Poverty and water management in the Sao Francisco river basin: Preliminary assessments and issues to consider
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Vosti, S. A., Torres, M., 2006. Poverty and water management in the Sao Francisco river basin: Preliminary assessments and issues to consider. São Francisco River Basin Research Brief 2. Colombo, Sri Lanka: CGIAR Challenge Program on Water and Food.
Permanent link to cite or share this item: http://hdl.handle.net/10568/16765
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.