Drought
Update: 05/08/2002
Rainstorms
during Mach and April have helped to green up vegetation, improve
stream flows temporarily, and provide the illusion that the
State's water supply situation has improved dramatically. However,
two months of rainfall at near-normal levels cannot erase the
rainfall deficit that has accumulated from 15 out of the last
19 months having significantly below normal rainfall. (Think
of getting only 2/3 of your salary for 15 months - it will take
more than two months at your usual salary to pump your bank
account back up to normal.)
From
October through April, precipitation should be recharging the
shallow groundwater system. However, since rainfall during this
period in 2001-2002 was at record lows, very little recharge
occurred and ground water levels are still very low. These levels
normally peak in April and May and then decline from May thought
October, as evapotranspiration from growing plants pulls water
out of the shallow groundwater system. We are starting the summer
with near-record low shallow groundwater levels. Therefore,
even with normal amounts of precipitation now, we would still
have record low, shallow groundwater levels this summer. Without
a long period of higher than normal rainfall, the next real
opportunity for recharging shallow groundwater will be in the
fall of 2002.
In
New Jersey the highest stream flows occur during late fall through
spring, November through May. Throughout much of this period
in 2001 -2002, the majority of New Jersey's streams have been
at or near record low levels due to record low rainfall. With
each rain event stream flows rise but quickly fall to levels
far below normal for this time of year. Even with the current
rains, stream flows are still significantly below normal for
his time of year. Stream flows are not expected to return to
normal until the shallow groundwater systems recover to normal
levels.
The
effect of a rainstorm on the drought can vary tremendously depending
on how fast and hard the rain falls, and for how long the rain
continues. A long, light rain allows more water to soak into
the ground and is therefore good for ground water recharge,
long term stream flow, and plant growth. Short, hard rains dump
so much water at once that it can't soak into the ground, resulting
in more runoff. Runoff is good for filling reservoirs, but does
not improve groundwater and only temporary improves stream flow.
Therefore, even though reservoir levels have been rising with
the rainfall in March and April, we must still conserve as much
water as possible, until both shallow groundwater and stream
flows return to near normal levels.
Past Drought Updates |