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

Introduction

National Estuary Program Tillamook Bay

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

Streamflow =

Runoff

+

Baseflow

Precip

Precip

Flow

Runoff,R

Baseflow,B B

R

Average Annual Rainfall

Precip, in

Hydrology Model

20.00

40.00

60.00

80.00

100.00

120.00

40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00

0.00

10.00

20.00

30.00

40.00

50.00

60.00

40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00

P

RO

P

BF

Runoff Grid

Baseflow Grid

Precip Grid

Event Mean Concentrations

011- 1921 - 2431 - 3341 - 4351 - 5461 - 6371 - 75

Runoff Concentrations

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

Future Work

More work on sediment Incorporate BMP effects Model calibration