The Santa Clara valley aquifer is a groundwater aquifer located in the southern San Francisco Bay Area. The geology of the Santa Clara valley aquifer consists of a complex stratigraphy of permeable and impermeable units. [1] Management of aquifer resources is associated with the Santa Clara Valley Water District.
In the early parts of the 20th century the Santa Clara Valley was a vegetable and fruit growing region. Ground water was pumped heavily and led to the Santa Clara valley to be the first region recognized to be affected by land subsidence in the 1940s. [2] Between 1912 and 1966 artesian pressure levels dropped more than 200 ft (61 m). The decreasing pressure heads resulted in land subsidence of up to 15 ft. (4.6 m). [3] Santa Clara Water Valley District and other water purveyors have work to refined management practices which have halted land subsidence. During the 1960s due to the substantial decrease in ground water the SCWVD began to import surface water. [4] The Central Valley Project and the California State water project provide the surface water which has been beneficial to the region.
The groundwater aquifer can be separated into two major regions the Upper and lower aquifer. The alluvial boundary which surrounds the valley allows for water to permeate through the ground which then flows horizontally into the confine region of the aquifer. [5] This system creates a convergent flow within the area which is bound by the topography of the region. The faults in the region also play a role in how groundwater is control which furthermore subdivides the aquifer into three sub regions. The hydrogeology of the aquifer has been significantly altered by surface water which is treated and recharged to the aquifer while also providing water to local users. [6]
Well core data indicate that the Santa Clara valley aquifer consists of between four and six different water bearing units. The aquifer is composed of both confined and unconfined units. Water bearing units are generally coarse-grained and separated by relatively fine-grained units. The thicknesses of coarse-grained sections vary between 10 and 25 ft. (3.0 and 7.6 m) in the southeast and between 50 and 200 ft. (15 and 61 m) in the south-central and southwestern areas of the valley. Temperature data from monitoring wells indicate that horizontal groundwater flow occurs primarily above 775 ft. (236 m) in southern-central regions and above 510 ft. (160 m) in southeastern areas. [7] Faults also play a big role in how water is control depending on the sediments permeability, the Silver Creek fault creates seasonal subsidence or uplift on the west side or long term uplift on the east side. [5] The Uplift has been associated with the dam on the eastern side of the Valley.
Subsidence has been a key issue in the region which led to 17 square miles of dry land to sink beneath high tide levels in the 1969, this region was adjacent to the San Francisco Bay. The region is now heavily rigged with ring dikes and control levees which work as flood control and prevent landward movement of salt water. Land subsidence created a need for controlling stream channels to ensure water flowed into the Bay. [2] [6] The majority of land subsidence has occurred in the confide region of the aquifer. [5]
The effort conducted in the valley has to halt subsidence which resulted in uplift from 1992 to 1998 the mean uplifted surveyed was 6.4 ± 2.2mm/yr which was noted in Sunnyvale and east San Jose. However, there is still a lot of land deformation from subsidence, but not notable from fault movement. [5] The majority of notable uplift has been noted to be in the southern most region of the confined zone of the aquifer which has been seen as seasonal. [5]
Decades of ground water depletion due to urban development and agriculture resulted in substantial land subsidence. The Santa Clara Valley Water District in part with other water purveyors have replenished ground water levels by artificial recharge which is occurring in the upper 500 ft. of the upper aquifer. [6]
Percolation ponds were built in the margins of the Santa Clara Valley to help increase the rate of recharge to utilize rainfall runoff. However, the Percolation pond did not produce any uplift, due to the compacted interbeds of the upper aquifer. [5] Recharge wells pump treated water into the confide region of the water which have produced uplift.
The quality of the groundwater is considered as "good", but if the demand for ground water exceeds the amount replenished. This would increase the risk of sea water intrusion which could alter the compositions of the aquifer which may degrade the water quality. [6] The characteristic of the water is identified to be Calcium bicarbonate which occurs in the region of 200 ft and above the subsurface while in-between 200 –1000 ft it is Id as sodium bicarbonate [8]
Santa Barbara County, officially the County of Santa Barbara, is located in Southern California. As of the 2020 census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa Maria.
Goleta is a city in southern Santa Barbara County, California, United States. It was incorporated as a city in 2002, after a long period as the largest unincorporated populated area in the county. As of the 2000 census, the census-designated place had a total population of 55,204. A significant portion of the census territory of 2000 did not incorporate into the new city. The population of Goleta was 32,690 at the 2020 census. It is known for being near the University of California, Santa Barbara, campus.
The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the locality. It can also be simply explained as the depth below which the ground is saturated.
Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from the surface; it may discharge from the surface naturally at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.
