Flood-Managed Aquifer Recharge (Flood-MAR)

Flood - MAR illustrated concept of aquifer recharge.

“Flood-MAR” is an integrated and voluntary resource management strategy that uses flood water resulting from, or in anticipation of, rainfall or snow melt for managed aquifer recharge (MAR) on agricultural lands and working landscapes, including but not limited to refuges, floodplains, and flood bypasses. Flood-MAR can be implemented at multiple scales, from individual landowners diverting flood water with existing infrastructure, to using extensive detention/recharge areas and modernizing flood management infrastructure/operations.

Flood-MAR projects can provide broad benefits for Californians and the ecosystems of the state, including:

Water supply reliability
Flood risk reduction
Drought Preparedness
Aquifer Replenishment
Ecosystem Enhancement
Subsidence Mitigation
Water Quality Improvement
Working Landscape
Preservation and Stewardship
Climate Change Adaptation
Recreation and Aesthetics

There is strong, and growing, interest across the state in understanding the benefits, limitations, concerns, costs, and funding opportunities for Flood-MAR projects. DWR plans to work with other state, federal, tribal, and local entities; academia; and landowners. Together, we will build on the knowledge and lessons from past and ongoing studies and programs, pursue expanded implementation of Flood-MAR, and make Flood-MAR an integral part of California’s water portfolio.

Multiple Benefit Floodplain Restoration

DWR has been working with partners to develop a systematic approach to identify floodplain restoration and expansion opportunities that provide high-quality salmonid habitat and enhance naturally occurring floodplain recharge. The Ecological Floodplain Inundation Potential (EcoFIP) toolkit facilitates the identification, analysis, and prioritization of multiple floodplain restoration opportunities at the reach or project scale. The pilot study tools help visualize and compare conceptual restoration designs for potential habitat and recharge benefits and quantify potential benefits and implementation costs. For more information, check out the StoryMaps linked below:

Multiple Benefit Floodplain Restoration Pilot Studies Overview

Upper San Joaquin Study Phase I

Upper San Joaquin Study Phase II

Pajaro Regional Flood Risk Management Project

Merced River Watershed Flood-MAR Reconnaissance Study

Merced River Watershed Flood-MAR Reconnaissance Study

To better understand climate vulnerabilities and how to address them, the California Department of Water Resources (DWR) conducted a three-year Merced study in partnership with Merced Irrigation District (MID) as a proof of concept to explore the effectiveness of Flood-MAR to concurrently reduce flood risk, improve water supply, and enhance ecosystems in the Merced River watershed, a tributary to the San Joaquin River. The Merced study is an exploratory watershed-scale analysis to develop and test analytical methods and models, assess climate change vulnerability, and evaluate adaptation strategies meeting multiple benefits that achieve these shared objectives:

Assess watershed vulnerability to climate change for flood protection, water supply, and ecosystems.
Develop Flood-MAR strategies reflecting a range of operational complexity and infrastructure improvements.
Quantitatively evaluate the performance of Flood-MAR strategies in providing multi-sector benefits and climate resilience.

First Of Its Kind Watershed Study Highlights How Innovative Tools Can Help Build Climate Resilience in the San Joaquin Valley

Following is the Merced River Watershed Flood-MAR Reconnaissance Study Report and supporting technical information records (TIR) that explain the development as well as the results of the study:

Coordinating Flood and Groundwater Management Brochure

The California Department of Water Resources (DWR) prepared this brochure to describe opportunities that improve use of floodwater for managed aquifer recharge (Flood-MAR) to reduce flood risk, increase groundwater recharge, adapt to climate change, and provide other benefits. Recent cycles of drought and flood provide an enhanced opportunity to strengthen the nexus between the flood management and groundwater management communities. Developing a resilient flood system will require decision-making that not only manages the surface water, but also the dynamic interchange of surface water and groundwater horizontally across floodplains and vertically through the subsurface.

Flood-MAR White Paper

Flood-MAR White Paper
The California Department of Water Resources (DWR) prepared this white paper to explore opportunities to use flood water for managed aquifer recharge (Flood-MAR) because DWR recognizes the need to rehabilitate and modernize water and flood infrastructure in California. Large-scale implementation of Flood-MAR can fundamentally change how flood and groundwater management are integrated by using flood water resulting from, or in anticipation of, rainfall or snowmelt for groundwater recharge on agricultural lands and working landscapes, including but not limited to refuges, floodplains, and flood bypasses.

Flood-MAR Research and Data Development Plan

Flood-MAR Research and Data Development Plan
This Flood-MAR Research and Data Development Plan (R&DD Plan) presents the work of the Flood-MAR Research Advisory Committee (RAC), a multidisciplinary group of subject matter experts across 13 research themes. The RAC was tasked to identify the research, data, guidance, and tools necessary to support and expand the implementation of Flood-MAR projects. Well-formulated Flood-MAR projects can benefit Californians and the environment through improved water supply reliability, flood-risk reduction, drought preparedness, aquifer replenishment, ecosystem enhancement, subsidence mitigation, water quality improvement, working landscape preservation and stewardship, climate change adaptation, recreation, and aesthetics.