La Ni？a Impacts on Austral Summer Extremely High-Streamflow Events of the Paranaíba River in Brazil

The extremely high-streamflow events of the Paranaíba River basin are found to be associated with La Ni？a phenomenon during December–February (DJF). Extreme events are identified based on their persistent flow for seven days and more after taking retention time into consideration. The extremely high-streamflow events are associated with the La Ni？a years; 80% of the high-streamflow events have occurred during La Ni？a phases. Therefore, a very-significant 80% and above correspondence of the La Ni？a events and the seasonal streamflow anomalies are found in DJF. Although climate variations have direct relationship with the rainfall, streamflow variations are considered as the surrogates to rainfalls. However, apart from climate variations the anthropogenic and land-use changes also influence streamflow variations. In this study, we have applied multivelocity TOPMODEL approach and residual trend analysis to examine the impact of land-use to the streamflow at the Fazenda Santa Maria gauge stations. However, the model residual trend analysis of the TOPMODEL approach cannot quantify the extent of land-use impact. Thus, La Ni？a phase is important components to understand and predict the streamflow variations in the Paranaíba River basin. 1. Introduction Streamflow plays a major role in the livelihood of the people in a river catchment. Hence, the scientific analysis of streamflow is very essential for the present and future generations. The influences of climate variability on the streamflows have been studied by Sahu et al., [1–3] in their previous studies of Indonesia, and found very good correlation of the impact of climate variability on the streamflow. Several studies performed on southeastern South America have used streamflows as indicators of climatic variability from the interannual to the seasonal scale [4–6]. It is stated that the climate variability and changes can be studied by analyzing river flows as a surrogate to rainfall, under the assumption that changes in the rainfall are reflected and likely amplified in streamflows [7, 8]. Moreover, it is easier to detect a change in streamflow than to directly observe changes in the basic climatic variables [9]. The Paranaíba River flows in the Rio Paranaíba of Brazil and in the state of Minas Gerais of the Mata da Corda Mountains (19°13′21′′S and 46°10′28′′W). The river is flowing at an altitude of 1,148 meters. The length of the river is approximately 1,000 kilometers. The Paranaíba and the Grande River both confluence and then form the second largest Parana River of Brazil, at the point to make the