Stockholm Junior Water Prize for flood warning system in small streams

Niklas Ruf and Jana Spiller from Germany won the Stockholm Junior Water Prize for their work on an affordable flood warning system for small streams. The winners received their award in August 2025 from Crown Princess Victoria of Sweden at Stockholm City Hall during the World Water Week in Stockholm.

Flooding is an increasing concern worldwide, with more frequent and larger floods affecting communities. Yet on smaller streams, real-time data is often lacking, limiting the possibility of early warnings. Over four years of work, Ruf and Spiller created a network of sensors linked to an app that provides live alerts to both experts and the public. Their system is already being scaled up across their region in consultation with numerous partners.

Scale-up

The Jury noted that we often lack the data needed to provide real-time warnings for smaller streams. “The winners have not only built a functioning system and an app that notifies experts and the public, but they are already working to scale this system across their region in consultation with numerous partners.”

A year of flood-focused excellence

This year, both Water Prizes highlighted flooding: the Stockholm Junior Water Prize went to German students Niklas Ruf and Jana Spiller for their innovative flood warning system, while the Stockholm Water Prize is awarded to Austrian professor Günter Blöschl, the world’s leading flood hydrologist. Together, their work underscores the urgency of addressing flood risks – from local innovations to global science.

Ahrtal floods

Germany was hit by severe floods of smaller streams in 2021. The Ahrtal floods were one of Germany’s most devastating natural disasters in recent history. In Juli of this year an unprecedented amount of rainfall caused the Ahr river, a tributary of the Rhine, to swell dramatically, resulting in catastrophic flooding. During these floods 135 people lost their lives and thousands had to move and live somewhere else.