The theoretical prediction that the concentration in storage is much greater than the tail of the in-stream breakthrough curve supports recommendations that in-stream measurements should be supplemented with direct measures in the hyporheic zone , In fact, sensitivity limits on in-stream measurements can often make it impossible to distinguish hyporheic exchange from in-stream data, making it essential to obtain direct subsurface measurements.but this can be substantially improved with basic field measurements of stream velocity, average depth and streambed slope, dimensions of major classes of topographic features, and bed hydraulic conductivity, followed by use of published statistical relationships or simple scaling laws .There is considerable interest in using heat as a tracer of hyporheic exchange because fluid temperatures can be measured quickly, easily, and reliably, and natural temperature fluctuations provide a signal in surface water relative to groundwater.

https://www.mdpi.com/2073-4441/15/11/2038