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Accueil du site → Doctorat → États-Unis → 1988 → Irrigation water management in small systems of Niger, West Africa

Cornell University (1988)

Irrigation water management in small systems of Niger, West Africa

Norman, William Ray

Titre : Irrigation water management in small systems of Niger, West Africa

Auteur : Norman, William Ray

Université de soutenance : Cornell University

Grade : Doctor of Philosophy (PhD) 1988

The record of state-sponsored irrigation development in the West African Sahel over the past several decades has largely been poor. This is particularly true in the case of large-scale irrigation development which has constituted the majority of lands newly developed for irrigation. This study was thus initiated to examine water management in small systems in the Sahelian region which appeared successful and to have maintained productivity for a considerable time. Two reservoir systems were studied in the Maggia Valley of south-central Niger. These systems operate under joint management, shared between the parastatal irrigation agency, ONAHA, and the local farmer cooperative. Research was focused primarily on the small 20 year-old, 65 hectare Moullela system, while a more moderate amount of research for comparative purposes was conducted at the much larger and newer 3.5 year-old, 250 hectare system at Galmi. Water use was examined in both systems on the main-system level (primary canal delivery), the GMP/sector level (secondary canal delivery), and on the parcel level. GMPs and parcels were selected and monitored at head, middle, and tail-end locations in each system. Issues related to local traditional irrigation practices and expertise, land tenure and use, indirect system benefits, and economics were addressed during the study. It was found that water is well managed at the Moullela system. Losses between the reservoir and the parcel were about 10 percent, while efficiencies were slightly less. Highest losses at both systems occurred as subsurface drainage resulting from excess applications in the parcel. At Moullela an effective and functional balance appears to have been achieved between state and farmer roles in system management. The Moullela system results in farmer satisfaction and sustained benefits, with an internal rate of return over its 20 year life of 21 percent (to the farmer) and 0 percent (to the state). Operation and maintenance costs are covered annually. Other indirect benefits, such as conjunctive groundwater use for irrigation and recessional agriculture in the reservoir, has served to enhance the system’s productivity. The Moullela system demonstrates that small systems may serve as one of a number of viable options for agricultural intensification and nutritional sustainability in sub-Saharan Africa.

Mots clés : Agricultural chemicals, Applied sciences, Pure sciences, Agricultural engineering

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