CROPWAT and GIS tools for AEU based Irrigation Demand Estimation of the Chalakudy River Diversion Scheme (CRDS) command area

E.B Gilsha Bai, K.P Rema, Asha Joseph, Mini Abraham, Anu Varughese


Irrigation is one of the major factors affecting the productivity of crops. Planning of irrigation schemes and efficiency assessment of the existing schemes require an accurate estimation of irrigation demand. Cropping patterns and their areal extent determine the quantity of irrigation water required. Crops and cropping pattern of a place and its water requirement mainly depends on the agroecological situation of the area. Hence, estimating irrigation demand considering parametric variations of agro-ecological units is necessary for planning irrigation. However, estimation of the cropped area and cropping patterns, which decides the capacity of irrigation schemes, is tedious without using GIS tools. The present study conducted in the command area of the Chalakudy River Diversion Scheme (CRDS) utilized the Image processing software ERDAS Imagine for the preparation of land use/ land cover map and ArcGIS for other spatial analyses of the maps. There were seven different agro-ecological units in the study area. The irrigation requirements of the crops/cropping pattern in these agro-ecological units were estimated using the CROPWAT 8.0 software developed by FAO. The results indicated that the water requirement of crops, especially that of paddy, varies with the agro-ecological unit. The total irrigation demand of different agro-ecological units was found to be proportional to the cropped area, but the seasonal variations in irrigation demand were similar in all agro-ecological units of the study area. The estimated average annual net irrigation requirement of the CRDS command area was obtained as 46.90 Mm3 . The average annual water release through the canal system was found deficient to meet this demand due to the lack of management and maintenance of the canal system.


Agro-ecological unit; ArcGIS; Chalakudy River Diversion Scheme; CROPWAT; ERDAS Imagine; Irrigation requirement. ;

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