The Hydroclimatological Behavior of the Brazilian State of Rio Grande do Norte and the Municipality of Caicó

Abstract The aim of this article is to analyze rainfall patterns in the Brazilian state of Rio Grande do Norte and the municipality of Caicó with the objective of providing inputs to support local water resource management in view of the frequent water shortages in the state and the municipality. The data used for this purpose were annual accumulated precipitation data from all the municipalities in the state (1963-2013) from the SUDENE and EMPARN databases, and precipitation, evaporation, and evapotranspiration data on Caicó (1996-2013) from the INMET database. For the hydroclimatological analysis, other research on the subject was consulted, the quartile coefficient of dispersion and redistribution coefficient were used in the statistical and geospatial analyses, and the aridity index was calculated. The results of the spatial analyses were plotted on maps using ArcGis 10.0. The data showed that there is a spatial pattern of rainfall in the state of Rio Grande do Norte, with the highest rainfall occurring along the east coast, followed by the west of the state, while the central part (including part of the north coast) is the driest. It was found that the spatial distribution of precipitation remained the same whether the year was dry or rainy, with the highest values always appearing along the east coast, followed by the west of the state and the mountainous areas of the sertão, and finally the central region. Caicó was classified as semi-arid and highly susceptible to desertification. In this municipality, potential evaporation was found to be about five times higher than precipitation on average each year, indicating just how vulnerable it is to water shortage.