasonal runoff would often cover the valley floor. Historically, floods could reach as large as 600,000 cfs (cubic feet per second) near Sacramento (one cubic foot is about the size of a basketball). Snow melt from the mountains and heavy rainfall would often overtop the river banks. Following hydraulic mining in the 1800s, immense quantities of sediment began to deposit in the river channels of the valley floor. The sediment essentially filled  the river channels and left no place for flood water to go.  The resulting floods covered large areas of the valley floor to great depth, with large property damage and loss of life.

To prevent future flood damage such as what happened in the flood of 1907, the state of California through the Central Valley Flood Protection Board and the Army Corps of Engineers developed the Sacramento River Flood Control Project (SRFCP). The SRFCP is a system of flood-relief structures and weirs that release Sacramento River and Feather River flows into a bypass system when flows exceed downstream channel capacity.

Video: This hydraulic model is a simulation of a swollen Sacramento River spilling over the Fremont weir into the Yolo Bypass as it floods as a result of high flow events. Notice that the floodwaters spread through individual irrigation ditches and drains.

The most downstream of the bypasses and a critical component of the SRFCP, the Yolo Bypass is a 59,000-acre floodway that serves as a flood relief valve and protects Sacramento and southern Sacramento Valley from seasonal inundation. At three miles wide and 40 miles long, the bypass can carry up to four times the flow of the river’s main channel during large floods. The Bypass lies within the Sacramento River’s historical floodplain and conveys floodwaters from major valley rivers including the Sacramento, American, and Feather Rivers, and west-side tributaries: Knights Landing Ridge Cut, Cache Creek, Willow Slough, and Putah Creek. The Bypass is designed for a capacity 500,000 cfs at the downstream end.

A schematic map of the Yolo Bypass. Courtesy of DWR. Point A shows the location of the Fremont Guage (FRE). Point B shows the location of the Yolo Bypass guage (YBY).

A schematic map of the Yolo Bypass. Courtesy of DWR. Point A is the location of the Fremont Guage (FRE). Point B is the location of the Yolo Bypass guage (YBY).

Weirs are lower, armored sections of levees that are used to divert high river flows through bypasses and ultimately to the Sacramento-San Joaquin Delta. Major weirs in the Yolo Bypass include the Fremont and Sacramento Weirs.

The Fremont Weir is two miles long and marks the beginning of the Yolo Bypass.  The Fremont Weir is passive, meaning that no management is needed to allow flood water to overflow into the Bypass.  Overflow waters of the Sacramento River, Sutter Bypass, and the Feather River run into the Yolo Bypass with a design capacity of 343,000 cfs.

Unlike the Fremont Weir, the Sacramento Weir is manually opened during high flow events. It consists of 48 gates that must be opened with a long hooked pole. The weir was designed primarily to protect the City of Sacramento from excessive flood stages in the Sacramento River channel downstream of the American River.  The Sacramento Weir can divert a maximum flow of 112,000 cfs. This year the Sacramento Weir opened for the first time since 2006.

How the Sacramento Weir works. Picture originally published by the Sacramento Bee on Jan 9, 2017.

How the Sacramento Weir works. Picture originally published by the Sacramento Bee on Jan 9, 2017.

Although flood control is the major function of the Yolo Bypass, the Bypass is a multi-benefit landscape.  During the non-flood season, agriculture and wildlife management are the main activities in the Bypass.  Agriculture in the Yolo Bypass is predominantly rice farming. The largest contiguous area of non-agricultural floodplain habitat is the Vic Fazio Yolo Bypass Wildlife Area, managed by California Department of Fish and Wildlife. At 16,600 acres, this area is a haven for waterfowl, shorebirds and wading birds, neotropical migratory birds, raptors, invertebrates, snakes, turtles, toads, and bats. Vegetation community types include managed seasonal and permanent wetland, natural seasonal wetland, natural perennial wetland, and riparian woodland.

An often unnoticed benefit of the flooded landscape is the benefit for juvenile salmon.  During winter floods, juvenile salmon are washed down from upstream rivers into the productive habitats of the Yolo Bypass.  Juvenile salmon grow much faster on the Bypass compared to the river channel the runs through Sacramento River.  Even though it is hard to observe while stuck in traffic, the thriving aquatic ecosystem in the flooded Bypass is much richer than the river not far away.

A flooded Yolo Bypass is a sign that the Sacramento River Flood Control System is working to protect the greater Sacramento area from flooding. Although less tangible, the Sacramento Flood Control System also serves a valuable ecosystem benefit by mimicking some of the historic flooding within a more controlled, human friendly environment. With more wet months to come in 2017, the Bypass will continue to remain an inland sea.   So the next time that you are stuck in traffic on the causeway take to moment to appreciate the amazing multi-benefit environment below you.

