Antropoceno: impactos antrópicos de mudanças no uso do solo e operação de reservatórios nas secas do Ceará

Abstract

The state of Ceará is characterized by long periods of rainfall, main factor of its hydrological droughts, associated to fluctuations of temperature anomalies of the surface of the Atlantic and Pacific Oceans. In this region, as a strategy of coexistence drought, small, medium and large reservoirs were built, whose flow regimes are not fully understood. It is proposed analyze the occurrence, evolution of droughts and feedbacks in function of the variability changes in the reservoir network. Several analyzes were used tools and methodologies such as changepoint, Wavelet Transform (TO), hydrologic modeling SMAP (Soil Moisture Accounting Procedure), dry indexes SPI and SRI (Standartized Precipitation Index and Standartized Runoff Index) and PDO and AMO (Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation). The selected study area comprised the hydrological basins of the of Iguatu, which measures the tributaries flowing into the Orós reservoir, and Arneiroz, along the natural runoff of the Iguatu basin. A double effect was identified of drought events, with higher values ​​of evapotranspiration associated with precipitation, a causal relationship between the PDO and AMO indexes and the precipitation of the region, with potential for the development of a precipitation forecasting model from the indexes. It was possible to detect a change in the flow pattern of the Arneiroz basin from 1995, with evidence of impact of reservoir operations on natural possible changes in land use that should be investigated in future studies. THE rainfall-flow modeling has demonstrated that the hypothesis of a homogeneous hydrological basin is not valid. The need for more complex modeling for represent reality faced reinforces that it is essential to reservoirs because they are increasingly necessary for future simulations.