A02.12 PWS Bayesian Flood Damage Analysis dated 2025.08.14.docx

14 AUG 2025

PERFORMANCE WORK STATEMENT (PWS)

Bayesian Enhancement of Flood Risk Management Depth-Damage Modeling

1. BACKGROUND

The Institute for Water Resources (IWR) is a United States Army Corps of Engineers (USACE) Field Operating Activity (FOA) located within the Washington, DC National Capital Region (NCR), in Alexandria, VA and with satellite centers in New Orleans, LA, Davis, CA, Lakewood, CO, and Pittsburgh, PA. IWR was created in 1969 to analyze and anticipate changing water resources management conditions, and to develop planning methods and analytical tools to address economic, social, institutional, and environmental needs in water resources planning and policy. IWR is currently responsible for a number water resources activities or programs, including evaluation of Civil Works (CW) strategic plans, CW policies and programs, investment and financial analysis, performance measurements and evaluations, infrastructure analysis, and other water related activities. IWR provides technical assistance to Corps divisions, districts, laboratories, Federal agencies, international organizations, financial institutions and other countries, in encompassing a broad range of topic areas related to levee and dam safety, risk assessment, dredging requirements, port/waterway transport, aquatic ecosystem restoration, environmental stewardship, flood and drought risk management, emergency preparedness, watershed planning, regulatory, multipurpose water resources including hydroelectric power, water supply and reallocation, recreation, and other water and related land resources issues. IWR seeks support on a Bayesian flood damage analysis related to the compilation of depth-damage functions widely used throughout USACE to evaluate flood damage.

2. PROJECT SCOPE

Over the past fifty years, USACE has developed a suite of depth-damage curves to estimate flood damages, which are critical for plan formulation, economic justification, and cost-benefit analysis. Historically, these curves have been primarily developed through limited post-flood surveys or expert elicitation from flood claims adjusters, structural engineers, and other subject matter experts. Currently, USACE employs national generic depth-damage functions, developed from post-flood surveys of seven diverse flood events, including riverine and hurricane flooding, and regional depth-damage functions, typically generated through expert elicitation with limited flood data.

This project addresses existing gaps by developing regional, flood-type-specific depth-damage functions using data-driven methodologies. Given the absence of a singular flood damage dataset sufficient for this purpose, a hierarchical Bayesian modeling strategy will be adopted, enabling the pooling of diverse data sources and the integration of expert knowledge. The resulting models will provide predictions for rainfall-driven and riverine flood types with region-specific applicability, overcoming limitations of national generic functions, which aggregate multiple geographic areas into a single depth-damage function. While existing regional depth-damage functions have greater specificity, they have largely been created through expert elicitation, often based on limited data from sometimes only a single flood event. This effort will combine regional specificity with the advantages of data-driven modeling across multiple flood events, leveraging Bayesian information pooling across region, flood type, and structure type.

A key strength of this Bayesian modeling framework is its flexibility, including the capability to handle incomplete structure-level data, accommodating gaps in existing structure inventories. The developed models will produce predictive distributions with explicit uncertainty quantification, significantly enhancing decision-making compared to traditional deterministic point-estimate methods. Where feasible, additional variables (such as flood duration, flood scope, or structural attributes such as building replacement value) may also be integrated, providing more refined and precise predictions. Additionally, the Bayesian methodology allows continuous updating as new flood data becomes available or as existing flood damage data is improved or corrected, ensuring the models remain relevant and reliable over time, even amid changes in flood-damage relationships or the data ecosystem.

Finally, these probabilistic depth-damage functions will be designed for integration into existing USACE workflows and tools, including HEC-FDA, directly facilitating benefit-cost analyses (BCAs) performed by Project Delivery Teams (PDTs). By explicitly quantifying uncertainty, these models will support sensitivity analyses and enable comparisons of mitigation scenarios under varying risk assumptions.

This proposed project would incorporate a hierarchical Bayesian methodology to improve the accuracy, interpretability, and generalizability of parcel-scale flood damage estimation. Traditional depth-damage functions typically apply deterministic relationships between water depth and structural loss, often derived from legacy empirical curves or expert judgment. These approaches obscure uncertainty and limit transferability across structure types or locations. In contrast, this proposed project treats flood damage estimation as a probabilistic inference problem, using hierarchical Bayesian methods to quantify uncertainty, integrate prior knowledge, and enable partial pooling across structurally similar assets.