Megan Nguyen is a GIS researcher at the Center for Watershed Sciences. Her work and interests revolve around a variety of topics such as drought impacts, flood mitigation, environmental policy, and education outreach.

Further Reading

Kelley, Robert (1989), Battling the Inland Sea: Floods, Public Policy, and the Sacramento Valley, University of California Press, Berkley, CA.

Suddeth, R. Dec. 2, 2014. Reconciling fish and fowl with floods and farming. California WaterBlog.

Fleenor, W. Suddeth, R. Oct. 18, 2013. Innovations in floodplain modeling: A test drive on the Yolo Bypass. California WaterBlog

Sacramento River Flood Control Project Weirs and Flood Relief Structures, by California Department of Water Resources, 2010.

Lund, J.R., “Flood Management in California,” Water, Vol. 4, pp. 157-169; doi:10.3390/w4010157, 2012.

Suddeth, R. and J. Lund “Multi-Purpose Optimization of Reconciliation Ecology for an Engineered Floodplain – Yolo Bypass, California,” San Francisco Estuary and Watershed Science, Volume 14, Issue 1, 2016.

Department of Water Resources. Yolo Bypass Flood Protection Presentation. http://baydeltaconservationplan.com/Libraries/Dynamic_Document_Library/6-28-11_Yolo_Bypass_Flood_Protection_Presentation.sflb.ashx

Center for Watershed Sciences. Nigiri Project. https://watershed.ucdavis.edu/project/nigiri-project-growing-rice-and-salmon-floodway

Center for Watershed Sciences. Sacramento River Flood Control Project. https://watershed.ucdavis.edu/project/sacramento-river-flood-control-project

 

Posted in flood, Floodplains, Planning and Management | Tagged | Leave a comment

Reconciling conservation and human use in the Delta

This view of a duck hunting club in Suisun Marsh shows both a highly modified environment and reflects its potential for being managed as a reconciled ecosystem. Photo by P Moyle.

This view of a duck hunting club in Suisun Marsh shows both a highly modified environment and reflects its potential for being managed as a reconciled ecosystem. Photo by P Moyle.

By John Durand, Peter Moyle, and Amber Manfree 

In a previous blog, we presented a Grand Scheme for habitat conservation in the North Delta Arc (the Arc). This follows up on our earlier broad vision for recreating a Delta more friendly to its native species.  In this essay, we give philosophical and historical reasons to approach habitat conservation on the regional scale of the Arc, using reconciliation ecology as our guide.

The Sacramento-San Joaquin Delta has been extensively altered over the past 150 years. Major changes include manipulation of river flows, alien species invasions, conversion of wetlands to agriculture and, most recently, climate change. Changes have been incremental and slow enough that successive generations of Delta residents, fishermen, scientists, and managers have not seen the full extent of transformation. Each generation assumes the conditions they encounter are not much different from those of the recent past. This problem of slowly shifting baselines means that our understanding of historical conditions shifts with changing conditions, because the change is difficult to accept and because we cannot directly observe what conditions were like in the more distant past (Pauly 1995; Papworth et al. 2009).

A recent review of anthropological studies, early travelogues, and scientific surveys of the Delta gives a better sense of the transformation. The Delta originally was a place where the sky darkened with migratory waterfowl in fall, where salmon runs crowded tributary rivers, tule elk browsed on oak-topped natural levees, and delta smelt were a common prey for fishes and birds. Flows in the Sacramento and San Joaquin Rivers were highly variable, but predictable in pattern, with winter floods and summer droughts. Such aspects of the historic landscape were gradually lost with marsh reclamation, damming, levee construction, water diversions and pollution from mining, agriculture, waste water and urban runoff. It is impossible to restore natural conditions—little quality habitat remains, connectivity among habitats has been lost, and many historically abundant species are extinct or their populations are greatly reduced in number.  Native species have been largely replaced by alien plant and animal species such as largemouth bass, Mississippi silversides and Brazilian waterweed. These new arrivals are abundant because they are adapted to conditions created by the expanding human-altered landscape.

Governor Brown’s EcoRestore initiative aims to provide habitat restoration projects to reverse the decline of native species and create habitat that functions to support native species . We agree that it is imperative that some of our pre-19th century historic natural legacy be maintained. Given the depth of transformation, restoration to perceived “baseline conditions” is impracticable. That historic Delta is lost.

