Modeling and Mapping of Groundwater Potential Zones of the Shewasoor Sub-Basin Using Analytical Hierarchy Process, RS and GIS Techniques in Kirkuk, Northeastern Iraq

Abstract


Introduction
Water is one of the precious, rare, and vital resources for various countries of the world.Groundwater is an essential artery for the continuation of human life.Groundwater plays an active role for all countries of the world in food security and economic development.(Roy et al., 2022).The shortage of surface water, especially in Iraq, has increased the demand for groundwater (Agha and Al-Tamimi, 2022).Continuously available water is very important for sustaining life (Ramzi and Al-Gburi, 2022).Today, due to poor management and over exploitation of groundwater, the accessibility of groundwater resources is under threat.Fresh groundwater is constantly under threat in different countries of the world; therefore, understanding the methods and techniques for groundwater recharge and the good management of surface water at the global level is extremely important for sustaining life (Muniraj et al., 2019).The surface water of the Shewasoor sub-basin is not permanently available; so groundwater represents main source in creating water security for these populations.The increasing agricultural activities and population largely dependent on need groundwater continuously (Al-Gburi and Al-Tamimi, 2020).With increasing population growth and human activities threatening groundwater, groundwater supply management is making a difficult challenge in all countries (Qadir et al., 2020).The population living at the Shewasoor sub-basin fundamentally depend on groundwater for their drinking as well as domestic needs, which has led to an increased exploitation of this natural resource.Remote sensing applications such as digital elevation models and satellite visuals are among the most important resources that must be available when conducting any study (Qubaa andAlsayiegh, 2020).The application of GIS along withRS are very important tools for monitoring and managing all natural resources (Dar et al., 2010).The use of GIS and RS techniques to map model potential groundwater zones is a very important method.Recently, the widespread development of satellite images, along with maps and corrected land cover data, has facilitated the identification of potential groundwater (Das et al., 1997).The Multi-Criteria Decision Analysis (MCDA), it is a structured technique for analyzing complex decisions using mathematics to determine factor weights (Forman and Gass, 2001).TheAnalytical Hierarchy Process (AHP) is an effective and important resource management technique.MCDA-AHP technique based on RSand GIS was used to accurately estimate groundwater potential of the Shewasoor sub-basin using some selected thematic maps, whichmany parameters vary based on data availability.For sustainability of life in any country, there must be an important resource such as groundwater (Al-Gburi et al., 2022).In current research, seven criteria were select to determine groundwater potential of Sheawasoor sub-basin, since the groundwater potential of the current sub-basin has not been study so far.The main objective of the research is to determine of groundwater potential zone anditsdistribution, which will benefit the Iraqi Ministry of Water Resources in terms of the material cost of groundwater management.Moreover, the research can be useful for controlling groundwater supply the Sheawasoor sub-basin to improve livelihoods and good environmental security.In addition, determining the drilling of groundwater wells in the future with scientific efficiency.

Study Area
The Shewasoor sub-basin is located at the northeast of Kirkuk Governorate.The Shewasoor subbasin is located between latitudes 35°51'21.6"N-35° 41' 29.1" N and Longitudes 44°30'7.5"E-44° 40' 42.9" E. The area of the sub-basin is 159 km 2 .The boundaries of the Shewasoor sub-basin are Al-Khassa sub-basin from the south, Chia sur sub-basin from the southeastern and Shwan sub-basin from the east (Fig. 1).According to tectonics, the Shewasoor sub-basin is located at the North-East of the Low folded Zone (Sissakian et al., 2017).Structurally, the limits of the sub-basin at the eastern and western side are Dara Quota Anticline and Chamchamal North Anticline respectively (Sissakian, 2013).Depending on hydrogeological setting, the Shewasoor sub-basin is located within aquifer of Mio-Pliocene sandstones (Krasny et al., 2006).Based on hydrogeological setting, the study area is located within Low Folded Zone according to (Al-Jibouri and Al-Basrawi, 2012).

Materials and Methods
To determine groundwater potential of the Shewasoor sub-basin, seven layers were selected i.e. geology, slope, elevations, lineament, drainage density, soil, lineament, and Land ues/Land (LULC) covers.All these data have been processed using the GIS, based on exploring the area for assessing the groundwater potential zone.After All the selected data have been transformed to a rasterized format, with resolution of 30 m.For geology map, the data were available from the (Stevanovic and Markovic, 2003).The slope, elevation and drainage density layer was prepared from ASTER satellite.The (LULC) that covers (10 m) map was taken from Esri website which was processed using supervised classification in GIS.Further, drainage density and lineament density were generated from the drainage density and lineament map using line density tool in GIS.The soil map was created according to Harmonized Global Soil Database.Reclassification maps after preparing all the data to a rasterized format with the same cell size were done.Then, weights have been assigned using AHP for the Scientist (Satty, 1980).Weighted Overlay Analysis (WOA) was performed by collecting the raster layers in the GIS to delineate the final groundwater potential map for Shewasoorsub-basin which was derived from the following equation (Malczewski,1999) Where:Weight Geology (WGo) and Rating (RGo).Weight Slope (Wslo) and Rating (Rslo).Weight Elevations (WE) and Rating (RE).Weight Lineament (WLi) and Rating (RLi).Weight Drainage Density (WDD) and Rating (RDD).Weight Soil (WSoi) and Rating (RSoi).Weight LULC (W LULC) and Rating (R LULC).However, the methodology of the Shewasoor in (Fig. 2).

