1. Introduction
The activities of urbanization, reclamation of the land and higher
agricultural production have increased due to the incredible increase of
human population (Sawant & Shete, 2016). These activities have makes a
higher demand for groundwater resources and it is increasing in higher
to higher day by day (Al Tanjil, Ahmed, Akter, Biswas, & Policy, 2019).
Therefore, it has become a new challenge for the supplying of safe
groundwater according to the demand of the population (Ahmed, Hasan,
Khan, & Hasan, 2019; Biswas et al., 2017). The authors (Hasan et al.,
2016; Mahmood & Environment, 2012) have indicated that the groundwater
has flowed north to south in Bangladesh. This is happened because most
of the rivers are connected in the north with the Bay of Bengal (Monir,
Khan, Hossain, & Hossain, 2011; Monir, Khan, Quamruzzaman, Kabir, &
Hossain, 2012) and elevation of these coastal areas is lower from the
north to south (Sarker, Van Camp, Islam, Ahmed, & Walraevens, 2018).
The coastal area is connected with 19 districts of Bangladesh. Such flow
of groundwater and elevation, salinity intrusion has been considered the
main cause of potential water resources (Mahmuduzzaman, Ahmed,
Nuruzzaman, & Ahmed, 2014). The coastal regions is found higher sandy
layers so irrigation activities have been considered a higher concern
because of groundwater reported by Rahman, Rahman, and Majumder (2012).
For this, the safe water zone is found in the higher depth of
lithological distribution (Mahmood & Environment, 2012). In the arid
period (March to August), the water demand became acute in every year in
Bangladesh because the water static table goes to low down (Mahmood &
Environment, 2012). Some authors (Rahman et al., 2012; Shammi et al.,
2016; Shammi et al., 2017) have investigated that this higher increased
stress of water demand has been emphasized the inhabitants collect water
resources from the higher depth of lithological layers. Moreover, the
safe water-bearing zone or saturated zone have been found in higher
depth along the coastal district’s areas of Bangladesh (Hasan et al.,
2016).
The step-down test is considered as short pocess and moderately simple
and cheaper than the other pumping tests because of this processes are
regulated the highest rate of flow water in a well (Ophey et al., 2019).
The proportion of abstraction on step-down test from the water level of
the well is increased in different numbers of steps (minimum 3 times )
(Abdalla & Moubark, 2018). Well-performance tests have been conducted
to estimate the losses of energy in the aquifer and the pumping well
which is developed during the extraction of groundwater. The procedures
of pumping well consist of increasing discharge rates (Q) at a stepwise.
Until the drawdown stabilized, it is measures every test temporary
changes in water levels at every step (Kruseman, De Ridder, & Verweij,
1970). Moreover, some researchers (Gahala, 2015; Louwyck, Vandenbohede,
& Lebbe, 2010) studied that the analytical process of step-drawdown
test assists to identify the quantify aquifer mechanisms which evaluate
the rate of flow into the well laminar/turbulent. The discharge rate (Q)
and time are proportional to the resistance of formation on the
water-bearing zone. The well (non-linear) loss has considered as the
parameter of difference between the immediately head of inside and the
outside casing during pumping of an aquifer (F. J. P. b. J. S. Driscoll,
St Paul, Minnesota, 1986). Jacob method (Jacob, 1947) has been applied
for determining the pumping rate, step down tests and the specific
pumping rate of an aquifer which has been considered as very easy and
low expensive for calculation (Abdalla & Moubark, 2018). According to
Jacob’s method, F. J. S. P. Driscoll, Minn (1986) has used the term of
aquifer loss in laminar and turbulent term of well loss. Bierschenk
(1963) also represented Jacob’s method in a graphical interpretation for
the determination of well loss and aquifer whereas Logan (1964) and
Gabrysch (1968) have proposed the transmissivity estimation method from
the loss coefficient of the aquifer. This transmissivity estimation
method has been evaluated by various graphical interpretations from the
coefficient on well loss. Singh (2002) has been applied this method for
the determination of transmissivity (T), stepdown, specific recharge
depends on Jacob method (Jacob, 1947). The single-well step-drawdown
test and its performance of well criteria (coefficient of well loss, the
efficiency of well) provides the estimation of highest yield (optimal
pumping propotion) under varying conditions of the water-level (Guttman,
Negev, & Rubin, 2017).
The lithology of subsurface deposits, saturation of (aquifer) thickness,
groundwater depth, hydraulic properties of the aquifer is controlled the
hydrogeologic characteristics and potential of grundwater resouces in a
area. In the previous study (M. T. Ahmed et al., 2019), it has
investigated the distribution of groundwater quality and its valuation
on Shagordari but there is no indicator of lithological distribution and
aquifer characteristics. Another study (M. Ahmed et al., 2019) has
indicated only the hydrogeological condition of Jessore but there is no
evaluation pumping rate or well performance according to hydrochemistry.
Moreover, several authors (Jahan et al., 2007; Tanvir Rahman, Rahman,
Majumder, & Technology, 2012) have also identified the depositional
environment of the aquifer by using the gamma-ray well log data.
However, there is no identification of well of recharge. As the water
level has been being decreased day by day so static water level and the
recharge rate condition of the water should be needed to water resources
safety. Moreover, it has evaluated by the authors (Abdalla & Moubark,
2018; Louwyck et al., 2010) that step drawdown (aquifer) pumping and
performance tests have been considered as the main process to determine
the sufficient and accurate assumption of groundwater resources in any
aquifer.
Therefore, this study evaluated the performance of well criteria, steps
drawdown and pumping tests of the investigation area. Hence, the main
objectives of this investigation area have indicated that the
identification of the safe zone according to various pumping rates, step
down test and estimation of well performance with its aquifer
characterization by the estimation of well loss and well efficiency, the
specific capacity of well and an optimal pumping rate of various
water-level conditions. This study also evaluated the lithologic
characteristics of the aquifer, water-bearing zone from the logging data
and levels of aquifer zone.