Shoreline retreat and beach nourishment are projected to increase in Southern California

Nature Portfolio (Springer Nature) | May 22nd, 2024

Sandy beaches in Southern California are experiencing rising coastal erosion due to changes in precipitation patterns and urban growth. As a result, beach nourishment is

Sandy beaches in Southern California are experiencing rising coastal erosion due to changes in precipitation patterns and urban growth. As a result, beach nourishment is necessary for mitigation. In our study, we forecast the rates of shoreline retreat and the required volumes of sand nourishment to mitigate it for the coming decades. We employ photogrammetric multi-decadal shoreline positioning and Digital Shoreline Analysis System methods to measure and predict the coastal evolution of the Gulf of Santa Catalina in Southern California. This region is hypothesized to be globally representative of other semi-arid sandy coasts facing similar hydroclimatic and anthropogenic challenges. Our findings indicate that Southern California’s shoreline retreat rates for sandy beaches will increase from the present average value of ~−1.45 to −2.12 meters per year in 2050 and to −3.18 meters per year in 2100. Consequently, the annual volume of sand required for beach nourishment could triple by 2050, increasing from the present-day amount of ~1223 to ~3669 cubic meters per year per kilometer. However, the associated cost for this nourishment will grow five times, exacerbating several coastal communities’ economic and logistical pressures. Similar trends are emerging globally, with semi-arid developing nations already grappling with coastal hazards and may struggle to manage the escalating costs of curbing beach nourishment.

Show Me the Water Plan: Urban Water Management Plans and California’s Water Supply Adequacy Laws

Golden Gate University (GSU) | October 11th, 2010

In 2001, California adopted two landmark pieces of legislation – Senate Bills (SB) 221 and 610 – that require local land use authorities to demonstrate long-t

In 2001, California adopted two landmark pieces of legislation – Senate Bills (SB) 221 and 610 – that require local land use authorities to demonstrate long-term water supply availability before approving new, large development projects. The details of these bills, which quickly became known as the “show me the water” laws, are distinct: SB 610 requires a “water supply assessment” at the relatively early stage of environmental review and covers residential, commercial, and industrial projects (a “project” is typically a development of more than 500 residential units, or a similarly large commercial or industrial development), while SB 221 requires a final check on water availability (a “written verification”) for residential projects of this same size threshold at the later stage of subdivision map approval. Despite these differences, the intent behind both laws is similar: they aim to forge an often missing link in California’s local planning process. Under these laws, cities and counties generally cannot make the determination of adequate water supplies on their own, but must instead obtain this documentation from the local water utility that would be serving the project. SB 221 and 610 are part of a broader state effort to impose water supply planning safeguards on a highly decentralized planning system. The proximate targets were the state’s fifty-eight counties and more than 475 incorporated municipalities that have local land use authority – forcing them to coordinate with the local water utilities to ascertain whether adequate supplies are available to support new development.4However, California’s urban water supply is also highly decentralized, with hundreds of utilities serving these diverse communities. The effectiveness of SB 221 and 610 depends on the quality of the planning efforts of these utilities. State efforts to impose some planning norms on water utilities began with the passage of the Urban Water Management Planning Act in 1983. The Act required all large urban utilities (defined as those serving at least 3,000 retail connections or supplying at least 3,000 acre-feet of water per year) to develop long-term plans for water supply and demand in their service areas, to be updated at least every five years, in years ending in zeros and fives. The list of required elements in these Urban Water Management Plans (UWMPs) has been updated numerous times, reinforcing the core purpose: to provide an assessment of the extent to which current and future water supply sources will be adequate to meet water demand at an appropriate level of reliability in normal years as well as during single or multi-year droughts. By and large, SB 221 and 610 were crafted to be in sync with the law governing utility planning. Water supply adequacy to support new development needs to be demonstrated over a twenty-year horizon, the minimum planning horizon for a UWMP.8 A utility’s UWMP can be used to demonstrate water availability under both SB 221 and 610, as long as the plan accounts for the increased water demand associated with the proposed development project. In keeping with California’s strong “home rule” tradition, these planning laws rely largely on citizen enforcement rather than direct regulatory oversight by the state. Thus, the laws provide the opportunity for citizens to challenge the responsible local agencies in civil suits.10Courts can invalidate the planning documents (UWMPs, water supply assessments, or written verifications), thereby holding up development approvals. SB 610 also introduced financial incentives to water utilities to submit UWMPs. Since 2002, only agencies with “complete” plans are eligible for state financial support for local projects. This change gave the California Department of Water Resources (DWR) the mandate to assess the plans for completeness but not for quality. In sharp contrast to climate change policy, where the California Attorney General has pressured local governments to bring their plans into compliance with state laws aimed at limiting greenhouse-gas emissions, the state has not actively sought to enforce the water supply adequacy laws though the judicial process. This Article reviews the effectiveness of California’s strategy of using enabling legislation and passive enforcement to encourage more integrated local water and land use planning. To shed light on the effectiveness of the current policy framework, the Article begins with a critical overview of the Urban Water Management Planning process, drawing on a detailed analysis of plans submitted in the early 2000s.13 It then evaluates how water supply assessments are proceeding, with a particular emphasis on steps used to identify adequacy, drawing on telephone surveys of land use authorities and water utilities conducted by the author in 2004 and 2009. A concluding section highlights shortcomings in the current system and suggests steps that could improve California’s planning process.

