Introduction to the FEMA Project Team: Surveying

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Detailed Description

The USGS assists FEMA with updating flood insurance rate maps throughout New England. This is in response to recent major flooding events and because of the need to update the 30 year-old effective flood insurance rate maps. This video gives a brief overview of the FEMA project team with a focus on the surveying component of the project.


Date Taken:

Length: 00:04:33

Location Taken: Augusta, ME, US


The United States Geological Survey was created by an act of Congress in 1879 and over the years, thousands of individuals have dedicated their time and effort in the progression of science and technology.

The water discipline accounts for just part of the scope of scientific work done by the USGS. The New England Water Science Center conducts water-resources investigations with federal, state, tribal, and local cooperators.

Part of the USGS Mission is to support other Federal Agencies. The Federal Emergency Management Agency or FEMA is one of our cooperators. We assist FEMA with updating flood insurance rate maps throughout New England as a response to recent major flooding events and because of the need to update the 30 year-old effective flood insurance rate maps.

We update these maps by watershed. We breakup each watershed project into three components: Surveying, Modeling, and Mapping. This video is primarily focused on the surveying component.

Our surveying takes us from the city-side to the country-side and we have a lot of work to do. We are committed to working year-round to get the job done. Using leading-edge technology, like the Trimble total station and the Esri Collector app, surveyors try to accurately represent the ground topography in a river or stream by collecting point data on dams, bridges, and culverts as well as making channel measurements every 500 to 1000 feet. This data as well as supplemental site information such as photos, sketches, and field notes are then passed on to the modelers who will create flood profiles based on this information.

Our survey work is typically done in two person teams with a lead and support person. The lead is responsible for planning trips, getting site photos, keeping clear notes, and ensuring the data collected is of good quality. The support person, as the name would suggest, is there to help the lead and in the case of new hires… learn.

Before going into the field the lead needs to plan the trip logistics. This includes travel logistics as well as considering what progress can be made during the trip. Before traveling government employees needs to submit a travel authorization and book a hotel room based on the per diem rate for their travel destination. Additional coordination between the lead and support person may be necessary if they are traveling from separate offices.

The main tool used for planning and tracking progress is ArcOnline. Once the lead surveyor gets their reach assignments they look at aerial imagery of their reaches in ArcOnline and identify structures that need to be surveyed.  Reference cross sections are then placed on these structures and in locations where channel measurements are needed. In the field surveyors can access the cross section data through the Collector app. From there they can edit the cross section layer and upload their notes and site photos. This information is updated in ArcOnline in real time.

After the cross sections are ready to go, field work can begin. Reference marks and ensuring their proper placement along the reach are essential in maintaining data integrity. Before setting reference marks or RMs, we use a Global Navigation Satellite System or GNSS receiver to check in on a benchmark with a known location and elevation. This is done to make sure the GNSS receiver is functioning properly. This also takes a little while. Once the receiver is checked in, RMs are set near structures along the reach.

From there we use the Reference Marks to tell the Total Station where it is in space so it can then calculate the distance and elevation to a given point.

The Lead sets up the measurement and makes sure the total station is looking at the prism before collecting the shot. The support person makes sure the prism is held level and still to ensure the point is collected in the intended location.

The lead will also collect supplemental site information such as a site sketch, field notes, and photos of the structure and upstream and downstream channel. All of the supplemental information as well as the point data collected by the total station can then be uploaded using the Collector App.

Once the data and site information is compiled for all detailed study reaches in the watershed, the information will be passed on to our modelers who will generate the flood profiles for these reaches. and then finally to our Mappers who will generate the final Flood Insurance Rate Maps for FEMA.

Welcome to the USGS.