2021 年 26 巻 2 号 p. 43-50
This study investigated and assessed the actual management of irrigation at the small-scale irrigation development site in northern area of Zambia and estimated the conveyance efficiency and the application efficiency as the basic specifications of the irrigation planning. Irrigation water is taken from the stream by the weir and directly distributed to the irrigated fields through the main earthen canal. Discharge measurements in earthen canal had been conducted at three locations, namely intake, middle stream and downstream, and the conveyance efficiency per km was calculated to be 80%/km. Regarding irrigation management, irrigation period, amount of irrigation, irrigation frequency and irrigated area for each section recorded by farmers have been assessed. Although excessive water had been irrigated by a few farmers, proper irrigation management had been done by most of farmers. In addition, evapotranspiration has been estimated by the penman method from measured meteorological data, and the application efficiency was calculated using evapotranspiration and average daily amount of irrigation. Application efficiency was estimated to be 50% from April to July when the evapotranspiration was low and 80% from August to October when the evapotranspiration was high.