Definition:Mean annual deep drainage. This is the amount of water draining
below the root zone.Interpretation:Significant deep drainage is confined to
irrigation areas, and wet areas where rainfall exceeds potential evaporation
at least for some months of the year: the southeast (including Tasmania), over
the eastern ranges and in the north.Deep drainage has a broadly similar
pattern to runoff, though with added variability through the influence of soil
texture.Notes: rule-based method is used to estimate the rate of deep
drainage on the basis of soil texture, with modification to account for
cultivation and irrigation.For this quantity, results are given for the aBASEa
(pre-1788) and aAGRICa (present day) conditions.The aAGRICa case includes
current agricultural inputs of water from irrigation.FWLeach.Agric a Mean
annual deep drainage (mm y-1) in the aAGRICa (present day)
scenarioFWLeach.Base a Mean annual deep drainage (mm y-1) in the aBASEa
(pre-1788) scenarioData is in geographics and GDA94.
See [further metadata](http://data.daff.gov.au/anrdl/metadata_files/pa_ddab_r9cl
__02411a01.xml) for more detail.