Climate warming enhancement of catastrophic southern California debris flows

Nature Portfolio (Springer Nature) | June 29th, 2020

The sequence of wildfires followed by debris flows, frequently affects southern California, reflecting its drought-heavy precipitation climate bipolarity. Organic debris

The sequence of wildfires followed by debris flows, frequently affects southern California, reflecting its drought-heavy precipitation climate bipolarity. Organic debris from incomplete burning is lighter than inorganic matter, and partially inviscid. Hence lower rainfall totals can trigger downslope motion than typically required by the underlying clasts of loose inorganic granular material. After advection downslope, the pebble-laden organic debris has a higher capacity for rilling; a positive feedback process. A mechanism is proposed whereby boulders are ‘rafted’ by organic debris. This coordinated movement of boulders greatly enhances the debris flow erosion capacity. This climate change sensitive debris flow enhancing mechanism, through organic–inorganic granular material interaction, is supported by observations and the numerical simulations. Using a model explicitly parameterizing erosion processes, including runoff entrainment, rilling incision, and bank collapse, the lifecycle of the Montecito debris flow of January 9, 2018 is simulated, providing quantitative estimates of mass conveyed and debris sorting at the terminus. Peak rafting speeds are ~ 12.9 m/s at ~ 300 m asl. Total boulder (effective diameter > 25 cm) volume involved for the Ysidro Creek area alone is ~ 5 × 104 m3, scattered between the region 50–260 m asl. Debris flows are highly repeatable and locations prone to debris flows are identified and their likelihood of realization estimated.

Climate-informed hydrologic modeling and policy typology to guide managed aquifer recharge

American Association for the Advancement of Science (AAAS) | April 21st, 2021

Harvesting floodwaters to recharge depleted groundwater aquifers can simultaneously reduce flood and drought risks and enhance groundwater sustainability. However, deploy

Harvesting floodwaters to recharge depleted groundwater aquifers can simultaneously reduce flood and drought risks and enhance groundwater sustainability. However, deployment of this multibeneficial adaptation option is fundamentally constrained by how much water is available for recharge (WAFR) at present and under future climate change. Here, we develop a climate-informed and policy-relevant framework to quantify WAFR, its uncertainty, and associated policy actions. Despite robust and widespread increases in future projected WAFR in our case study of California (for 56/80% of subbasins in 2070–2099 under RCP4.5/RCP8.5), strong nonlinear interactions between diversion infrastructure and policy uncertainties constrain how much WAFR can be captured. To tap future elevated recharge potential through infrastructure expansion under deep uncertainties, we outline a novel robustness-based policy typology to identify priority areas of investment needs. Our WAFR analysis can inform effective investment decisions to adapt to future climate-fueled drought and flood risk over depleted aquifers, in California and beyond.

Co-producing actionable science for water utilities

Climate Services (Elsevier) | July 7th, 2016

This article explores the efforts of four water utilities to co-produce actionable science by forging partnerships with scientific institutions to explore integrating cl

This article explores the efforts of four water utilities to co-produce actionable science by forging partnerships with scientific institutions to explore integrating climate considerations into their specific management context. The experiences of these four utilities and their scientific partners, as part of the Piloting Utility Modeling Applications project of the Water Utility Climate Alliance, provide a wealth of empirical evidence to illustrate some of the core concepts formulated to explain how to produce usable information and how to link research to decision making. Through these four case studies of co-production, we identify three findings that bridge principles and practice: each utility engaged in contextualizing research; in building and leveraging knowledge networks; and in embracing an entrepreneurial approach to their research agenda. In several instances, unanticipated but innovative assessment techniques were developed by science partners in collaboration with water utilities to fit the utility’s specific needs. The paper concludes by discussing some of the hard realities of co-production illustrated by these cases that should be kept in mind by people contemplating similar projects.

Coastal Plain of Orange County, Basin 8-001 Alternative to a Groundwater Sustainability Plan

Orange County Water District (OCWD) | January 1st, 2017

Collaborative Versus Technocratic Policymaking: California’s Statewide Water Plan

California State University, Sacramento, (CSUS) | January 1st, 2008

In 2001, the California Department of Water Resources embarked on one of the most elaborate public involvement processes in state history. Over the course of five years a

In 2001, the California Department of Water Resources embarked on one of the most elaborate public involvement processes in state history. Over the course of five years and 200 meetings, a 65-member Stakeholder Advisory Committee and a 350-member Extended Review Forum worked with agency staff to produce a new water plan for California. The process consumed some 23,000 person-hours in face-to-face discussions alone. Although the state had been updating its water plan approximately every five years since 1957, the 2005 process produced a dramatically different type of document. For one thing, the 2005 Update is conceptually more accurate, complex, nuanced, and comprehensive. The policy recommendations described in its strategic plan address a broader range of issues—including climate change and environmental justice—yet they engendered somewhat less political controversy than the policies identified in the 1998 Update. Moreover, there is evidence that the collaborative process used in 2001-2005 catalyzed improvements in the relationships among California's historically warring water stakeholders, and also sparked the beginnings of positive cultural changes within certain quarters of DWR.This research report authored by Ariel Ambruster catalogues the outcomes of the 2005 Water Plan Update process and those of its predecessor, the 1998 Update.

