Urban Water Research
Todd Rasmussen
Associate Professor of Hydrology
The University of Georgia, Athens
and
Pending Director, Urban Water Research Institute
The University of California, Irvine
Atlanta, Georgia
“the fastest-spreading human
settlement in history"
Time Magazine
March 22, 1999
Ag/Poultry
Forests
Gainesville
Lake Lanier
Buford Dam
Urban Water Issues
• Stormwater Management
• Nonpoint Sources of Pollution
• Source Water Protection
• Water Conservation
• Wastewater Reuse
• Wastewater Infrastructure
Roles of Science• Data
• Data collection - monitoring and experimentation
• Data storage, and dissemination - databases
• Information• Data interpretation - forming relationships between data
• Information storage and dissemination - information systems
• Knowledge• Understanding relationships - predicting outcomes
• Knowledge storage and dissemination - models
• Wisdom• Using knowledge for the public good
Hydrology
EPA/NSF Lake Lanier Water and Watersheds Project
+ Community beliefs and references change
+ Short- and long-term beliefs are different
+ Beliefs change in response to knowledge
+ Water quality can be characterized using the Rating Curve approach
+ Nutrient dynamics in the epilimnion and sediments control hypolimnetic O2
+ Water quality and habitat control community structure
+ Phosphorus-iron chemistry dominates nutrient dynamics
Society
Ecology
Water Research Strategy
• Identify relationships at the watershed scale– Public involvement: Defining Quality of Life– Prioritization: Best to Worst– Obtain information: “Soft” and “Hard”
• Develop solutions at the local scale– Feasibility assessments: economic, legal,
engineering, ecologic, societal– Demonstration: education and outreach
Lake Lanier Strategy
• Watershed Analyses– Contaminant Rating Curve approach for TMDLs– Whole-Lake Loading Rates
• Implementation Strategies– Laboratory and Pond experiments– Simple BMP approaches (Meta Models)– Communicating results
1
10
100
1,000
10,000
0.1 1 10 100
Normalized Discharge, Q / Qo
Su
spen
ded
Sol
ids
Con
cen
trat
ion
, mg/
L
West Fork Little River near Clermont
Chestatee River near Dahlonega
Chattahoochee River at Cornelia
Chattahoochee River at Norcross
Sediment Rating Curve
Nutrient Rating Curve
1
10
100
1,000
10,000
1 10 100 1,000 10,000
Sediment Concentration (mg/L)
Ph
osp
hor
us
Con
cen
trat
ion
(µ
g/L
)
Point Source: Flat Creek
Take Home Message
• Total Maximum Loads can be quantified
– By using Rating Curves that correlate contaminant
concentrations with discharge
– Then establishing the concentration at mean discharge
• Preventing - reducing stormwater should be a priority
– Sediment in stormwater degrades aquatic habitats
– Stormwater contains nutrients, pathogens, etc.
Options to Reduce Nonpoint Pollution
• Stormwater Interception Strategies
– Riparian and Floodplain Protection
– Filter and Infiltration Strips
– Headwater Ponds and Wetlands
• Source Minimization
– Controls and Limits on Loading Rates
– Land Use Restrictions
Stormwater Mitigation
• Conventional stormwater disposal practices– Stormwater channels, tunnels– Detention basins
• Onsite stormwater disposal alternatives
• pervious pavements• raingardens• constructed wetlands• wet ponds• drywells
• infiltration strips• mulching• riparian buffers• greenspaces• contour terracing
Onsite Stormwater Mitigation
• Surface Infiltration– Mulching, Vegetated Swales, Raingardens
• Subsurface Percolation– Drywells, Leach Fields
• Stormwater Retention– Constructed Wetlands
•Vegetated Swales
Drywell
Impacts of Impervious Surfaces
• Impervious areas < 10% – Minimal impacts on aquatic systems
• Impervious areas > 25% – Complete loss of aquatic integrity
• Treecover < 40% & Greenspace < 20%– Increases stormwater runoff– Degrades water quality
Implementation Strategies
• Who Pays?– Downstream water users are willing to pay because it is
cheaper to prevent contamination than to treat the contaminated water
– Developers are willing to pay if all parties are treated equitably
• Who Benefits?– Landowners are paid to reduce nonpoint source pollution
– Water users who obtain clean water
– The Environment!
What is Needed
• A watershed management authority who– Collects fees from wastewater connections, septic systems,
water supply systems, owners of properties with impervious
surfaces
– Pays land users to reduce historical inputs
– Monitors watershed conditions to ensure that efforts are
effective
– Enforces existing laws for egregious violations
– Supports environmental education
Needed …• Model Ordinances
– Stormwater Control– Riparian Buffers and Landscaping– Water Conservation and Grey-Water Reuse– Urban Forests and Green Space
• Other Measures– Conservation Easements (Land Trusts)– Transferable Development Rights (TDRs)
• More Ideas => Search for:– “Rules for Healthy Streams”
Water Resources Programs• Measurement and Assessment
– Water Quality and Quantity
• Effects on Aquatic Ecosystems– Hydromodification– Habitat Impairment
• Human Systems, Technology, and Policy– Education and Outreach– Demonstration Projects– Model Ordinances
How to Assure Success
• Data Needs– Examples of water quality treatment options
• Information Needs– Regional differences in effectiveness
• Knowledge Needs– Parameters or processes that are key to success
• Wisdom Needs– Relative ability for local communities to apply
Hydrology
Society
Ecology