1. GIS-Hydro Database for Tres Palacios Bay Stephanie Johnson GIS in Water Resources Class Presentation November 21, 2006 Dr. David Maidment – Advisor UT - Center for Research in Water Resources (CRWR)

2. Study Area

3. Tres Palacios Bay  Determined to not meet dissolved oxygen standards of 5 mg/L  TCEQ begins a dissolved oxygen TMDL study  Overseen by Dr. Paul Montagna, Texas A&M Corpus Christi  Water quality monitoring for the past 2 years  UT-CRWR asked to help with water quality modeling

4. Objective of Project  Develop a GIS-based dataset for future water quality modeling  Introductory qualitative analysis of monitoring data  Use as a test for webscraper tool that calculates duration curves

5. Dataset  Base map – used as a guide  Developed by Sally Morehead, M.S. at UT-Austin Marine Science Institute for initial efforts in study  Hydrography  Tyler Jantzen at CRWR - NHDPlus data  Jantzen is supported by TNRIS to develop TX NHDPlus Data for his M.S. thesis  General data  Texas General Land Office (GLO) – Political boundaries, roads, etc.  Federal agencies – NRCS soil and landuse, etc.  Local data sources  TCEQ – Water quality monitoring stations  Dr. Paul Montagna – water quality monitoring points in Tres Palacios Bay SoilsRoads/Cities

6. Tres Palacios Bay Watershed

7. Monitoring Points  1 USGS flow gage on the Tres Palacios River  27 TCEQ TRACS river monitoring points  4 monitoring points in Tres Palacios Bay  17 TCEQ TRACS monitoring points in Tres Palacios Bay

8. Qualitative Analysis  Patterns in low D.O. levels  Location  Time of year  Natural events (flow regime)  Theorize potential sources of pollution  Non-point vs. point  Municipal vs. rural (Yet to be completed)

9. Load Duration Curve  Basically a cumulative frequency distribution  Derived from a flow duration curve  Multiply flow duration curve by the desired pollutant concentration and a conversion factor  Outcome: allowable load/day

10. Source: White Paper (1): Advantages and Disadvantages of Using Load Duration Curves to Estimate Existing and Allowable Loads for the Development of Nutrient TMDLs Applying the water quality standard of 0.05 mg/L TP: Low Flow High Flow Example

11. Webscraper for Duration Curve Creation

12. Raw Data

13. Calculations

14. Flow % Range Flow Regime Number of Samples Avg FC Loading (CFU/100mL) Avg Single Sample Target (CFU/100mL) % Load Reducti on Avg Geometric Mean Target (CFU/100mL) % Load Reducti on 0-10High Flow481.11E+141.39E+1387.6%6.93E+1293.8% 10-30 Moist Conditions1131.45E+121.32E+128.6%6.61E+1154.3% 30-70Normal Flow1794.70E+112.47E+1147.6%1.23E+1173.8% 70-90 Dry Conditions697.39E+108.59E+10-16.2%4.29E+1041.9% 90-100Low Flow22.22E+093.84E+10-1629.1%1.92E+10-764.6% Overall Average822.27E+133.11E+12-300.3%1.56E+12-100.2% Calculations (cont.)

15. Future Work  For GIS Project  Qualitative analysis of monitoring data  Create more duration curves for Tres Palacios River  Future Modeling  Use data to develop a dissolved oxygen water quality model  Use runoff and land use data to determine the nutrient load from each catchment  Create duration curves for non-point source nutrient loads

16. Credits  Thanks to: Dr. David Maidment, Tyler Jantzen, Dr. Paul Montagna, Ernest To, Sally Morehead, CRWR staff Photos from: http://www.portofpalacios.com

17. Questions?