Hydrology is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydrologist. Hydrologists are scientists studying earth or environmental science, civil or environmental engineering, and physical geography. Using various analytical methods and scientific techniques, they collect and analyze data to help solve water related problems such as environmental preservation, natural disasters, and water management.
An aquifer is an underground layer of water-bearing material, consisting of permeable or fractured rock, or of unconsolidated materials. Aquifers vary greatly in their characteristics. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer, and aquiclude, which is a solid, impermeable area underlying or overlying an aquifer, the pressure of which could lead to the formation of a confined aquifer. The classification of aquifers is as follows: Saturated versus unsaturated; aquifers versus aquitards; confined versus unconfined; isotropic versus anisotropic; porous, karst, or fractured; transboundary aquifer.
A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the drainage divide, made up of a succession of elevated features, such as ridges and hills. A basin may consist of smaller basins that merge at river confluences, forming a hierarchical pattern.
The San Joaquin River is the longest river of Central California. The 366-mile (589 km) long river starts in the high Sierra Nevada, and flows through the rich agricultural region of the northern San Joaquin Valley before reaching Suisun Bay, San Francisco Bay, and the Pacific Ocean. An important source of irrigation water as well as a wildlife corridor, the San Joaquin is among the most heavily dammed and diverted of California's rivers.
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.
Groundwater recharge or deep drainage or deep percolation is a hydrologic process, where water moves downward from surface water to groundwater. Recharge is the primary method through which water enters an aquifer. This process usually occurs in the vadose zone below plant roots and is often expressed as a flux to the water table surface. Groundwater recharge also encompasses water moving away from the water table farther into the saturated zone. Recharge occurs both naturally and through anthropogenic processes, where rainwater and/or reclaimed water is routed to the subsurface.
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 Klamath Basin is the region in the U.S. states of Oregon and California drained by the Klamath River. It contains most of Klamath County and parts of Lake and Jackson counties in Oregon, and parts of Del Norte, Humboldt, Modoc, Siskiyou, and Trinity counties in California. The 15,751-square-mile (40,790 km2) drainage basin is 35% in Oregon and 65% in California. In Oregon, the watershed typically lies east of the Cascade Range, while California contains most of the river's segment that passes through the mountains. In the Oregon-far northern California segment of the river, the watershed is semi-desert at lower elevations and dry alpine in the upper elevations. In the western part of the basin, in California, however, the climate is more of temperate rainforest, and the Trinity River watershed consists of a more typical alpine climate.
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. Management of aquifer resources is associated with the Santa Clara Valley Water District.
The Coachella Valley Water District is an independent special district formed in 1918, specifically to protect and conserve local water sources in the Coachella Valley. Since then, the district has grown into a multi-faceted agency that delivers irrigation and domestic (drinking) water, collects and recycles wastewater, provides regional storm water protection, replenishes the groundwater basin and promotes water conservation.
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.
The California water resource region is one of 21 major geographic areas, or regions, in the first level of classification used by the United States Geological Survey in the United States hydrologic unit system, which is used to divide and sub-divide the United States into successively smaller hydrologic units. These geographic areas contain either the drainage area of a major river, or the combined drainage areas of a series of rivers.
For the use of hydrologists, ecologists, and water-resource managers in the study of surface water flows in the United States, the United States Geological Survey created a hierarchical system of hydrologic units.
Southern California Coastal water resource subregion is one of 10 hydrologic subregions within the California water resource region and is one of 222 water resource subregions in the United States hydrologic unit system. The Southern California coastal subregion, sometimes called the South Coast Hydrologic Subregion, is a second-level subdivision covering is approximately 11,000 sq mi and extends from Rincon Creek on the north to the international border with Mexico on the south. The South Coast Hydrologic Subregion is composed of three third-level hydrological units. The federally-defined Southern California Coastal water resource subregion equates roughly with the state-designated South Coast hydrologic region. Per a USGS report of 1976, "Water deficiency is prevalent in the South Coastal subregion." By 1955 the region was found to be experiencing measurable levels of saltwater intrusion due to overdrawn aquifers and several wells were abandoned as a consequence. Part of the solution was injecting Colorado River water from the aqueduct into local wells to defend against the salted water, a practice called artificial recharge.
The South Coast hydrologic region of California is one of the 10 major hydrologic regions of the state as identified by the California Department of Water Resources. The South Coast hydrologic region has a surface area of about 11,100 sq mi (29,000 km2), and includes all of Orange County, major portions of Los Angeles, Riverside, San Bernardino, San Diego, and Ventura counties, and a small portion of Santa Barbara County. The state-defined South Coast hydrologic region is roughly equivalent to the federally-defined Southern California Coastal water resource subregion. The South Coast hydrologic region has 78 state-recognized alluvial groundwater basins and subbasins.
Santa Ana water resource basin is one of three hydrologic basins within the Southern California Coastal water resource subregion and is one of approximately 2,200 water resource basins in the United States hydrologic unit system. The Santa Ana water resource basin is a third-level subdivision of the United States hydrologic unit system.
The Colorado River hydrologic region of California is one of the 10 major hydrologic regions of the state as identified by the California Department of Water Resources.
Laguna–San Diego Coastal water resource basin is one of three hydrologic basins within the Southern California Coastal water resource subregion and is one of approximately 2,200 water resource basins in the United States hydrologic unit system.
