Effect of roots depth on velocity of exchange flow in canopy area

Exchange flows in vegetated areas are always influenced by various factors. This study investigated how the floating vegetation depth modulates exchange flow induced by negative heat flux of surface cooling in open water. The system features two domains: open water and an aquatic canopy area where floating vegetation exists. Negative heat flux, like that from nighttime cooling, establishes density difference between these areas that promotes intrusion of warm water into the open water at surface. Velocity distribution is measured by PIV method. The experiments are done for a range of vegetation density (۰ to ۳%) and root depth ratio (۰ to ۰.۸۴). It is found that the depth of roots layer in the canopy affects velocity and flow rate of exchange flow. The depth of intrusion flow is depended on solid volume fraction and depth of roots layer. It is also found that the drag force in the canopy area is the main factor affecting the velocity of exchange flow.

Keywords:

Exchange flow , Surface cooling , PIV method , Floating vegetation , Drag force