Effect of different cropping pattern on groundwater of naogaon district using mathematical modelling

Abstract

Bangladesh is an agricultural based and densely populated country of south Asia. It relies heavily on the domestic crop production. Her economy rolls upon the agricultural production across the country. Naogaon district located in the north west region of the country lacks industrialization. Crop production is the main profession of the people which is rice based. Dry period rice covers the maximum area and needs higher irrigation. Surface water sources like rivers are limited and cannot meet the demand of irrigation. For these reasons the irrigation is dependent on groundwater. To meet the irrigation demand in dry period huge numbers of STW and DTW are used. Due to over abstraction and less in recharge the extent of area with lowered groundwater level is increasing. Therefore, in this study the effect of change in cropping pattern with low water consuming crop has been investigated to maintain sustainability of the agriculture in Naogaon district. In this study MIKE SHE model has been simulated from year 2002 to 2015. The model has been calibrated for the period 2011 to 2014 and validated for 2015. An analysis of temporal and spatial variation of groundwater level indicates that in this district dry period area coverage of groundwater level of 0 to -7 m has been reduced from forty seven percent in year 2002 to twenty six percent in year 2015. In year 2002, groundwater level in this upazila Patnitola, Niamatpur was -7 to -14 m for ninety percent which also indicates stress condition. In year 2015, groundwater level in this two upazilas was bellow -20m. Groundwater level in Mohadevpur upazila was within -7 to -14 m for 50% area in 2002. But in year 2015 groundwater level in this upazila reduced significantly and went bellow -20 m for ninety percent area. In order to improve the groundwater condition in Naogaon district three different cropping pattern such as (50% boro & 50% wheat) [Option-1], (100% wheat) [Option-2] and (50% boro & 50% vegetable) [Option-3] have been investigated by simulating groundwater level using MIKE SHE model from year 2011 to 2015. The result shows that cultivating wheat instead of Boro improve the groundwater level significantly in year 2015. This groundwater level is almost same as the dry period groundwater level in 2005.