灌漑・排水システム工学

Comparative Analysis of Water Saving Techniques for Irrigating More Land with Less Water in Nguruman Scheme, Kenya: Design Principles and Practices

Abstract

Muya EM, Sijali IV, Radiro M and Okoth PFZ

A review of the past studies has demonstrated that rehabilitation of an irrigation scheme through infrastructural development and agricultural production value chains alone will not sustain the targeted agricultural production unless scientific principles, aimed at enhanced water use efficiency are incorporated in the development agenda to avoid future water losses and shortages. In Nguruman, the available water supply has the capacity to meet irrigation water requirement of 5,332,809 m3 to irrigate the targeted 800 ha per year. However, with increasing number of farmers engaging in irrigated agriculture, more area is expected to be brought under irrigation to meet the increasing food demands, thus requiring significant amount of water savings through enhanced water use efficiency. For this reason, analysis and review of the irrigation design challenges, operational realities and technological options for improved water use efficiency was carried out in terms of the quantities of water saved and additional area that can be irrigated by each of the technological options considered in relation to the farmers’ irrigation methods. The technological options reviewed were: drip plus digital instruments; drip plus analog instruments; sprinkler plus digital instruments; sprinkler plus analog instruments and farmers’ irrigation method. It was deduced from literature review that drip plus digital instruments, drip plus analog instruments, sprinkler plus digital instruments and sprinkler plus analog instruments could save 465,600, 433,132, 365,520 and 323,637 m3 of irrigation water respectively relative to the farmers’ method. The additional area to be irrigated using water saved from drip plus digital instrument, drip plus analog instrument, sprinkler plus digital instrument and sprinkler plus analog instrument was 146.3, 136.7, 115.4 and 104.1 ha respectively. Since drip irrigation plus digital instrument had the highest water saving potential, it was identified as the most appropriate technology to be used tested, validated and applied to irrigate more land with less water in Nguruman Irrigation Scheme.