Non point source pollutant modeling
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Non-Point Source Pollutant Modeling. Analysis and Prediction David Munn. Non-Point Source Pollution. Does not come from a single source Results from pollutants being washed out of large areas during storms Difficult to model without use of GIS or current NPSP models. Goals.

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Non point source pollutant modeling

Non-Point Source Pollutant Modeling

Analysis and Prediction

David Munn


Non point source pollution
Non-Point Source Pollution

  • Does not come from a single source

  • Results from pollutants being washed out of large areas during storms

  • Difficult to model without use of GIS or current NPSP models


Goals
Goals

  • Predicting pollutant runoff loads

  • Defining problem areas within the Watershed

  • Determine what factors effect pollutant loading

  • Determine streams with highest impact

  • Pollutants considered:

    • BOD

    • Suspended Solids

  • Total Phosphorous

  • Total Nitrogen


Study area
Study Area

  • Brazos County

  • Buffered boundary


Process overview
Process Overview

  • Gather data

  • Data preparation

    • Reproject grids and shapefiles

    • Clip themes and set analysis extents

  • Calculate curve numbers

  • Delineate watersheds

  • Calculate pollutant contribution

  • Determine weighted accumulation

  • Analyze data


Data themes
Data/Themes

  • DEM

    • TNRIS

  • Soil Classification

    • STATSGO

  • County Boundaries

    • ESRI, Tiger files

  • Land Use/Land Cover

    • Txdata, Provided by Dr. Olivera

  • Precipitation

    • Txdata, Annual and Monthly

  • LULC Pollutant Contribution Data

    • Cornell University Hydraulics Study


Reprojecting
Reprojecting

  • Reprojected grids using ArcInfo-Workstation

  • Reprojected geographic shapefiles using CRWR-Vector

  • Data Already in a Projection was reprojected using ArcCatalog

  • Final Projection: State Plane 1927

    • Central Texas, Zone 5376

    • Units = feet


Delineating watersheds

CRWR-Prepro

Burned in Streams

Filled Sinks

Determined Flow Direction

Determined Flow Accumulation

Defined Streams

Segmented Streams

Defined Outlets

Delineated Watersheds

Vectorized Grids

Delineating Watersheds


Curve numbers
Curve Numbers

  • Used to determine runoff

  • STATSGO data spatially documents soil types (component makeup)

  • Scripts provided by CVEN 689 Website

    • Soilgrp script – calculates % of hydrologic groups per soil type

    • cn script – creates curve numbers based on soil composition


Run off

Rainfall given per month (January)

Calculate Run-off (mm) using SCS method

Map Calculator combined formulas with rainfall and CN

Created new grid giving run-off depth per cell

Run-off


Pollutant contributions
Pollutant Contributions

Q (mm)

Cell size (ft2)

Pollutant Concentration (mg/l)

= Mass (mg)

* Map Calculator


Pollutant flow accumulation
Pollutant Flow/Accumulation

  • Weighted flow accumulation

  • Executed in ArcInfo

  • Assigns weights to cells based on a Grid

Weights

Direction

Accumulation


Analysis
Analysis

  • Determine what land-uses and soil types contribute the largest amount of pollutants

  • Determine what rivers suffer the greatest impact

  • Locate areas that contribute large masses of pollutants


Land use relationships zonal summaries
Land Use Relationships (Zonal Summaries)


Soil type relationships zonal summaries
Soil Type Relationships(Zonal Summaries)


Impacted rivers
Impacted Rivers

  • Method

    • Map query

    • Changed to shapefile

  • Results too dependent on general accumulation

  • More statistical work needed


Areas of concern
Areas of Concern

* TP / TN

* BOD / SS


Conclusions
Conclusions

  • Urban areas contributed the largest mass of BOD and suspended solids per unit area

  • Agricultural areas contributed the largest mass of Nitrogen and Phosphorous / area

  • Rivers > 700,000 cell accumulation were impacted

  • Soil types differed in impact between pollutants

    • Nutrients:

      Crocket-Luling-Benchley & Zack-Zulch-Booneville

    • BOD and Suspended Solids

      Zack-Zulch-Booneville


Future applications
Future Applications

  • Determining Pollutant Concentrations

    • Calculate run-off volume using weighted accumulation

    • Sum run-off volumes with base flows

    • Calculate in-stream concentrations

  • Better Statistical Analyis of Impacted Rivers


Problems
Problems

  • REPROJECTING!!!!!!!

  • Calculating pollutant contributions

    (map calculator)

  • Floating point analysis


Questions

QUESTIONS

What up?


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