Abstract:
Fresh water scarcity is one of the major problems in the southern region of Bangladesh.
Khulna and Satkhira were selected as the study area since these two districts are widely
recognized as areas affected by the most severe groundwater salinity problem. The main
objective of the study was to delineate suitable aquifers for agricultural and drinking water
supply in these two districts and the outcome of the study was a database for groundwater
salinity distribution at different depths, which could be potentially useful for planning of
southwest coastal groundwater resources as well as for any future research requiring
salinity data.
The study was conducted mainly based on secondary data and information. Secondary data
included borehole electrical resistivity logs from Department of Public Health and
Engineering (DPHE), electrical conductivity (EC) measurements by Bangladesh Atomic
Energy Commission (BAEC), Bangladesh Agricultural Development Corporation (BADC)
and Bangladesh Water Development Board (BWDB). Resistivity data were interpreted and
verified for groundwater salinity (in terms of electrical conductivity), and together with
other direct EC measurements were used to map groundwater salinity across the study area
for different depths. A large number of lithological logs available in the study area were
analyzed and treated in two-dimensional environment to produce stratigraphic units and
determine vertical distributions of subsurface formations. These data together with salinity
maps were used to identify suitable aquifer areas with acceptable limits of salinity for
agricultural (i.e. irrigation water use for paddy) and drinking water uses.
In Satkhira district, most of the suitable aquifers in terms of drinking and irrigation
purposes are found in the shallow zone, while in few cases they are found in the main
aquifer. Shallow aquifers at Chandanpur union in Kalaroa upazila contain fresh water zone
i.e. EC is below 1000 μS/cm which is suitable both for irrigation and drinking water
purposes. Banshdaha and Labsa unions in Satkhira sadar also have the fresh water in
shallow aquifers. On the other hand, Brahmarajpur and Dhulihar unions of Satkhira Sadar
do not have suitable aquifers either for drinking or irrigation purpose due to EC range
above 3000 μS/cm. Shallow aquifers in Nagarhata union of Tala, Parulia union of Debhata,
Assauni union of Assasuni, and Shyamnagar union of Shymnagar contain the fresh water
which is suitable for both drinking and irrigation purposes. The shallow aquifers in Kulia
union of Debhata, Nalta and Sreeula unions of Kaliganj and Shyamnagar and Ranjannagar
unions of Shyamnagar are not suitable for drinking but are suitable for irrigation purpose.
In Khulna district, the shallow aquifer zone in most unions (except Chalna and Koyra) of
Koyra upazila belong the high EC that is not suitable for either drinking or irrigation
purpose. In Chalna union of Koyra, water is suitable for both drinking and irrigation, and in
Koyra union water is suitable for only irrigation. The shallow aquifers in Dacope upazila in
general have high EC contents (greater than 4000 μS/cm) except Batiaghata union, where
water is suitable for irrigation. The water quality in Batiaghata upazila is better, with most
shallow aquifers suitable for both drinking and irrigation except Dighalia where water is
suitable for only irrigation. Rupsha, Phultala, Terokhada, Khulna metro upazilas have fresh
shallow aquifers suitable for both drinking and irrigation, while shallow aquifer of Dighalia
upazila is suitable for irrigation only.