As a workable alternative, we promote the idea of reconciling current land uses with desirable ecological outcomes. A reconciliation approach to Delta conservation offers opportunities to recapture lost ecological functions that support threatened species. It involves creative management of the current landscape to balance benefits for fish, waterfowl, food webs, and human uses. This idea can help to manage the emergence of novel ecosystems globally, landscapes with new conditions and  combinations of organisms with no historical analogue, but which provide valuable and viable species conservation opportunities, as well as human benefits (Rosenzweig 2003; Hobbs et al. 2006).

 

 

This map of North and Central Sacramento-San Joaquin Delta shows reserve networks across the North Delta Arc of Habitat, and the Yolo Bypass Floodplain. Click link or image for detailed information on the reserves. View the full map here.

This approach may involve some dramatic and expensive actions that involve earth moving to recreate marshes and meandering channels. But more often, it involves working with farmers, duck club owners, anglers, and other stakeholders to adjust breaching of levees and the operation of tidal gates to facilitate the movement of water across the landscape.

The Nigiri project on the Yolo Bypass illustrates this concept.  Here, young salmon are raised in rice fields before being released to the Delta and before farmers need to plant, with involvement of local farmers, state agencies, county government, CalTrout, and UC Davis. But Nigiri is not the only reconciliation project in the Delta. In Suisun Marsh, the Potrero Duck Club, historically operated as a private hunting club, is being managed to promote not only water fowl, but as an incubator to create food for the larger aquatic ecosystem. Although these sites differ from historical conditions, they effectively capture the ecological functions of an earlier Delta that are largely lost: they grow and disperse food, act as nursery habitat for young fish and provide food for nearby wildlife. While opportunities to re-create the Delta’s original habitats have faded, opportunities have arisen to create new habitats that serve human needs, provide ecosystem services, and support native fish and wildlife. We see wild lands being integrated with managed lands as the most productive way to create a reconciled Delta.

In future essays, we will explore the use of reconciliation ecology to several important sites in the Delta. These include: Meins Landing, Montezuma Wetlands, Potrero Club, Lindsey Slough, Denverton Slough, Blacklock Pond, Liberty Island, North Liberty Mitigation Bank and Beaver Ponds, Prospect Island and Roaring River.

John Durand is a researcher specializing in estuarine ecology and restoration at the UC Davis Center for Watershed Sciences. He oversees projects in the north Delta Arc of habitat including the Cache Lindsey complex and Suisun Marsh.  Peter Moyle is a UC Davis Professor Emeritus of fish biology and an associate director of the Center for Watershed Sciences. Amber Manfree is a postdoctoral researcher with the UC Davis Center for Watershed Sciences.

Further reading

Hobbs RJ, Arico S, Aronson J, Baron JS, Bridgewater P, Cramer VA, Epstein PR, Ewel JJ, Klink CA, Lugo AE, et al. 2006. Novel ecosystems: theoretical and management aspects of the new ecological world order. Glob. Ecol. Biogeogr. 15:1–7.

Mount J, Bennett W, Durand J, Fleenor W, Hanak E, Lund J, Moyle P. 2012. Aquatic ecosystem stressors in the Sacramento–San Joaquin Delta. Public Policy Inst. Calif.

Moyle PB, Light T. 1996. Fish invasions in California: do abiotic factors determine success? Ecology 77:1666–16670.

Nichols FH, Cloern JE, Luoma SN, Peterson DH. 1986. The modification of an estuary. Science 231:567–567.

Papworth S k., Rist J, Coad L, Milner-Gulland E j. 2009. Evidence for shifting baseline syndrome in conservation. Conserv. Lett. 2:93–100.

Pauly D. 1995. Anecdotes and the shifting baseline syndrome of fisheries. Trends Ecol. Evol. 10:430.

Rosenzweig ML. 2003. Reconciliation ecology and the future of species diversity. Oryx 37:194–205.

Sommer TR, Nobriga ML, Harrell WC, Batham W, Kimmerer WJ. 2001. Floodplain rearing of juvenile Chinook salmon: evidence of enhanced growth and survival. Can. J. Fish. Aquat. Sci. 58:325–333.

Whipple A, Grossinger RM, Rankin D, Stanford B, Askevold R. 2012. Sacramento-San Joaquin Delta historical ecology investigation: Exploring pattern and process. Richmond, CA: San Francisco Estuary Institute-Aquatic Science Center Historical Ecology Program Report No.: 672.

Posted in Conservation, Delta, reconciliation | Tagged , , | 1 Comment

California’s Wettest Drought? – 2017

plot_esi-6

By Jay Lund

Wet.  After five years of drought, most of California finally has become wet.  The mountains are exceptionally wet and covered with snow.  The state’s reservoirs are fuller than their long term average (with a few exceptions).  Flood control structures are being employed, some for the first time since 2006.

