Temporal and Spatial Patterns of Groundwater Recharge Across a Small Watershed in the California Sierra Nevada Mountains

Frontiers in Water (Frontiers) | May 17th, 2022

Mountain-block groundwater recharge is a crucial freshwater source in arid to semiarid watersheds worldwide; yet its quantification is difficult due to (1) hydrogeologica

Mountain-block groundwater recharge is a crucial freshwater source in arid to semiarid watersheds worldwide; yet its quantification is difficult due to (1) hydrogeological heterogeneities especially in bedrock-dominated regimes, (2) drastic altitudinal ranges in climate, land use and land cover, and (3) mixing with deep groundwater derived from adjacent basins (i.e., interbasin groundwater flow). In this study, we test the utility of soil water-balance (SWB) modeling to quantify mountain-block groundwater recharge in the South Fork Tule River watershed in the California Sierra Nevada Mountains. This 1,018 km2 watershed is instrumented with 3 USGS stream gages that allow for the development of a refined recharge (i.e., baseflow) calibration dataset via multi-objective optimization-based hydrograph separation. The SWB model was used to compute groundwater recharge and other water balance components at a daily time step using a 30-m grid cell size for a 40-year (1980–2019) study period. Mean annual recharge and runoff were estimated at 3.7 in/yr (3.0 m3/s) and 1.4 in/yr (1.2 m3/s), respectively, with modified Nash Sutcliffe Efficiency indices of 0.61 between baseflow and SWB-derived recharge, and 0.90 between hydrograph separation- and SWB-derived runoff. There is a strong correlation between annual recharge and rainfall (Pearson R = 0.95, p < 0.001) which attests to short residence times in the unsaturated zone and the immediate impact of droughts in 1990, 1999, and 2013. However, results of a modified Mann-Kendall trend analysis indicate no directional trends in recharge or runoff throughout the study period. Parameter sensitivity analyses reveal a persistent overprediction of recharge over baseflow that is particularly pronounced in the upper reaches of the watershed. This is likely related to the SWB model only considering soil characteristics at the surface and not simulating the fate of potential recharge below the root zone where it may be impeded from reaching the aquifer by shallow, impermeable bedrock. This limitation should be considered carefully for future water supply projections in this and comparable bedrock-dominated settings.

Temporal changes in the vertical distribution of flow and chloride in deep wells

National Groundwater Association (NGWA) | July 4th, 2005

The combination of flowmeter and depth‐dependent water‐quality data was used to evaluate the quantity and source of high‐chloride water yielded from different depth

The combination of flowmeter and depth‐dependent water‐quality data was used to evaluate the quantity and source of high‐chloride water yielded from different depths to eight production wells in the Pleasant Valley area of southern California. The wells were screened from 117 to 437 m below land surface, and in most cases, flow from the aquifer into the wells was not uniformly distributed throughout the well screen. Wells having as little as 6 m of screen in the overlying upper aquifer system yielded as much as 50% of their water from the upper system during drought periods, while the deeper parts of the well screens yielded 15% or less of the total yield of the wells. Mixing of water within wells during pumping degraded higher‐quality water with poorer‐quality water from deeper depths, and in some cases with poorer‐quality water from the overlying upper aquifer system. Changes in the mixture of water within a well, resulting from changes in the distribution of flow into the well, changed the quality of water from the surface discharge of wells over time. The combination of flowmeter and depth‐dependent water quality data yielded information about sources of high‐chloride water to wells that was not available on the basis of samples collected from nearby observation wells. Changing well design to eliminate small quantities of poor‐quality water from deeper parts of the well may improve the quality of water from some wells without greatly reducing well yield.

Temporal concentrations of Quaternary ammonium compounds in wastewater treatment effluents during the COVID-19 pandemic, 2020–2021

Elsevier | November 19th, 2024

Temporal variability in irrigated land and climate influences on salinity loading across the Upper Colorado River Basin, 1986-2017

Environmental Research Letters (IOP) | January 19th, 2024

Temporary Restraining Order in Kings County Farm Bureau et al v. California State Water Resources Control Board

Superior Court of California, County of Kings | July 11th, 2024

Temporary Urgency Change Petition for February 1, 2023, through March 31, 2023

California State Water Resources Control Board (SWRCB) | February 13th, 2023

Ten Rivers in America's Future, No. 2. The Central Valley of California

U.S. Water Resources Policy Commission | July 1st, 1950

Tentative Ruling, Friant Water Authority vs. Eastern Tule Groundwater Sustainability Agency

Superior Court of California, County of Tulare | June 25th, 2024

Term 91: Stored Water Bypass Requirements

California State Water Resources Control Board (SWRCB) | April 8th, 2012

Pursuant to numerous Board decisions (D-1485, D-1641, Order 2001-05), the Projects are required to release stored water to meet water quality standards in the Delta (incl

Pursuant to numerous Board decisions (D-1485, D-1641, Order 2001-05), the Projects are required to release stored water to meet water quality standards in the Delta (including flow and salinity standards) where natural flows are insufficient. The obligation was originally placed on the Projects as an interim measure pending future studies of how the obligation to meet water quality standards would be shared with other appropriators. In return for resolving Project protests on subsequent applications to appropriate water, Term 91 was developed and made a condition to permits issued after 1965. Term 91 prohibits diversions by these Permittees when natural and abandoned flows to the Delta are insufficient to meet the water quality standards and the Projects are supplementing such flows with previously stored water to meet the standards. The purpose of this report is to explore the enhanced use and more vigorous enforcement of diversion curtailments as a means to achieve flow standards. This subject matter is relevant to the Delta even through the Projects are under a present and legal obligation to meet existing flows standards.

Testimony of Mark Cowin at Little Hoover Commission on Integrated Regional Water Management

Little Hoover Commission | September 24th, 2009

As the Little Hoover Commission evaluates California’s water governance structure and forms recommendations for improving coordination, efficiency, transparency, and ac

As the Little Hoover Commission evaluates California’s water governance structure and forms recommendations for improving coordination, efficiency, transparency, and accountability, it will be valuable to consider the role of Integrated Regional Water Management (IRWM). IRWM is the application of broader Integrated Water Management principles on a regional basis. IRWM integrates local agency responses to regional resource management issues and facilitates compliance with State laws and policies. Over the past decade, IRWM efforts have emerged across California as some local governments and agencies sought a path forward from long, debilitating law suits and many others responded to financial incentives offered by the State. As a consequence, many local governments and agencies are working more closely on a regional basis and better integrating their resource management decisions. This typically results in both more efficient and sustainable water management plans and better representation and transparency in water management decisions.