“Modeling, along with monitoring and research, are the three legs of the scientific stool that support ecosystem restoration and management. Monitoring tells us what is happening, research tells us why and how it is happening, and modeling provides insights about what can happen under different management alternatives. Modeling tools for the San Pedro River Watershed include groundwater, surface water and land cover.”

Featured Groundwater Modeling

“Ground-water flow model of the Sierra Vista Subwatershed and Sonoran portions of the Upper San Pedro Basin, southeastern Arizona, United States, and northern Sonora, Mexico” by Don Pool and Jesse Dickinson. Read USGS SIR 2006-5228 here.

This report describes the ground-water model developed as part of the USPP initiative to better understand the hydrogeology of the regional aquifer system of the Sierra Vista Subwatershed. The model synthesizes the results of much of the science that the USPP has supported since 2000 including regional hydrologic analyses, ephemeral stream channel recharge and flow distribution information, riparian water needs, stream-aquifer interactions etc. The process of developing the model has led not only the scientists of the USPP, but also land managers, policy makers and others to a more complete understanding of the hydrologic system. The model also represents a tool that can provide insight to the potential hydrologic ramifications of water-management actions.  While the Decision Support System (DSS) tool is no longer operational, you can still learn about it via linked report.

“Interim Update to Sierra Vista Subwatershed Pumping and Artificial Recharge Rates in the Upper San Pedro Basin Groundwater Model” Prepared for The Nature Conservancy, By Laurel J. Lacher (2017)

 This study incorporates the best available data into the U.S. Geological Survey’s 2007 published groundwater model for the Upper San Pedro Basin (Pool & Dickinson, 2007). This interim update to the model comes six years after the last pumping update (Lacher, 2011), and provides a more accurate accounting of both actual pumping in the Sierra Vista subwatershed (SVS) over the 2003 to 2015 period, and of projected pumping from 2016 to 2100. These improvements are designed to make simulated impacts to baseflows and groundwater elevations as accurate as possible to inform water management decisions, but they do not include any new model calibration or changes to the historic model period (1902-2003). Additional updates are anticipated in future years as new data become available.

The files provided include all of the input files needed to run the simulations described in this report in MODFLOW-2000.  Output files are provided for verification purposes.


The Nature Conservancy (“TNC”) is providing interested parties access to the updates to the U.S. Geological Survey 2007 Pool & Dickinson published groundwater model for the Upper San Pedro Basin (the “Data”) for the purpose of informing water conservation in the Sierra Vista Subwatershed.  The Data were developed by Lacher Hydrological Consulting (“LHC”) on behalf of TNC, and TNC owns the Data.

By accessing and/or downloading the Data from the “Interim Update to Sierra Vista Subwatershed Pumping and Artificial Recharge Rates in the Upper San Pedro Basin Groundwater Model” you understand and agree to the following:

A.  TNC and LHC make no warranty, express or implied, as to the Data’s accuracy or applicability to your particular desired use. All Data are provided “as is.”

B.  The Data shall be used for water management and conservation purposes only. Any further sale, distribution or transfer to a third party of these Data, in whole or in part, is prohibited.

C.  Any publication or use of the Data in the public domain shall include an acknowledgment of TNC as the owner of the Data and LHC as developer of the Data. Any reports, products or derivative products from the Data shall also include such acknowledgments.

D.  If the Data are altered or changed in any way, you must disclose any changes made, as well as attribute the original Data to TNC and LHC.

Click here to access the report.

Click below to access the compressed model files and readme file:

Readme file

MODFLOW-2000 executable and related files

Featured Surface Water Modeling

AGWA Automated Geospatial Watershed Assessment, A GIS-Based Hydrologic Modeling Tool

Automated Geospatial Watershed Assessment (AGWA) – A GIS-Based Hydrologic Modeling Tool: Documentation and User Manual Version 1.32

Evaluating Hydrological Response of Future Land Cover Change Scenarios in the San Pedro River (US/Mexcio) with the Automated Geospatial Watershed Assessment (AGWA) Tool (USFS, GTR SRS-211, p92-101)

Modeling Runoff Response to Land Cover and Rainfall Spatial Variability in Semi-Arid Watersheds (EMA 64: 285-298, 2000)

Scenario Analysis for the San Pedro River, Analyzing Hydrological Consequences of a Future Environment (EMA 94: 115-127; 2004) [link to Kepner et al. 2004] and poster

Simulated Changes in Runoff and Sediment in Developing Areas near Benson, Arizona (EPA/600/R-06/158 & ARS/.1873)

Featured Land Cover Modeling

Assessing Impacts of Landuse and Landcover Change on Hydrology for the Upper San Pedro Watershed (Journal of Hydrology 407:105-114; 2011)

Hydrological Impacts of Mesquite Encroachment in the upper San Pedro watershed (Journal of Arid Environments 82: 147-155; 2012)