Thiem Equation Calculator (Excel 280kB Aug13 09)įor this exercise we will assume the permeability (K) of the aquifer is 400 feet per day (ft/d), the Riley well (Q R) pumps at an average rate of 200 gallons per minute (gpm), Well G (Q G) pumps at an average rate of 700 gpm, and Well H (Q H) pumps at an average rate of 400 gpm. Note the assumptions used to simplify the equation Theim equation used for the EXCEL spreadsheet calculator. A link to the EXCEL spreadsheet occurs below. Although there are multiple tabs on the spreadsheet, the tab labeled 'Summary' is the only one required to complete this exercise. The lower graphic represents a cross section along column 14 on the map in the upper left corner of the spreadsheet. Wells G and H are to the right of the river line and the Riley well is on the left. It should be noted the yellow and white curved lines on the EXCEL worksheet represent the Aberjona River. In this exercise, we will explore different well pumping rates and how they would affect groundwater flow in the aquifer underlying Aberjona River Valley. The Thiem equation is embedded into the cells of the worksheet and automatically calculates drawdown at specified distances based on cell dimensions.
The solution to the Thiem equation assumes the the drawdown (s 2) at the distance (r 2) is zero. The model assumes the aquifer is isotropic, homogeneous, flat lying, infinite, flow is steady-state, wells discharge at the uniform rate, and the wells have no borehole storage. The worksheet is based on the dimensions and locations of wells G and H. This assignment utilizes the Thiem equation (see image below) in an EXCEL worksheet to create a two-dimensional groundwater flow model that computes drawdown relative to steady-state pumping from wells. Learning Module: Groundwater Flow and Wells G & H Student Assignment Overview
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