Belt of fluctuation

{
  "id": "MLC-T-MET-003880",
  "term": "Belt of fluctuation",
  "field": "Meteorology and atmospheric science",
  "definition": "A zone of the subsurface between the highest and lowest levels reached by the water table, within which the soil or rock alternates between saturated and unsaturated as the water table rises and falls with recharge and drought. Its thickness equals the range of water table fluctuation. Below it lies the zone that stays saturated all year, and above it the zone that stays unsaturated.",
  "synonyms": [
    "zone of fluctuation",
    "belt of phreatic fluctuation",
    "belt of water-table fluctuation"
  ],
  "url": "https://mlchart.com/terminology/meteorology/belt-of-fluctuation/"
}