Ndego Project

Irrigation Project at Kayonza District

Information

Client: Kayonza District
Location: Byimana, Ndego
Date: 2019
Catetory: Irrigation
Time: 1 Month

The irrigation system is operated using solar-powered submersible pump sets, with one pump operating as the duty unit and one additional pump maintained as a standby unit.

It is proposed to provide HDPE pipes of 90 mm diameter, PN10 rating, as the main pipeline for conveying water to the reservoir submains. HDPE pipes of 90 mm, 63 mm, and 50 mm diameter, PN10 rating, are provided for the lateral distribution network.

As effective solar radiation is available for approximately 6 hours per day, the irrigation system has been designed to irrigate the crops within this period on an alternate-day schedule.

The operation of both the sprinkler and surface irrigation systems depends entirely on the intensity of solar radiation available at the site. In the event of insufficient solar radiation, irrigation may need to be postponed and completed on the following day.

Paramaters

Area under irrigation: Installed hydrants and surface irrigation covering 20 ha.
Crops: Maize, beans, and bananas.
Water resource: Lake.
Available irrigation time: Maximum 6 hours per day.
Water application methods: Sprinkler and surface systems.
Sprinkler system: Gravity-fed system connected to hydrants; surface irrigation uses hose pipes, and sprinkler nozzles are mounted on pipe headers that are reconnected as needed.
Pump discharge: 150 m³ per day.
Distance between hydrants: 50 m.
Operating pressure: 22 m (2.5 kg/cm²).
Sprinkler spacing and pattern: 22 m × 22 m, square layout.
Precipitation rate: 5.28 mm per hour.

Number of sprinklers and hydrants in 20ha plot

Number of sprinklers and hydrants (20 ha plot)

32 sprinklers are in working condition, 32 sprinklers are in standby (advance) mode, and there are 35 hydrants.

Sprinkler system description

Sprinkler laterals are portable (shiftable/movable) and fixed pipe systems. Quick coupling (QC) HDPE pipes are 63 mm PN6.3, with one end male and the other end female, fitted with metal latch-type clamps for the manually moved system (old system). For the new system, 90 mm PN10 HDPE pipes are used, with 371 m of fixed mainline pipes. Lateral/sub-main lines consist of 90 mm PN10 pipes totaling 1,520 m. Water application pipes are 50 mm PN10, totaling 2,429 m.

Sprinkler sub-main (buried system)

Buried HDPE pipes of 90 mm PN10 are installed underground. Sprinkler hydrants are installed at 24 m intervals along each sub-main, and 10 sprinkler hydrant points are taken off each sub-main.

Sprinkler Hydrant

G.I. valve 2″, HDPE tee 2″, and G.I. 2″ pipes with G.I. 2″ elbows are installed at every 22 m distance along each water application line (HDPE pipes 50 mm PN10). Hydraulic valves (3″) with pressure pilots are installed at each sub-main for on/off control and pressure regulation as required.

Butterfly valve (3″) – flush valve

Butterfly valves of 3″ are installed at the end of each sub-main to flush out the sub-main.

Air release valves at sub-main

PVC air release valves of 2″ are installed on the HDPE mainline of 110 mm.

HDPE main lines

A 110 mm PN10 HDPE pipeline is provided as the feeding main for all sprinkler sub-mains (old system). Additionally, 90 mm PN10 HDPE pipes are used as sub-main lines feeding lateral pipes of 50 mm PN10 (new system).

Non return valve

A C.I. non-return valve of 4″ is provided on the mainline to prevent water hammer and back pressure in both the old and new systems.

Auto quick pressure relief valve

An auto quick pressure relief valve of 2″ is installed after the pump unit to release sudden pressure build-up in the system and prevent pipeline failure (old system). Check valves of HDPE type 3″ are installed on the delivery pipe and connected to both the new and old systems. In addition, 35 pieces of HDPE-type check valves of 2″ are installed on lateral lines feeding all hydrants.

Manual bypass cum pressure relief valve

A manual bypass cum pressure relief valve of 3″ is installed on the two distribution lines after the pump unit to release sudden pressure build-up in the system and prevent pipeline damage.

Filtration unit

A screen filtration unit with a 200 mm diameter casing pipe is installed to filter water from physical impurities such as silt, clay, sand, and other solid particles.