Daily Objectives, Principles of Hydrogeology

Objectives 1

Department of Earth Science |Northeastern Illinois University

PRINCIPLES OF HYDROGEOLOGY
ESCI 337
Spring, 2009

Daily Objectives #14 (March 5, 2009) Dr. Sanders

By the end of today's class, you should be able to do the following:

Flow Nets, continued

w Review: List the three kinds of lines that can be found on a flow net.

w Review: List the three kinds of flow system boundaries that might appear on a typical flow net.

w Review: Tell what a piezometer is and explain how to use one to obtain information on hydraulic head, elevation head, and pressure head.

w Using a flow net, estimate a hydraulic gradient, and explain how different gradients appear on a flow net.

w For flow through a homogeneous medium, explain the effect of changing gradient.

Darcy's Law

w State Darcy's Law and explain its variables.

w Use Darcy's Law to calculate the discharge through a portion of an aquifer as depicted on a flow net.

Finding and Using Subsurface Data for Illinois

w Find a given location based on data from the Public Land Survey System (township, range, section)

w Use the ISGS online database ("ILWATER") to locate well records for a given location in the Public Land Survey System

w To get to the ISGS database, go to the Earth Science Department web page, click "Terrific Links!" and then the link for the ISGS. At their home page, find ILWATER near the top of the page. Read the instructions for accessing data, disable your popup blocker, and then open the ILWATER mapping web interface. Practice zooming in, zooming out, and panning. To locate well records, you must be at the proper zoom level; you'll know it when you get there because "Water and Related Wells" will appear in the "Layers" column to the right. When you see this, you can use the "Select Within" tool to outline an area. A list of well records will appear at the bottom of the screen. Click each one to see the record, or use the "Identify" tool to click on a specific dot.

w Using the borehole data and regional geologic reports, identify hydrostratigraphic units. (You may have to refine and revisit this step many times after doing the next step. This is an iterative process.)

w Plot a cross section (or "fence diagram") based on the borehole data. On the cross section, clearly identify the hydrostratigraphic units.

Hydrogeologic Maps and Cross Sections (Homework #4)

w Explore the questions, issues, and difficulties that commonly arise in constructing hydrogeologic cross sections.

w Gather data on the subsurface conditions of the study area.

Department of Earth Science | Northeastern Illinois University