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Purdue Status Report
Summer Meeting 2012
Midwest Spatial Decision Support Interest Group
Region 5 EPA
July 9, 2012
Bernie Engel, Larry Theller, Youn Shik Park, Laurent Ahiablame. Agricultural and Biological Engineering
Purdue University
Topics• L-THIA LID improvements
• Fox River Project update (L-THIA Owls)
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
4
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
The Problem
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
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
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
Improving L-THIA-LID
L-THIA-LID Interface (VBA)
Runoff (distributed approach)2( 0.2 )
( 0.8 )
P S
QP S
P Ia
0Q P Ia
Baseflow0.953 1.424 1.26029.896bQ BDA APCP BFI
LID Effectiveness Index
100 NoLID LID
NoLID
LID
Q QEI
Q
142.100726.0 CNBFI
Little Eagle creek
Little Buck creek
Little Eagle Creek Little Buck CreekLand use Area (ha) Percent Area (ha) PercentLow Density Residential 3872.8 54.8 3273.0 74.1Commercial/Industrial 2260.2 32.0 538.9 12.2High Density Residential 271.0 3.8 1.4 0.0Road/Street 573.6 8.1 366.3 8.3Bare soil 16.0 0.2 - -Grass/Pasture 77.4 1.1 238.2 5.4Total 7070.9 4417.7
Scenario DescriptionS1 existing conditionS2 25% rain barrel/cisternS3 50% rain barrel/cisternS4 25% porous pavementS5 50% porous pavementS6 S2 + S4
Little Eagle Creek Flow (%) TP (%) TN (%)Runoff
Scenario 2 6 5 6
Scenario 3 11 11 12
Scenario 4 3 3 3
Scenario 5 5 5 6
Scenario 6 8 8 9Baseflow
Scenario 2 -1 -1 -1
Scenario 3 -2 -2 -2
Scenario 4 -1 -1 -1
Scenario 5 -1 -1 -1
Scenario 6 -2 -2 -2Total flow
Scenario 2 2 5 3
Scenario 3 5 9 6
Scenario 4 1 2 1
Scenario 5 2 4 3
Scenario 6 4 7 5
LID Scenario Runs: 1991-2010 Effectiveness of LID practices
Little Buck Creek Flow (%) TP (%) TN (%)Runoff
Scenario 2 3 2 3
Scenario 3 5 5 6
Scenario 4 4 4 4
Scenario 5 8 7 8
Scenario 6 7 6 7Baseflow
Scenario 2 0 0 0
Scenario 3 -1 -1 -1
Scenario 4 -1 -1 -1
Scenario 5 -1 -1 -1
Scenario 6 -1 -1 -1Total flow
Scenario 2 1 2 1
Scenario 3 2 4 3
Scenario 4 2 3 2
Scenario 5 4 6 4
Scenario 6 3 5 3
Effectiveness of LID practices LID Scenario Runs: 1991-2010
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
“Fox River” Project
• Corps 516(e) project is collaboration with Michigan State University Institute of Water Research.
• Tools work together behind the interface.• High-resolution data for 4 Priority
Watersheds.• Medium-resolution data for entire Great
Lakes area.
Extends L-THIA online tool to entire Great Lakes area.
Floating, semi-transparent toolbars, collapsible menus, open architecture for partners, improved editing performance.New Area of Interest tool : Polygon
“Select by HUC” to use a single HUC 12, 10, 8 outline.
Tool will now allow use of a polygon as an area of analysis.
This will improve ability to model zoning and LID BMP areas.
-Display of HIT target layers-EPA Waters layers-GIS layers-Multi-resolution data layers
New Results Options