Paulo Roberto Coelho Lopes, Aderaldo de Souza Silva, José Barbosa dos Anjos, Everaldo Rocha Porto
EMBRAPA - Semi-árido
Caixa Postal 23
56.300-000, Petrolina -PE, Brasil
E-mail:proberto@cpatsa.embrapa.br

In this paper the results of a ten-year study on superficial hydrology are presented. It describes eight hydrographic micro-catchments with different natural vegetation's (caatinga) management systems in the Brazilian semiarid region, dealing with induced superficial runoff, catchment and storage of rainwater for small irrigation projects. Eight experimental micro-catchments were built in an unvaried area with the objective of evaluating several hydrological combinations of natural vegetation and soil management for induction of superficial runoff of rainwater and conservation of the natural vegetation. The experiment was carried out in micro-catchments (plots) with areas varying from 1.1 to 2.7 hectares and slopes from 0.7 to 1.4%. At the lowest spot of the plot (water exit of the superficial runoff), a Parchall gutter and a linigraph to measure flow-out were installed. In each plot a pluviometer was installed to measure the exact amount of rainfall in the area. During the duration of the study, in the one plot that had been totally deforested and where watercourse terraces had been built, the efficiency of superficial water runoff and soil losses were the highest. Followed by the plot deforested in alternate strips (50% of the original vegetation was taken out), with intense drainage and NaCl application in the deforested strips (300 g m-2) and the plot deforested in alternate stripes and building terraces in those places as a base. There was no superficial water runoff in the plot where the natural vegetation was kept without alteration.