Reevaluation of the Safe Yield of the Beaumont Basin

Beaumont Basin Watermaster (On-Going)

Project Objective
Since 2012, TH&Co has been providing hydrogeological services to the Beaumont Basin Watermaster for the implementation of the Judgment. Per the Judgment, it is required to reevaluate the Safe Yield of the basin every 10 years. TH&Co was charged with reevaluating the safe yield for the period from 2003 to 2013.

Project Approach
In order to reevaluate the Safe Yield and provide a tool for basin management decisions, TH&Co developed a coupled surface and groundwater flow model of the area encompassing the adjudicated basin. The model was developed using USGS’s code MODFLOW and Infil v.3. The methodology to develop the model included hydrogeological basin characterization, numerical model development, formatting and input of groundwater production and recharge data, model calibration, and sensitivity analysis. Other aspects of the model included:

• Model area is approximately 33 square miles,
• Model constructed with two layers and discretized with 200-ft grid cells,
• Incorporates monthly stress periods,
• Incorporates a detailed analysis of pumping for agricultural operations and land use changes associated with urbanization, and
• Successfully calibrated for the period from 1927 through 2013.

Project Results
The Beaumont Basin groundwater flow model was successfully calibrated and used to reevaluate the safe yield of the basin under three potential future basin operational scenarios. Based on the analysis, TH&Co recommended a Safe Yield for the period 2013 through 2023.