Towards the continuous monitoring of the extreme events through satellite radar altimetry observations

Abstract

Changes in the frequency and magnitude of extreme hydrological events (floods and droughts) are one of the most significance consequences of the climate change and their monitoring is therefore essential in many fields. However, the number of the global in situ discharge measurements has been declining since the eighties and the global supply of available data is often restricted in many parts of world. All these reasons have fostered in the last decades the exploitation of new technologies, such as satellite data, in the estimation of river discharge. In this study, satellite altimetry water level data are used to set-up a consistent and up-to-date river discharge dataset by means of rating curves for different sites across the world. Long continuous river discharge time series so obtained are used to perform a trend analysis on extreme hydrological events. Specifically, peak-over threshold values are extracted from the discharge time series, as proxy variables of independent extreme events, and the trend analysis is then carried out to identify changes in the magnitude of extreme events.The analysis permits to identify areas of the world prone to floods, like the West Africa, or drought so that appropriate actions for disaster risk mitigation and continuous improvement in disaster preparedness, response and recovery practices can be adopted.