Forecasting Edwards Aquifer Water Level Brian Overton Budi Yulianto ChiYan Cheung Jessica Sison Leann Lewis Terran Fiske

Outline The Edwards Aquifer, Background and Objective Regression Models and Variables Time Series Decomposition Model ARIMA Model Model Comparisons and Selection Conclusion

A Brief Background on the Edwards Aquifer The Edwards aquifer is a cavernous limestone reservoir in the south-central Texas area. The aquifer is replenished by waters flowing from area rivers and rainfall over its recharge zones (San Antonio, New Braunfels, San Marcos and parts of Austin). Purpose: To use statistical analysis to determine the most effective model to forecast the water level in the Edwards Aquifer

‘95 - ‘96 Drought ‘98 Drought El Nino

Regression Models Complete Model Comal Springs Model Complete without Comal Springs Complete Interaction and Interaction 2 Stepwise Raw and Interaction Stepwise Raw, Raw 2, Interaction, Interaction 2

Comal Springs Models: A Special Case

Aquifer Water Level versus the Comal Springs Flow

Regression Variables Average Precipitation Average Temperature Average Salado Treatment Plant In-Flow Average Dos Rios Treatment Plant BOD Texas Unemployment Rate Southwest Retail Sales Natural Gas Production

Regression Models

Time Series Decomposition Model

Autocorrelation analysis PAC’s indicates first order autoregressive SAC’s dampens toward 0

Conclusion Best Model was... R, R 2, I, I 2 Stepwise Regression

Questions?