The resulting parcel-level models generate predictive distributions of expected losses, with associated credible intervals that support more robust decision-making. These probabilistic depth-damage functions can be packaged for use in USACE-aligned workflows, including HEC-FDA, and enhance existing Benefit-Cost Analyses (BCAs) conducted by Project Delivery Teams (PDTs). By representing uncertainty explicitly, these models help PDTs conduct sensitivity analyses, compare mitigation scenarios under varying risk assumptions, and communicate downside risk in constrained or data-limited environments.

Bayesian models will be trained and validated using structure-level data, including FEMA IA claims, NFIP claims, municipal assessments, and engineered vulnerability estimates, where available. This work builds directly on standard USACE-compatible modeling inputs, but extends their utility through modern, transparent inference techniques.

This strategy supports robustness, transferability, and methodological transparency, all while maintaining fidelity to observed data and well-supported physical relationships.

Deliverables:

• Bayesian model code and validation datasets.

• Probabilistic parcel-level depth-damage functions with credible intervals, compatible with HEC-FDA integration.

• Technical documentation of model structure and training methodology.

• Guidance for use in PDT workflows, including cost-benefit analysis, sensitivity testing, and uncertainty communication.

3. GENERAL REQUIREMENTS

The following sub-sections provide details of various general requirements for this effort.

3.1. Non-Personal Services

The contractor shall provide strictly non-personal services and contractor employees are not subject to direct supervision and control by the Government. The contractor shall advise and support the Government but shall not make final decisions or certifications on behalf of the Government nor perform any inherently governmental functions. The contractor and its employees shall not represent the government nor appear to represent the government in performance of these contract services. Contractor personnel shall clearly identify themselves as contractor employees in all interactions during contract performance.

3.2 Contract Administration

The contractor shall establish processes and assign appropriate resources to effectively administer the requirement. The contractor shall respond to Government requests for contractual actions in a timely fashion, ideally within 24 hours. The contractor shall have a single point of contact between the Government and Contractor personnel assigned to support contracts or task orders. The contractor shall assign work effort and maintaining proper and accurate time keeping records of personnel assigned to work on the requirement.

The contractor shall accomplish the assigned work by employing and utilizing qualified personnel with appropriate combinations of education, training, and experience. The contractor shall maintain the technical competency of their employees by providing initial and refresher training as required to meet the task order PWS requirements. The contractor shall be responsible for any subcontract management necessary to integrate work performed on this requirement and shall be responsible and accountable for subcontractor performance on this requirement. The contractor shall also be responsible for insuring timely payment to subcontractors. The prime contractor will manage work distribution to ensure there are no Organizational Conflict of Interest (OCI) considerations.

3.3 Place of Performance

All work will be performed at the contractor’s site. Routine check-in meetings will take place virtually.

3.4 Period of Performance

The period of performance is expected to be 12 months following the Notice to Proceed.

3.5 Materials

All materials, minus expendable supplies, purchased by the contractor with funds from this task order and used under this task order, become and remain the property of the Government.

3.6 Other Direct Costs (ODCs)

There is no travel expected with this contract and the supplies would be minimal, therefore no travel or other direct costs are budgeted for the proposed work

4. PERFORMANCE REQUIREMENTS (TASK AREAS)

Task 4.1: Baseline Summary of USACE and FEMA Depth-Damage Functions as well as USACE’s Cost-Benefit Analysis Procedures for Flood Risk Management Projects The Contractor shall review and summarize all active USACE depth-damage functions along with relevant recent FEMA depth-damage functions and others performed by academia. This review shall include identification of key aspects of the existing USACE depth-damage functions, such as data sources, flood events utilized, methodologies applied (expert elicitation vs. data-driven), function types (e.g., riverine, coastal), and secondary variables (e.g., wave action). The contractor will, with USACE assistance, seek to acquire any flood damage datasets which were used in the creation of depth damage curves for possible use in the later modeling task. The Contractor will also summarize FEMA's recent depth-damage function development efforts. The purpose of this task is to document lessons learned to ensure compatibility and integration of newly developed functions into the existing USACE modeling ecosystem.

In addition, the Contractor, with guidance from USACE, shall conduct a comprehensive review of USACE’s cost-benefit analysis procedures and methodologies related to flood risk management projects. Key topics will include flood simulation software, national structure inventory, structure inventory sampling methods, and existing USACE procedural guidance. The Contractor shall receive training on the USACE flood simulation software (including capabilities and limitations), and familiarize themselves with the National Structure Inventory database, and understand sampling methodologies used to create local structure inventories which are used in benefit cost analysis for flood risk management.

