Estimation of Irrigation Water Demand in Paddy Fields of Northwestern Bangladesh Using Remote Sensing and GIS
Shahid, S
Friedrich-Schiller-Universitšt Jena

Paddy is the major crop in Bangladesh and grown in nearly 80% of the cultivated land. Paddy agriculture in the Northwestern Districts of Bangladesh relies heavily on irrigation. Scarcity of water for irrigation during dry season in the recent years has hampered the rice production in the area. Estimation of the agricultural water deand is therefore essential for water resources development and planning of Northwestern Bangladesh. However, lack of available data is a major problem in accurate estimation of agricultural water demand in Bangladesh. In the present paper, satellite images, soil information, and long-term average meteorological data are used to estimate the irrigation water demand in an area of 10 000 km2 of Northwestern Bangladesh. Net irrigation water requirement is calculated from reference evapotranspiration, crop coefficients, effective precipitation and amount of water needed for land preparation and seepage lose. ASTER images are synthesized for extracting the extents of paddy fields. Penman-Monteith method is used to calculate reference evapotranspiration from climatic data. The spatial distribution of crop factor is calculated from crop height, canopy variables and Leaf Area Index derived from MODIS data. Soil information is used to estimate the spatial distribution of water requirement for land preparation and seepage lose. Finally, all the information are combined in a Geographic Information System to estimate the spatial and temporal distribution of irrigation water requirements in paddy fields.


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