Analysis of variable climate (rainfall, air temperature and potential evapotranspiration) in Jeremoabo Pole (Bahia-Brazil) as indicators of vulnerability to desertification
ISBN 978-85-88783-11-9
Authors
1dos Santos Sales, T.; 2Moura Oliveira, J.H.
1UNIVERSIDADE ESTADUAL DE FEIRA DE SANTANA Email: thayane.sales19@gmail.com
2UNIVERSIDADE ESTADUAL DE FEIRA DE SANTANA Email: jmouraoliveira8@gmail.com
Abstract
The objectives of this study was to analyze the climatic variables (precipitation, air temperature and potential evapotranspiration) in the regional Polo Jeremoabo, northeastern Bahia Brazil as desertification vulnerability indicators by spatial these variables using interpolation methods. Interpolation is a mathematical process of finding intermediate values between discrete values of a function. Five methods of interpolation were used: Inverse Distance Weighting - IDW, Natural Neighbor Top to Raster, polynomial function (Spline) and Ordinary Kriging . The method Inverse Distance Weighting (IDW) consists of multiplying the sample values by the inverse of their respective distances from the reference point for interpolation of values. Natural Neighbor method is a function that uses the triangulation Veronoi, and not extrapolate the values obtained, the method is limited to a circular area within the field of points. The polynomial function (spline) function, in turn, values estimated using a function that minimizes the curvature of the surface. Have Top to Raster method using local interpolation, without losing the surface continuity. And Ordinary Kriging method considers the floating or moving average for the whole area through a linear combination of values. To apply these functions, we used a basis of 27 weather stations facts of climate variables rainfall, air temperature, potential evapotranspiration of northeastern Bahia sector. The Jeremoabo Regional Pole study area is located in northeastern Bahia in the semi-arid region, inserted in the drought area, also composing the Susceptible Area Desertification (ASD) in Brazil. The Pole is comprised of 13 municipalities. The taking its predominant area occupied by vegetation of Caatinga trees and shrubs. in a high climate variability region is of great irregularity of rainfall during the year, its concentration is usually from March to April, recording a rainfall ranging from 400 mm to 1000 mm annually and an average temperature of 24°C. However, according to the tests of spatial information on the distribution is dominated research over the years isohyets 300 to 600 mm per year in most municipalities pole. The spatial distribution of these data and their effectiveness from the new values generated by the interpolation procedure were observed. Each interpolation method has specific points and shapes, thus differs in geographical positioning of established intervals. Thus, statistical criteria were used to accuracy the estimated values, through the calculation of the waste, the Total Scale Waste (TER) and the Middle Scale of Errors (ESM). From these calculations we can see which method has low curvature. All methods were effective because their index values Normalized Residual (IRN) are minimal. With the spatial analysis of the results generated by interpolating along with the statistical criteria applied to evaluate the accuracy of the new data sets, it was possible to obtain important information for research beyond demonstrate the broad potential of geotechnology for environmental studies and particularly in the development of indicators of desertification. According to the geostatistical method validation used in the research, the polynomial function function (Spline) (polynomial function - (streaks) showed better results, getting smaller index Normalized Residual (IRN).
Keywords
Interpol of variable climate; Geotechnology; Desertification