SWAT Modeling of Priority Watershed- Phase II

SWAT Modeling of Priority Watershed- Phase II

2013 NPS Conference – September 19, 2013

Dharmendra SaraswatAssoc. Prof,/Ext. Engineer-

Geospatial501-681-5987 (mobile)[email protected]

Naresh PaiPost-Doctoral Associate

Mike DanielsExtension Water Quality and

Nutrient Management Specialist

Tom RileyInterim Assistant Director- CED and

Director, Public Policy Center

Project# 11-900

mailto:[email protected]

OBJECTIVE

Project Objective

Prioritize 12-digit HUCs using SWAT model output


BACKGROUND

Phase II(2011 – 2013)

SWAT Modeling Project12-digit HUC Prioritization

1

2

3


OVERALL PROJECT APPROACH

Land-use/management

practices

SWATSWAT

Topography

Soils

Temperature Precipitation

Calibration/Validation

Calibration/Validation

Prioritization(Flow-weighted concentration)

Prioritization(Flow-weighted concentration)

PBIASNSER2

RSR

Point Sources


BEST MODELING PRACTICES (BMPS)

Sensitivity analysis

Check potential model problems using SWAT Check*

Annual calibration

Monthly calibration/validation

Qualitative comparison with AWRC data (monthly data from Oct 2011-Sept 2012 and then storm samples through March 2013)

Uncertainty analysis

Subwatershed prioritization*White et al., 2012


PRIORITIZATION RESULTSPoteau


Critical source area analysis (CSA) suggested that merely 5% of the watershed area was responsible for 26%, and 34% of the sediment and TP overland loads, respectively. In contrast, the nitrate loading was relatively uniform in this watershed.

UNCERTAINTYPoteau


Results suggest that 55% of observed data at Cauthron and 49% of observed

data at Hackett, respectively was found within 95% confidence interval of the

best simulations as shown by the 95PPU plot.

SWAT model uncertainty band (i.e. 95PPU, shown in green) at Cauthron and its comparison with the observed (shown in blue) and best simulated (shown in red) data.

SWAT model uncertainty band (i.e. 95PPU, shown in green) at Hackett and its comparison with the observed (shown in blue) and best simulated (shown in red) data.

PRIORITIZATION RESULTSStrawberry


Critical source area analysis (CSA) suggested that merely 5% of the watershed area was responsible for 85%, 22%, and 16% of sediment, TP, and NO3-N loads, respectively.

PRIORITIZATION RESULTSUpper Saline


Critical source area (CSA)

analysis indicated that merely 5% of

the watershed area was responsible

for 28%, and 13% of the sediment

and TP overland loads, respectively.

In contrast, the nitrate loading was

relatively uniform in this watershed.

COMPARISON WITH MONITORING DATA


Source: Massey et al., 2013

Overall Summary

1)the load comparisons were favorable across all three watersheds;

2)The mean concentration comparison during base flow conditions at the selected HUC 12 level showed relations in the ranks of the sites within the Poteau and Upper Saline Watersheds for NO3-N and TP, but not TSS. The monitoring data and SWAT output were not related at the Strawberry Watershed.

3)These results increase our confidence in the subwatershed prioritization by SWAT model for the Poteau and Upper Saline Watersheds, but not necessarily for the Strawberry Watershed.

ACKNOWLEDGEMENTS

EPA, Region VI


SWAT Modeling of Priority Watershed- Phase II

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