We can now better understand the balance needed for California’s water system – which must operate for many sometimes-conflicting purposes in a climate with wild swings in water availability.  Every year, California must operate for drought, flood, public and ecosystem health, and economic prosperity (or at least financial solvency).

Where is California’s Drought today?

Here are today’s numbers:

2017 will not be a surface water drought for California.  Precipitation and snowpack in much of the state already exceeds that for an entire average water year.  And we still have two months to go in California’s wet season.

Despite these wet conditions, California has remnants of drought, some of which will persist for decades.  Some Central Coast reservoirs remain very low.  Groundwater in the southern part of the Central Valley remains more than 10 million acre-ft below pre-drought levels.  Most of the groundwater deficit is in dry parts of the San Joaquin and Tulare basins, which could take decades to recover – with long-lasting effects on local wells.  The millions of forest trees which died from the drought will need decades to recover, if the warmer climate allows.  Native fish species, already suffering before the drought, are in even worse conditions today.

Drought indicator myths

Given the variety of drought impacts and conditions, many “drought indicators” seem Quixotic and distract policy and management discussions.

The US Drought Monitor is a common drought indicator, based mostly on soil moisture – designed mostly to indicate drought for rain-fed agriculture.  This index is most useful for stress to forests and un-irriggated pasture and crops, which not California’s biggest drought issue.  California relies much more on large reservoirs and aquifers, which allow crops and cities to survive otherwise California’s beautiful and devastating dry summers.  The US Drought Monitor, while a convenient general public service, is misleading for California’s most common drought issues.  National statistics often have such regional problems.

Still less useful, in my mind, is the idea of a “snow deficit” accumulating over drought years.  Snowpack in California physically resets to zero each summer as snow melts – Accumulating snow deficit over years has no physical meaning – and little management meaning.  Real drought deficits do accumulate as aquifer overdraft, reservoir drawdown, dry soil, and cumulative impacts to forest and fish populations, which can take years or decades to recover.  Less snow last year does not reduce water this year except for reduced storage in reservoirs or aquifers – where water deficits are managed and more properly measured or estimated.

Drought indicators should have physical and management meaning, or are more likely to mislead and confuse.  Fortunately, California is more successful with managing droughts than developing drought indicators.

Moving forward

Although the drought is largely over, California remains a dry place.  As a big dry place, some parts of California can be in drought while others are in flood (contrasting Santa Barbara and Sacramento today).  Local and regional effectiveness and adaptability are vital for water management in California.

The end of drought does not solve California’s most important water problems. Groundwater sustainability (implementing SGMA), Sacramento-San Joaquin Delta sustainability, effective ecosystem management, and fixing rural drinking water systems remain major problems.  Solving these issues involves difficult water accounting, integrated management, and finance issues at local and statewide levels.

Progress on these long-term issues is harder and requires more persistence than making progress during the urgency of a drought.  But we should reserve “drought” management for unusually dry conditions, or risk losing the public confidence that democratic governments and effective water utility management require.

Leaving the drought, California has a clearer picture of the important work that remains to be accomplished. The next drought (and flood) could be coming soon.

Jay Lund is a professor of civil and environmental engineering and director of the Center for Watershed Sciences at UC Davis.

Some further reading

The banality of California’s ‘1,200-year’ drought

You Can’t Always Get What You Want – A Mick Jagger Theory of Drought Management

Is shorting fish of water during drought good for water users?

Lund, J., “After drought, California urgently needs to focus on big picture of water management,” Sacramento Bee, Op-Ed, 29 January 2017.

Posted in California Water, Drought, Uncategorized, Water Supply and Wastewater | Tagged | 16 Comments

Episode 3: “Unraveling the Knot” Water Movement in the Sacramento-San Joaquin Delta – Managing Flows

By William Fleenor, Amber Manfree, and Megan Nguyen

Delta water diversions have significant effects on flows and water quality within the Delta. Diversions can re-direct river flows and draw salt water inland from the sea, impacting water quality and the environment. Episode 3 explores how water diversion quantity affects in-Delta flow directions and quantities. This episode also looks at how in-Delta gates and barriers are used to improve in-Delta flows and water quality.

