A Water Quality Loading Model for Tillamook Bay Patrice A. Melancon Thanks to: Dr. David Maidment Dr. Michael Barrett Dr. Francisco Olivera Dr. Maidment’s Research Group

Outline 4 Introduction 4 Problem and Objective 4 Why use GIS? 4 Developing the Model 4 Using the Model 4 Conclusions and Future Work

Introduction 4 National Estuary Program 4 Tillamook Bay

Problem and Objective 4 My work is focusing on two issues: ²High Coliform loads ² High Sediment loads 4 Developing a model that can serve as a Management Tool

Problem History 4 Coliform contamination: ²Animals confined in winter; manure storage ²Liquid and solid manure applied as fertilizer ²Cow access to streams 4 Sediment contamination: ²Largely linked to logging practices ²Roads linked to frequent landslides

Why Use GIS? 4 Basic precept of Water Quality Modeling ²Load = Flow x Concentration 4 Spatial Variability 4 ArcView’s Hydrology Function 4 Grids and Coverages

GIS Grid Representation 4 Surface divided into equal-sized cells 4 Each cell has a value 4 Value represents only one specific characteristic Bay Depth Below MSL

GIS Coverage Representation 4 Surface represented as polygons, lines, or points 4 Each record contains information on multiple characteristics

Developing the Model 4 ArcView Hydrology Functions Flow Direction Flow Accumulation DEM Accumulation in Streams

Hydrology Model Streamflow = Runoff + Baseflow Precip Flow Runoff,R Baseflow,B B R

Average Annual Rainfall Precip, in

Hydrology Model P RO P BF Runoff Grid Baseflow Grid Precip Grid

Event Mean Concentrations Runoff Concentrations

Pollutant Loadings 4 EMC grid x Flow grid = Load grid 4 Flow accumulations of flow and load grids 4 Predicted pollutant concentrations = Accumulated Load Accumulated Flow

Using the Model 4 Incorporate Effects of BMPs ²Current focus is on CAFOs ²3 BMPs to model 4 Representing spatial distribution ²Farm location vs land affected ²Use spatial average 4 Analysis by subwatershed or land use

Model Analysis 4 Clip out subwatershed of interest 4 Export data to analyze BMP effects or contribution Trask River Land UseTrask River Coliform Runoff Load

Conclusions 4 Can build effective management tool 4 Effects of BMPs and relative contributions can be examined

Future Work 4 More work on sediment 4 Incorporate BMP effects 4 Model calibration