Determine the channel width $($w$)$ to depth $($d$)$ ratio at sediment threshold conditions. The rectangular channel carries a bankfull peak discharge of $540$ m$3/$s and has a longitudinal slope is$0\mathrm{.}0015.$ The channel bed conditions are underloose $($very strong structure$).$ Information is available from a riverbed survey which has determined that the bed material consists of gravel with a D$50$ of $25$ mm$.$In your solution, assume that w$/$d $>20.$