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