Using satellite data to expand understanding of river flow dynamics

Using satellite data to expand understanding of river flow dynamics
by Simon Mansfield
Sydney, Australia (SPX) Sep 30, 2024

Since 1953, an equation known as at-a-station hydraulic geometry (AHG) has been used to explain the relationship between river width, depth, velocity, and river discharge - the volume of water flowing through a river channel. AHG plays a key role in hydraulic engineering, flood prediction, and navigation. However, traditional methods for studying AHG through field research offer limited sample sizes and geographic scope, which do not fully capture the complexity of the factors affecting river discharge.

A new study, published in the 'Journal of Remote Sensing', explores the use of satellite data to enhance the understanding of AHG by incorporating remote sensing technology. The researchers aimed to overcome the limitations of field-based studies by using satellite imagery to track river changes globally.

"Understanding the response of width to changing discharge in different rivers is crucial for hydraulic modeling and river management. However, previous research is limited in spatiotemporal coverage by field measurements and only offers a fragmentary understanding in confined areas. This study introduces new data sources - multi-temporal river width data derived from Landsat and global discharge observations built upon years of progresses by the community - to provide a more comprehensive scope," said Zimin Yuan, a researcher at the Institute of Remote Sensing and GIS at Peking University in Beijing.

The team utilized a variety of datasets spanning from 1979 to 2020 and compared their results against Google Maps images to verify the data. This effort resulted in the creation of a global AHG dataset. The researchers identified 18 variables linked to AHG, which they grouped into six categories: hydrology, physiography, climate, land cover, geology, and human influences. They also considered how different river patterns - such as meandering, braided, or straight - affect AHG.

The study found that a 1% increase in river discharge typically leads to a 0.2% increase in river width, though this relationship is affected by factors such as soil composition, forest coverage, and human activities. For instance, rivers with cohesive soil and high forest cover showed less variation in width in response to discharge changes.

"We found that a 1% increase in discharge will result in a median of 0.2% increase in river width worldwide. Reaches characterized by cohesive soil, high forest coverage, and less human influences typically exhibit weaker response of width to discharge changes. River planform patterns are correlated with width response, and the relationship can be well correlated by climatic conditions," Yuan added.

Looking ahead, the researchers plan to expand their work by exploring the impact of river depth on discharge using remote sensing technology and aim to reconstruct global river channel shapes using the data collected in this and future studies.

The research was supported by the National Natural Science Foundation of China, the Beijing Nova Program, and the Yunnan Provincial Science and Technology Project at Southwest United Graduate School.

Research Report:Revisiting At-a-Station Hydraulic Geometry Using Discharge Observations and Satellite-Derived River Widths