  The Euclid space telescope will observe ~10^5 strong galaxy-galaxy
gravitational lens events in its wide field imaging survey over around half the
sky, but identifying the gravitational lenses from their observed morphologies
requires solving the difficult problem of reliably separating the lensed
sources from contaminant populations, such as tidal tails, as well as
presenting challenges for spectroscopic follow-up redshift campaigns. Here I
present alternative selection techniques for strong gravitational lenses in
both Euclid and the Square Kilometer Array, exploiting the strong magnification
bias present in the steep end of the Halpha luminosity function and HI mass
function. Around 10^3 strong lensing events are detectable with this method in
the Euclid wide survey. While only ~1% of the total haul of Euclid lenses, this
sample has ~100% reliability, known source redshifts, high signal-to-noise and
a magnification-based selection independent of assumptions of lens morphology.
With the proposed Square Kilometer Array dark energy survey, the numbers of
reliable strong gravitational lenses with source redshifts can reach 10^5.
