Articles | Volume 373
12 May 2016
 | 12 May 2016

Human signatures derived from nighttime lights along the Eastern Alpine river network in Austria and Italy

Serena Ceola, Alberto Montanari, Juraj Parajka, Alberto Viglione, Günter Blöschl, and Francesco Laio

Abstract. Understanding how human settlements and economic activities are distributed with reference to the geographical location of streams and rivers is of fundamental relevance for several issues, such as flood risk management, drought management related to increased water demands by human population, fluvial ecosystem services, water pollution and water exploitation. Besides the spatial distribution, the evolution in time of the human presence constitutes an additional key question. This work aims at understanding and analysing the spatial and temporal evolution of human settlements and associated economic activity, derived from nighttime lights, in the Eastern Alpine region. Nightlights, available at a fine spatial resolution and for a 22-year period, constitute an excellent data base, which allows one to explore in details human signatures. In this experiment, nightlights are associated to five distinct distance-from-river classes. Our results clearly point out an overall enhancement of human presence across the considered distance classes during the last 22 years, though presenting some differences among the study regions. In particular, the river network delineation, by considering different groups of river pixels based on the Strahler order, is found to play a central role in the identification of nightlight spatio-temporal trends.

Short summary
This paper analyses the evolution in space and time of human presence in terms of settlements and associated economic activities along the Eastern Alpine river network in Austria and Italy by using high-resolution satellite images. To this aim, nocturnal artificial luminosity images and the geographical location of streams and rivers are employed. Our results reveal a significant increase of nighttime lights, and thus of human presence.