Executive Summary: A New View of Risk
Urban flood risk in Richmond is evolving. While riverine flooding from the James River is well-understood, the threat from short-duration, high-intensity rainfall (pluvial flooding) is growing, directly threatening underground power infrastructure. EO data provides an unparalleled ability to diagnose these complex risks, moving beyond static flood maps to inform dynamic operational decisions and long-term capital planning. This analysis demonstrates how NASA data can map flood pathways, identify at-risk assets, and build a more resilient grid.
of Major Outages
are now linked to extreme weather events in Virginia. This trend underscores the urgency of integrating climate-informed data into grid planning.
Increase in Impervious Surfaces
in key urban watersheds since 1990. This growth, mapped by Landsat, directly correlates with increased stormwater runoff and flash flood frequency.
Primary Drivers of Major Outages
Extreme weather is the dominant factor, far surpassing other causes and highlighting a critical vulnerability.
Richmond's Dual Flood Threat
Dominion's underground assets face two distinct flood types. Understanding both is critical for effective risk management. EO data helps differentiate and model these pathways, revealing how surface water infiltrates and compromises subterranean systems.
1. Fluvial (Riverine) Flooding
This is large-scale, slow-onset flooding from the James River overflowing its banks, driven by widespread rainfall or upstream snowmelt (e.g., Feb 2025 event, Hurricane Agnes). While Richmond's floodwall protects parts of downtown, this flooding causes widespread inundation and sustained high groundwater levels.
Impact on Underground Assets:
- Sustained hydrostatic pressure on vault walls.
- High groundwater tables submerge duct banks.
- Widespread, prolonged outages in low-lying areas.
2. Pluvial (Urban/Flash) Flooding
This is rapid, localized flooding caused by intense, short-duration rainfall that overwhelms storm drains (e.g., July 2025 event, Hurricane Gaston). Impervious surfaces create rapid runoff that flows along streets, ponding in low points, underpasses, and utility corridors.
Impact on Underground Assets:
- Rapid infiltration into manholes and vaults from street level.
- Storm drains backflow into utility conduits.
- Flash flooding compromises pad-mounted transformers.
A History of High Water: Case Study Timeline
Recent and historical events illustrate the evolving nature of Richmond's flood risk, shifting from primarily riverine events to a hybrid risk dominated by intense, flashy urban floods.
Hurricane Agnes (1972)
Type: Fluvial (Riverine). The record-breaking flood on the James River. This event set the benchmark for flood protection and defined the city's relationship with the river, leading to the construction of the floodwall.
Hurricane Gaston (2004)
Type: Pluvial (Urban/Flash). A catastrophic flash flood from a stationary rain band. This event demonstrated the severe vulnerability of urban basins like Shockoe Creek to extreme rainfall, independent of the James River's level.
February 2025 Winter Storm
Type: Fluvial (Riverine). Heavy rain and snowmelt pushed the James to ~16 ft, triggering floodwall closures. EO data (SMAP) showed high antecedent soil moisture, which amplified runoff and contributed to the high crest.
July 2025 Convective Storm
Type: Pluvial (Urban/Flash). Torrential downpours caused widespread flash flooding and power outages. GPM IMERG data captured rainfall rates exceeding 3 inches/hour, overwhelming stormwater systems and flooding underground infrastructure.
Diagnosing the Risk with EO Data
NASA's suite of Earth-observing satellites provides a multi-layered view of flood risk, from the long-term changes in land cover that create runoff, to the real-time conditions that precipitate a flood event.
Growth in Impervious Surfaces (1990-2025)
Landsat data quantifies the conversion of natural terrain to rooftops, roads, and parking lots. This growth in key urban watersheds, like Shockoe and Gillies Creek, is a primary driver of increased pluvial flood risk, as less water can infiltrate the ground.
Antecedent Conditions: Feb 2025 Storm
EO data shows *why* a storm causes flooding. Before the Feb 2025 event, NASA's SMAP satellite showed soil moisture was already near saturation. With nowhere to go, subsequent rainfall became immediate runoff, exacerbating the James River's crest.
Storm Analysis: July 2025 Flash Flood
NASA's GPM IMERG product provides high-resolution rainfall data. During the July 2025 storm, it measured rainfall rates that far exceeded the "10-year design storm" capacity of local storm drains, explaining the rapid and widespread urban flooding that inundated underground vaults.
Mapping the "Hot Spots": Where Water Meets the Grid
By integrating EO-derived hazard data with Dominion's asset information, we can move from general risk to a specific, actionable map of vulnerability. This framework pinpoints "hot spots" where flood-prone areas intersect with critical underground infrastructure.
The EO-Informed Risk Framework
Risk is a function of three components, all ofwhich can be measured or informed by NASA data.
Flood depth, duration, and velocity.
EO Data: GPM (Precip.), SMAP (Soil Moisture), DEMs (Flow Paths), SAR (Inundation).
Location of assets in hazardous areas.
EO Data: Landsat (Urban Extent) + Dominion Asset Maps (Vaults, Ducts).
Asset design, age, and protection.
EO Data: Informs asset-specific threats (e.g., pluvial vs. fluvial) to guide hardening.
Neighborhood Risk Hot Spots
This analysis correlates modeled pluvial flood depth (from DEMs and rainfall data) with underground asset density. Neighborhoods in the top-right quadrant (e.g., Scott's Addition, Shockoe Slip) represent the highest-priority areas for inspection and hardening, as they combine deep, frequent flooding with a high concentration of critical assets.
A Resilient Path Forward: EO-Informed Decision Pathways
EO data supports a tiered strategy for grid resilience, informing immediate operational decisions, guiding medium-term capital investment, and stress-testing long-term modernization plans.
Short-Term (1-3 Years)
Operational & Tactical
- Prioritize inspections, sealing, and hardening of high-risk vaults identified in "hot spot" analysis.
- Integrate near-real-time GPM rainfall and SMAP soil moisture data into pre-storm staffing and staging decisions.
- Pre-deploy pumps and crews to at-risk manholes before pluvial flood events.
Medium-Term (3-10 Years)
Capital Planning
- Factor EO-based flood risk (pluvial and fluvial) into capital planning for new underground circuits and substation siting.
- Use Landsat-derived urban growth models to anticipate future runoff and design new infrastructure accordingly.
- Co-locate resiliency investments with city stormwater and green infrastructure projects.
Long-Term (10-30+ Years)
Strategic Modernization
- Use NASA climate projection data to stress-test grid modernization plans against future rainfall and storm surge scenarios.
- Model long-term scenarios for rerouting critical feeders away from future high-risk flood zones.
- Inform long-range undergrounding strategy and cost-benefit analysis with climate-adjusted risk data.
Recommendations: The SSAI-Dominion Partnership
We propose a collaborative pilot program to operationalize these insights and co-develop next-generation resilience tools for Dominion Energy.
1. Joint Risk Map
Develop a high-resolution, integrated "flood-and-grid" risk map for downtown Richmond and key neighborhoods, layering EO data with Dominion's asset registry.
2. Shared Data Pipeline
Establish a cloud-based data pipeline (e.g., API) to feed near-real-time NASA products (GPM, SMAP) directly into Dominion's GIS and outage management dashboards.
3. Co-Designed Pilot
Select a high-risk area, apply EO-based risk assessment to guide upgrades, and jointly monitor the performance and ROI over future storm seasons.