Water Resources and Hydrology of California

Chapter SixRediscovering the Golden State:

California Geography

Chapter Six Vocabulary

Reclamation

Runoff

Spanish Era

Stream flow

Water allocation

Water delivery systems

Water diversions

Water pricing

Watershed

Water budget

Water colonies

Water pollution

Water projects

Water rights

Water table

William Mulholland

Hydrologic cycle

Inland drainage

Irrigation

Native Americans

Peak discharge

Permeable

Porous

Aquifer

California Doctrine

Drainage basin

Efficiency and conservation

Evapotranspiration

Flood control

Freshwater environments

Ground water

Hydraulic mining

Lag time

Multipurpose reservoirs

Overdrafting

Per capita use

California Hydrology

• It takes a combined knowledge of geology, geomorphology, weather and climate, and plat communities to understand California Hydrology.

California Hydrology

• Humans have a huge impact on California’s water systems.– Engineers, and

chemists help to distribute water through the state for diverse uses.

– Social scientists-economists, lawyers, politicians work on problems related to current and future use.

Lake Mead

California’s Hydrology• Water plays a vital role in California’s

natural and human landscapes.– Geographers and hydrologists work with

connections and relations in California’s vast water systems.

Los Angeles Aqueduct

Geographers and Hydrologists

• Work with the relationships between:– Identify many

different groups with interests in the water system

– Land use planners– Policy makers

Geographers and Hydrologists

• Work with the water system to:– Help the public make

informed decisions about California’s water future

– Improve the quality of life and living environments for all citizens

– Educate the public– Study an ever

changing waterscape

Natural Waterscapes

• Input and California’s Water Budget– 200 million acre-feet of

water falls on California as precipitation

• 1 acre-foot equal to about 320,00 gallons

• About how much one or two families use per year

Natural Waterscapes

• Average precipitation only about 23 inches– 79% of average for US

• North gets more, south gets less

• West gets more, east gets less

Natural Waterscapes

• 80% of precipitation falls November-March

• Mediterranean Climate!– 2/3 falls in Northern

California• About 75 inches a year

in north• About 10 inches a year

in south• About 2 inches a year in

deserts

Natural Waterscapes

• Year to year brings extreme variation.– Moisture comes from

storms blown in off the Pacific Ocean

– Water flows in from Oregon

– Water from the Colorado River flows in

• El Nino and La Nina• Localized droughts

Natural Waterscapes

• More than 200 million acre-feet that is not stored is lost to evaporation or runoff.– 150 million acre-feet of

all incoming water is lost to evapotranspiration

– 50 million acre-feet is lost to runoff

• ¼ of California’s water budget

Santa Ana River

Natural Waterscapes

• 1/3 of runoff is captured and used for human uses– Only a little runs off

unused• Usually during bad

storms

Natural Waterscapes

• Humans interfere with California’s natural hydrological cycle– Rerouting,

pumping, and distributing

– 40 million acre-feet– For farming, urban

uses

Natural Waterscapes

• Capture about 20 % of all water in California before evaporation– ½ for human uses– ½ lost to evaporation

• So 10% of California’s water is lost to evaporation

Natural Waterscapes

• Human influence has complicated an otherwise simple water budget– Water budget:

• A water budget states the rate of change in water stored in an area, such as a watershed, and is balanced by the rate at which water flows into and out of the area.

• An understanding of water budgets and underlying hydrologic processes provides a foundation for effective water-resource and environmental planning and management.

Natural Waterscapes

• Output– Precipitation either evaporates or is stored in

the ground, snow pack, or behind barriers (human or natural.)

• What remains is runoff

Natural Waterscapes

• Output– Groundwater comes

back to the surface through evapotranspiration and springs

– Reemerging groundwater contributes to the base flow of many of California’s streams Whitmore Hot Springs

Natural Waterscapes

• Output– On impermeable

surfaces or saturated ground:

• Excess water must evaporate or runoff

– In California– Fall-rain soaks in– Spring-rain falls on

saturated ground» slides

La Conchita

Natural Waterscapes

• Output– Snowmelt

• Captured• Measured in the

Sierra Nevada’s April 1st

– Flood control?– Storage measures?

