## 1 Introduction  
Once water demand exceeds availability due to population expansion and development, groundwater becomes a critical freshwater resource, especially in countries under arid conditions with surface water deficits [1, 2]. Water obstruction in neighboring regions,and climate change aggravate water scarcity and freshwater resource depletion [3], while pollution from various anthropogenic sources further deteriorates water resource quality and quantity [4]. During rural area development, land utilization might impair the natural groundwater recharge mostly in terms of quantity reduction and to lesser extent in terms of quality deterioration [5]. In Kazakhstan's arid areas, groundwater resource demand is constantly increasing [6] to a level where half of Kazakhstan's freshwater supply relies on groundwater and the rest on surface flow. Groundwater resource assessment should consider the basin's geology and hydrogeology, groundwater quantity versus recharge and usage, groundwater quality, and environmental challenges [7]. Groundwater resource assessment using a water balance by groundwater level fluctuation method and base flow hydrograph analysis of the Koyna River Basin, India, supplied a static groundwater reserve assessment and safe exploitable dynamic groundwater reserve potential [8]. During intensive pumping, a significant thickness of the aquifer is drained, and it transitions to an unsaturated state. Under these conditions, subsidence phenomena may occur, especially under seismic impacts [9]. Integrating existing datasets over a geographic information system (GIS) platform enables the delineation of climatic, hydrological, hydrogeological, and environmental features as well as rainfall-runoff modeling. This basic knowledge enables groundwater resource planning for groundwater-dependent ecosystems, such as in the Pilbara region of Western Australia [10]. There are two major types of mathematical models, namely stochastic and deterministic [11; 12]. Stochastic models allow for assessing the relations between the statistical characteristics of aquifers and their flow and transport properties. Stochastic approaches rely on treating hydrogeological parameters as a random field and estimating their properties from prior estimates and available state variables (for example, heads and concentration measurements) [13]. The strengths and weaknesses of stochastic approaches in hydrogeology are discussed in [14]. Deterministic models use closed-form mathematical formulas or the solution of a linear system of equations to interpolate data. These models are based on in-depth knowledge of the aquifer's physical processes [15]. Modern deterministic surface and subsurface flow models, such as FEFLOW, can represent river-aquifer exchange accurately, as demonstrated for unconfined aquifer processes in the Papillons catchment of the lower Var valley [16]. Mathematical deterministic computerized groundwater models are a set of equations that describe groundwater flow and water balance in an aquifer. The equations are solved for each node and the groundwater movement from one node to the neighboring node [17]. Numerical groundwater flow models can be used as a forecasting tool for aquifer water management, to test or refine various conceptual models, and to estimate hydraulic parameters; once integrated, they can also be used for water management [18]. Such models can predict how an aquifer might respond to anthropogenic changes, such as changes in pumping schemes and natural conditions, such as a changing climate [19]. MODFLOW is a nominal platform for groundwater flow assessment, which is usually used for the simulation of large-scale phreatic porous media aquifers [20]. The integration of several different scale models and functional modules over a GIS platform to represent spatial and vertical hydrological variations enables the application of MODFLOW for modeling crystalline and karstic aquifer complexes [21].