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U SING G IS TO M AP C OASTAL W ATER Q UALITY AT I MPERIAL B EACH. Andrew Judd GIS in Water Resources University of Texas. T IJUANA, M EXICO. Important part of Mexico’s growing economy Growth has not come without a price
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USING GIS TO MAP COASTAL WATER QUALITY AT IMPERIAL BEACH Andrew Judd GIS in Water Resources University of Texas
TIJUANA, MEXICO • Important part of Mexico’s growing economy • Growth has not come without a price • Infrastructure not kept pace with industrial development and population growth • Overtaxed sewer systems spill into Tijuana’s waterways • Most of which ultimately drains to the Tijuana River
IMPERIAL BEACH, CALIFORNIA • Coastal community south of San Diego • Located at estuary of Tijuana River • Continual coastal water quality issues from untreated wastewater flow in Tijuana River • Contaminated water dispersed along the coastline through ocean currents California Pacific Ocean Imperial Beach
Imperial Beach Testing Stations Tijuana River Flow Gage GIS PROJECT • Create GIS format for assessment of Imperial Beach water quality as it relates to Tijuana River Flow • Several water quality testing stations on Imperial Beach coastline • River flow gage at the South Bay International Wastewater Treatment Plant • Use data to create temporal map of water quality and river flow
DEFINITIONS • In general, level of water quality dependant on what is in the water and what the water is used for • With untreated wastewater issues, coliform bacteria used to test for contamination • Bacteria generally not harmful, but indicate presence of disease-causing pathogens • This project using enterococci bacteria subgroup for water quality data • Enterococci recommended by EPA for ocean water because the bacteria most closely mimic pathogens’ salt water life cycle
PROJECT DATA • Water quality testing data from SDCOOS website (MPN/100mL) • Testing at Imperial Beach stations somewhat sporadic (daily to weekly) • Flow data for Tijuana River from IBWC website (MGD) • Flow gage at upstream end of river estuary, used as general indicator of flow level • Averaged river flow and water quality data over weekly basis to allow for comparison
MAP CREATION • Testing station locations (latitude, longitude) from SDCOOS website • Tijuana River reach from NHD website • Weekly averaged bacteria and flow data converted to dbf format • Linked data to stations using tracking analyst tools • Using playback manager, can view time series of bacteria and flow data Map of Imperial Beach Water Quality Testing Stations created with ArcGIS
ANIMATION OF TIME SERIES DATA • For February to May 2000 • Displays weekly averaged Imperial Beach bacteria levels and Tijuana River flow • Levels of bacteria and flow symbolized according to magnitude • SHOW MOVIE
ANALYSIS OF TIME SERIES DATA • Week of 2/14/2000, Tijuana River flow and bacteria at low levels • During following two weeks, river flow above 100 MGD • Bacteria testing at high levels throughout 3.5 miles of coastline • Beaches are closed when enterococci levels exceed 104/100mL • During week of 2/28/2000 bacteria levels exceed 1000/100mL
ANALYSIS OF TIME SERIES DATA (cont.) • Although flow levels decrease, bacteria levels remain high at all IB Stations until week of 3/27/2000 • Flow and bacteria levels fluctuate until May of 2000 • Flow levels begin to decrease and during week of 5/1/2000 high bacteria localized to estuary • By 5/8/2000, sustained low flow and bacteria levels
CONCLUSIONS • Strong relationship between Tijuana River flow and Imperial Beach bacteria levels • Contaminated flow in Tijuana River carries effects throughout Imperial Beach coastline • ArcGIS is an effective tool for displaying groups of time series data
ADDITIONALINFORMATION • San Diego Coastal Ocean Observing System (SDCOOS) through University of California San Diego • Has water quality data as well as ocean current, water temperature, weather data and more Bacteria Levels on 11/29/04 from SDCOOS website (www.sdcoos.ucsd.edu)