urban water research todd rasmussen associate professor of hydrology the university of georgia,...

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