A summary of USGS resources and data related to flooding hazards in Wisconsin.
What is a flood?
A flood occurs when relatively high water overflows the natural or artificial banks of a stream or coastal area and submerges land not normally below water level.
Why do floods occur?
In Wisconsin, floods usually are caused by one of three scenarios:
- In the summer, thunderstorms associated with slow-moving frontal systems
- In the winter, floods can occur when rain falls on snow causing rapid snowmelt
- Ice-jam floods are also a hazard during the winter
Wisconsin hydroclimatology
The principal moisture-bearing air masses for Wisconsin originate in the Gulf of Mexico (moisture can also come from air masses originating in the Pacific Ocean, but these lose most of their moisture crossing the Rocky Mountains). Lake-effect precipitation is a minor source of moisture for Wisconsin; lake-effect precipitation is most noticeable in the early winter when the cold air blowing over the unfrozen Great Lakes absorbs moisture, which then is precipitated as snow on the lake shores.
Factors that contribute to flood events in Wisconsin streams include:
- drainage area
- storage (the percentage of drainage area covered by lakes, ponds, swamps, and wetlands)
- heavy rainfall, snowfall, or snowmelt
- soil permeability of the least-permeable soil horizon
- forest and vegetation cover (the percentage of drainage area covered)
In urban areas, factors contributing to flooding include:
- drainage area
- percentage of drainage area that is impervious (parking lots, roads, rooftops)
USGS flood data
Real-time and historical information on floods in Wisconsin is available through the USGS National Water Information System (NWIS).
A map of Wisconsin gages currently at high-flow or flood conditions can be found here. Click on a site to get a summary of conditions, view the current hydrograph, or see a chart of how the current stage compares with historical peak flows and floods. Animations of current and historical high-flow and flood events (by date) are also available.
A table of current discharge measurements and historical peaks for all real-time streamgages in Wisconsin is also available. You can use the USGS WaterAlert service to receive an email or text alert if a particular streamgage exceeds a user-specified gage height or discharge value.
How the USGS contributes to flood response
During a flood, the USGS and the National Weather Service work in concert with its own precipitation data to forecast river stages and flow conditions on large rivers and their associated tributaries. The USGS collects streamflow data, the NWS collects precipitation data and combines both types of data to make flood forecasts. The USGS will continue to measure the actual height of the flood during the event.
During large, regional flood events, the USGS will deploy field crews to install temporary rapid-deployment streamgages and sensors ahead of the storm to track flooding as it happens. Some of these sensors will relay real-time information to emergency managers during the flood event, while others will be retrieved by the field crews as soon as floodwaters have receded. These hydrographers will also look for physical evidence of high-water marks left behind by the flood. Post-flood analyses allow USGS scientists determine the extent of the flood and help communities prepare for future flood events.
Below are other science projects associated with this project.
Flood frequency in Wisconsin
June 2008 floods in southern Wisconsin
Below are data or web applications associated with this project.
WaterWatch (surface water)
WaterWatch displays maps, graphs, and tables describing real-time, recent, and past streamflow conditions for the United States, including flood and droughts. Real-time information generally is updated on an hourly basis.
Surface-water data for Wisconsin
Real-time, daily, peak-flow, field measurements, and statistics of current and historical data that describe stream levels, streamflow (discharge), reservoir and lake levels, surface-water quality, and rainfall in Wisconsin. Surface-water data are collected and stored as either discrete field-water-level measurements or as continuous time-series data from automated recorders.
Below are publications associated with this project.
Changes in streamflow characteristics in Wisconsin as related to precipitation and land use
The USGS National Streamflow Information Program and the importance of preserving long-term streamgages
How does a U.S. Geological Survey streamgage work?
Flood of June 2008 in Southern Wisconsin
Flood hazards— A national threat
Large floods in the United States: where they happen and why
Flood-frequency characteristics of Wisconsin streams
Estimating magnitude and frequency of floods for Wisconsin urban streams
Flood of July 1-5, 1978 on the Kickapoo River, southwestern Wisconsin
A summary of USGS resources and data related to flooding hazards in Wisconsin.
What is a flood?
A flood occurs when relatively high water overflows the natural or artificial banks of a stream or coastal area and submerges land not normally below water level.
Why do floods occur?
In Wisconsin, floods usually are caused by one of three scenarios:
- In the summer, thunderstorms associated with slow-moving frontal systems
- In the winter, floods can occur when rain falls on snow causing rapid snowmelt
- Ice-jam floods are also a hazard during the winter
Wisconsin hydroclimatology
The principal moisture-bearing air masses for Wisconsin originate in the Gulf of Mexico (moisture can also come from air masses originating in the Pacific Ocean, but these lose most of their moisture crossing the Rocky Mountains). Lake-effect precipitation is a minor source of moisture for Wisconsin; lake-effect precipitation is most noticeable in the early winter when the cold air blowing over the unfrozen Great Lakes absorbs moisture, which then is precipitated as snow on the lake shores.
Factors that contribute to flood events in Wisconsin streams include:
- drainage area
- storage (the percentage of drainage area covered by lakes, ponds, swamps, and wetlands)
- heavy rainfall, snowfall, or snowmelt
- soil permeability of the least-permeable soil horizon
- forest and vegetation cover (the percentage of drainage area covered)
In urban areas, factors contributing to flooding include:
- drainage area
- percentage of drainage area that is impervious (parking lots, roads, rooftops)
USGS flood data
Real-time and historical information on floods in Wisconsin is available through the USGS National Water Information System (NWIS).
A map of Wisconsin gages currently at high-flow or flood conditions can be found here. Click on a site to get a summary of conditions, view the current hydrograph, or see a chart of how the current stage compares with historical peak flows and floods. Animations of current and historical high-flow and flood events (by date) are also available.
A table of current discharge measurements and historical peaks for all real-time streamgages in Wisconsin is also available. You can use the USGS WaterAlert service to receive an email or text alert if a particular streamgage exceeds a user-specified gage height or discharge value.
How the USGS contributes to flood response
During a flood, the USGS and the National Weather Service work in concert with its own precipitation data to forecast river stages and flow conditions on large rivers and their associated tributaries. The USGS collects streamflow data, the NWS collects precipitation data and combines both types of data to make flood forecasts. The USGS will continue to measure the actual height of the flood during the event.
During large, regional flood events, the USGS will deploy field crews to install temporary rapid-deployment streamgages and sensors ahead of the storm to track flooding as it happens. Some of these sensors will relay real-time information to emergency managers during the flood event, while others will be retrieved by the field crews as soon as floodwaters have receded. These hydrographers will also look for physical evidence of high-water marks left behind by the flood. Post-flood analyses allow USGS scientists determine the extent of the flood and help communities prepare for future flood events.
Below are other science projects associated with this project.
Flood frequency in Wisconsin
June 2008 floods in southern Wisconsin
Below are data or web applications associated with this project.
WaterWatch (surface water)
WaterWatch displays maps, graphs, and tables describing real-time, recent, and past streamflow conditions for the United States, including flood and droughts. Real-time information generally is updated on an hourly basis.
Surface-water data for Wisconsin
Real-time, daily, peak-flow, field measurements, and statistics of current and historical data that describe stream levels, streamflow (discharge), reservoir and lake levels, surface-water quality, and rainfall in Wisconsin. Surface-water data are collected and stored as either discrete field-water-level measurements or as continuous time-series data from automated recorders.
Below are publications associated with this project.