Flood Early Warning System

What is it?

Flooding from extreme rainstorms can cause safety concerns and property damage. To help with emergency response efforts and to keep people safe, we launched the Flood Early Warning System (FEWS) that predicts severe weather and helps the city prepare for flooding.

Benefits

Predict flooding along Raleigh’s creeks.
Notify City Leaders, Emergency Management, and the public of potential flooding.
Close roads (as needed) sooner.

How it Works

We're focused on collecting data and using technology to determine:

When streams may flood;
How high floodwaters may get;
How much lead time we have to prepare; and,
What resources are needed.

Data Used
Stream and rain gauges	Gauge-Adjusted Radar Rainfall (GARR) (Provides real-time data on rainfall amounts across Raleigh)
Soil saturation	Infiltration rates
Weather Forecasts	Subsurface runoff
Drainage network	Soil moisture
Watershed properties	Reservoir information

The dashboard that provides data from the system is for city staff only. You can use this map to track storms with us.

Phases

Phase 1 (Complete)
Forecast flooding in Raleigh along Crabtree Creek between Ebenezer Church Road and US 1.

Phase 2 (Complete)
Forecast flooding in Raleigh along Walnut Creek, Marsh Creek, and the rest of the Crabtree Creek watershed.

During this phase, we also worked with US Geological Survey (USGS) to install four rain gauges at fire stations in Raleigh. These gauges collect data every five minutes.

Phase 3 (Complete)

Expanded data collection to more areas known to flood, started to monitor conditions at specific dams in Raleigh, developed a web app that simulates and helps predict different types of flooding conditions, and connected all gauges to the latest alert system to receive 5-minute data from all gauges.

During this phase we also installed additional flood monitoring cameras along with six new rain gauges and one new stream gauge.

Phase 4 (To begin Spring 2023)

Collection Times

A US Geological Survey stream gauge near Walnut Creek — A stream gauge on S. State Street.

In coordination with USGS, as of the Summer of 2022 we now collect and transmit gauge data every five minutes at all our stream and rain gauge locations (instead of every fifteen minutes or every hour as in years past).

Note: The current gauge data is not available right away. There is a brief processing period from when data is collected to when it's available on the USGS website or our dashboard.

Process

We are working on this program with consultant, Vieux and Associates. The process includes:

Getting details on floodprone areas;
Identifying types of warning alerts;
Recommending flood forecasting for 'hotspot' areas;
Gathering data and modeling stream flow and flooding;
Inventorying and mapping the stormwater system; and,
Setting up, maintaining, and expanding the early warning system to track flooding conditions.