CS31E - Concurrent Session 31E: The NRCS Model to Estimate Monetary Benefits of Watershed Dams from a Specific Storm or Series of Storms

Since 1948, the NRCS Watershed Programs assisted with the construction of nearly 12,000 dams in 1,271 projects in 47 states. NRCS planned and designed most watershed dams to provide flood control, erosion control, water supply, and/or recreation. Typically, watershed dams are earthen embankments ranging from 20 to 90 feet in height with earthen vegetated auxiliary spillways and concrete or metal principal spillways.

This paper describes the basis of the NRCS model that estimates the monetary benefits provided by each watershed dam in the nation each day. The model summarizes the benefits data by various geographical units such as watershed project, county, congressional district, state, and nation. It accumulates the benefits for various time intervals (daily to year-to-date) as well as any user-defined period back to 2005. The model archives the rainfall amounts, storm frequencies, and benefits computed for each geographical area for future use. It also archives the daily rainfall recorded for each watershed dam. The model reports the benefits for any geographical area for any archived past time period.

The model uses the National Weather Service (NWS) daily rainfall data, NWS precipitation depth-duration-frequency data, and the NRCS National Inventory of Dams (NID) data. The monetary benefits data comes from the NRCS watershed POINTS database that includes the results of the economic analyses completed during the original project planning and authorization to assure that the benefits exceeded the cost of construction. NRCS updates the monetary benefits annually to current dollars. The total average annual monetary benefits for all watershed projects with dams is over $1.4 billion.

The monetary benefits consider flood damage reduction to crops, pastures, fences, farm buildings, equipment, livestock loss, residential and commercial properties, utilities, roads, railroads, and bridges, as well as non-flood benefits such as water management (irrigation), livestock water, municipal water supply, recreation, and improved fish and wildlife habitat.

The information from the model is helpful for educating residents and decision makers about the value of these projects, the benefits they provide to their community, and the need to maintain this important public infrastructure so it can continue to serve generations to come,. The model reports the benefits immediately after a storm occurs so that news stories can report on the damage that did not occur due to the watershed projects, during the news cycle while the rest of the media is focusing on the devastation caused by the storm.