Significant challenges to the sustainability of the California coast considering climate change

National Academy of Sciences (NAS) | July 29th, 2024

Simulation of Groundwater and Surface-Water Resources of the Santa Rosa Plain Watershed, Sonoma County, California

U.S. Geological Survey (USGS) | April 25th, 2014

Water managers in the Santa Rosa Plain face the challenge of meeting increasing water demand with a combination of Russian River water, which has uncertainties in its fut

Water managers in the Santa Rosa Plain face the challenge of meeting increasing water demand with a combination of Russian River water, which has uncertainties in its future availability; local groundwater resources; and ongoing and expanding recycled water and water from other conservation programs. To address this challenge, the U.S. Geological Survey, in cooperation with the Sonoma County Water Agency, the cities of Cotati, Rohnert Park, Santa Rosa, and Sebastopol, the town of Windsor, the California American Water Company, and the County of Sonoma, undertook development of a fully coupled groundwater and surface-water model to better understand and to help manage the hydrologic resources in the Santa Rosa Plain watershed. The purpose of this report is to (1) describe the construction and calibration of the fully coupled groundwater and surface-water flow model for the Santa Rosa Plain watershed, referred to as the Santa Rosa Plain hydrologic model; (2) present results from simulation of the Santa Rosa Plain hydrologic model, including water budgets, recharge distributions, streamflow, and the effect of pumping on water-budget components; and (3) present the results from using the model to evaluate the potential hydrologic effects of climate change and variability without pumpage for water years 2011–99 and with projected pumpage for water years 2011–40.

Small Water Systems and Rural Communities Drought and Water Shortage Contingency Planning and Risk Assessment, Part 1

California Department of Water Resources (DWR) | March 25th, 2021

This report is submitted pursuant to California Water Code (CWC) Section 10609.42, which directs the California Department of Water Resources (DWR) to identify small wate

This report is submitted pursuant to California Water Code (CWC) Section 10609.42, which directs the California Department of Water Resources (DWR) to identify small water suppliers and rural communities that may be at risk of drought and water shortage vulnerability, and to propose recommendations and information in support of improving their drought preparedness. The report is published in two parts: Part 1 deals with drought and water shortage contingency planning recommendations, and Part 2 presents a methodology of drought and water shortage vulnerability assessment and risk scoring. Additionally, below are links for Part 1 appendices. Appendix 1: Literature Review Appendix 2: Proposed Water Shortage Contingency Plan Components for Small Water Systems Serving 1,000 to 2,999 Service Connections Appendix 3: Proposed Umbrella Water Shortage Contingency Plan Components Appendix 4: Indian Health Service Template for a Drought Contingency Plan for a Tribal Public Water System Appendix 5: County Drought Advisory Group General Funding and Financing Issues

Snow Survey Procedure Manual

California Department of Water Resources (DWR) | October 1st, 2014

By any measure, California’s agriculture, hydroelectric production, domestic use, riparian health, and recreation all put tremendous demands on the state’s often limi

