Zoneamento agro-climatológico para o Estado de Pernambuco baseado em índices de disponibilidade hídrica.

Abstract

An agroclimatic classification of the Pernambuco State based on water deficit índices (R and MAI) and the Identification of the homogeneous rainfall regions based on the asymmetry coefficient of Pearson are propcsed in this work. For this purpose the ten-day precipitation totais of 63 locations and the monthly temperature means of 13 locations in the State of Pernambuco are used. The missing temperature data was estimated by a quadratic function based on local coordinates. The potential evapotranspiration for each locality was obtained through the Thornthwaite & Mathers water balance procedures. The precipitation probabilities were calculated using the Gamma probabiiity function and the Kimbairs method. The moisture availability index MAI (ratio of dependable precipitation to potential evapotranspiration) and the weekly water availability index R (ratio of actual evapotranspiration to potential evapotranspiration) and the Pearson asymmetry coefficient, were calculated and analyzed graphically. The results of this work show that the R index was an efficient methodology to define the regions water regimes. The MAI index and the asymmetry coefficient methodologies were not adequate to represent the regions water regimes of Pernambuco state. The Pernambuco state has sufficient water availability to crops with upto 120 days of vegetativa cycle, in the eastern parts of the state ( between the longitudes of 37,2° W and 34,9° W) and in the North (between 40,7°W: 7,7°N and 37,9°W: 7,4°N). The rest of the state has no conditions of water availability to agricultural practices without suplementary irrigation. The results presented here, have the primary objective of contributing directly to the water resources planning towards agricufture in the State of Pernambuco.