Some lessons:

  • The two biggest in-Delta diversions are the State Water Project (SWP) and the Federal Central Valley Project (CVP) near Tracy. CVP exports are fairly constant during the irrigation season and draw water from south Delta Channels, while the nearby SWP exports occur in big gulps, taking water on high tides into Clifton Court Forebay.
  • The Delta Cross Channel (DCC) near Walnut Grove helps move Sacramento River water to pumps in the south Delta. Open DCC gates direct additional flow southward into the central Delta, moving fresh water from the northern to southern Delta, supplying fresh water to the pumping plants. Large flows of Sacramento River water toward these diversion pumps reverse net flows in Old and Middle Rivers in the southern Delta.
  • Gates and flow barriers in the southern Delta keep lower-quality San Joaquin River water away from the pumps and improve south Delta water quality.
  • Heavy pumping in the southern Delta can lower water elevations in local channels so much that farmers cannot siphon water onto their fields, forcing farmers to pump water. Agricultural barriers during higher pumping months keep the water elevation high enough for siphoning in some Delta channels (Old River, Grant Line Canal and Middle River).
  • The Head of Old River Fish Barrier, on the San Joaquin River, directs migrating fish downstream rather than toward the pumps and improves export water quality by reducing flows of lower-quality San Joaquin River water to the pumps.
  • Agricultural barriers and the fish barrier along the San Joaquin River increase net negative flows in Old and Middle Rivers.

Flows change in the north Delta due to the Cross Channel and in the south Delta due to barriers and the Cross Channel. The overall effect does not change net outflow, but shifts net outflow contributions from the Sacramento River to the San Joaquin River. Unnatural water circulation from north to south entrains fish in the pumps and the southern Delta, and disrupts natural gradients between the rivers and ocean that cue fish movements.

William Fleenor is a senior researcher who specializes in hydrodynamics and hydraulic modeling at the UC Davis Center for Watershed Sciences. Amber Manfree is a postdoctoral researcher with the UC Davis Center for Watershed Sciences. Megan Nguyen is a GIS researcher at the Center for Watershed Sciences.

Further Reading

A Tale of Two Deltas: A Comparison of Transport Processes in the Predevelopment and Contemporary Delta (Jon Burau, as summarized by Maven, 2016)

Episode 1: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Introduction

Episode 2: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Tidal Forces

Episode 3: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Managing Flows

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Episode 2: “Unraveling the Knot” Water Movement in the Sacramento-San Joaquin Delta – Tidal Forces

By William Fleenor, Amber Manfree, and Megan Nguyen

Tides are the biggest driver of Delta flows, and in Episode 2 we look at their impacts in different locations under a variety of inflow conditions.  Tides have a twice-daily cycle in the region, with a range of about six feet at Martinez.  In the first part of the animation, we remove all in-Delta controls and diversions and fix inflows at a common moderate early summer level to isolate effects of tidal forces from those of inflows, gates, and export diversions.  When the moon and sun are more aligned (full and new moon periods), tidal magnitude is greater.  Distances to the moon and sun influence tidal magnitude as do winds and barometric pressure.  Winds and barometric pressure are fixed in this animation.

The main lessons are:

  • Tidal ‘sloshing’ greatly exceeds Delta outflows. Tidal flows can be 400,000 to 600,000 cubic feet per second (cfs) at Martinez, while net outflows are often a few thousand cfs.
  • A given amount of tidal force exists at the Golden Gate, and a change in one location in the estuary has effects throughout.
  • Sacramento and Stockton Deep Water Ship channels have been deepened and straightened with dredging, which increases tidal flows up these channels and decreases tidal flows (and mixing) in other Delta channels.
  • Higher Spring tides, occurring when the sun and moon are more aligned, add volume to the Delta and by themselves can produce brief net negative flows on Old and Middle Rivers.

The second part of the animation varies Delta inflows to demonstrate how inflows and tidal forces interact, again without major Delta diversions.  We look at inflows lower than those previously shown, representing late summer, and two higher inflow levels.  Finally, we show effects of a flood pulse moving through the Yolo Bypass. The main lessons are:

  • Lower inflows increase tidally driven negative flows through Old and Middle Rivers.
  • As inflows increase, tidal influence diminishes from the upstream direction and net negative flows from the tides cease in Old and Middle Rivers.
  • Flood flows through the Yolo Bypass greatly reduce tidal influences.

Modeling produces a better understanding of natural and anthropogenic influences on Delta flows, which can help improve planning and policy-making for the Delta.

Coming next in Episode 3 is an examination of flow and salinity effects of major water diversions from the Delta.

William Fleenor is a senior researcher who specializes in hydrodynamics and hydraulic modeling at the UC Davis Center for Watershed Sciences. Amber Manfree is a postdoctoral researcher with the UC Davis Center for Watershed Sciences. Megan Nguyen is a GIS researcher at the Center for Watershed Sciences.

