Discover the "climate footprint" of drought on the world's rivers

Mohammad ALHADDAD

Rivers are of great importance in human history as the first incubators of human civilizations, where rivers have been used as a source of water and food and as a means of movement from prehistory to the present day.

Rivers typically flow from a higher place to a lower elevation.

Like any other ecosystem, rivers are affected by climate conditions, according to a new study by researchers from the University of Bristol published on 16 September in the journal Nature on a clear global climate footprint.

According to ancient studies, rivers have a concave shape (similar to the internal shape of the vessel), but the current study says that this is not the rule for all rivers, but some rivers have a semi-straight longitudinal section.

It is not entirely clear why this discrepancy occurred in the form of river sectors, but the new study may shed some light on it. The new research suggests that the shape of the river is essentially a sign of the region's long-term climate: humid climates have a greater impact on the concave form of river sectors, while arid rivers have slope-like features.

Climate Impact
The study's lead author, Xuan Ann Chen, of the University of Bristol's School of Geosciences, says the findings do not come as a surprise.

"The longitudinal sections of rivers gradually form over tens of thousands to millions of years, so they tell a big story about the history of the region's climate. the river".

Precipitation is controlled by the climate, which in turn affects surface runoff and carving processes, as well as sediment deposition. So far, however, researchers have lacked a systematic data set on river sectors covering all regions of the earth. Chen and his colleagues prepared this database.

Researchers obtained data on river sectors from NASA satellites, including observations of more than 330,000 rivers from around the world. The present study is the first to illustrate the forms of rivers differentiated across different climatic zones.

In humid areas, rivers tend to flow continuously throughout the year, which means that they continuously transport sediment and erode the sides of the river and turn it into a more trapped form until equilibrium is reached.

When the climate becomes drier, rivers cause less erosion, and in arid climates the flow is inconsistent. Using a digital model that mimics the evolution of the river, researchers have been able to support their observations and confirm that climate is the main driver of this change.