IDENTIFICATION AND ESTIMATION OF WATER LOSSES ALONG THE HEAD REACH OF THE MAIN CANAL OF THE BAGUINÉDA IRRIGATION SCHEME (OPIB, MALI): THE CASE OF UNAUTHORIZED OFFTAKES

The Baguinéda Irrigated Perimeter Office (OPIB), located 35 km east of Bamako on the right bank of the Niger River, operates a 3,000-ha gravity irrigation scheme. In a context of climate change and low river floods, this peri-urban scheme suffers from numerous unauthorized connections (pipes and motor pumps) along the head reach of its main canal, a 10-km section with no official offtake. These withdrawals reduce network efficiency and aggravate the water deficit during the dry season.
This study aims to identify these offtakes, estimate their discharges, and assess their impact on water delivery to the scheme. 
The installations were inventoried in the field using a Garmin GPS receiver and a survey form, and then mapped in QGIS. Discharges were estimated from manufacturer data for the motor pumps and from the pipe (submerged-orifice) equation for the direct connections.
Eighty-nine (89) unauthorized offtakes were identified (62 pipes and 27 motor pumps), with diameters ranging from 63 to 300 mm, for an estimated total withdrawal of 1.783 m³/s. Relative to the main canal discharge (10.878 m³/s), this withdrawal represents a loss of 16.4%, with a severe impact on the dry season.
Measures are proposed to reduce these losses, improve network efficiency, and strengthen OPIB’s own revenue by formalizing these offtakes through a water fee.