Proposta de uso racional da água de reservatórios não-estratégicos para agricultura irrigada

Abstract

Water scarcity faced by arid and semiarid regions requires the adoption of measures such as construction of major strategic dams for the purpose of accumulation of water during the rainy season for use in the dry season. But small towns, farmers and rural communities are also building spontaneously thousands of small reservoirs to ensure their water supply due to noncompliance by the strategic reservoirs. However, small reservoirs often cannot get through long periods without complete emptying and therefore do not guarantee regulated flow with high security. With the above, the aim of this work with the development of a model to define criteria for the rational operation of non-strategic reservoirs, focused on maximizing income from irrigated agriculture in the Brazilian semiarid region. The model is composed of three routines: i) water balance in the reservoir due to the water inflows and effluents, the reservoir geometry and characteristics of the river basin; ii) water balance of culture and simulation of agricultural cultivation; iii) economic analysis for the calculation of income from irrigated agricultural cultivation. Four reservoirs were analyzed located in the rural settlement May 25, Madalena, Ceará, having used a series of climate data from 1986 to 2014. The crop used for these analyzes was the corn (Zea mays), because there cultivars adapted to different temperature and humidity conditions and among the cereals grown in Brazil, corn is the most significant. The simulation indicated that the rational use of Rule water reservoir is variable between them, and that the operation with 90% guarantee, practiced in strategic reservoirs, it is inefficient in small reservoirs for water use in irrigated agriculture. The model shows that it is possible to rationalize the use of water from dams in order to maximize the income of farmers through irrigated agriculture.