With advancements, remote sensing technology could become useful for managing NPRs. Remote sensing has the potential to extract more hydrological information that currently cannot be extracted using conventional in-situ measurement methods. 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 data are successfully used for monitoring wetlands and lakes, but little is known about their capabilities for monitoring pools along NPRs. Furthermore, this paper provides an overview of the potential and limitations of using remote sensing data for monitoring NPRs. This review paper examines challenges for collecting data on these hydrological attributes of NPRs using current methods. The current understanding and methods used for monitoring NPRs are mostly derived from perennial rivers perspective. 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. Some rivers that were previously classified as perennial have evolved to be NPRs in response to climate change and socio-economic uses. Non-perennial rivers (NPRs) account for more than 50% of the world’s river network and their occurrence is expanding. It consists of 11 phases containing 29 activities. DRIFT-ARID, reported on here, is an adaptation of the DRIFT approach to begin addressing these and other issues. When applied to the semi-permanent Mokolo River, challenges particular to, or accentuated by, non-perennial rivers included the reliable simulation of hydrological data, the extent of acceptable extrapolation of data, difficulties in predicting surface-water connectivity along the river, and the location and resilience of pools, as well as whether it was possible to identify a reference (natural) condition. DRIFT is an EWR method for perennial (or near-perennial) rivers that has been developed in South Africa over the past two decades and is now widely applied nationally and internationally. Current EWR assessments require hydrological and other data that may not be available for such rivers and some adaptation in the methods used seems necessary. Despite non-perennial rivers comprising about 30–50% of the world's freshwater systems, data on their hydrology, biota and ecological functioning are sparse. Environmental water requirement (EWR) assessment methods, for ascertaining how much water should be retained in rivers to sustain ecological functioning and desired levels of biodiversity, have mostly been developed for perennial rivers.
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