Abstract

Currently, almost 90% of the global water consumption is caused by the irrigation activities, and more than 40% of the crops are produced under the irrigated conditions. This study is an attempt to estimate the irrigation water requirement (IWR) and crop water requirement (CWR) for some selected crops (Aus, Amon, Boro, Maize, Potato, Bean, Sugarcane, Banana, Tobacco, Wheat, Tomato, Peas, Groundnut, Peeper, Cabbage and Watermelon) in northwestern Bangladesh. Two selected districts (Dinajpur and Rangpur) and an adjacent upazila of Saidpur of Nilphamari district have been taken as a case study area. Necessary meteorological (rainfall, temperature, humidity, wind speed, sunshine hours) and crop data (crop coefficient and crop calendar) have been collected for 30 years period from 1982 to 2012. FAO CROPWATv8.0 has been applied for necessary calculation of CWR and IWR along with the developing of cropping patterns. The FAO Penman-Monteith method is used for estimating the reference evapotranspiration (ET0) by using meteorological data in the framework of CROPWAT model as it regarded as a good estimator for a wide variety of climatic conditions. The analysis indicates that FAO Penman-Monteith suits very well for the study area and can be successfully used. The estimated monthly ET0 demonstrates that evaporative demand from month April to October is very high, which reveals that the water losses are very high in these months. The obtained CWR for the selected crops indicates that maximum water requires for Rice. It also shows that Wheat, Peeper, Sugarcane and Banana exhibits comparatively higher water requirement than the other crops grown in the study area. The study concludes that IWR for month June to September is relatively low but for the other month irrigation requirements are comparatively very high due to the prevailing monsoon season in that period. The study also concludes that total IWR for Rangpur, Dinajpur and Saidpur are 644714, 1004745, and 47474 million lite