Bacteria Loadings Watershed Model Copano Bay watershed Copano Bay watershed Copano Bay Carrie Gibson CE 394K.2 Surface Water Hydrology Spring Semester 2005 University of Texas at Austin Instructor: David R. Maidment

Background Section 303(d) of 1972 Clean Water Act (CWA) Section 303(d) of 1972 Clean Water Act (CWA) Texas Surface Water Quality Standards Texas Surface Water Quality Standards Fecal Coliform Bacteria Fecal Coliform Bacteria Enterococci Enterococci Aransas River Copano Bay Mission River

1. Identify major bacterial sources in Copano Bay watershed. 2. Calculate total bacterial loadings, Total Maximum Daily Loads (TMDLs), from bacterial sources. 3. Determine amount of load reductions that is needed to meet water quality standards. Project Overview

Objective of Term Project Model the accumulation and transport of bacteria from upstream watersheds to Copano Bay. Model the accumulation and transport of bacteria from upstream watersheds to Copano Bay. Use Model Builder in Arc Toolbox of ArcGIS 9.0. Use Model Builder in Arc Toolbox of ArcGIS 9.0. Modify Schematic Processor. Modify Schematic Processor. Decays bacteria loads along streams segments Decays bacteria loads along streams segments Calculates increase in concentration in bay due to upstream bacteria loadings (CFSTR model) Calculates increase in concentration in bay due to upstream bacteria loadings (CFSTR model)

GIS Data Preparation: Arc Hydro Terrain Preprocessing Terrain Preprocessing Watershed Delineation Watershed Delineation Create Geometric Network Create Geometric Network Use WRAP Hydro Use WRAP Hydro Bacteria Monitoring Stations USGS Gauge Stations Water Segment Endpoints Watersheds

Basis of Calculations Load (cfu/year) = Flow (m 3 /year) * Concentration (cfu/m 3 )

Runoff Calculations Ann Quenzer’s Thesis (based on land use) Ann Quenzer’s Thesis (based on land use) Agriculture Agriculture Q = * exp ( * P ) Forest Forest Q = * exp ( * P ) Urban Urban Q = 0.24 * P Open Water Open Water Q = 0 Q = Runoff (mm/year) P = Precipitation (mm/year) – from PRISM

Runoff Calculations (continued) Tools Used Tools Used Spatial Analyst Spatial Analyst Analysis Mask Analysis Mask Raster Calculator Raster Calculator Example: Agriculture Example: Agriculture Mosaic Mosaic Q = * exp ( * ) = Q Agriculture + Q total (mm/yr) Q OpenWater +Q Forest + Q Urban = PQ

Runoff Calculations (continued) Model Builder (Overview) Agriculture Forest Urban Open Water

Spatial Analyst/Raster Calculator Spatial Analyst/Raster Calculator [mm/year]*(30m)*(30m)*(1m/1000mm) = [m 3 /yr] [mm/year]*(30m)*(30m)*(1m/1000mm) = [m 3 /yr] 0.9 * [mm/year] = [m 3 /year] Zonal Statistics Zonal Statistics Sum of runoff in delineated watersheds Sum of runoff in delineated watersheds Runoff Calculations (continued) Model Builder (Overview) Runoff per Watershed (m 3 /year)

Event Mean Concentrations (EMCs) From Reem Jihan Zoun’s thesis, Estimation of Fecal Coliform Loadings to Galveston Bay From Reem Jihan Zoun’s thesis, Estimation of Fecal Coliform Loadings to Galveston Bay Join EMC table to Land Use polygon feature class Join EMC table to Land Use polygon feature class Land Use Code Category Fecal Colonies per 100 mL 11 Open Water 0 21 Low Intensity Residential 22, High Intensity Residential 22,000 23Commercial/Industrial/Transportation22, Bare Rock/Sand/Clay 0 32 Quarries/Strip Mines/Gravel Pits 0 41 Deciduous Forest 1, Evergreen Forest 1, Mixed Forest 1,000 51Shrubland2,500 61Orchards/Vineyards/Other2,500 71Grasslands/Herbaceous2,500 81Pasture/Hay2, Row Crops 2, Small Crops 2, Urban/Recreational Grasses 22, Woody Wetlands Emergent Herbaceous Wetlands 200

