Estimating rainfall infiltration for groundwater recharge using infiltration index method: A case study in Rajshahi District, Bangladesh

摘要

Infiltration rate in soil is a measure at which the soil is able to absorb rainfall. It replenishes the soil moisture deficiency and the excess moves downward by the force of gravity called deep seepage or percolation and builds up the groundwater table. The study was conducted in three large Upazilas under Rajshahi district from 2002 to 2013 to estimate the rainfall infiltration for groundwater recharge which are the pre-condition to meet the large demand of irrigation supplies that are the key to economic growth. Rainfall data was collected from Upazila Agriculture Office DAE, Rajshahi. The data were analyzed to show the rainfall variations, runoff, infiltration rate and percentage of infiltration from total rainfall for different years. In this paper, W-index method was used for better and quick assessment of rainfall infiltration in study areas. The result illustrate that the average annual rainfall Infiltration rate were found 80.61, 79.12 and 72.20 cm/year for Godagari, Paba and Puthia Upazila respectively and the average percentage of annual infiltration from total rainfall were found 58.3%, 58.76% and 58.80% for three study areas respectively.