What is a low head dam?
A low head dam is a manufactured structure, built in a river or stream channel, extending fully across the banks. A low-head dam is designed and built such that water flows continuously over the crest from bank to bank. If water levels rise downstream, a submerged hydraulic jump can form that produces an upstream directed current that traps any recreationist who might go over the dam.
More than 1,000 fatalities have occurred at structures such as these. Not all low-head dams produce this current. Our three-year project culminated in the production of the map of the contiguous United States below that shows the location of the more than 13,500 low-head dams in what we call the alpha version of the inventory.
How Can I Help?
In collaboration with the Association of State Dam Safety Officials (ASDSO) and the U.S. Society on Dams (USSD), ASCE-EWRI is committed to assisting in the location and inventorying of low-head dams. Of the various subcommittees in the task force, one is the development and testing of apps to collect field information on these low head dams. The intent is for users to easily document the coordinates and photo of a low head dam using their mobile device. The group is capturing locations through other means such as existing state inventories, Google Earth and machine learning techniques.
Currently, there are two apps explored by the subcommittee – a web-based app and Survey123 app. The web-based app is being piloted and can be accessed by using this QR code.
The collected data is mapped as shown, with location icons consolidated when looking at the entire country and individual locations visible with a closer look. Ultimately, the goal is to fill the entire map with all low head dam locations in the country to serve as a living tool for government entities, outdoor organizations, engineers, and the general public.
The importance of field verification understood by all engineers for informed decision making. Each entry is a contribution towards greater low head dam safety. The subcommittee asks for your contribution by spreading the word about the opportunity to capture a low head dam using the QR code to make an entry. If your work or personal hobbies involves frequent encounters with low head dams, we are especially interested in your involvement. A few minutes taken to capture a low head dam is invaluable when it could lead to a difference of a life being saved because the location was known and appropriate corrective actions were taken to improve safety. With virtual collaboration at its height, this feat is possible and truly exciting to be a part of.
This training document offers an in-depth tutorial on how to catalogue low heads dams via Google Earth.
As low-head dams are located and catalogued, updates of the inventory of low-head dam locations in your state will be reflected in this existing inventory of low head dams.