(NepRWA 2004) 48 ft 3 158 ft 3 198 ft 3 What will change to the hydrology of the marsh if it were...

Hydrology and the Neponset

Christopher A. Lynum

(NepRWA 2004)

48 ft3

158 ft3

198 ft3

Mosquito ditches

• Allow tides to penetrate higher into the marsh

than otherwise could

• Thought to lower marsh water table

• Mosquito ditches can naturally fill in

• Or mechanically filled as restoration effort

Ditch plugging and filling

• Plugging: – Plugging the entry of the ditch – May require extensive maintenance

• Filling:– Can fill in using spoil if present– Perceived as more costly but likely restores a

greater area of marsh

Ditch plugging and filling

• Need to consider other factors– Ditches in marsh elevation process– Sea Level Rise

Corman et al. 2012

Ditch plugging and filling

• Have to maintain elevation relative to sea level rise– Resist submerging the marsh or converting to open

water– Promote natural accretion

• Determine proper elevation in relation to the tide level that will create a hydrologic regime.– Especially one where the desired vegetation is adapted

Corman et al. 2012

• If filling affects elevation• Create new creeks using dredging techniques– Allows for flow of water further into marsh

• Case studies:– Neponset River Marsh– Broad Meadows Marsh

Dredging

Neponset River Marsh

2005

2004

2013

Broad Meadows Marsh2008

2013

Questions?