Flood warning
Flood policies guide flood risk management activities at the federal, state, and local levels.
Our staff has provided technical input to a variety of flood policy initiatives including the preparation of guidelines for flood insurance studies, and national flood risk investigations.
We are members of the Association of State Floodplain Managers (ASFPM) and have assisted ASFPM staff on national projects. We are part of a national consulting team to FEMA Headquarters and the Regions providing Subject Matter Expertise (SME) on the natural and beneficial functions of floodplains and ecosystem restoration, regional flood management planning, and numerical modeling.
UAV aerial photography used to identify floodplain inundation for flood risk and ecosystem habitats.
cbec staff has worked diligently for many years to identify opportunities to rehabilitate floodplains and reconnect rivers to them, managing floodplains for multiple objectives.
Our hydrogeomorphic survey crews utilize advanced hydrologic, hydrographic and topographic survey techniques, combined with the latest hydrodynamic and ecologic modeling techniques, to identify opportunities to enhance floodplain functions without impacting complementary objectives (agricultural and urban development).
We provide FEMA map change services (such as LOMRs, CLOMRs) and assessments of ecosystem services that, in turn, provide new economic input for floodplain management actions. We frequently provide input into the US Army Cops of Engineers (USACE) 409 permitting process as it relates to flood risk management and levee integrity.
Many of cbec’s projects involve flood risk management and this factor is usually of promary concern. However, these projects are usually multi-objective and therefore we must also consider many other factors. We have qualified Certified Floodplain Managers (CFM) on staff and our Professional Engineers (PE) supervise all our projects.
2-dimensional modeling is used to identify velocity vectors and inundation depth for a potential floodplain restoration project in Southern California.
cbec staff utilize sophisticated 1-, 2- and 3-dimensional models to analyze hydrodynamic interaction between river channels and their floodplains. The results of these analyses are used not only to assess flood risk, but also for ecological enhancement and design. The graphic shown here illustrated floodplain inundation mapping for a proposed mitigation bank in Southern California. At this site it was important not to raise flood elevations, while re-establishing riparian wetlands and riparian forest to provide ecological mitigation enhancement credits. Quite a challenge!
Large scale mapping of the Sacramento Valley utilizing rapid GPU modeling technology. Here 2-dimensional hydrodynamic model mapping shows inundation at the 200-year event.
cbec were one of the first consultants to utilize Graphical Processor Unit (GPU) technology for rapid 2-dimensional models of vast geographic areas in the United States. In recent years cbec undertook a project to model the whole of the Sacramento Ricer system from just south of Hamilton City to the confluence with the Sacramento-San Joaquin River Delta, a feat that had never been achieved preciously in 2-dimensions, and has not been achieved since. The model was calibrated and validated using high water mark data from 1997 to 2006, and was subsequently used to model a suite of alternatives developed by a multi-stakeholder group focused on managing the Sacramento Valley from multiple perspectives. Construction of the model demonstrates that no project is too large for cbec ecohydrologists and ecoengineers.
Oblique aerial view of the Yolo Bypass on a receding flood.
Our staff has been involved in numerous sustainable flood risk management projects including levee setback projects (two of the largest in California and pioneering projects in the UK) and floodplain storage and enhancement projects.
We understand the demands of combining geomorphology, hydrology, hydraulics, and ecology into our designs.
We identify the opportunities and constraints associated with each project and utilize sophisticated decision support tools and models to identify and prioritize areas appropriate for implementation of sustainable flood risk management.
Often projects involve complex stakeholder groups with individuals that have competing goals and aspirations. Sometimes these situations can be challenging. cbec staff are experts in tackling these challenges using various types of decision support tools, such as hydrodynamic and sediment transport models. Often an education process is required to explain complex technical phenomena and modeling tools with advanced graphical output can dramatically help. cbec staff has worked in the Yolo Bypass of the northen Central Valley of California for over 15 years.
The model shown here provides depth and velocity vectors for a potential tidal wetland restoration project in the Sacramento-San Joaquin Rivers Delta.
Pescadero Estuary
Frequently, it is important to consider existing infrastructure – we rarely build from a blank slate! By enhancing our ecosystems through rehabilitation, we must consider the existing needs of humans and reconcile these against all other beneficial uses of our landscape. This is fundamental to cbec’s philosophy and our ecohydrologists and ecoengineers consider these factors in everything we do.
cbec’s staff regularly interface with traditional civil engineers, planners, biologists, ecologists, landscape architects and permitting experts to develop projects. Through coordinated efforts we consider the interfacing needs of our ecosystems in terms of infrastructure and our aquatic environment.
Where possible, we will remove aging infrastructure if it is not needed, or work with other specialties to upgrade, improve or replace existing infrastructure or design new infrastructure. We regularly work with bridge and levee engineers and geotechnical engineers when working on highway infrastructure and our flood control system features.
Photograph and inundation modeling output from Pescadero Marsh in the Central Coast of California
The example shown here provides an illustration of sediment transport modeling used to demonstrate sediment accretion at an existing bridge crossing at the Pescadero Road Bridge. At this site the balance of ecosystems and critical infrastructure was considered in order to collaborate on a solution to minimize sedimentation issues at this bridge structure. Fish passage along with flood conveyance were critical considerations for the local populations and stakeholders.
cbec staff utilize the latest aerial techniques, such as UAV technology, for a variety of monitoring techniques. Shown here, UAVs were used by cbec FAA qualified pilots to map vegetation for hydrodynamic mnodeling purposes. cbec field staff also monitored water levels and flow in the same flood control channel, a critical piece of the Sacramento flood control system.
One of the most important projects recently undertaken in recent years by cbec was for Yolo County. The Yolo Bypass Dranage and Infrastructue Improvement Project identified and prioritized 12 projects in the Yolo Bypass that could benefit dranage and irrigation, ecosystem enhancement and recreational activities. This report was completed in 2015 and to date, 9 of these projects have either been constructed or are in various stages of design!
