Process · Glossary
Water Cycle
Also: WCI, Water Cycle Index
Definition
How effectively rainfall is captured, held and used by a piece of land. The second of the four ecosystem processes.
The Water Cycle process is about what happens to the water that falls on a piece of land. Total rainfall is given by climate; the ecological question is what fraction of it the land uses (captures, infiltrates, holds, and cycles through plant and soil) versus what runs off, evaporates straight back, or drains uselessly through.
A well-functioning water cycle shows up in many of the indicators an experienced walker reads on the ground: spongy soil, slow puddles, deep root zones, riparian strips that hold their colour into a dry summer, valley bottoms that stay productive in drought. A poor water cycle shows up as runoff scars, capping, gullies, fields that brown a fortnight before their neighbours, ponds and ditches that flash full and then dry hard.
EcoIntel’s Water Cycle Index (WCI) scores this 0–100 per field using satellite indicators of canopy moisture (NDMI), root-zone soil moisture (SMAP), surface temperature relative to site mean (cooling index), topographic wetness, and the temporal stability of vegetation through dry spells.
When WCI is the limiting indicator for a field, the conversation is about infiltration, organic matter, ground cover, and landscape-position interventions (keyline patterns, riparian work, water-harvesting earthworks), not about irrigation.