IDENTFYING THE POTENTIAL CAUSES OF WATERLOGGING IN IRRIGATED AGRICULTURE IN THE CASE OF FINCHA SUGARCANE PLANTATION, ETHIOPIA

Abstract

Many sugar estates in Ethiopia have threatening of the sustainability due to extremely shallow groundwater level. For this, Fincha’a sugar Estate is the good example that, waterlogging problem is becoming the major problem on sustainability of current sugar cane production yield. Identifying the potential causes for waterlogging in the area is very crucial to make best decision about the field water management system. The aim of this study is to investigate the potential causes of waterlogging at Fincha Sugar cane Plantation using spatiotemporal analysis. The spatial dependence of the groundwater level indicated that the estimated groundwater level modeled with semivariogram models with a nugget effect. In this study, the analysis of annual and seasonal groundwater level trends of the year 2000 to 2014 indicates that most portion of the area has been affected by waterlogging problem and there is steadily rising trend of groundwater level throughout the time. The rising of annual maximum ground water level varies from 15cm to 280 cm above the ground surface whilst the annual minimum ground water level varies from 240 to 410cm below ground surface. The groundwater level increases as compare to belg season due to maximum rainfall contributions to the rise of groundwater level in Kiremt season. The fluctuations of groundwater levels were also different in magnitude from one piezometer to other piezometer due to different factors, like rainfall in the area, soil type, slope, drainage condition and field water management system. Based on this, development of shallow groundwater level in the area, formation of unproductive land and swap area could be common phenomenon of the estate. This could be affecting the soil productivity and the environmental wellbeing of community living in the area. On the other hand, there is increased demands for further expansion of cultivation areas by 85 ha/year on average with intention of replacing unproductive lands which were demoted due to water logging problems. Conversely, the sugar cane production yield decreased by 63 qt/year. As a recommendation, without proper management of the shallow groundwater table in the area, development of new irrigation commands could not be feasible to optimize production yield of the scheme. The surface and subsurface drainage system should be installed for proper field water management system and future improvement of sustainable production.