Geological Map
The geological formation of any water basin is another decisive factor that controls groundwater availability due to the infiltration and runoff rate depending on the porosity of rocks  (Abijith et al., 2020).The Shewasoor sub-basin contains two geological formations Mukdadiyah and Bai-Hassan (Fig. 3A) (Stevanovic and Markovic, 2003).The Bai-Hassan Formation covers most of the sub-basin, while the Mukdadiyah Formation occupies the eastern part of the study area.Depending on the geological map, the Bai-Hassan Formation is considers to have a higher value than the Mukdadiyah Formation for the groundwater potential ; due to contains that it has a slight percentage of clays compared to the Mukdadiyah Formation.So that value of the Bai-Hassan Formation is considers 4, Fig. 3A, while value of the MukdadiyahFormation is 3 (Fig. 3B).

Slope
The slope is one of the most important elements in any geomorphological system (Maroof, 2022).The gentle slope always represents good chance opportunity for groundwater recharges and has excellent aspirations for groundwater development (Roy and Mandal, 2022).In any water basin, steep The slopes map for Shewasoor sub-basin, categorized into five zones (Fig. 4A).The rating value however, represents very poor groundwater potential zone and vice versa (Fig. 4B).

Elevations
Elevations have an important role in most of the hydrogeological and hydrological studies, especially in terms of drainage density of the basin and surface runoff (Al-Gburi et al., 2022).The elevations value of the Sewahsur sub-basin ranged from 329-1186 (m) (Fig. 5A).Based on the elevation map, the map was classified into five zones (Fig. 5B).The value 5 was considered very good groundwater potential and vice versa.

Lineament
Lineaments like faults and dykes mainly found over the geological formations active (Kaliraj et al., 2014).The higher lineament density in any water basin reflects higher groundwater potential because lineaments density are superb site of porosity and permeability (Ghosh et al., 2020).The principal lineaments particularly faults trended in the north, central and south of the Shewasoor sub-basin; which ranged from 0 to 2.33 km/km 2 (Fig. 6A).The rating value werecategoried into five zones from 1 to 5 (Fig. 6A).The rating value five represents very good groundwater potential zone and vice versa.

Drainage Density
Drainage density is an influential factor in groundwater potential (Ganapuram et al., 2009).High drainage density leads to low permeability of base or underlying rocks (Shao et al., 2020).The drainage density of the sub-basin was classified into five categories, which values ranging from 0 to 10.3 km/km2 (Fig. 7A).The assigned rating values range from 1 to 5 (Fig. 7B).The very good groundwater potential zone ranking five in the sub-basin.

Soil
Soils foundation arean influential factor in groundwater potential and its characteristics vary, with respect to grain size and types (Arun et al., 2021).According to reference for Soil, there is one soil class which is loam in the Shewasoor sub-basin (Fig. 8A).The rating value two is represents poor groundwater potential zone (Fig. 8B).Land use/land cover is one of the factors that have a real role in influencing penetration and runoff.As a result, the land use/land cover factor has an effective role in influencing groundwater recharge (Ifediegwu, 2022).Land use/land cover contain six categories which are (water, built, trees, crops, scrub ground and bare ground) at Shewasoor sub-basin (Fig. 9A).Based on rating value Land use/Land cover map of the sub-basin have values 1, 2, 4, and 5 which are categorized as one for build (very poor groundwater potential), two for bare land (poor groundwater potential), four for trees, crops and scrub ground (high groundwater potential) and five for water body (very high groundwater potential) body areas (Fig. 9B).

Groundwater Potential Zone (GWPZ)
The groundwater potential maps consider one of an important map for understanding the distribution and determination of the presence groundwater in any water basin.The groundwater potential map indices were categorized into five zones from very low to very high (Fig. 10).Very low groundwater potential account for roughly 6.92% of the all sub-basin (11 km2), whereas the low groundwater potential represents about 24.27% of the total area sub-basin (38.6 km2).Around 29.94% of the total area (47.6 km2) is rated as having medium groundwater potential, About 28.62% (45.5 km2) is classified as having a high groundwater potential; while 10.25% (16.3 km2) is classified as having very high groundwater potential.

Conclusions
The groundwater potential study is regarding as one of the applied hydrogeological studies.The use some technologies such as (GIS and RS) in addition to hierarchical analysis processes is very important to detect the groundwater at present and future.According to the applications used in this study, several factors have been studied and analyzed such as (geology, slope, elevation, lineament density, drainage density, soil, LULC).The highest elevation are located at the western, eastern and southern parts of the Shewasoor sub-basin, but the lowest elevation is located at the north part of the Shewasoor sub-basin.The results showed Shewasoor sub-basin were divided into five zones: from very low groundwater potential to very high groundwater.Groundwater potential was discovered in the southern, eastern, western parts and some part at the center of the sub-basin from very low-to-low, due to the influence of geological, elevations and low lineament in these parts.Groundwater potential was detected at the northern and some central parts of the sub-basin, as well as some small southern part due to geological formation, such as (Bai Hassan Formation); which contains a high percentage of pebbly sandstone, conglomerate and a low percentage from clay.In addition, the effect of low elevations on the northern and the middle parts of Shewasoor sub-basin discover very high and high values of groundwater potential.

Fig. 2 .
Fig. 2. Flow chart for determining groundwater potential map of theShewasoor sub-basin

Table 2 .
Weighted groundwater potential factors for Shewasoor sub-basin