Event Mean Concentrations (continued) Model Builder (Overview) cfu/m 3

Event Mean Concentrations (continued) * [C (cfu/m 3 )][Q (m 3 /yr)] Sums grid cell values for each watershed = [(cfu/yr)] Annual Bacterial Loading per grid cell Model Builder (Overview)

Bacterial Loading (cfu/year) Bacterial Loadings per Watershed

Model Builder: Summary Runoff (m 3 /yr) Concentration (cfu/m 3 ) Load (cfu/year) Cumulative Loading per Watershed Cumulative Runoff per Watershed Schematic Processor

Schematic Processor Schematic Network Schematic Network Feature Classes Feature Classes SchemaNode (watershed or junction in stream network) SchemaNode (watershed or junction in stream network) SchemaLink (straight lines that connect Schematic nodes) SchemaLink (straight lines that connect Schematic nodes) Watershed Drainage Junction Bay Watershed to Junction Junction to Junction Junction to Bay

Schematic Processor (continued) Implemented using dynamic linked libraries, DLLs Implemented using dynamic linked libraries, DLLs clsDecay.dll clsDecay.dll Simulates decay of bacteria along stream segments Simulates decay of bacteria along stream segments load passed = load received * e -kt load passed = load received * e -kt k = first-order decay coefficient (day -1 ) - stored as attribute in SchemaLink t = travel time along streams, t (days) - stored as attribute in SchemaLink Decay

Schematic Processor (continued) clsCFSTR.dll clsCFSTR.dll Calculates the increase in concentration of a bay due to bacteria loadings. Calculates the increase in concentration of a bay due to bacteria loadings. Assumptions Assumptions Bay is completely mixed and acts as Continuous Flow, Stirred Tank Reactor (CFSTR) Bay is completely mixed and acts as Continuous Flow, Stirred Tank Reactor (CFSTR) Inflow = Outflow Inflow = Outflow c = L/(Q+kV) c = L/(Q+kV) c = concentration in bay (cfu/m 3 ) L = bacteria load entering bay (cfu/yr) Q = total flow (m 3 /yr) – stored as attribute in SchemaNode k = first-order decay coefficient (day -1 ) - stored as attribute in SchemaNode V = volume of bay (m 3 ) – stored as attribute in SchemaNode

Parameters (Inputs) Parameters (Inputs) SchemaLink (SrcTypes 1 and 2) SchemaLink (SrcTypes 1 and 2) Travel Time (t in days), Decay Coefficient (k in day -1 ) Travel Time (t in days), Decay Coefficient (k in day -1 ) SchemaNode SchemaNode SrcType 3 – Copano Bay SrcType 3 – Copano Bay Volume (V in m 3 ), Decay Coefficient (k in day -1 ) Volume (V in m 3 ), Decay Coefficient (k in day -1 ) Cumulative Runoff (Q in m 3 /year) Cumulative Runoff (Q in m 3 /year) SrcType 1 – Watersheds SrcType 1 – Watersheds Bacterial Loading per Watershed (L in cfu/year) Bacterial Loading per Watershed (L in cfu/year) Schematic Processor: Summary Determined by User Calculated from Previous Steps in Model Builder

Results: Cumulative Runoff (m 3 /yr)

Results: Bacterial Loading (cfu/yr)

Results: Concentration (cfu/100mL)

Tasks to be Completed Determine travel times of river segments and decay coefficients of bacteria. Determine travel times of river segments and decay coefficients of bacteria. Incorporate point source bacteria loadings into non- point source bacteria loading model. Incorporate point source bacteria loadings into non- point source bacteria loading model. Determine locations and bacteria loadings from horses, cattle, waterbirds (probable candidates), WWTPs Determine locations and bacteria loadings from horses, cattle, waterbirds (probable candidates), WWTPs Compare model loads and concentrations to existing monitoring data. Compare model loads and concentrations to existing monitoring data.