A study of the influential factors affecting the slopes of deposited sediments behind the porous check dams and model development for prediction

Spacing between check dams depends on the stream bed slope, effective height of check dams and slope of deposited sediments behind the check dams. The slope of deposited sediments is more important than the other two factors because of complications in the way of its occurrence and its measurement after several years of dam construction. This research presents the effective factors affecting the slope of deposited sediments behind 60 selected check dams among 2000 evaluated ones in the watershed of Doroudzan Dam. Such factors as stream bed slope, slope of deposited sediments behind dams, height of check dams, width of stream on the dam site, sand, silt, clay, granule, pebble, cobble and D50 of sediments were assessed. Based upon the collected data three models: linearlogarithmic, modified linear –logarithmic and simplified linear-logarithmic, for determining the slope of the deposited sediments as well as the space between check dams were developed and compared. The results showed the factors significantly affecting the slope of deposited sediments are: stream bed slope, height of check dams, stream width, sand, granule and D50 of sediments.