Groundwater overview
CE 473/573 Fall 2010
Lecture 2
Hydrology & Geology
Hydrologic cycle
M. Ritter, U. Wisc.-Stevens Pt.
Aquifers in the U.S.
?
Ogallala aquifer
Recharge = 22 mm/y
Extraction = 55 mm/y
Saturated thickness
Ogallala aquifer
Water level change from
1980 to 1995
> 40 feet
> 20 to 40 feet
> 10 to 20 feet
> 5 to 10 feet
> -5 to 5 feet
> -10 to -5 feet
> -20 to -10 feet
> -40 to -20 feet
< -40 feet
Irrigation Research Foundation
Aquifers in Iowa
GW Atlas of the U.S.: IA, MI, MN, WI
Aquifers in Iowa
Implications: Ethanol production
Institute for Agriculture and Trade Policy
Implications: Ethanol production
Implications: ethanol production
From the DM Register:
[The executive director of the Iowa Renewable Fuels Association]
said water used by ethanol facilities is "a drop in the bucket“
compared with the total groundwater usage in the state.
More than half of the water used by ethanol plants evaporates during
production or is treated and released back into streams. That,
essentially, continues the natural cycle of water, [he] said.
Water Supply
USGS monitoring wells
Measuring conductivity
h
h
Time
Borehole permeameter
Transmissivity in Iowa
Implications of GW flow: wetlands
Loss of wetlands area: 89% (Iowa), 53% (U.S.)
Implications of GW flow: wetlands
Legislation aims for “no net loss” of wetlands, but who has authority?
Appeals Court: hydrologic
connections between the site and
navigable waters
Stevens: include groundwater
with a significant nexus of
connection to more distant
navigable waters
Scalia: Stevens’s definition of
wetlands is “beyond parody”
Wells
Well and cone of depression
Des Moines Water Works supply
Infiltration gallery
Radial collector wells
Source: DM Water Works
Des Moines Water Works supply
Des Moines Water Works supply
Does denitrification occur in the soil? Does the water “short circuit”?
Source: DM Water Works
Effects of pumping
Water quality concerns
Well recommendations
Pumping affects streamflow
Mechanism of subsidence
Subsidence in the U.S.
Subsidence example: CA
Saltwater intrusion
Contaminants
Point source pollution
From Mission 2010: Clean Water:
petroleum products
Most serious source of contamination is _________________.
240 million gallons
People in the U.S. dump or bury ____________________
of automobile oil per year.
Nonpoint source pollution
Drainage from agriculture
Arsenic in groundwater
EPA MCL = 10 mg/l
Leaky underground storage tanks
Contaminants
BTEX: benzene, toluene, ethylbenzene, and xylenes
methyl tert-butyl ether (MTBE)
LUSTs in Boulder CO
Otis Air Force Base
“The Plume”
Yucca Mountain, NV
Yucca Mountain, NV
…colloidal groundwater migration must
have played an important role in
transporting the plutonium. Models that
either predict limited transport or do not
allow for colloid-facilitated transport may
thus significantly underestimate the extent
of radionuclide migration. (Kersting et al.
1999)
Groundwater models
Groundwater model
Modflow example