Runoff Research Promotes Healthier Aquifers
McGinnis September 24, 2008
Where rain falls can influence the quality of surface water before it
enters underground reservoirs, some of which provide water that eventually
comes out of our taps.
That's one conclusion from a collaborative study by the
Agricultural Research Service (ARS) and
the University of Arizona (UA). The ARS
and UA scientists are investigating how urban landscapes influence storm runoff
and water pollutants. The focus of their study is the greater Tucson
metropolitan region, which has quadrupled in size since the early 1960s.
Like many Arizona cities, Tucson is looking into "enhanced stormwater
recharge" to capitalize on the region's rare, but intense, downpours. Enhanced
recharge is the process of improving groundwater reservoirs with strategic
engineering, such as artificial wells to store water or porous pavement that
allows more water to trickle into aquifers.
Understanding how housing density affects the region's aquifers can be
helpful in identifying the best enhanced-recharge methods for a specific area.
McLain, an ARS microbiologist at the
Arid-Land Agricultural Research Center in Maricopa, Ariz., is working with
a team of UA scientists, led by Kathleen Lohse of the
School of Natural Resources, to
examine how housing density affects the levels of nutrients, fecal bacteria,
metals and organic pollutants in storm runoff.
They're also researching whether and how those substances enter
aquifers. This information is essential for selecting optimal enhanced-recharge
Impervious surface areas, such as paved parking lots, have higher
runoff than absorbent surfaces. Preliminary studies show that this allows for
less processing of pollutants, leading, in turn, to higher levels of enteric
bacteria and nutrients in the water samples.
Ultimately, this collaboration will assist in developing effective
best management practices for promoting aquifer water quality. For example, an
effective recharge method for the kind of runoff mentioned above might allow
the water to slowly filter through the soil, removing pollutants before the
water enters underground reservoirs.
ARS is a scientific research agency of the
U.S. Department of Agriculture.