Height Modernization – Leveling the Nation

Aerial view of New Orleans after Hurricane Katrina.

The Earth’s surface is constantly changing, either rising or falling depending on a variety of geographical conditions. The result is that we may be more vulnerable to flooding and other natural disasters. Because of this vulnerability, we need elevation measurements that are more accurate to help us understand how these factors affect communities across the United States. That’s why NOAA constantly updates its height measurements.

NOAA's National Geodetic Survey Height Modernization Program combines GPS technology with land surveying techniques to enable us to determine elevations quickly and accurately. For years, GPS was used to determine accurate positions (latitude and longitude). Now, with NOAA’s program, GPS can efficiently establish accurate elevations for a wide variety of needs.

National Benefits

Reliable elevation data are essential for scientific inquiry as well as safety and convenience. It can measure how fast a piece of land is sinking (a process called subsidence) or improve aircraft navigational aids to make approach-and-landing procedures safer.

Subsidence marker shows how much the land has sunken.

High resolution (Credit: NOAA)

Because the data precisely pinpoints the rise and fall of land surfaces, it can help make water delivery and drainage systems more efficient and reduce urban and agricultural runoff and water pollution. Elevation data also helps create more precise modeling of storm-surge and pollution trajectories during extreme weather and hazardous spill events.

Height Modernization also improves disaster preparedness and recovery and infrastructure projects. GPS is especially useful when latitude, longitude, and elevation must be quickly established in areas where the local infrastructure has been largely destroyed; when a construction, public works, or transportation project involves large-scale coverage; and when difficult, rugged terrain lies between survey points.

Using Elevation Data to Protect Lives and Property

	Fully Funded Height Modernization Programs	Year Joined
1	California	2000
2	North Carolina	2000
3	Louisiana	2002
4	South Carolina	2002
5	Wisconsin	2002
6	Mississippi	2003
7	Washington	2004
8	Alabama	2004
9	Arizona	2006
10	Texas	2006
11	New Mexico	2006
12	Colorado	2008
13	Kansas	2008

The Height Modernization Program began in the 1990s in two states. Today, more than two dozen states are engaged in Height Modernization, but only 13 are fully funded. The program enables people anywhere in the country to get accurate elevation data more efficiently than with costly, time-intensive, traditional surveying methods.

Especially in the Gulf of Mexico, shifts in the shoreline from sinking land and rising seas increase the risk of flooding from storm surges, and could cause millions of dollars in property damage. Data from the Height Modernization Program, combined with other data sources, can be used to understand the damage to infrastructure so local government officials can mitigate costs as rebuilding efforts are launched.

A Safer Future

Whether it is for safe and efficient transportation and commerce, understanding climate change and mitigating damage from coastal storms by monitoring sea levels, or providing information to help emergency response personnel plan for and respond to natural disasters, having accurate heights is critical. NOAA’s height modernization program does just that.

To learn more about NOAA’s program, visit the National Geodetic Survey’s Height Modernization Program Web site.