MODELAGEM HIDROLÓGICA UTILIZANDO OS DADOS DE PRECIPITAÇÃO PERSIANN-CDR E O MODELO SWAT PARA A BACIA DO RIO PIANCÓ - PB

Abstract

Precipitation is one of the most important variables in hydrological modeling and in the study of the hydrological cycle. Due to the relative scarcity of rainfall data in certain periods and regions for a number of reasons, the use of other precipitation data sources has proven to be feasible. In this sense, the PERSIANN-CDR is one of the alternatives for carrying out studies in places where the observed data are scarce. This research intends to model the rain-flow process with data estimated by this algorithm and to analyze the performance of the simulated flows, as well as the PERSIANN-CDR precipitation estimates for the Piancó River basin (PRB) in the state of Paraíba, and thereby verify the feasibility of using such data for semi-arid regions. The PRB is a subbasin of the Piranhas-Açu River and is located in the southwestern of Paraíba state, inserted in the northeastern semi-arid in the region called "Polígono das Secas". For the modeling, the Soil and Water Assessment Tool - SWAT model was used, which consists of a hydrossedimentological, semi-distributed, continuous and physically based model capable of simulating surface runoff processes, sediment production, etc. in association with GIS. The model was calibrated using the SWAT-CUP software, according to the SUFI-2 algorithm, using 19 parameters and 300 iterations. The calibration period was from 2003 to 2011 and the validation period from 1983 to 1987. Based on the statistical indices of the PERSIANN-CDR data for the PRB, it can be observed that the algorithm is able to represent well the precipitation behavior in monthly and annual scale, but the daily scale was not well represented. In addition, the indices also demonstrated that the algorithm data tend to overestimate the precipitation values observed. Simulated flow rates in the calibration and validation period, both for observed and estimated precipitation data, performed very well, with R² and COE greater than 0.80. The results showed that the data of the PERSIANN-CDR can be used in the region of the PRB in rainfall-flow modeling, being a possible alternative for other regions that have scarce observed data.