ASSESSMENT AND MAPPING OF GROUNDWATER LEVEL AT SUGARCANE PLANTATION OF WONJI SHOA SUGAR FACTORY

Abstract

Waterlogging has significantly affected the cane agriculture at WSSE, which is the oldest sugarcane plantation in the country established for commercial sugar production. A study was undertaken to assess the temporal pattern and spatial distribution of GWT in the estate, to evaluate the effect of rehabilitation works on the level and distribution of GWT and to map the GW distribution in the cane plantation. GWT data was collected in representative sites throughout the cane plantation. ArcGIS (ver. 9.2) of ESRI was used for mapping the spatial distribution of GW in the cane plantation of the estate. The study indicated that 14% and 60% of the cane area were in most severely waterlogged and critically waterlogged condition, respectively. The study also revealed that deep percolation from reservoirs and seepage from big unlined supply canals had been the most contributing factors for the development of shallow GWT in the cane plantation. Cane fields near deep drainage channels had showed consistently lower GW levels indicating that improved drainage helps to lower the level of GW in the cane plantation. On the other hand, lack of proper maintenance of the field drainage system and lack of proper infield irrigation water management are identified to be the causes for the increase in GW level in the area affected by severe waterlogging. Hence, it is recommended to practice improved irrigation management in the cane plantation by taking into account the contribution of GW to crop water requirement and to undertake regular and proper maintenance of the infield and main drainage channels. It is also recommended to undertake regular monitoring of the GW level in the cane plantation to establish the temporal trend in GW level taking into consideration of all contributing factors for the rise in GW level in the cane plantation and establish a critical GW level for sustainable sugarcane production in the estate.