By any measure, California’s agriculture, hydroelectric production, domestic use, riparian health, and recreation all put tremendous demands on the state’s often limited water resource. Because of California’s Mediterranean climate, little significant precipitation occurs during the summer and autumn months. Accurate assessments of mid-winter precipitation, therefore, are a vital determinant of the state’s available water. During most years, maximum snow water equivalent1 (SWE) in the Sierra Nevada denotes the annual peak of surface water resource. Snow water equivalent is a key index not only for forecasting stream and river flow timing and amount, but for a wide variety of water management decisions targeted days and months into the future. The goal of the snow survey is to obtain an accurate measure of SWE at predetermined locations: snow courses. Snow courses typically have between five and ten measurement points spread out over one or more straight-line transects. Transects can be short, or several hundred meters in length. Some snow courses are coincident with recording or data-transmitting weather instrumentation; many others stand alone in very wild and remote locations. Most snow courses are measured once per month throughout the winter (accumulation) and spring (ablation) seasons, though some may be measured at different frequencies. Several California snow course records go back to the 1920s (some to 1910). Data from the measurements are used to develop—and continuously refine—indices of stream flow for the respective watersheds. A critical first step in characterizing the spatial and temporal distribution of California’s SWE is by measuring its 261 snow courses throughout the state. The aim of this document is to address snow survey procedure and equipment, review data collection, and discuss surveyor safety. While some subjects (avalanche safety, wilderness first aid) are, in their entirety, beyond the scope of this work, industry standards and procedures are presented. The author hopes this document will find utility as an office-based training manual for those new to snow surveys, as well as a field guide and reference to all who conduct snow surveys. As of this writing, many advances in the remote sensing (by ground-, aircraft- and spacecraft-based instrumentation) of snow cover are being developed. No doubt these developments in both procedure and instrumentation will continue to advance. However, there currently exists no practical, automated technique with which to measure SWE at the number of locations and at the point-accuracy of ground-based, manual measurements. Manual measurements remain the standard for calibrating and “ground-truthing” automated instrumentation, and have the advantage that they can be obtained independent of most surface and weather conditions. For the foreseeable future, snow surveys will continue to be a vital part of the water management structure in California.

Social and economic impacts of climate

American Association for the Advancement of Science (AAAS) | August 9th, 2016

For centuries, thinkers have considered whether and how climatic conditions—such as temperature, rainfall, and violent storms—influence the nature of societies and th

For centuries, thinkers have considered whether and how climatic conditions—such as temperature, rainfall, and violent storms—influence the nature of societies and the performance of economies. A multidisciplinary renaissance of quantitative empirical research is illuminating important linkages in the coupled climate-human system. We highlight key methodological innovations and results describing effects of climate on health, economics, conflict, migration, and demographics. Because of persistent “adaptation gaps,” current climate conditions continue to play a substantial role in shaping modern society, and future climate changes will likely have additional impact. For example, we compute that temperature depresses current U.S. maize yields by ~48%, warming since 1980 elevated conflict risk in Africa by ~11%, and future warming may slow global economic growth rates by ~0.28 percentage points per year. In general, we estimate that the economic and social burden of current climates tends to be comparable in magnitude to the additional projected impact caused by future anthropogenic climate changes. Overall, findings from this literature point to climate as an important influence on the historical evolution of the global economy, they should inform how we respond to modern climatic conditions, and they can guide how we predict the consequences of future climate changes.

South Coast Hydrologic Region Groundwater Update

California Department of Water Resources (DWR) | April 1st, 2015

The primary goal of the South Coast Hydrologic Region (South Coast region) groundwater update is to expand information about region-specific groundwater conditions for Ca

The primary goal of the South Coast Hydrologic Region (South Coast region) groundwater update is to expand information about region-specific groundwater conditions for California Water Plan Update 2013 and to guide more informed groundwater management actions and policies. A second goal is to steadily improve the quality of groundwater information in future California Water Plan (CWP) updates to a level that will enable regional water management groups (RWMGs) to accurately evaluate their groundwater resources and implement management strategies that can meet local and regional water resource objectives within the context of broader statewide objectives. The final goal is to identify data gaps and groundwater management challenges that will guide prioritizing of future data collection and funding opportunities relevant to the region. This regional groundwater update is not intended to provide a comprehensive and detailed examination of local groundwater conditions, or be a substitute for local studies and analysis. Nonetheless, where information is readily available, this update does report some aspects of the regional groundwater conditions in greater detail.

