Remotely sensed applications in monitoring the spatio-temporal dynamics of pools and flows along non-perennial rivers: a review

Non-perennial rivers (NPRs) account for more than 50% of the world's river network and their occurrence is expanding. Some rivers that were previously classified as perennial have evolved to be NPRs in response to climate change and socio-economic uses. There is inadequate understanding of the spatio-temporal dynamics of flows and pools along these rivers due to lack of data, as a priority of river monitoring has been placed on perennial rivers. The current understanding and methods used for monitoring NPRs are mostly derived from perennial rivers perspective. This review paper examines challenges for collecting data on these hydrological attributes of NPRs using current methods. Furthermore, this paper provides an overview of the potential and limitations of using remote sensing data for monitoring NPRs. Remote sensing data are successfully used for monitoring wetlands and lakes, but little is known about their capabilities for monitoring pools along NPRs. Remote sensing has also been successfully used to estimate discharge of large perennial rivers; however, this has not been fully explored for NPRs. Remote sensing has the potential to extract more hydrological information that currently cannot be extracted using conventional in-situ measurement methods. With advancements, remote sensing technology could become useful for managing NPRs.