a water quality loading model for tillamook bay patrice a. melancon thanks to: dr. david maidment...
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A Water Quality Loading Model for Tillamook Bay
Patrice A. Melancon
Thanks to:Dr. David MaidmentDr. Michael Barrett
Dr. Francisco OliveraDr. Maidment’s Research Group
Outline
Introduction Problem and Objective Why use GIS? Developing the Model Using the Model Conclusions and Future Work
Problem and Objective
My work is focusing on two issues: High Coliform loads High Sediment loads
Developing a model that can serve as a Management Tool
Problem History Coliform contamination:
Animals confined in winter; manure storage
Liquid and solid manure applied as fertilizer
Cow access to streams
Sediment contamination: Largely linked to logging practices Roads linked to frequent landslides
Why Use GIS?
Basic precept of Water Quality Modeling Load = Flow x Concentration
Spatial Variability ArcView’s Hydrology Function Grids and Coverages
GIS Grid Representation
Surface divided into equal-sized cells
Each cell has a value
Value represents only one specific characteristic
Bay Depth Below MSL
GIS Coverage Representation Surface
represented as polygons, lines, or points
Each record contains information on multiple characteristics
Developing the Model
ArcView Hydrology Functions
Flow Direction
Flow Accumulation
DEM Accumulation in Streams
Hydrology Model
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RO
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Runoff Grid
Baseflow Grid
Precip Grid
Pollutant Loadings
EMC grid x Flow grid = Load grid Flow accumulations of flow and
load grids Predicted pollutant concentrations
= Accumulated Load
Accumulated Flow
Using the Model
Incorporate Effects of BMPs Current focus is on CAFOs 3 BMPs to model
Representing spatial distribution Farm location vs land affected Use spatial average
Analysis by subwatershed or land use
Model Analysis
Clip out subwatershed of interest Export data to analyze BMP effects
or contribution
Trask River Land Use Trask River Coliform Runoff Load
Conclusions
Can build effective management tool
Effects of BMPs and relative contributions can be examined
Land UseStreamflow, %
ContributedFecal Coliform, %
ContributedUrban 0.76 2.01
Rural Residential 0.44 4.69
Dairy Operations 2.66 87.21
Forest 89.04 3.84
Other 7.10 2.24
100 100
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