Upon completion, the Contractor will align their modeling approach with existing USACE workflows to minimize disruption and provide a short update to USACE and how depth-damage functions are used in USACE economic evaluations. This update will comprise a baseline and will be ultimately incorporated into the Contractor’s final report. In doing so, the Contractor shall engage flood insurance adjusters, depth-damage experts previously involved in USACE expert elicitation forums, and USACE economists with experience working on Flood Risk Management (FRM) PDT teams.

Task 4.2: Compile and Prepare Structure-Level Flood Loss Datasets The Contractor shall compile, prepare, and consolidate structure-level flood loss datasets from diverse sources, including FEMA Individual Assistance (IA), National Flood Insurance Program (NFIP), municipal governments, USACE, and relevant research institutions and will be shared with USACE upon completion. These datasets will serve as a baseline for comparison against the USACE generic depth-damage functions.

The Contractor shall collaborate with FEMA, USACE, and additional relevant agencies to thoroughly understand each dataset’s characteristics, identify potential weaknesses, and strategize methods for addressing these within the modeling framework. This task will conclude with a summary of dataset-specific findings and their strategic relevance to the modeling effort via a short interim report. The contractor will ensure that the modeling effort and data consolidation is predictive of damage consistent with USACE National Economic Development (NED) standards.

Task 4.3: Develop Hierarchical Bayesian Regression Models for Flood Depth-Damage Relationships and Train Models and Evaluate Predictive Accuracy and Uncertainty Coverage

Leveraging the datasets from Task 4.2, the Contractor shall develop hierarchical Bayesian regression models linking flood depth with structural damages, tailored with structure-type-specific priors. The modeling strategy, developed in consultation with USACE, shall integrate diverse datasets and existing expert-elicited depth-damage functions.

Models shall explicitly consider regional variations, at a minimum of 4 regions of the US (Northeast, Southeast, etc.) and may include preselected regions or utilize data-driven region classification approaches. Additionally, the Contractor shall explore the inclusion of secondary variables in the models, such as pluvial vs. fluvial flood type, flood duration, scope of aggregate flooding, and structure-level characteristics such as building replacement cost and foundation type. The Contractor will produce depth-damage functions for at least one-story and two-story structures with and without basements as well as a preliminary analysis of content damage functions. Additionally, the contractor will provide a strategy for PDT teams to accommodate non-covered structure types that can sometimes predominate in flood risk management projects using the developed models.

Following the development of the Hierarchical Bayesian Regression Models, the Contractor shall train the developed hierarchical Bayesian models using subsets of observed flood damage claims. Predictive accuracy and uncertainty coverage of the trained models shall be rigorously evaluated and documented on left out data.

Task 4.4: Compare Developed Models to Traditional Deterministic Depth-Damage Functions Once the newly-developed hierarchical Bayesian models are developed, the Contractor shall perform a comparative analysis of the newly developed models against existing USACE generic and regional depth-damage functions. This comparison will highlight similarities, differences, and potential implications for future cost-benefit analyses conducted by USACE. One element of this comparison will be using the new models in a cost-benefit analysis through flood simulation of an already-performed feasibility study, and comparing the results/decision criteria produced using the new models to those from the original feasibility study.

Task 4.5: Format Outputs for USACE Compatibility and Integration The Contractor shall format the probabilistic outputs from the developed models to ensure compatibility with existing USACE workflows, such as integration with HEC-FDA and the Project Delivery Team (PDT) cost-benefit workflows.

Task 4.6: Draft Report and Path Forward for Future Flood Damage Modeling The Contractor shall produce a comprehensive report documenting the entire modeling process, including datasets utilized, modeling assumptions, priors, diagnostic assessments, and validation procedures as described in prior Tasks. This documentation must clearly delineate the scenarios in which the developed models are applicable for cost-benefit analysis, including practical guidance and a worked example demonstrating a complete cost-benefit analysis. The report shall highlight the comparative analysis between previous depth-damage workflows and newly developed models (both old and new as well as regional variations), and a clear illustration of how the uncertainty analysis can be completed and incorporated in decision making.

Models will also be accommodating of some amounts of missing structure data, in training and in simulation inference. A description of how the models can be used with missingness in structure inventories will be provided, along with a worked example, and guidance on what types of missingness the model will be appropriate for accommodating.

Acknowledging the evolving nature of flood damage modeling and the associated data dependencies, the Contractor shall prepare a “Path Forward” report outlining strategies for future improvements in flood damage modeling. This document will identify approaches for refining the developed models as new data becomes available, recommend enhancements to USACE flood damage survey methodologies, project future modeling capabilities considering anticipated data collection improvements, and specifically address strategies for integrating coastal flooding considerations.

