| Sumario: | Of the approximately 17 million
who inhabited the SFRB
in 2003, about 3.7 million
(approximately 21%) were poor by
Brazilian standards (living on about
one minimum salary or less). Just over
four million people lived in rural areas
of the SFRB and nearly one-third of
them (about 1.2 million) were poor.
But the rural poor were not distributed
evenly across the SFRB (see
Figure 1). The proportion of the rural
poor tended to be lower in the southern
portion of the SFRB, primarily in
the state of Minas Gerais, the mountainous
zone where the São Francisco
River begins. Rural poverty, by this
measure, tended to be higher in the
central and northern zones, with some
municípios registering proportional
rates of poverty well in excess of 50%
of the rural population.
The depth of poverty matters
greatly; Figure 2 depicts the spatial
distribution within the SFRB of
the extreme poverty, i.e., individuals
belonging to households living on
less than one-third of the Brazilian
monthly minimum salary per person.
These extremely poor households are
located almost exclusively in the central
and northern zones of the SFRB.
While poverty is central to our
research, training, and outreach
mandates, it is also interesting to
focus attention on municípios that
are less poor, in part because we may
learn something from these less-poor
municípios that may be useful to their
more-poor counterparts. Reviewing
Figures 1 and 2, it is easy to identify
less-poor municípios in the central
and northern zones of the SFRB
where rural poverty was especially
concentrated. One has to wonder
what factors might cause neighboring
municípios to have such different rural
poverty rates; might water availability
have something to do with this?
Water Availability in the SFRB
While water availability is difficult to
define and even more challenging to
measure, at any resolution, Figure 3
depicts estimated water availability for
the SFRB, by município. Our measure
of water availability considers annual
precipitation, base evapotranspiration,
catchment area upstream,
and slope (how likely is rainfall or
run-on likely to ‘stay’ on the receiving
farm); municípios that appear
in darker blue have more available
water than those in green or
yellow. No seasonal or other water
storage, or artificial conveyance of
water, is included in this measure
of water availability; this measure
of water availability may be most
useful in areas where irrigated
agriculture relies on precipitation
as well as on local diversions of
direct runoff from the upstream
catchment.
Two important patterns emerge,
one that we have been long
familiar with and another that is
somewhat surprising. The familiar
pattern is that of generally higher
measures of water availability in the
southern and central zones of the
SFRB than in the northern zone; this
corresponds to known variations in
annual rainfall, which ranges from a
high of about 1,500 mm/year in the
southern zone to a low of about 500
mm/year in some areas of the northern
zone.
The surprising pattern is the presence
of relatively water-scarce municípios
in the high-rainfall southern
zone, and some relatively water-rich
municípios in the arid northern zone.
Other variables in the water availability
measure as well as scale of analysis
(resolution) explain these differences.
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