Natural Waterscapes

• Evaporation and Water Demands– Water Deficit = total annual

potential for evaporation usually exceeds actual precipitation

– Most of the year California is in a water deficit

• Except for north of San Francisco

– Surplus in the winter– Deficit in the summer

Natural Waterscapes• Groundwater

– Fills pore spaces and saturates permeable and porous regolith, soil, and rocks scattered across about half of California

• Usually found in aquifers in valleys– Some under the volcanic plateau in the north– Some in granite

Natural Waterscapes

• Groundwater– At one time 450 large and

small ground water reservoirs

– 1.3 billion acre-feet (cover the state in 13 feet of water-Lake Tahoe would cover the state with one foot if emptied)

– Artesian wells and fountains were common

• Now many depleted – 850 million acre-feet remain

• Only 17% accessible

Natural Waterscapes

• Groundwater– Only about

50 large groundwater reservoirs left

• All being used

Natural Waterscapes

• Groundwater– Central Valley– 15,000 square miles

water– Aquifers within the

water table• 400 to 4000 feet deep• Recharged annually by

runoff from rain and snow

– Take faster than it can recharge

– Take water that would recharge

Natural Waterscapes

• Groundwater– Last century

aquifers affect by overdrafting, pollution, subsidence, and salt water intrusion

California is only one of two states left that has yet to enact a comprehensive statewide groundwater management system. Currently there are no controls over the amount drawn from underground aquifers.

Natural Waterscapes

• Runoff– If water is not

evaporated or stored it must runoff

• 35% of precipitation runs off into oceans or inland basins

• Variable in time and space

– More in north than south

– More in winter/spring– More in El Nino

years/less La Nina

Natural Waterscapes

• Runoff– 40% of the states

runoff heads for San Francisco Bay

– Where the Sacramento and San Joaquin Rivers meet

• Sacramento River flows out of the Trinity Mtns.

• San Joaquin River flows out of the Sierra Nevada Mtns.

– The Delta is made up of 700 interconnected waterways.

Delta

Natural Waterscapes

• Runoff– 40% San

Francisco Bay– 40 % Northern

California– 20 % all of

Southern California

• Where the population is Russian River

Natural Waterscapes

• Runoff– Gauging stations

• Along all substantial waterways

• Hydrographs used to analyze stream flow patterns

• Plan and manage water storage and flood control

Natural Waterscapes

• Runoff– Perennial versus intermittent– Coastal streams-just get rainfall drainage

Intermittent stream

Northern and Central California Rivers and Streams

• Northern and Central California have the greatest discharge areas

Northern and Central California Rivers and Streams

• Trinity River as an example– Drains a mix of direct

rainfall and delayed snow melt

• Higher discharges from winter to spring

– Eventually flows into the Klamath River

• Klamath is the largest drainage basin in California

Northern and Central California Rivers and Streams

1. Klamath River2. Sacramento River3. Eel River4. Feather River5. Smith River

• Eel and Smith peak winter• Sacramento and Feather peak later, draining snow melt

• All flowed and flooded into the Central Valley until the great flood control projects.

Northern and Central California Rivers and Streams

• Kings, Tule, and Kaweah Rivers– All drain inland– Tulare Lake

• Was 4 times bigger• Used to flood and

connect to Buena Vista Lake

Rivers and Streams of Southern California

• Los Angeles River– Very small in comparison

to northern California, 1000 acre-feet at peak in winter

• Mojave River– Drains inland and soaks

into the desert

• Colorado River– Exotic, source out of state,

flows along border

http://upload.wikimedia.org/wikipedia/commons/0/07/Los_Angeles_River_Glendale.jpg

Rivers and Streams of Southern California

• Owens River– Once filled Owens

Lake, largest in California at one time

– Flowed past the lake and filled other desert basins

– Today: entire river redirected to Los Angeles

– Dried up Owens Lake and the river

Northern versus Southern California

• Stark contrast between wet north and dry south

• Much of Northern California’s water is stored and controlled too– Massive state water

projects– 18% of the least

accessible protected by Scenic Rivers Program

Lakes

• Lake Tahoe largest– Shared with

Nevada– Can only use about

6 surface feet

• Clear Lake– Largest entirely in

California

Lakes

• Goose, Eagle, and Mono– All large eastern

lakes– Inland basins

Lakes• Surprise Valley,

Honey Lakes– Dry inland basins– Alkaline basins,

saline sinks, playas– Fill with water in wet

years

Wet and Dry Cycles

• 1861-62 inundated– Lake 60 miles across formed in the Central Valley

• March 1938– 87 dead, 290,000 acres flooded

• 1955, 1964-65, 1997, north• 1969, 1978, 1983, and 1992 south

– California is a laboratory for the study of how a diverse variety of drainage basins respond to floods and droughts.

– How people modify drainage.

How Floodwaters Accumulate

• Precipitation gradually accumulates behind natural barriers and in the soil to recharge ground water tables– The surface becomes saturated and slowly

releases water as runoff– Runoff accumulates in channels and streams– Peak flows are produced– Can lag behind periods of heavy precipitation