Science-based Talk Outline Guidelines for Successful Roadside Ditch Management to Mitigate 1. Flooding – drivers Floods, Droughts and i - climate change Degraded Water Quality ii - watershed management
2. Ditch research project
3. Ditch management recommendations
Rebecca Schneider Dirt and Gravel Roads Dept. Natural Resources Conference Cornell University September 22, 2009
Clinton Franklin # FEMA Disaster St. Lawrence Flood events per County from Jefferson Essex
1994-2006 Lewis Hamilton
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i g Oswego k n r i e Sa h Orleans Oneida s Niagara O H ra Monroe Wayne to a no Fulton ga nd W Genesee a a Schenectady n c o g Montg. t e a g s Ontario Madison n n i g Cayug a d i m e n o r Erie o in a g Otsegoa Rensselaer y S l y iv Yates t n oh an W L r ns r a h lb le ki o n c A y p C e S ia ua s hu m h b q gu c To C e m u u Steuben S Greene lu ta ra Allegany Delaware o u tta ha a Tioga Broome C C C s s e Chemung Ulster h c 0x t Sullivan u 1x Avg flood damage D Orange Putnam 2x costs: ~$50 million/yr Westchester 3x Rockland April 16, 2007, NY 4x Flood damage estimates in U.S., 2002 R. Pielke, M. Downton, Z. Barnard-Miller Suffolk 6x NY City Boulder, CO. www.flooddamagedata.org 7x Nassau
A broader perspective - Northeastern U.S. Climate – Precipitation has been increasing in NY and the Northeast Future directions
2006 Union of Concerned Scientists http://www.northeastclimateimpacts.org
http://yosemite.epa.gov/oar/globalwarming.nsf/content/ us-newyork.html Poor Watershed Management Balance between precipitation, runoff , infiltration , and evapo-transpiration Watershed divide
Watershed: all of the area which captures rainfall and contributes to stream flow, i.e. the “bowl”. Cross-section of a watershed
Watershed divide
rain
Groundwater High flow contribution – base flow
Stream numbering
Overland runoff Low flow via stream channel networks
Natural stream flow patterns Photo: Y. Arthus Bertrand
Impervious Surfaces: Rooftops Parking lots Driveways Compacted Soils: Lawns, Crop fields Impervious surfaces impact the natural patterns of flow: Talk Outline • in frequency and magnitude of floods • in summer droughts • degraded water quality – erosion • loss of diversity of fish and aquatic animals 1. Flooding – i - climate change post-development ii - watershed management
2. Ditch research project stream height pre-development 3. Ditch management recommendations
time (hrs/days/weeks)
Roadside Ditches – Managed by highway staff to prevent the unrecognized factor road flooding and traffic accidents in stormwater runoff management rarely linked to watershed mgmt issues
What role do they play in flooding, droughts, and pollution?
On-going Research GPS and GIS mapping of the on ditch networks ditch networks relative to natural 1) Map: stream channel systems in • ditch lengths, 6 watersheds. • mgmt types • connections to streams
2) Monitor: • Total water flow Without Ditches • Suspended sediment • Dissolved chemicals • Bedload sediment
Paine’s Creek Watershed, With Ditches Lansing, NY Ditches intercept ~1/4 of Mean Peak conc. by Percent of exposed substrate at the bottom
the surface runoff in 7 our watersheds and shunt it rapidly 6 downstream Ditch 4 Ditch 2 where it is injected 5 Ditch 7 as high flow Ditch 3 (incised) into the streams. 4 Ditch 8 Ditch 6 Ditch 5 old 3 Ditch 1 y = 0.0316e0.0413x R2 = 0.7413 Ditch 5 new Mean Peak conc. Mean(kg/m^3) Peak 2 Ditch 3 (scraped) Ditch drainage Regression basins 1 Stream 0 Road ditches 0 20 40 60 80 100 120 % exposed substrate at the bottom Ditch outflows VEGETATED BARE
Ditches are a source Summary of Chemicals Transported in Ditches of sediment and associated Dissolved Chemical Loads contaminants to Element Total load (kg) Ortho-Phosphates 1.43 downstream Nutrients Total P 83.43 A diversity of waters, especially NO - + NO - 21.43 3 2 chemicals when scraped. Al 22.64 dissolved in the Mn 1.48 water and Fe 52.27 adsorbed on the Trace Ni 6.39 sediment particles Metals Cu 1.28 are transported by Pb 0.25 ditches Cr 3.79 downstream. Zn 2.90 Na+ 11,100.58 Mg2+ 737.39 De-icers Cations K+ 75.78 Ca2+ 3,205.36
Anions As3- 0.16
Large quantities of gravel, rocks and other bedload move out of ditches and form deltas in the streams. Current Research: Potential influence on stream erosion.
Current research: Ditches as conduits of human pathogens Ditch influence on to downstream erosion? drinking water
Moose River, Adirondacks reservoirs
Methods E. coli Quantification
Positive for Idexx’s Total Coliforms Colilert/Quantitray Method ™
Positive for E. coli
EPA Std.
Talk Outline
1. Flooding – i - climate change ii - watershed management
2. Ditch research project
3. Ditch management recommendations Guideline #1: Goal: To provide some guidelines for better Create and maintain a shallow, gently sloping ditch. • easier to maintain by mowing – many landowners roadside ditch design and maintenance will do it themselves which accomplish the following: • safer for traffic • less likely to erode 1) Reduce work load and costs.
2) Keep stakeholders happy.
3) Prevent erosion, protect water, and maintain a healthy environment.
Don’t overditch – 18 -24 inches depth is plenty deep enough to carry away stormwater Avoid the V-shaped ditch - the bottom is easily incised and starts the erosion process.
Guideline #3 Guideline #2: Wherever possible, mow ditches regularly Plan ahead to prevent erosive water flows. instead of scraping. • Consider drainage areas upslope that may contribute to erosive flows. • Use check-dams to slow velocities. • Use hydroseeding immediately after ditching Guideline #4: • Hydroseed early in the season to allow sufficient Minimize erosion of gravel and rocks that move growing time, and not immediately before rain. as bedload into streams.
• If scraping is necessary, do it in patches with vegetated strips left downslope to capture sediments.
Guideline #5 Disconnect ditches from streams. Use permeable pavements or • Use infiltration basins or detention ponds that allow for vegetation along road shoulders. groundwater recharge. • Use multiple, under-road culverts to spread out the flow.
Guideline #6 Reduce transfer of runoff Guideline #7 from land to ditches. Communicate! Be part of the dialogue and provide • Increase infiltration of rain leadership concerning stormwater management water on land with landowners and town government. associated with houses, parking lots, and farms. Questions ?
B. Hecht
Acknowledgments: Collaborators: T.Walter, D.Buckley, K. Falbo, J. Diaz-Robles, B.Buchanan Road drainage is a critical component of traffic safety Funding: USDA CSREES, Cornell (funding); Cayuga Lake Watershed Network, as well as flood prevention and water quality improvement ! Town of Candor, Cortland, Enfield Highway Depts., City of Ithaca Planning Dept.