| Highly productive regional aquifers – T (10–100) m2/d, q (1–10) l/s.m, Q (5–25) l/s for wells and/or springs – or locally extremely productive aquifers in which flow is mainly intergranular |
| Moderately productive regional aquifers – T (1–10] m2/d, q (0.01–1] l/s.m, Q (0.5–5] l/s for wells and/or springs – or locally highly productive aquifers in which flow is mainly intergranular |
| Highly productive regional aquifers – T (10–100) m2/d, q (1–10) l/s.m, Q (5–25) l/s for wells and/or springs – or locally extremely productive aquifers in which flow is mainly through regularly developed system of fissures of volcanic and sedimentary rocks and karst openings |
| Moderately productive regional aquifers – T (1–10] m2/d, q (0.01–1] l/s.m, Q (0.5–5] l/s for wells and/or springs – or locally highly productive aquifers in which flow is mainly through regularly developed system of fissures and joints of sedimentary and volcanic rocks |
| Low productive fissured regional aquifers – T [0.1–1] m2/d, q [0.001–0.01] l/s.m, Q [0.05–0.5] l/s for wells and/or springs – in which flow is mainly developed in irregular system of fissures and weathered mantle of metamorphic and igneous rocks – hard rocks |
| Aquitards – Minor aquifers with local and limited groundwater resources – T < 0.1 m2/d, q < 0.001 l/s.m, Q < 0.05 l/s |
| Aquicludes formation with essentially no groundwater resources (aquifuge, solid rocks/blind rocks) |
| Moderately productive regional aquifers – T (1–10) m2/d, q (0.01–1) l/s.m, Q (0.5–5) l/s for wells and/or springs – or locally highly productive aquifers with alternating layers of fissured and intergranular permeability (aquifers with mixed permeability) |