1. 2011 DOE Biomass Program Review
Effectiveness of low impact development practices in two urbanized watersheds: Retrofitting with rain barrels/cisterns and porous pavements
Laurent Ahiablame
Prof. Bernard Engel, Prof. Indrajeet Chaubey
Date, 2012
RD&D Project Presentation Template

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
Three methods for calculating BFI values

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

7. Little Eagle creek Little Buck creek Little Eagle Creek
Little Eagle Creek
Little Buck Creek
Land use
Area (ha)
Percent
Low Density Residential
3872.8
54.8
3273.0
74.1
Commercial/Industrial
2260.2
32.0
538.9
12.2
High Density Residential
271.0
3.8
1.4
0.0
Road/Street
573.6
8.1
366.3
8.3
Bare soil
16.0
0.2 -
Grass/Pasture
77.4
1.1
238.2
5.4
Total
7070.9
4417.7
Calibration period ; validation period ; application period
Scenario
Description S1
existing condition S2
25% rain barrel/cistern S3
50% rain barrel/cistern S4
25% porous pavement S5
50% porous pavement S6
S2 + S4

8. Little Eagle Creek LID Scenario Runs: 1991-2010
Flow (%)
TP (%)
TN (%)
Runoff
Scenario 2 6 5
Scenario 3 11 12
Scenario 4 3
Scenario 5
Scenario 6 8 9
Baseflow -1 -2
Total flow 2 1 4 7
LID Scenario Runs:
Effectiveness of LID practices

9. Little Buck Creek LID Scenario Runs: 1991-2010
Flow (%)
TP (%)
TN (%)
Runoff
Scenario 2 3 2
Scenario 3 5 6
Scenario 4 4
Scenario 5 8 7
Scenario 6
Baseflow -1
Total flow 1
LID Scenario Runs:
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
Baseflow was not calibrated as baseflow was previous developed and validated for Indiana conditions. These LID options can be used to retrofit urbanized watershed without any taking down any buildings, without further disturbing watershed existing condition.