Monitoring and Characterization of Waterlogged Irrigation Fields in the Fincha’a Watershed, Nile Basin of Western Ethiopia

Abstract

Waterlogging is becoming the major threat to the sustainability of cultivated land in Fincha’a Valley Sugar Estate (FVSE). In the present study timely and accurate detection of waterlogged areas through piezometer monitoring and remote sensing indicators, along with their characterization and severity classification has been made. Accordingly, spatial maps of average GWT depth of the last 12 years (2000 to 2012) were produced in a Geographic information system (GIS) (ArcGIS 10.3) environment from 40 groundwater monitoring piezometer data. Results of the study revealed that FVSE, after nearly 20-25 years of irrigation, is experiencing a serious water logging problem. About 324.4 km 2 (75.5%) of the delineated sugarcane plantation fields are severely waterlogged and 105 km 2 (24.5%) are critically waterlogged. The study also revealed that the GWT depth for all selected sugarcane plantation fields is very shallow in summer (0.5m) compared to autumn (0.8m), spring (1.1m) and winter (1m) seasons. The groundwater depth is extremely shallow (<1m below ground) in most of the sugarcane plantation fields throughout the entire season and showed great spatio-seasonal variability. Despite the fact that winter is the driest season, GWT depth of the season kept shallow (1m) which shows factor that control GWT in the study area is not only rainfall. It was identified that GWT depth at FVSE was extremely shallow, at all seasons, exceeding the critical depth (1.5 m) recommended for sugarcane crop.