Laurent Ahiablame Prof. Bernard Engel, Prof. Indrajeet Chaubey Date, 2012

1. Effectiveness of low impact development practices in two urbanized watersheds: Retrofitting with rain barrels/cisterns and porous pavements Laurent Ahiablame Prof. Bernard Engel, Prof. IndrajeetChaubey Date, 2012

2. The Problem • How effective are LID practices at the watershed scale? • LID practices - lot level control measures • Current focus of research – runoff management with LID practices. • Impacts of LID practices on baseflow need to be investigated • at the lot scale • at the watershed scale

3. How to Proceed? • Monitoring – most appropriate (perhaps), expensive, time consuming, sometimes impossible. • Modeling – convenient, less expensive, time efficient, sometimes may be complex. • Modeling – L-THIA-LID

4. L-THIA Modeling of LID Practices • Standard procedure for LID modeling • Representation of LID practices • CN values • Consideration of design guidelines • Sizing factors • Computation of runoff, baseflow, total flow • Threshold area: IF watershed area ≥ 120 ha => baseflow • Computation of LID effectiveness index • Baseflow core equation • Regression model for Indiana conditions • Relationship between baseflow and LID practice • BFI versus CN • Baseflow pollutant coefficients

5. Improving L-THIA-LID • LID practices currently represented in L-THIA-LID • Bioretention/rain garden • Open wooded space • Porous pavement • Swale • Porous pavement + swale • Permeable patio • Green roof • Disconnected impervious surfaces

6. Improving L-THIA-LID Runoff (distributed approach) Baseflow LID Effectiveness Index L-THIA-LID Interface (VBA)

7. Little Eagle creek • Little Buck creek

8. Little Eagle Creek LID Scenario Runs: 1991-2010 Effectiveness of LID practices

9. Little Buck Creek LID Scenario Runs: 1991-2010 Effectiveness of LID practices

10. Summary • Simulated runoff, baseflow, and total flow for the baseline compared well with observed values during calibration and validation periods. • Calibration: R2 and NSE > 0.5 • Validation: R2 > 0.4; NSE > 0.3 • Effectiveness of LID practices at the watershed scale • Runoff + pollutants: 2 to 12% • Baseflow + pollutants: -1 to -2% • Total flow + pollutants: 1 to 9% • Good LID options for retrofitting in urbanized watershed • 25% rain barrel/cistern adoption • 25% porous pavement adoption • 25% rain barrel/cistern + 25% of porous pavement adoption