CVEN9630: A slug test analysis was performed on a piezometer in a sandy unit. Fig. 1 shows the water level response after the pressure: Groundwater Hydrology Assignment, UNSW, Singapore

Question 1

A slug test analysis was performed on a piezometer in a sandy unit. Fig. 1 shows the water level response after the pressure in a piezometer is released. Measurements depicted by the dots in Fig. 1 are also recorded in Table 1. The construction details of the piezometer are as follows: The outside casing and screen diameter (2∙ 𝑅) is 6 cm, while the casing wall thickness is 5 mm. The screen length is 1.5 m. The mean aquifer grain size d50 = 1 mm.

• Use the data provided in the table to calculate the hydraulic conductivity of the aquifer.
• Calculate the maximum velocity at which the water enters the piezometer screen.
• Does Darcy’s law apply? If not, how else could the slug test be evaluated?

Question 2

The objective is to use an Excel spreadsheet to investigate various boundary conditions for a simple rectangular confined aquifer. The aquifer heads and flow are modeled using a finite difference scheme based on the analysis of Frank and Reilly [1987]. In Excel, you need to set up an aquifer model of an area 1100 m wide (in the x-direction) by 1400 m long (in the y-direction). Use a finite difference discrimination where ∆x = ∆y = 100 m. Your model will then be 12 nodes wide in the x-direction (extending from node 0 to node 11) and 15
nodes long in the y-direction (extending from node 0 to node 14). Assume that the aquifer transmissivity is 300 m2/day. The upper left corner is labeled A, and the other corners are B, C, and D (in a clockwise direction).