Monitoring, Databases and Modelling by Andrea Welker, Ph.D., PE, Professor, Civil and Environmental Engineering, Villanova University

1. Knowledge Base – Monitoring,
Databases, and Modeling
Monitoring and modeling of watersheds and stormwater
control measures are critical to determining what data we
have, what data we need, and to predict the effects of changes
on a watershed. Modeling can also be used to evaluate
different alternatives so that limited funds are spent wisely.

2. Speakers
• Andrea Welker, Villanova University: Modeling
of individual stormwater control measures
• Jeffery Featherstone, Temple University:
Modeling of watersheds
• Stefanie Kroll, Academy of Natural Sciences of
Drexel University: Watershed monitoring and
data management throughout the Delaware
Watershed

3. Recap of key points from last year’s
Knowledge Base Session
• Citizen monitoring is important
• Interest in creating a watershed
website/database
• Effective use of modeling tools is needed
• Reduce barriers through innovative
approaches

4. Modeling Individual Stormwater
Control Measures (SCMs) with
HYDRUS
Andrea L. Welker, PhD, PE
Professor

5. Outline
• What is HYDRUS
• What equipment we need
• What we hope to do with it

6. HYDRUS
• HYDRUS can be used to model water, heat,
and solute movement in variably saturated
porous media
– 1D is free
– 2D is not free (we own it)
• The model uses a finite-element approach in
space and a finite-difference approach in time

7. • The Richards
equation is used to
mathematically
model the flow of
water
• Models transient
conditions
(Radcliffe and
Simunek 2010)

8. Key parameters required
• Weather, e.g. rain and runoff
• Configuration of stormwater
control measure
• Soil parameters
– Soil Water Characteristic Curve to
determine relationship between
water content and suction
– Hydraulic conductivity to measure
how easily soil can transmit water

9. Goals of modeling
• Use before rain gardens or
wetlands are built to
predict effectiveness
• Compare to actual
behavior
• Calibrate to actual
behavior
• Extrapolate behavior
Infiltration
Evapotranspiration
Water quality (solute transport)
Effect on groundwater table

10. For example – design chart for
infiltration and evapotranspiration
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
0
1
10
100
0 20 40 60 80 100 120 140
CumulativeET(cm)
Cumulativeinfiltration(cm)
Time (hours)
Clay loam
Silty clay loam
Sandy clay
Clay
Sand
Loam
Silty loam

11. Prior work with HYDRUS
• Not commonly used for stormwater design –
yet!
• Has been used extensively for
– water balance landfill cap design (very similar to
rain gardens)
– agricultural applications