The draft report will integrate the current modeling effort within the broader trajectory of flood damage modeling research, offering actionable insights for continued advancement of USACE flood risk management capabilities.

Task 4.7. Final Report Following an independent review of the draft report, Contractor will address any comments and revise the draft report in accordance with IWR’s Editorial Review Board requirements.

5. DELIVERABLES AND DELIVERY SCHEDULE

The Contractor shall provide reports and other print deliverables in publication quality format and provide web publishable versions of such deliverables. The table below identifies a set of deliverables that are required under this task order. Several of the tasks can be performed concurrently and the PDT will be expected to provide regular check-in meetings to maintain project momentum and to flag and resolve any issues associated with the contract. Since these findings and report(s) are likely to be published, they would need to comply with the IWR Style Guide as shown in the following link: IWR Style Guide

Deliverable Type Frequency and Quantity of Deliverables

A01 Review and Summarize USACE and FEMA Depth-Damage Functions as well as USACE’s Cost-Benefit Analysis Procedures for Flood Risk Management Projects

Within 30 days of NTP

A03 Develop Hierarchical Bayesian Regression Models for Flood Depth-Damage Relationships and Train Models and Evaluate Predictive Accuracy and Uncertainty Coverage

Within 180 days of NTP

Contractor may invoice monthly upon completion of tasks.

The Government has unlimited rights to all documents and materials produced under this contract. All documents and materials, to include the source codes of any software, produced under this contract shall be Government owned and are the property of the Government with all rights and privileges of ownership/copyright belonging exclusively to the Government. These documents and materials may not be used or sold by the contractor without written permission from the Contracting Officer. All materials supplied to the Government shall be the sole property of the Government and may not be used for any other purpose. This right does not abrogate any other Government rights.

In compliance with Department of Defense Issuances (DoDI) 8500.01 (2014) section 3.c.2, DoDI 8510.01 (2016) section 3.d, and USACE ER 25-1-112 (2014) section 7.1.3; all information systems (IS) and platform information technology (PIT) systems developed and/or supported under this contract shall comply with all DoD, DISA, Army, and USACE cybersecurity and architectural requirements. This includes IS/PIT compliance with DISA Security Technical Implementation Guides (STIG) and being categorized IAW CNSSI 1253 using security controls developed in accordance with (IAW) the risk management framework (NIST SP 800-53). STIG compliance includes, but is not limited to most current version of the DISA published Application Security and Development STIG and the internet access point (IAP) demilitarized zone (DMZ)

STIG.

6. PERFORMANCE REQUIREMENTS SUMMARY (PRS): Performance Standards

Deliverables completed in accordance with Schedule (All statements) 95% of the time

Operational/Effective (All statements)

Recommendations are Implementable

7. GOVERNMENT FURNISHED PROPERTY (GFE)

Not applicable.

8. OTHER REQUIREMENTS

Contractor will be staffed by a diverse and highly qualified team having specific experience with engineering modeling, Bayesian inference, flood resilience planning, working with large datasets and strong familiarity with USACE’s Flood Risk Management mission as well an understanding of the Corps guidance, and use of depth-damage functions for economic evaluations.

8.1 Identification of Contractor Employees

All Contractor personnel attending meetings, answering Government telephones, and working in other situations where their status is not obvious to third parties must identify themselves, to include proper marking of signature blocks in correspondence, to avoid creating an impression in the minds of members of the public that they are Government officials. The Contractor shall ensure that all documents or reports, produced by Contractors are suitably marked as Contractor products or that Contractor participation is appropriately disclosed.

8.1.1 Contractor Identification Badges:

Contractor personnel shall be easily identifiable through the display of badges IAW Contractor Identification (AE Reg. 27-715). The Contractor (to include subcontractors) shall provide each of their employees an easily readable identification badge. The badge must include the employee’s name, the contractor’s company name, the functional area of assignment, and a recent color photograph of the employee. Companies with U.S. Government contracts will require their employees to wear these badges visibly when performing work at Government workplaces and while performing duties in the presence of the public.

Contractor employees shall identify themselves by name and company affiliation when answering the telephone, presenting briefings, conducting or attending meetings, and seminars. All Contractor correspondence (written, facsimile, and email display) shall include their company name.

