Floods this year, despite its destructive nature, will hugely benefit farmers by recharging the groundwater level ensuring availability of sufficient water for irrigation during the dry season.
This was stated by a study by Water Resources Engineering (WRE) Department of the BUET. The study also says the deluge will also improve the quality of underground water. Flood deposited nutrient-rich fine-grained sediments to a large area of farm land making it more fertile.
The study further says the groundwater level is expected to remain three to four feet below the ground during the dry season as it has been submerged for about two months. This will increase irrigation facilities in summer.
Experts believe that this year's irrigation season will save farmers at least Tk 300 crore for not having to use fuel for irrigation machines. When the groundwater table drops one foot, the farmers have to spend an additional Tk 100 crore a year.
This time the groundwater table will be up by 3 to 4 feet in some areas due to prolonged floods. In addition, rising groundwater levels will reduce arsenic outbreaks and also prevent landslides.
The main source of stored water in the groundwater table is water leaking from surface water bodies (rivers, canals, lakes, ponds, etc.). The water flows from the catchment area of the surrounding area where the water is collected.
In addition, rainwater and irrigation water penetrates the upper soil layers and slowly accumulates in the lower layers after reaching the surface. Groundwater levels rise when rainfall is high and water accumulates above the surface for a long period of time.
According to the survey conducted by Water Resources Engineering (WRE) Department of Bangladesh University of Engineering and Technology (BUET), 61 per cent areas of Bangladesh were submerged by 1988 massive floods and 68 per cent in 1998, raised the groundwater level by up to 4 feet.
This year's floods have inundated 41 percent areas of the country. At the same time, the amount of rain this year was more than that of the previous monsoon years. The groundwater table is expected to rise three to four feet higher than the normal underground water table.
Professor Rafiqul Islam of Soil Science department of Bangladesh Agricultural University said vast areas were under water as the floods were prolonged. There is still water remaining at many places. This will naturally increase the groundwater reserves. In that case, depending on the type of soil, groundwater level will increase by 3 to 4 feet somewhere.
“One of the benefits of prolonged flooding is the increase in groundwater tables. This leads to increased irrigation facilities. Irrigation will save the farmers from spending big amount of money on fuel. As a result of floods, a lot of silt is deposited on the land and the land becomes fertile which increases crop production. Rising groundwater levels also reduce arsenic outbreaks and landslides,” he added.
According to the Bangladesh Agriculture Development Corporation (BADC), the country is currently pumping water using around 1.7 million shallow tubewells. These can draw water from 22 to 24 feet below the ground. But now in many areas water is not available even 24 feet below the ground.
In this situation, the farmers of all those places are digging five more feet re-installing shallow tubewells. Even after that water is often not available in many places. In the dry season, about five lakh shallow tubewells become useless in Bangladesh.