  Surveys open up unbiased discovery space and generate legacy datasets of
long-lasting value. One of the goals of imaging arrays of Cherenkov telescopes
like CTA is to survey areas of the sky for faint very high energy gamma-ray
(VHE) sources, especially sources that would not have drawn attention were it
not for their VHE emission (e.g. the Galactic "dark accelerators"). More than
half the currently known VHE sources are to be found in the Galactic plane.
Using standard techniques, CTA can carry out a survey of the region |l|<60
degrees, |b|<2 degrees in 250 hr (1/4th the available time per year at one
location) down to a uniform sensitivity of 3 mCrab (a "Galactic Plane survey").
CTA could also survey 1/4th of the sky down to a sensitivity of 20 mCrab in 370
hr of observing time (an "all-sky survey"), which complements well the surveys
by the Fermi/LAT at lower energies and extended air shower arrays at higher
energies. Observations in (non-standard) divergent pointing mode may shorten
the "all-sky survey" time to about 100 hr with no loss in survey sensitivity.
We present the scientific rationale for these surveys, their place in the
multi-wavelength context, their possible impact and their feasibility. We find
that the Galactic Plane survey has the potential to detect hundreds of sources.
Implementing such a survey should be a major goal of CTA. Additionally, about a
dozen blazars, or counterparts to Fermi/LAT sources, are expected to be
detected by the all-sky survey, whose prime motivation is the search for
extragalactic "dark accelerators".
