MSWEP como fonte alternativa de dados de precipitação para modelagem hidrológica com o SWAT em bacias hidrográficas com escassez de dados

Abstract

As precipitation is one of the most important elements in the hydrological cycle, obtaining data that accurately represents the spatial and temporal variability of precipitation in a given area, becomes a relevant step. However, in developing countries it is common to find a rainfall network with low density, many gaps, short time series and with questionable quality, which makes the use of these data a limiting factor for many studies. Thus, it is necessary in many cases to use alternative sources for rainfall data measurement, such as those from satellites. In this sense, the Multi-Source Weighted-Esemble Precipitation product (MSWEP v.2) has stood out, due to its global coverage, refined spatial and temporal resolution, showing good results also in hydrological modeling. In this work, MSWEP v.2 precipitation product was used as an alternative source of precipitation data in the Guaporé-RS River watershed, a watershed characterized by a scarce rainfall network. The quality of precipitation estimated by MSWEP v.2, was evaluated in comparison with the ground-based rainfall data, and with alternatives to increase the representativeness of the precipitation series in the watershed, such as the extension of the series, reduction of the number of gaps, increase in rainfall network density, and improvements in the precipitation spatialization process. For this, alternative scenarios that incorporate measures from the MSWEP v.2 product, or use the product measured entirely, were compared with a reference scenario that used the available ground-based rainfall network. The evaluated alternatives proved to be a good strategy, since the problems found in the existing rainfall network were effectively mitigated, obtaining long series, without gaps and with high spatial density. After the viability of using MSWEP data was proven, the strategies for assembling alternative precipitation scenarios were used as an input database in the SWAT model (Soil & Water Assessment Tool) and applied in the Guaporé-RS River watershed, to assess how this measurement improves the quality of hydrological modeling. It was found that with alternative precipitation data based on MSWEP, modeling results obtained were very similar to those resulting from ground-based rainfall, however, with an improvement in the simulation low flow periods. From the studies carried out, it was found that the precipitation product of MSWEP v.2 could be used as an alternative to replace, or complement, the rainfall network of the watershed with conditions of low quality or nonexistence, as it allowed to increase the density and the quality of the ground-based rainfall network, reducing the uncertainties in hydrological modeling.