Water
Parameters
Annual renewable yield per square meter
450
Annual renewable-yield proxy in liters per square meter of map land. One L/m² is one millimeter of water depth, so 450 represents 450 mm/year: the upper end of the USGS 325-500 mm/year recharge class for glaciated parts of the conterminous US. Real sustainable yield cannot be inferred from recharge alone; pumping can also deplete storage and capture groundwater that would have discharged to streams. Microlandia deliberately collapses those site-specific effects into one fixed map budget. The value is multiplied by physical land area and the scenario multiplier when GROUNDWATER_BUDGET is first created, then frozen so later balance changes do not rewrite an existing city’s limit.
Source: USGS Scientific Investigations Report 2018-5091 — estimated groundwater recharge
Daily crop water need per square meter
5
Irrigation one square metre of staffed farmland draws per sim day. One L/m² is one millimeter of water depth, so 5 is 5 mm/day and a 10 m tile draws 500 L. It stands for a median crop, not any particular one: FAO’s indicative seasonal crop water needs (Table 14) divided by each crop’s growing period put all 21 crops between 3.2 and 6.3 mm/day with a median of 4.5, rounded up to 5, which is also the mid-season need of a field crop in a sub-humid, moderate climate (Table 5: ETo 5-6 mm/day × mid-season Kc ≈ 1). The sim has no off-season and no rain on fields, so the rate is charged every day a farm is staffed and reads as a fully irrigated, year-round operation; a temperate farm that irrigates 100-150 days a year draws about a third of this over the year. Water is priced by the land a farm covers; its jobs and crates are still those of a much larger farm, so per crate of food the draw is now well under real irrigation footprints. When a tile knows what it grows this becomes a per-crop table: grapes on drip sit under the median, livestock several times over it (Mekonnen & Hoekstra 2011).
Large scenario multiplier
2
Bonus multiplier applied to the city-wide groundwater cap on the large scenario (Campara). Campara sits over an unusually deep, well-recharged aquifer that roughly doubles the effective annual yield versus the same land area elsewhere, the map’s signature advantage. 2× is a deliberately gamey round number rather than a calibrated coefficient: real aquifer recharge varies by an order of magnitude with geology and climate (USGS, Streamflow and the Hydrologic Cycle). Classic and river scenarios use a 1× multiplier (no bonus).
Source: USGS — Streamflow and the Hydrologic Cycle (river-aquifer exchange)