Geoscience Reference
In-Depth Information
People sought new sources of water as, year at er year, the drought con-
tinued. h e use of groundwater became especially popular: private well
owners deepened existing wells or drilled new ones, and thirsty consumers
in the San Joaquin Valley extracted eleven million acre-feet more ground-
water than could be replenished naturally, further lowering the water table.
Cloud-seeding operations were expanded in the Sierra Nevada in the hopes
of increasing precipitation, even if only by a fraction of a percent.
Overall, the 1987-92 drought resulted in i nancial losses of $3 billion to
the state of California. h is was an even greater i nancial disaster than the
drought of the 1930s had been. h e state's population had expanded by over
four times what it had been earlier in the century, and a burgeoning agricul-
tural industry relied more heavily on water from reservoirs.
California has not experienced as severe a multiyear drought since 1992,
but the population of the state continues to grow and is predicted to double
by the year 2050. Moreover, California faces an uncertain climatic future:
global warming is predicted to change the state's hydrology, with less snow-
pack and overall warming and drying, more frequent l ooding as more winter
precipitation falls as rain rather than snow, and an increase in major storms.
California, like the rest of the American West, also faces the recurrence of
more severe climate events. h
is will be discussed in the coming chapters.
climate: the long view
h e extreme climate events of the past century and a half that have been
presented in this chapter were indeed severe. However, paleoclimate evidence
suggests that they were by no means the worst we can expect from nature. In
fact, compared to what records indicate of the long-term climate patterns for
this region, the climate of the North American West over the past 150 years
has been nearly ideal for human settlement.
We are now learning that the l oods and droughts of this period are
an incomplete sampling of the extreme events that have been a “normal”
part of the West's hydrology for thousands of years. h e clues from past
climates depict extremely dry periods—in some cases lasting decades or even
centuries—ot en punctuated by torrential rains and l oods. We now realize
that vastly larger l oods and more severe and protracted droughts, though
rare, are as inevitable as the earthquakes and volcanic eruptions that Pacii c
Coast residents know will occur.