Further reading

A Tale of Two Deltas: A Comparison of Transport Processes in the Predevelopment and Contemporary Delta (Jon Burau, as summarized by Maven, 2016)

Episode 1: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Introduction

Episode 2: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Tidal Forces

Episode 3: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Managing Flows

Posted in Delta | Tagged , , | 5 Comments

Episode 1: “Unraveling the Knot” Water movement in the Sacramento-San Joaquin Delta

By Bill Fleenor, Amber Manfree, and Megan Nguyen

In 2010, John DeGeorge of RMA, Inc used animated model results to illustrate specific flow and water quality issues in the Delta to the State Water Board. The Center for Watershed Sciences, working with John and using RMA software, has assembled a series of narrated animations to show some major forces acting on Delta flows and water quality. The goal is to “Unravel the Knot” of California’s Delta – at least some it – in terms of flow and water quality.

In Episode 1 we start with general background of California water and the role and significance of the Delta.

The main points are:

  • The Sacramento-San Joaquin Delta watershed covers 40% of California and most of the water used in the state by humans. Rain and snowmelt feed rivers, supporting a wide variety of habitats and large populations of wildlife.
  • The Delta is a critical hub in California’s water infrastructure, conveying fresh water from the wetter northern part of the state to farms and cities in the drier south. Water deliveries supporting intensive agriculture and supplying urban areas have spurred enormous economic growth. This has come with significant environmental tradeoffs.
  • The Delta is largely tidally influenced, and potential for rapid large-scale flooding of sunken island interiors, combined with sea level rise impacts, threaten its use as a conduit for water delivery, and raise the possibility of sudden, sweeping environmental changes.
  • Understanding how water moves in the Delta can help in planning for the future. This video series examines each component of water movement separately, and explains how shifts in water management, levee failure, and sea level rise might change the Delta and California’s water supply in the years ahead.

William Fleenor is a senior researcher who specializes in hydrodynamics and hydraulic modeling at the UC Davis Center for Watershed Sciences. Amber Manfree is a postdoctoral researcher with the UC Davis Center for Watershed Sciences. Megan Nguyen is a GIS researcher at the Center for Watershed Sciences.

Further Reading

A Tale of Two Deltas: A Comparison of Transport Processes in the Predevelopment and Contemporary Delta (Jon Burau, as summarized by Maven, 2016)

Episode 1: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Introduction

Episode 2: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Tidal Forces

Episode 3: “Unraveling the Knot” – Water movement in the Sacramento-San Joaquin Delta – Managing Flows

Posted in Delta | Tagged , , | 8 Comments

Indicators of a drought ending in northern California

sacramento-weir-flowing-january-2017

Sacramento Weir flowing into Yolo Bypass, January 2017, for first time since December 2005, photo: Jay Lund

Jay Lund

Droughts are common in California, a large, generally dry, and hydrologically complex place.  So it is hard to rely on a single index of the end or beginning of a drought.  A single storm is rarely enough to end a drought in California, especially a long drought like the one that seems to be mostly ending now.  Regular hydrologic statistics can be used as indicators of drought, but these do not do justice to how droughts actually end (or begin).

Here are some less formal indicators that the current drought is ending, although in some ways this drought and its impacts will endure for decades to come.

  • Guerneville on the Russian River has flooded. This is usually about the first town to flood in California. Guerneville floods so often that I wonder how it is still there or has not become just a summer camp!
  • Van Sickle Island in the Delta floods. Usually this is the first Delta island to flood.  It has some of the Delta’s lowest and weakest levees, but has mostly ducks for residents.
  • Most reservoirs are full, or at least filled to levels where they are kept partially empty for possible floods.
  • Weirs and bypasses are actively draining the Sacramento Valley. The mighty Fremont Weir has taken control of the Sacramento River, flowing at almost 200,000 cfs.  The Sacramento Weir, completed in 1916, is open for the first time since December 2005.  Awesome!
  • Skiing exists, and seems relatively good. Count the skis racks on cars heading East on Friday afternoons, or heading West at the end of the weekend.  Count the conversations about ski lift lines and ticket price strategies at work on weekdays.
  • My roof leaks and the kids scoff at raking wet leaves. We all have our own personal drought indicators.
  • I feel a need to remind people how dangerous flowing water and floods are.  Don’t wade or drive into moving water, even if it is shallow.  Be careful.

California must now deal with the aftermath of the drought and preparing for the next one, even as some parts of California still suffer from the drought and some areas worry about flooding.  Hopefully southern California, especially poor Lake Cachuma, benefits from storms in the weeks to come.  We live in a complex place.  But it works better if we work at it.

So, back to my roof and putting my kids to work.  Another storm is coming later this week.

p1112753-mov

Fremont Weir, several feet under water, taking water from Feather and Sacramento Rivers into Yolo Bypass, January 2017. Flow about 180,000 cfs over 2 miles of weir.  Don’t enter if you value your life – very dangerous.