The Governor Edmund G. Brown California Aqueduct is a system of canals, tunnels, and pipelines that conveys water collected from the Sierra Nevada Mountains and valleys of Northern and Central California to Southern California. Named after California Governor Edmund Gerald "Pat" Brown Sr., the over 400-mile (640 km) aqueduct is the principal feature of the California State Water Project.
The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of the Edwards Plateau in the U.S. state of Texas, it is the source of drinking water for two million people, and is the primary water supply for agriculture and industry in the aquifer's region. Additionally, the Edwards Aquifer feeds the Comal and San Marcos Springs, provides springflow for recreational and downstream uses in the Nueces, San Antonio, Guadalupe, and San Marcos river basins, and is home to several unique and endangered species.
The Santa Ynez River is one of the largest rivers on the Central Coast of California. It is 92 miles (148 km) long, flowing from east to west through the Santa Ynez Valley, reaching the Pacific Ocean at Surf, near Vandenberg Space Force Base and the city of Lompoc.
Santa Maria River on the Central Coast of California, is formed at the confluence of the Sisquoc River and Cuyama River, just east of the city of Santa Maria, and flows 24.4 miles (39.3 km) to its delta at the Pacific Ocean.
The Cuyama River is a 118-mile-long (190 km) river in southern San Luis Obispo County, northern Santa Barbara County, and northern Ventura County, in the U.S. state of California. It joins the Sisquoc River forming the Santa Maria River. The river's name comes from an Indian village named for the Chumash word kuyam, meaning "clam" or "freshwater mollusk".
Overdrafting is the process of extracting groundwater beyond the equilibrium yield of an aquifer. Groundwater is one of the largest sources of fresh water and is found underground. The primary cause of groundwater depletion is the excessive pumping of groundwater up from underground aquifers.
The Los Gatos Creek runs 24 miles (39 km) in California through Santa Clara Valley Water District's Guadalupe Watershed from the Santa Cruz Mountains northward through the Santa Clara Valley until its confluence with the Guadalupe River in downtown San Jose. The Guadalupe River then continues onward into San Francisco Bay.
The Santa Clara Valley Water District provides stream stewardship, wholesale water supply and flood protection for Santa Clara County, California, in the southern San Francisco Bay Area.
Groundwater-related subsidence is the subsidence of land resulting from unsustainable groundwater extraction. It is a growing problem in the developing world as cities increase in population and water use, without adequate pumping regulation and enforcement. One estimate has 80% of serious U.S. land subsidence problems associated with the excessive extraction of groundwater.
The Cuyama Valley is a valley along the Cuyama River in central California, in northern Santa Barbara, southern San Luis Obispo, southwestern Kern, and northwestern Ventura counties. It is about two hours driving time from both Los Angeles and the Santa Barbara area.
Temecula Basin is a sedimentary basin, which, along with the Aguanga Basin, is part of the Elsinore Fault Zone, in southwestern Riverside County, California. The Temecula Basin is a basin of down faulted Mesozoic basement rock, overlain by late Cenozoic continental sediments.
The Central Valley in California subsides when groundwater is pumped faster than underground aquifers can be recharged. The Central Valley has been sinking (subsiding) at differing rates since the 1920s and is estimated to have sunk up to 28 feet. During drought years, the valley is prone to accelerated subsidence due to groundwater extraction. California periodically experiences droughts of varying lengths and severity.
Borrego Valley Groundwater Basin, located in the very southern region of California, is one of the driest basins in the state. With climate change predicted to have strong effects into foreseeable future, the region is viewed with a skepticism in the sustainable use of water at current rates of consumption. Both natural and man-made geographic divisions within this basin allow for a closer inspection of the various management techniques implemented throughout the years, and provide a basis for what may be pursued for an uncertain future.
Joseph Fairfield Poland (1908–1991) was the founding expert in the hydrogeologic field of land subsidence. He committed 50 years of his life to understanding and bringing awareness to the issue. Land subsidence results from over pumping groundwater that leads to compaction of unconsolidated aquifer systems and is the leading cause of land subsidence. He pioneered invaluable research on the subject throughout his career at United States Geological Survey (USGS).
Principal aquifers of California are those principal aquifers of the United States that lie within the California state boundaries. Per the Oxford Dictionary of Environment and Conservation, an aquifer is a "body of permeable and/or porous rock that is underlain by impermeable rock and through which groundwater is able to flow."
{{cite journal}}: Cite journal requires |journal= (help){{cite journal}}: CS1 maint: multiple names: authors list (link){{cite journal}}: Cite journal requires |journal= (help)| Canada | |
|---|---|
| United States |
|
| Mexico | |
| South America | |
| Australia | |
| New Zealand | |
| Africa | |
| Middle-East | |
| Europe | |
| Related articles | |
