Gravity-Fed Drip Irrigation from a Raised Tank Without a Pump: A Low-Head Design for a 0.1 Hectare Plot, Its Water Budget and Its Uniformity Limits

Drip kits assume a pressurised supply, but a village tank on a stand delivers only two to three metres of head. This paper designs a drip system that runs on tank head alone, with no pump, for a 0.1 hectare tomato plot (25 m by 40 m). A 5,000 L tank whose base sits 2.00 m above the field feeds 20 laterals of 40 m in four zones through 13.6 mm internal-diameter lateral pipe with emitters every 0.40 m. SIMULATED, NOT MEASURED; nothing was built or field-tested. At the design inlet head of 2.50 m the mean emitter discharge is 1.935 L/h and emission uniformity is 98.84 percent. Mid-season tomato demand of 5.98 mm/day requires 6,644 L/day gross, in 1.72 hours per zone, with the tank refilled twice a day. The design holds its 85 percent uniformity threshold up to 100 m lateral length on flat ground and up to a 2.4 percent uphill slope at 40 m; it fails at 105 m on the flat and at a 2.5 percent uphill slope, and the slope limit tightens to 1.7 percent at a low tank.