Jay Lund is a professor of civil and environmental engineering and director of the Center for Watershed Sciences at UC Davis.  He came to California just after the 1986 flood and in time for the 1988-92 drought.

Further reading

Sacramento River Flood Control Project Weirs and Flood Relief Structures, by California Department of Water Resources, 2010.

Lund, J.R., “Flood Management in California,” Water, Vol. 4, pp. 157-169; doi:10.3390/w4010157, 2012.

Suddeth, R. and J. Lund “Multi-Purpose Optimization of Reconciliation Ecology for an Engineered Floodplain – Yolo Bypass, California,” San Francisco Estuary and Watershed Science, Volume 14, Issue 1, 2016.

 

Posted in Drought, Uncategorized | Tagged | 6 Comments

Tails of California’s Drought

plot_esi-4by Jay Lund

Storms are filling reservoirs, building snowpack, and flooding in ways not seen since the most recent California drought began in 2012.  The state’s reservoirs today contain 1.2 million acre-ft more water than the long-term average for this time of year (the first time above average in 6 years).  Two years ago reservoir storage was 8 million acre-ft below average.  Most of the state’s precipitation and snowpack are far above average, boding well for this water year.

In terms of surface water, most of California is no longer in drought.  The accumulated reservoir and soil moisture deficits of the last 5 years have been filled in most of the state.  Only Santa Barbara, supplied by Lake Cachuma (currently 11% of average storage), faces major urban drought.  Most water shortages last year, from inability to move water across the Delta to the southern Central Valley, seem to be overcome this year.   Today, San Luis Reservoir contains 93% of its long-term average storage for this time of year. Unless the remainder of the year is incredibly dry and warm, 2017 will not be a drought for surface water, with perhaps a few local exceptions.

For groundwater, aquifers in northern California should be doing quite well.  They were not terribly depleted during the drought and have wetter conditions to more readily refill them.  For the southern Central Valley and southern California, wetter conditions will reduce pumping and increase recharge.  But these regions have less surface water to recharge aquifers, and the southern Central Valley typically has net aquifer overdraft in all but the wettest years. Some southern Central Valley aquifers might never recover to pre-drought levels.

Droughts often have long tails, especially for extended droughts over such a large state.  Groundwater in the southern Central Valley might rise some, but will remain low, keeping some wells stranded and increasing pumping costs for years and perhaps decades.  Drought damage to California’s forests could require decades to recover, or, if higher temperatures persist, the ecology of many forests might shift to new normal conditions.  Native fish also will likely need years to recover – with impediments from already depleted numbers and highly disrupted and altered ecosystems.

Droughts usually bring water shortages, but not all water shortages are from drought.  Some speak of drought as permanent for California.  But, it is better to think of California being a dry place with permanent water shortages (except in unusual wet years), which is also prone to drier than average years, which are droughts.  California must reconcile itself to being a dry place and some long-term water shortages.  It must also prepare for periods of drier than average conditions with greater shortages and costs, which are droughts.

For policy-makers the distinction is important. If every year is labeled a drought crisis or emergency, then “drought” loses important meaning and urgency needed to motivate and conserve to higher levels in drier conditions.  In addition to managing during drought, we must manage other years for normally dry conditions, which will often include deliveries less than desires and storing water and suppressing some demands in preparation for still-drier drought conditions.

As this drought goes out the door, it will say, in the words of our former Governor, “I’ll be back.”

Jay Lund is a professor of civil and environmental engineering and director of the Center for Watershed Sciences at UC Davis.

Some further reading

You Can’t Always Get What You Want – A Mick Jagger Theory of Drought Management

Improving mandatory State cutbacks of urban water use for a 5th year of drought

The banality of California’s ‘1,200-year’ drought

Why utilities shy from mandatory water saving during a drought

Is shorting fish of water during drought good for water users?

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Out With the Old Drought and In With the New?

By Jay Lund

We are just a few months into this year’s wet season, and progress has been great.  Statewide, California is about 800,000 acre ft below average surface water storage for this time of year.  California’s water year began with surface storage about 3 million acre ft (3 full Folsom Reservoirs) less than historical averages for October 1.  This was already a great improvement from the previous year’s being 8 maf below average in January 2016.

While we are still in early days for this water year (October 2016-September 2017), California precipitation is above average for this time of year, 178% of average in Sacramento Valley, 145% in San Joaquin Valley, and 127% in Tulare Basin.  Southern California is further behind, but has gotten some good storms in recent weeks.  Overall snowpack is 72% of average for this time of year (perhaps reflecting warmer conditions).  If no more precipitation fell in northern California, with more than 3 months left in the wet season, total precipitation would be a bit less than the 2015 water year.

