Measuring Land Subsidence from Space

U.S. Geological Survey (USGS) | April 13th, 2000

Interferometric Synthetic Aperture Radar (InSAR) is a powerful new tool that uses radar signals to measure deformation of the Earth’s crust at an unprecedented level of

Interferometric Synthetic Aperture Radar (InSAR) is a powerful new tool that uses radar signals to measure deformation of the Earth’s crust at an unprecedented level of spatial detail and high degree of measurement resolution. InSAR is now being used by the USGS and others to map and monitor subsidence caused by the compaction of aquifer systems. Geophysical applications of radar interferometry take advantage of the phase component of reflected radar signals to measure apparent changes in the range distance of the land surface (Gabriel and others, 1989; Massonnet and Feigl, 1998). Ordinary radar on a typical Earth-orbiting satellite has a very poor ground resolution of about 3 to 4 miles because of the restricted size of the antenna on the satellite. Synthetic Aperture Radar (SAR) takes advantage of the motion of the spacecraft along its orbital track to mathematically reconstruct (synthesize) an operationally larger antenna and yield high-spatial-resolution imaging capability on the order of hundreds of feet.

Measuring What Matters: Setting Measurable Objectives to Achieve Sustainable Groundwater Management in California

Union of Concerned Scientists | September 1st, 2015

Groundwater supplies between 30 and 50 percent of California’s water supply, depending on precipitation, and represents a storage reservoir that is over three times gre

Groundwater supplies between 30 and 50 percent of California’s water supply, depending on precipitation, and represents a storage reservoir that is over three times greater than available surface water storage. The California Water Action Plan (CNRA, CDFA, and CEPA 2014) identifies groundwater as “a critical bu?er to the impacts of prolonged dry periods and climate change on our water system.” Many groundwater basins have historically experienced significant chronic overdraft and related negative impacts. California’s ongoing drought helped spur the state to enact legislation to strengthen local control and management of groundwater basins. Governor Jerry Brown signed the threebill package (AB 1739, SB 1168, SB 1319), known as the Sustainable Groundwater Management Act (SGMA), into law on September 16, 2014. SGMA represents California’s attempt to regulate groundwater comprehensively for the first time in the state’s history. SGMA, which went into e?ect on January 1, 2015, lays out a process and a timeline for local agencies to achieve sustainable management of groundwater basins (see Box 1). It also provides tools, authorities, and deadlines meant to lead to achievement of the legislation’s purpose. For local agencies involved in implementation, the requirements are significant and are expected to take many years to accomplish. While setting measurable objectives is a new requirement, it is by no means a new concept in natural resource management. This report summarizes the theory and practice of setting measurable objectives for groundwater management, using examples from California and elsewhere. The goal is to begin to develop a shared knowledge base and to identify key features of e?ective measurable objectives.

Merced Groundwater Subbasin Groundwater Sustainability Plan

Merced Subbasin Groundwater Sustainability Agency (MSGSA) | November 12th, 2019

Merced Groundwater Subbasin Groundwater Sustainability Plan (Revised)

Merced Subbasin Groundwater Sustainability Agency (MSGSA) | July 6th, 2022

Due to size, this file has been divided into six part. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6

Due to size, this file has been divided into six part. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6

Merced River Watershed Flood-MAR Reconnaissance Study

California Department of Water Resources (DWR) | November 15th, 2023

DWR, in partnership with the Merced Irrigation District (MID), is conducting a preliminary study using flood waters for managed aquifer recharge that can reduce flood ris

DWR, in partnership with the Merced Irrigation District (MID), is conducting a preliminary study using flood waters for managed aquifer recharge that can reduce flood risk, increase surface and groundwater supply reliability, and enhance ecosystems in the Merced River Basin. This Merced River Reconnaissance Study (study) is exploring the potential, feasibility, and effectiveness of Flood-MAR concepts, testing theories, and assessing strategies in overcoming barriers and challenges to project planning and implementation. The study will assess current conditions of the Merced River watershed and the vulnerability of these watershed management characteristics to a range of potential climate change futures. The study will also describe the public and private benefits that may be achieved through Flood-MAR strategies and quantify a range of benefits that Flood-MAR could provide in or adjacent to the Merced River watershed.

