Improving Appropriate Technologies for Small Scale Irrigation in Semi-arid Areas: a Case Study on Mabote District of Mozambique

Abstract

Chapter II addresses the use of earth dams as an appropriate technology for rainwater harvesting for small scale irrigation. The effectiveness of this technology in the Mabote district has been hindered by incorrect site selection resulting in non operational structures. This chapter focuses in the identification of suitable areas for the installation of earth dams using geographic information system (GIS) techniques. GIS was also used to evaluate rainwater harvesting in general, including small scale, in-situ applications. Chapter III addresses the use of human powered pumps as an appropriate technology for small scale irrigation. Failure of human powered pumps has been reported in the Mabote district, where farmers had difficulties in maintaining such devices. Therefore, in this study, two human powered pumps were submitted to continuous operation and their durability was evaluated. GIS modeling showed that less than 1% of the Mabote district area is highly suitable for the installation of earth dams. Therefore, correct site selection, using reference maps produced herein, would reduce losses of resources due to ineffective dam installation. However, the results showed a comparatively large potential (43% of the district area) for the use of in-situ water harvesting techniques. A treadle pump and a rower pump were evaluated, where the last performed better. Pump durability was influenced by the moving parts, where the pistons are the main concern followed by the pulley assembly. Routine maintenance is recommended, which should not exceed 200-400 hours of operation. The author suggests that human powered pump manufactures include spares of the listed parts in the `new pump kit'. Human powered pump designers are also encouraged to improve designs to make access to parts easier, during maintenance operations.