South of Kern River Groundwater Sustainability Plan (GSP) for Certain Lands Overlying the Kern County Subbasin

South of the Kern River Groundwater Sustainability Agencies (SoKR GSAs) | July 27th, 2022

Southeast California Regional Basin Study

U.S. Bureau of Reclamation (USBR) | September 1st, 2015

The United States Department of the Interior’s WaterSMART (Sustain and Manage America’s Resources for Tomorrow) Basin Study Program is a 21st Century approach to help

The United States Department of the Interior’s WaterSMART (Sustain and Manage America’s Resources for Tomorrow) Basin Study Program is a 21st Century approach to help address water supply challenges. The Southeast California Regional Basin Study (Study) takes a collaborative approach to solve local water supply and regional conveyance and storage issues. As part of this Study, the Bureau of Reclamation’s Southern California Area Office cooperated with the Borrego Water District (BWD), Coachella Valley Water District (CVWD), Imperial Irrigation District (IID) and other interested regional stakeholders to assess water supply and demand challenges in the Southeast California region. This Study’s report is comprised of seven chapters; they are: introduction, supply, demand, alternative strategies, alternative analysis, findings, and references. Three appendices provide additional details regarding climate change modeling results, engineering design and economic analysis. The Study focuses on a regional area encompassing the Coachella, Borrego and Imperial Valleys. The Study addresses current and future supply and demand imbalances, provides an assessment of existing infrastructure resources, and develops options and alternatives to solve identified issues and help plan for an uncertain water supply future. The local stakeholders provided substantial informational resources on historical and projected supply and demand, and existing infrastructure. The water districts’ background information includes numerous groundwater, urban water and integrated regional planning studies, all of which were produced and/or updated between 2010 and 2012. Extensive supply and demand studies for the Colorado River Basin and California’s Central Valley – the two imported water supply sources for the Study area – also contributed data to this Study. Reclamation’s Colorado River Basin Water Supply and Demand Study (Colorado River Basin Study) (Reclamation, 2012) and the California Department of Water Resources biennial State Water Project (SWP) report (State of California, 2012 a and b) were both completed in 2012. Reclamation’s Colorado River Basin Study included several technical analyses related to optimal water utilization, conveyance and storage alternatives relative to climate change and future water supply uncertainty. Because the Southeast California Basin Study region is dependent on both Colorado River and SWP imports, several sections of the Study reference and/or summarize both reports extensively. Existing data was used to develop structural and non-structural options to resolve supply-demand imbalances and future uncertainty. Non-structural options included governance, and regulatory or operational changes that could facilitate stakeholder processes to better conserve water or improve the use of existing facilities to convey and store water. Non-structural options were addressed qualitatively due to the complexity of interagency negotiations that would likely be involved. The structural options involved an appraisal level design effort to evaluate pipeline alignments to convey water supplies between the Study stakeholders. Both the structural and non-structural options were assessed in their capability to resolve regional water supply and demand relative to future climate uncertainties. Climate change scenarios analyzed the potential impacts increasing temperatures and changes in precipitation may have on supply and demand across the Study area. The analysis addressed both local and imported supply sources. Climate change is expected to result in increasing temperatures across the Study area and in the Colorado River and SWP basins over time. As temperatures continue to increase, annual precipitation will become more variable. Precipitation changes may affect recharge of the Study area’s local groundwater aquifers and the Colorado River and SWP snowpacks. The climate effects on imported supply have been extensively discussed in the Colorado River Basin Study and the biennial SWP report. Increasing temperatures will increase both supply and demand uncertainty. CVWD could see an increase in SWP supply deliveries under average or greater precipitation-snowpack conditions. Dry years or extended droughts could substantially decrease SWP deliveries. However, CVWD and IID receive the majority of their supply from the Colorado River. Future climate scenarios indicate an increased potential for lower basin shortages. As senior water right holders and under the Secretary of the Interior’s Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead, IID and CVWD would not be impacted by short-term shortage issues. The Colorado River Basin Study analysis indicates these shortage vulnerabilities could be mitigated by up to 50% through a variety of management actions and operational changes. Each Study option was assessed as an adaptive strategy to climate change. The structural options to convey and store water in the Borrego Valley groundwater basin are not viable at the present time. A non-structural option may be more cost-effective for the Study region, have the potential to meet the Study objectives, and may offset climate change uncertainty that is impacting available imported water supplies. Further study effort could include fostering groundwater sustainability in the Borrego Valley and promoting opportunities for additional groundwater banking between IID and CVWD in the Coachella Valley, per an October 2003 agreement. Other water and related resource options generated from discussions during the course of this Study include increasing storage opportunities at Lake Henshaw Dam, implementing best practices for flood control basins, and brackish desalination. These options may all play a greater role in diversifying the region’s water supply in the future. However, additional study is required to assess these water resource options.