Colorado River Accounting and Water Use Report: Arizona, California, and Nevada

U.S. Bureau of Reclamation (USBR) | May 15th, 2024

In accordance with Article V of the Consolidated Decree of the United States Supreme Court in Arizona v. California et al. 547 U.S. 150 (2006) (Consolidated Decree): �

In accordance with Article V of the Consolidated Decree of the United States Supreme Court in Arizona v. California et al. 547 U.S. 150 (2006) (Consolidated Decree): “The United States shall prepare and maintain, or provide for the preparation and maintenance of, and shall make available, annually and at such shorter intervals as the Secretary of the Interior shall deem necessary or advisable, for inspection by interested persons at all reasonable times and at a reasonable place or places, complete, detailed and accurate records of: (A) Releases of water through regulatory structures controlled by the United States; (B) Diversions of water from the mainstream, return flow of such water to the stream as is available for consumptive use in the United States or in satisfaction of the Mexican Treaty obligation, and consumptive use of such water. These quantities shall be stated separately as to each diverter from the mainstream, each point of diversion, and each of the States of Arizona, California and Nevada; (C) Releases of mainstream water pursuant to orders therefor but not diverted by the party ordering the same, and the quantity of such water delivered to Mexico in satisfaction of the Mexican Treaty or diverted by others in satisfaction of rights decreed herein. These quantities shall be stated separately as to each diverter from the mainstream, each point of diversion, and each of the States of Arizona, California and Nevada; (D) Deliveries to Mexico of water in satisfaction of the obligations of Part III of the Treaty of February 3, 1944, and, separately stated, water passing to Mexico in excess of treaty requirements; (E) Diversions of water from the mainstream of the Gila and San Francisco Rivers and the consumptive use of such water, for the benefit of the Gila National Forest.” This Colorado River Accounting and Water Use Report: Arizona, California, and Nevada presents the records compiled pursuant to the Consolidated Decree for Calendar Year 2023. Copies of this and previous years’ reports may be found on the Bureau of Reclamation’s website.

Colorado River Basin August 2022 24-Month Study

U.S. Bureau of Reclamation (USBR) | August 16th, 2022

Colorado River Basin Water Supply and Demand Study

U.S. Bureau of Reclamation (USBR) | December 1st, 2012

The Colorado River Basin Water Supply and Demand Study (Study), initiated in January 2010, was conducted by the Bureau of Reclamation’s (Reclamation) Upper Colorado and

The Colorado River Basin Water Supply and Demand Study (Study), initiated in January 2010, was conducted by the Bureau of Reclamation’s (Reclamation) Upper Colorado and Lower Colorado regions, and agencies representing the seven Colorado River Basin States1 (Basin States) in collaboration with stakeholders throughout the Colorado River Basin (Basin). As defined in the Plan of Study, the purpose of the Study is to define current and future imbalances in water supply and demand in the Basin and the adjacent areas of the Basin States that receive Colorado River water over the next 50 years (through 2060), and to develop and analyze adaptation and mitigation strategies to resolve those imbalances. The Study does not result in a decision as to how future imbalances will or should be addressed. Rather, the Study provides a common technical foundation that frames the range of potential imbalances that may be faced in the future and the range of solutions that may be considered to resolve those imbalances.

Colorado River Drought Contingency Plan Authorization

United States Congress | April 16th, 2019

Authorized Drought Contingency Plans (DCPs) for the Upper and Lower Colorado River Basins, which required reduced Lower Basin deliveries beyond previous curtailment plans

Authorized Drought Contingency Plans (DCPs) for the Upper and Lower Colorado River Basins, which required reduced Lower Basin deliveries beyond previous curtailment plans at specified Lake Mead storage levels, committed Reclamation to additional water conservation efforts, and put in place plans to coordinate Upper Basin operations to enhance Lake Powell storage levels and prevent the loss of hydropower generation.

Colorado River Hydrologic Region Groundwater Update

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

The primary goal of the Colorado River Hydrologic Region (Colorado River region) groundwater update is to expand information about region-specific groundwater conditions

The primary goal of the Colorado River Hydrologic Region (Colorado River 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 meant to serve as a guidepost for prioritizing 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. Where information is readily available, the update does report some aspects of the regional groundwater conditions in greater detail.