Mid-Kaweah Groundwater Sustainability Agency 2022 First Amended Groundwater Sustainability Plan

Mid-Kaweah Groundwater Sustainability Agency (MKGSA) | July 27th, 2022

Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9

Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9

Mid-Kaweah Groundwater Sustainability Agency Groundwater Sustainability Plan

Mid-Kaweah Groundwater Sustainability Agency (MKGSA) | December 18th, 2019

Midcoast Groundwater Study Phase III, San Mateo County, California

San Mateo County | June 4th, 2010

San Mateo County ‘Midcoast’ extends from northern Half Moon Bay to Devils Slide along Highway 1. It encompasses the communities of Montara, Moss Beach, Seal Cove, Pri

San Mateo County ‘Midcoast’ extends from northern Half Moon Bay to Devils Slide along Highway 1. It encompasses the communities of Montara, Moss Beach, Seal Cove, Princeton, El Granada, and Miramar. Domestic water is supplied to the southern part of the region by Coastside County Water District (CCWD), providing services from Half Moon Bay to Princeton, and by Montara Water and Sanitary District (MWSD) on the north, servicing Montara and Moss Beach. Private wells are scattered through both service districts and outlying areas. With the exception of CCWD, which meets much of its demand through long-term contractual agreements with San Francisco Public Utilities Commission, the source of domestic water is from local surface water and groundwater resources. The carrying capacity of the local resources may be considered as the population that can be sustained using conservation measures during an extended drought without undue stress to valued natural habitats.

Middle Santa Ana River Watershed TMDL Task Force

Santa Ana Watershed Project Authority (SAWPA) | July 5th, 2018

The Task Force is an 18-agency collaborative effort organized by the Santa Ana Watershed Project Authority. It was formed in January 2006 to coordinate water quality impr

The Task Force is an 18-agency collaborative effort organized by the Santa Ana Watershed Project Authority. It was formed in January 2006 to coordinate water quality improvement activities related to bacteria in the Middle Santa Ana River Watershed. The activities were designed to manage or eliminate sources of bacterial indicators in local waterbodies. The Task Force supports on-going source investigation efforts to identify major sources of bacterial indicators and to understand how to best address them. Task Force resources are allocated on a risk-reduction priority basis in order to achieve compliance where it will provide the greatest improvement in public health.

Mitigating land subsidence in the Coachella Valley, California, USA: An emerging success story

International Association of Hydrological Sciences (IAHS) | April 22nd, 2020

Groundwater has been a major source of agricultural, municipal, and domestic water supply since the early 1920s in the Coachella Valley, California, USA. Land s

Groundwater has been a major source of agricultural, municipal, and domestic water supply since the early 1920s in the Coachella Valley, California, USA. Land subsidence, resulting from aquifer-system com- paction and groundwater-level declines, has been a concern of the Coachella Valley Water District (CVWD) since the mid-1990s. As a result, the CVWD has implemented several projects to address groundwater overdraft that fall under three categories – groundwater substitution, conservation, and managed aquifer-recharge (MAR). The implementation of three projects in particular – replacing groundwater extraction with surface water from the Colorado River and recycled water (Mid-Valley Pipeline project), reducing water usage by tiered-rate costs, and increasing groundwater recharge at the Thomas E. Levy Groundwater Replenishment Facility – are potentially linked to markedly improved groundwater levels and subsidence conditions, including in some of the historically most overdrafted areas in the southern Coachella Valley. Groundwater-level and subsidence monitoring have tracked the effect these projects have had on the aquifer system. Prior to about 2010, water levels persistently declined, and some had reached historically low levels by 2010. Since about 2010, however, groundwater levels have stabilized or partially recovered, and subsidence has stopped or slowed substantially almost every- where it previously had been observed; uplift was observed in some areas. Furthermore, results of Interferometric Synthetic Aperture Radar analyses for 1995–2017 indicate that as much as about 0.6 m of subsidence occurred; nearly all of which occurred prior to 2010. Continued monitoring of water levels and subsidence is necessary to inform the CVWD about future mitigation measures. The water management strategies implemented by the CVWD can inform managers of other overdrafted and subsidence-prone basins as they seek solutions to reduce overdraft and subsidence.