Virtual Watershed
NSF Biocomplexity in the Environment
Program 2004-2008
Christopher Lant (Geography) PI
Steven Kraft, Jeff Beaulieu (Agr. Economics)
John Nicklow (Civil Engineering)
Michelle Zhu (Computer Science)
Raja Sengupta (Geography) McGill
George Malanson (Geography) Iowa
The Modeling Approach
Land Use is the Lynchpin Between
Social Factors and Environmental Results
Corn
Other crops
Pasture
Wheat
Soybean
Forest
Urban
Water
1999 Landuse
Polygon
Classification
2000 Landuse
Polygon
Classification
2001 Landuse
Polygon
Classification
2002 Landuse
Polygon
Classification
2003 Landuse
Polygon
Classification
2004 Landuse
Polygon
Classification
Contingent probabilities of land use in a field given land
uses in the previous year
Use last Year Corn
All Corn
.07
Probability that a hectare will contain
Soy Double Grass Forest
Total
.81
.01
.11
.00
1.00
All Soybeans .48
.34
.01
.17
.00
1.00
Double Crop
.03
.24
.02
.72
.00
1.00
Pasture/Hay
.02
.07
.01
.89
.00
1.00
Forest
.00
.00
.00
.00
1.00
1.00
Land Use Change Hypotheses
(1) The use chosen for a field is influenced by the
physical geographic characteristics of the field
such as soil type and slope. (Yes)
(2) The use chosen for a field is influenced by
economic costs and opportunities for various uses.
(Yes)
(3) The use chosen for a field is influenced by the
historical use of that field. (Yes)
(4) The use chosen for a field is influenced by the
use of neighboring fields. (No)
EcologicalEconomic
Production
Possibility
Frontiers
and their
Evolution
Create sets of Initial Alternatives
(Initial Population)
GA Logic
Evaluate fitness, Rank the alternatives
Choose mates(pairing)
Repeat
Create offspring (crossover)
Multiple Generations
lead to
Optimal Solution
Mutate
Optimal Solution
Corn vs. Soybeans: A Classic Trade-off
Corn vs. Hay: A Classic Trade-off
Hay vs. Soybeans: A Classic Trade-off
Sediment and Water Quality Index:
Highly Correlated
R = -0.97
Phosphorus and Water Quality Index:
Highly Correlated
R = -0.99
Nitrogen and Water Quality Index:
Highly Correlated
R = -0.98
Carbon and Water Quality: Complementary
R = 0.83
Water Quality and Flood Control: Complementary
R=0.70
Carbon and Flood Control: Slightly Complementary
R=0.24
Corn and Water Quality: A Trade-Off
R = -0.83
Corn and Flood Control: A Slight Trade-off
R=-0.24
Carbon and Corn: A Trade-Off
Soybeans and Water Quality: A Trade-Off
R=-0.46
Flood Control and Soybean Yield: A Trade-off
R = -0.89
Carbon and Soybeans: No Relationship
Hay and Water Quality: Complementary
R = 0.90
Hay and Flood Control: Complementary
R = 0.71
Carbon and Hay: Complementary
The Overall Ecological-Economic PPF
R = -0.83
What We’ve Learned About the PPF
1) Landscapes that yield high or low sediment yields also
yield corresponding N and P yields with correlations of
0.93 - 0.98.
2) Competition among crops for land produces as classic
PPF
3) Soybeans, and especially corn, is a trade-off with all
ecosystem services, but hay is complementary.
4) Carbon correlates positively with water quality at 0.84.
5) The current land use pattern is very sub-optimal, more so
with respect to ecosystem services than gross margin.
Users Working with the PPF
Users Working with the PPF
Any Questions?
Virtual Watershed Diagram from Proposal