But drought remains in some parts of California.  The Santa Barbara area is at great risk now, with its Lake Cachuma still at 8% of capacity and 11% of average storage for this time of year.  But continued wetness in southern California might resolve this.

Fish and forests throughout the state, and groundwater south of Delta will have lingering effects from previous years of drought if most of California continues to be wet.

If this year continues to be mostly wet, water shortages are still likely for some parts of California.  The drought and growing demands have left some parts of California, particularly the southern Central Valley, in an largely permanent structural drought.  Here, there is more water demand than water available.  This condition developed from growing water demands for increasingly profitable agriculture and for growing cities encountering reduced ability to import water from the Delta due to endangered species and Delta water quality.  This gap will worsen as restrictions ending groundwater overdraft come to bear (to provide more drought security for profitable agriculture) and as environmental flow requirements increase.

Overall, drought conditions continue to lessen in most of California, but it is still early days.  Even with continued wet conditions the drought could worsen in some areas, such as Santa Barbara, even as it disappears from other areas.  And the previous years of drought will have a long tail of impacts in many areas, and innovations from the drought, such as groundwater management, need to be with us for a long time.

Some lessons from this drought?

You Can’t Always Get What You Want – A Mick Jagger Theory of Drought Management

The banality of California’s ‘1,200-year’ drought

Improving mandatory State cutbacks of urban water use for a 5th year of drought

Jay Lund is Director of the Center for Watershed Sciences and a Professor of Civil and Environmental Engineering at the University of California – Davis.

Two notes of celebration for 2016!

First, CaliforniaWaterBlog.com ends 2016 having surpassed 800,000 views since 2011, with almost 8,500 subscribers.  Thanks to everyone!  We hope our short essays are useful, or at least entertaining.

Second, UC Davis now has a professional master’s degree program in Environmental Policy and Management, geared especially for students with science or engineering backgrounds seeking leadership careers in policy and management.  This program has been too long in coming, but has a bright future at the world’s strongest overall environmental campus.  For more information, see: https://epm.ucdavis.edu/

 

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Shadow theater and data management for the Delta – a video

By Amber Manfree

Data and data management are persistent concerns for the Delta and California water more generally. Data Wars: A New Hope, a shadow puppet play on the subject, was shown at the 2016 Bay-Delta Science Conference in Sacramento. The challenge of the Conference’s theme, “Science for Solutions: Linking Data and Decisions,” is illustrated by characters such as a lonesome marsh wren and a striped bass with a Boston accent.

The video highlights a fundamental problem facing Delta stakeholders: how to make sound decisions based on science when no one seems to agree on objectives. It lends some comic relief to a seemingly intractable issue. It was also fun to create.

Over a dozen scientists collaborated on this work, including voice-overs by Bruce Herbold and Peter Moyle and puppet design by Micah Bisson and Rosemary Hartman. Musical accompaniment was arranged and recorded by Kyle Phillips. Amber Manfree, an avid shadow puppeteer, directed the project. Video production and technical advice from Megan Nguyen translated the play to video.

Thoughts on Communicating Science

Packaging science to appeal to a broad audience is critical, yet scientists and technical people rarely have training in communication. Those who create scientific content can improve communication in two ways: by honing skills and collaborating with others.

1. Gain Skills. Even scientists can develop and improve artistic skill, but it takes attention and effort. Like ice skating, slick graphics require by many, many attempts. Cultivating a habit of sketching in field notebooks or hand-drawing charts before generating them digitally is one way to get started. Paying attention to and mimicking well-designed graphics aids rapid advances. Once basic graphics have been laid out, they can almost always be improved with feedback from reviewers and touch-ups with graphic design software such as Adobe Photoshop, Illustrator, or GIMP/GNU. Online tutorials are widely available.

2. Collaborate. Expand your network and collaborate with talented visual communicators, secure funding to support them, bring them into your fold, and learn from them. The Bay-Delta Science Conference Art Committee worked to pair artists with scientists to create original works for the conference. This expanded how scientists think about communication, and expanded how artists approached their work.

Amber Manfree is a postdoctoral researcher with the UC Davis Center for Watershed Sciences. When she isn’t sampling fishes, data gazing, or researching, she can be found designing materials that join art and science.

Further Reading

Some examples of art-science collaborations:

http://artsciencefusion.ucdavis.edu/

http://www.lasertalks.com/

http://fsml-art.blogspot.com/

https://www.exploratorium.edu/arts/artist-residence

KeckCAVES: http://keckcaves.org/

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