8.2. SECURITY & SAFETY

8.2.1 Security

The security requirements described below apply to all contract personnel (including all employees of the prime Contractor and Subcontractors) supporting the performance requirements for this contract. The Contractor is responsible for compliance with these security requirements. Questions regarding security matters shall be addressed to the designated Government representative (e.g., Contracting Officer Representative (COR), Requiring Activity (RA) representative, or Contracting Officer (if a COR or other RA representative is not appointed)). Contract personnel are critical to the overall security and safety of US Army Corps of Engineers (USACE) installations, facilities and activities, and security awareness training contributes to those efforts. Contractor personnel and vehicles are subject to search when entering federal installations. Additionally, all contract personnel shall comply with Force Protection Condition (FPCON) measures, Random Antiterrorism Measures (commonly referred to as “RAMs”), and Health Protection Condition (HPCON) measures. The Contractor is responsible for meeting performance requirements during elevated FPCON and/or HPCON levels in accordance with applicable RA plans and procedures. In addition to the changes otherwise authorized by the changes clause of this contract, should the FPCON or HPCON levels at any individual facility or installation change, the Government may implement security changes that affect contract personnel. The Contractor shall ensure all contract personnel are aware of their security responsibilities, including any site-specific requirements identified in local policies or procedures.

All contractor employees who require physical access to government-controlled facilities or logical access to government information and or information systems are subject to a fitness determination and appropriate vetting.

The work under this contract will be UNCLASSIFIED and network or facility access is not required except for participation in meetings therefore the contractor(s) will not require a Common Access Card (CAC). Contractor employees may require access to government facilities for meetings, site visits, to gather data, etc. Infrequent contractor access to a government facility shall be coordinated by the government technical point of contact (TPOC) or the contracting officer representative (COR). The COR or TPOC for each contract is the liaison between the security office and the contractor and will coordinate any visits with the security office.

8.2.2 Safety

Contractor Compliance: The contractor and its subcontractors shall comply with Public Law 91-596 (Occupational Safety and Health Act (OSHA)) and the Environmental, Safety, and Occupational Health (ESOH) (DODD 4715.1E). These requirements shall be incorporated into the contractor’s safety and health program. The Department of Defense (DoD) participates in the OSHA Voluntary Protection Program (VPP). Contractor personnel performing services on a DoD installation shall participate in the local VPP. Information on the VPP is available at https://www.osha.gov/dcsp/vpp/all_about_vpp.html.

Mishap Notification: The contractor and its subcontractors (if applicable) shall promptly report pertinent facts regarding mishaps while performing services under this contract at government facilities. Contractor personnel shall promptly notify the COR or TPOC and cooperate in any resulting safety investigation.

8.3 QUALITY CONTROL/QUALITY ASSURANCE

8.3.1 Quality Control (QC)

The Contractor shall develop a quality control plan (QCP) and implement a quality control program to satisfy the specific requirements of this contract. An optimal QCP shall identify potential problem areas and evolve over the life of the contract. The Contractor shall provide the QCP to the KO and COR for approval no later than 30 calendar days after contract award. The Contractor shall update the QCP as required and provide copies to the KO and COR for approval.

8.3.2 Quality Assurance (QA)

The Government will monitor the Contractor's performance under this contract in accordance with the Government’s quality assurance surveillance plan (QASP). The QASP defines how the performance standards will be applied, the frequency of surveillance, and the acceptable quality levels (performance thresholds). The Government has the right to conduct inspections and performance evaluation at any time and at any place where contract performance occurs. If any aspect of the performance is not in conformance with the requirements of this contract, the Government has the right to issue to the Contractor a Contract Discrepancy Report (CDR). The Contractor shall explain in writing why performance was not in conformance with the requirements of the contract, how performance will be returned to conformance, and how recurrence of the problem will be prevented in the future. The Contractor shall complete and return the CDR to the Contracting Officer and COR within five workdays after receipt of the CDR. The Contractor shall maintain copies of all inspection and evaluation reports. Government review of contractor deliverables will be guided by the QASP. The QASP will be based on the requirements and acceptance criteria in the PWS and aligned with the design, implementation and testing plans in coordination with the contractor.

9. APPLICABLE DOCUMENTS

· IWR Research Report 85-R-5 “Business Depth-Damage Analysis Procedures”

· IWR Style Guide To be included in the TORFP documents.

10. CONTRACTING OFFICER REPRESENTATIVE AND/OR TECHNICAL POINT OF CONTACT (TPOC)

A contracting officer representative (COR) and/or technical point of contact (TPOC) will be appointed on each task order. The COR and TPOC have no authority to direct the contractor in any way to alter the contractual obligation. The contracting officer is the only individual authorized to make changes to the contract.