the utility of spatially explicit variables in watershed scale phosphorus water quality modeling

1

The utility of spatially explicit variables in watershed scale phosphorus water quality modeling

Mark BreunigGEOG 681

What?

The utility of spatially explicit variables in watershed scale phosphorus water quality modeling

Although efforts are underway to set stream standards in Wisconsin and elsewhere, there is still controversy regarding the mechanisms that control stream phosphorous concentrations. This represents a collective misunderstanding of the fundamental processes that control water quality at the catchment scale (Boomer et al. 2008). It is a very common practice for researchers to attribute poor results to inadequate spatial data (Hunsaker et al. 1995; Soranno et al. 1996; Jain et al. 2000; Jones et al. 2001; Richards et al. 2006; Boomer et al. 2008).

Why?

WARNING:USLE & its derivatives used at the “field scale” =

USLE & its derivatives used at the “watershed scale” =

Purpose of Model: to increase the effectiveness of watershed-scale phosphorus water quality modeling

Taxonomy of Model: Deterministic, empirical, inductive

Data Inputs: Field Data collected by USGS2001 NLCD (National Land Cover Database) - USGS30 DEM – USGSSSURGO – NRCS

The Data

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

-2.50

-2.00

-1.50

-1.00

-0.50

0.00

0.50

% Ag vs Log(TPmedF)

% Agriculture

Log

(TPm

edF)

2001 – 157 sites2002 – 78 sites2003 – 5 sitesTotal: 240 sites

R2 = 43%p < 0.001

Σ(eFLag* β)

Σ(eFLall* β)

Pixel Value(proportion – no units)

0

10

20

30

40

50

60

70

80

90

100

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000

Pixe

l Val

ue (%

effe

ctive

)

Distance (m)

0.05000

0.01000

0.00250

0.00100

0.00043

0.00022

0.00011

0.00006

0.00003

0.00001

0.00000

0.0%10.0%

20.0%30.0%

40.0%50.0%

60.0%70.0%

80.0%90.0%

100.0%

-2.5

-2

-1.5

-1

-0.5

0

0.5

f(x) = 0.83620511211752 x − 1.44411517151365R² = 0.455085267094821

Pixel Value vs logTPmedF

ProblemsSSURGO !!!30 m DEM!!!Model Conceptualization

Further WorkCV SlopeCumulative SlopeKsat_r