Estimate hours to apply a target depth with drip tape, plus total zone flow in GPM — from tape rating, length, and row spacing.
Use this for vegetable beds or row crops on drip tape when the label gives gpm per 100 ft (or you convert from gph emitters) and you know bed/row spacing and how many inches you want to apply.
Long run times on clay may need cycle-and-soak. Well capacity must exceed zone GPM.
Zone GPM scales with tape length. Gallons needed use the wetted area (or row spacing × length if wetted width blank). Hours = gallons ÷ (GPM × 60).
zone_gpm = (tape_ft ÷ 100) × gpm_per_100ft
area_ft² = tape_ft × wetted_width_ft
gallons = area_ft² × inches × 0.623
hours = gallons ÷ (zone_gpm × 60)
0.623 converts inch·ft² to gallons. If wetted width is empty, area ≈ tape_ft × row_spacing.
0.45 gpm/100 ft, 7,260 ft tape, 2.5 ft wetted width, 1 in target:
Zone ≈ 32.7 gpm · area ≈ 18,150 ft² · ≈ 11,307 gal · time ≈ 5.8 hours.
Assumptions: tape at rated pressure; uniform emission; precipitation treated as average over the wetted strip.
Limits: does not model distribution uniformity, filtration losses, or slope. Split long sets on heavy soils.
Responsibility: match crop ET and soil intake — local Extension schedules override generic inches.
Convert: gpm/100 ft ≈ (gph_per_emitter × emitters_per_100_ft) ÷ 60.
Row spacing places the tape. Wetted width is how wide each tape actually wets — often narrower than row spacing on wide beds.
Split into multiple zones so each zone’s GPM stays under supply.