Agricultural water and energy use in the Senegal River Valley

Abstract:

Assessment of the productivity of irrigation water is important measuring the performance of irrigation schemes especially in water scarce areas. Equally important for performance is the energy cost of providing water for irrigation. Sahel irrigation schemes are dependent on pumping water from rivers into a network of gravity operated channels. In the Senegal River valley in Senegal the cost of pumping water and for irrigation has been estimated to be 20-25% of total rice production costs. Irrigation schemes in the valley are characterized by low water productivity. We analysed rice production, irrigation water use and energy use for supplying irrigation water at Pont Gendarme, Ndiawar and Ngallenka MCA irrigation schemes in the Senegal River valley. For the 2013 rainfall season the mean yield ranged between 6 and 8t ha^-1. Dry season yield ranged between 1.7 and 6.8t ha^-1. Energy use for irrigation in the Ndiawar irrigation scheme was 8kg MJ^-1 and 6.4kg MJ^-1 in the 2013 and 2014 rainfall seasons respectively. In 2014 (rainfall season) energy productivity of irrigation water was 8.5, 8.0 and 16.4 kg MJ^-1 at Ngallenka MCA, Ndiawar and Pont Gendarme respectively. Dry season (2014) energy productivity at Ndiawar and Pont Gendarme was 3.4 and 11.2kg MJ-1 respectively. Productivity of irrigation water was similar for all schemes (0.37kg m^-3 at Pont Gendarme, 0.42kg m^-3 at Ngallenka MCA, and 0.41kg m^-3 Ndiawar). Energy use for the supply of irrigation water in the rainfall season ranged from 403 to 1,002MJ ha^-1. Dry season irrigation energy use was 589MJ ha^-1 Pont Gendarme and 331MJ ha^-1 at Ndiawar. Reducing water use in these schemes through better water management will result in lower production costs and increased margins for the farmers. The observations from 2013 – 2014 highlight the importance of using both water and energy productivity to assess performance of irrigation schemes.