Utilization of the SWAT Model and Remote Sensing to Demonstrate the Effects of Shrub Encroachment on a Small Watershed

Transcription

1 Utilization of the SWAT Model and Remote Sensing to Demonstrate the Effects of Shrub Encroachment on a Small Watershed Jason Afinowicz Department of Biological and Agricultural Engineering Texas A&M University

2 Shrub Encroachment Replacement of herbaceous growth with woody species Active process over the past century Potentially caused by a number of human factors and climate change Shrub species such as Juniper and mesquite are assocaited with increased water consumption and transpiration

3 Brush Control Factored into many water quantity BMPs Reducing new-growth cedar in the Edwards recharge zone may lead to increased recharge Studies have been conducted to determine the effects of these techniques Methods include mechanical removal as well as more environmentally friendly manual methods

4 Overview of Project Hydrologic simulation of a watershed with brush cover Electronically remove the brush and determine the changes on the modeled hydrology

5 The SWAT Model The Soil and Water Assessment Tool (SWAT) is a basin and watershed scale model for estimating the effects of management practices on water quantity and quality. SWAT can incorporate many factors into the simulation, including land cover, soil types, weather, and crop growth. The SWAT 2000 model was integrated into the EPA s Better Assessment Science Integrating point and Non-point Sources (BASINS) package.

6 Honey Creek Located in western Comal County Part of the Upper Guadalupe watershed (HUC ) and is in the contributing region of the Edwards Aquifer Drains approximately 6000 acres Remains active throughout the year due to the activity of several springs Site of an in-progress brush control study utilizing two upstream branches of the creek

7 Data Surface Elevation 30-meter Resolution DEMs for Anhalt and Bergheim Quads Provided by TNRIS Hydrography RF3 Reach Files for Upper Guadalupe Basin Provided by EPA Soil Distribution SSURGO 2.0 Data for Comal and Hays Counties Provided by USDA-NRCS Land Cover Landsat ETM+ Image: 20 October 1999 (LE ) Provided by TNRIS Weather Data Rainfall, Temperature, Solar Radiation, PET, and Windspeed Provided by Texas ET Network, San Antonio Station (1/96 10/98)

8 DEM and Reach Data 30-m DEMs of the Anhalt and Bergheim quads were mosaiced to produce an elevation grid which covered the entire Honey Creek area

9 SSURGO Data SSURGO provides a high-resolution alternative to STATSGO soil data SWAT is built to read data found in STATSGO datasets Data for Comal County is provided in the new SSURGO 2 format A User Soils table obtained from the Texas A&M Spatial Sciences Lab aided in the integration of this data

10 Landsat Data Band 1: Visible Blue Band 2: Visible Green Band 3: Visible Red Band 4: Near Infrared Land Cover Classifications Band 5: Middle Infrared Band 6: Thermal Infrared Band 7: Middle Infrared Band 8: Panchromatic Classification Scheme Using ENVI

11 Landsat Data Original DOQQ Unclassified 0.69% FRSE 43.06% RNGB 31.83% RNGE 24.42% 1-m DOQQ courtesy of TNRIS Parallel Piped Mahalanobis Distance Maximum Likelihood Minimum Distance

12 Climate Data SWAT allows for the input of historical rainfall, temperature, solar radiation, and windspeed data, as well as the ability to name a user defined weather generator. Climate data is entered in two separate dbf tables Potential ET can also be read into the simulation.

13 Pre-Analysis with BASINS Delineate the Honey Creek basin using the DEM and RF3 datasets Assign spatial data pertaining to land cover and soil distribution

14 Control Simulation

15 Experimental Simulations Experiment 1: Replace RNGB land cover with RNGE to demonstrate complete removal. Experiment 2: Replace RNGB land cover with RNGE to demonstrate complete removal AND replace FRSE with RNGB to demonstrate partial clearing of dense areas.

16 Water Yield Total Water Yield Results Without October 1998 Data Yield (Acre-Feet) Control Run Experimental Run 1 Experimental Run October-95 May-96 December-96 June-97 January-98 July-98 February-99 Month

17 Jan-96 Feb-96 Mar-96 Apr-96 May-96 Jun-96 Jul-96 Aug-96 Sep-96 Oct-96 Nov-96 Dec-96 Jan-97 Feb-97 Mar-97 Apr-97 May-97 Jun-97 Jul-97 Aug-97 Sep-97 Oct-97 Nov-97 Dec-97 Jan-98 Feb-98 Mar-98 Apr-98 May-98 Jun-98 Jul-98 Aug-98 Sep-98 Oct-98 Change In Water Yield Change In Simulated Water Yield Month Yield (Acre-Feet) Experimental Run 1 Experimental Run 2

18 Groundwater Recharge 800 Aquifer Recharge Results Without October 1998 Data Percolation (Acre-Feet) Control Run Experimental Run 1 Experimental Run October-95 May-96 December-96 June-97 January-98 July-98 February-99 Month

19 Change In Recharge Jan-96 Feb-96 Mar-96 Apr-96 May-96 Jun-96 Jul-96 Aug-96 Sep-96 Oct-96 Nov-96 Dec-96 Jan-97 Feb-97 Mar-97 Apr-97 May-97 Jun-97 Jul-97 Aug-97 Sep-97 Oct-97 Nov-97 Dec-97 Jan-98 Feb-98 Mar-98 Apr-98 May-98 Jun-98 Jul-98 Aug-98 Sep-98 Oct-98 Change In Simulated Groundwater Recharge Month Percolation (Acre-Feet) Experimental Run 1 Experimental Run 2

20 ET Evaoration-Transpiration ET (Inches of Water) Control Run Experimental Run 1 Experimental Run October-95 May-96 December-96 June-97 January-98 July-98 February-99 Month

21 Change in ET Change in Simulated Evaporation-Transpiration Jan-96 Feb-96 Mar-96 Apr-96 May-96 Jun-96 Jul-96 Aug-96 Sep-96 Oct-96 Nov-96 Dec-96 Jan-97 Feb-97 Mar-97 Apr-97 May-97 Jun-97 Month Jul-97 Aug-97 Sep-97 Oct-97 Nov-97 Dec-97 Jan-98 Feb-98 Mar-98 Apr-98 May-98 Jun-98 Jul-98 Aug-98 Sep-98 Oct-98 ET (Inches of Water) Experimental Run 1 Experimental Run 2

22 Future Goal: Calibration Increased Enhancement integration of the of model satellite of with available land gauging cover data data techniques now being recorded Creation of a GIS system for targeting brush removal

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