Department of Earth Science |Northeastern
Daily Objectives #14
(March 5, 2009)
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
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.
For flow through a homogeneous medium,
explain the effect of changing gradient.
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,
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.
and Cross Sections (Homework #4)
Explore the questions, issues, and difficulties
that commonly arise in constructing hydrogeologic cross sections.
Gather data on the subsurface conditions of the
Department of Earth Science | Northeastern Illinois University
Copyright 2009 Laura L. Sanders.
Last updated March 5, 2009.