Hydraulic resistance determination in marsh wetlands

Restoration of degraded and creation of constructed wetlands require proper hydraulic design. Of particular importance is the accurate determination o f flow resistance factors and the proper use of resistance equations, somet hing essential for computing basic hydraulic parameters, such as depth and velocity, and for modeling the hydrodynamics of the system. In this study, selected previous theoretical, laboratory and field studies on wetlands and vegetated-channel hydraulics are reviewed, and existing data from these st udies are extracted and compiled in a common database. Resistance determini ng parameters are discussed, and results are summarized and presented, aimi ng at obtaining laws governing the flow, and deriving values for frictional factors under various flow scenarios. Graphs of Darcy-Weisbach f or Mannin g's n versus appropriate hydraulic parameters are presented. A modified n-V R graph is also presented, appropriate for marsh preliminary hydraulic anal yses and design. These graphs also indicate missing information and can gui de in future research.