Delineation of Groundwater Potential Zone Through Geospatial Technique, Multi-Criteria Decision Analysis, And Analytical Hierarchy Process

Study Region: This study area is located in a subtropical semi-arid climatic zone of India, suffering due to the low availability of water. Hence, delineation of the groundwater potential zone (GWPZ) had performed through the geospatial technique, the multicriteria decision analysis (MCDA), and the analytical hierarchy process (AHP). Study Focus: The thematic-layers of the geology, geomorphology, soil types, lineament-density, the slope of the topography, drainage-density, land-use, and land-cover developed and created by utilizing available supplementary data and digital satellite images. GWPZ had classied into 5 classes like excellent, good, moderate, poor, and very-poor. The summary of the methodology adopted for the delineation of GWPZ has given in g-2. New Hydrological Insights for the Region: It had observed that the consistency index (CI) was 0.0106, while the random index (RI) for 7 variables considered from standard tables is 1.32. The calculated consistency ratio (CR) in this study was 0.0080 lower than 0.1000. This low CR indicated moderate consistency in the results of pairwise comparisons among the thematic layers assigned weight for analysis. Hence, the AHP model used for this research work has shown reasonably good accuracy. The statistics of GWPZ indicated ~3.97% of study-area possessed excellent GWPZ, ~37.09% very-good, ~41.72% moderate, ~15.23% poor, and ~1.99% very-poor. This model of the GWP map shows that the Area Under the Curve (AUC) of the Receiver Operating Characteristic Curve (ROC) is ~0.726. It indicated good agreement between experimental results and predicted results. Proterozoic rocks. The eld study elevations ranged between 324-561m. The projected area in this research falls under the Yamuna river-drainage system supported with few seasonal rivers. The Parbati River and Kumo River are tributaries of the Chambal River drain that occupied most of the Guna district. The Eastern zone of the study-area drained through the Sindh River, and the ow direction of the river towards the north with a low-gradient. very good (0.80–0.90), good (0.70–0.80), average (0.60–0.70), (0.50–0.60) (Andualem and Demeke 2019; Naghibi et al. 2015; Parashar et al. 2018; Srivastava 2020). This model of the GWP map has shown AUC ~ 0.726, which indicated good agreement between experimental results and GWP model prediction results.


Introduction
Groundwater is one of the signi cant sources of freshwater in comparison to other freshwater sources available on the earth's surface (Senanayake et al. 2016;Shiklomanov 1993). The demand for freshwater has been increased signi cantly in the last few decades due to population growth, rapid urbanization, and industrialization. The availability of the groundwater in the speci c geographical areas depends on the geology, lithology, topography, fractures, porosity, slope, lineament-density, drainage pattern, precipitation, climatic condition, types of land-use, and land-cover Approximately 10% of the available freshwater gets contaminated due to leaching of contaminants from the point and nonpoint source, mismanagement of the water resource, etc. Thus, the demands of the available freshwater have been increasing day by day worldwide in the last few decades. It was observed that the groundwater table depleted due to the high rate of withdrawal in comparison to the recharge rate.
Surface and subsurface water is used preferably as a freshwater source in this semi-arid study-area. Groundwater is the more precious comparison to surface water and broadly utilized for various purposes like irrigation, domestic, and commercial requirements. Surface water is available in small proportions through the seasonal rivers for a certain period only. Hence, groundwater importance has increased in this region as a source of fresh water. The study-area reported a sharp decline in groundwater table due to the excess withdrawal of sub-surface water in various proportions for irrigation, industrial consumption, and domestic requirement (Srivastava and Ramanathan 2018a). The scienti c communities suggested that the decrease in groundwater table in wells, streams, and lakes caused the signi cant decline of the water quality, land subsidence, and increased groundwater pumping costs (Wada et al. 2010).
The scarcity of water and overexploitation of available subsurface water has created concern in scienti c communities. It further motivates us to evaluate the Groundwater Potential (GWP) status in this subtropical climatic zone of India. The assessment of GWP is always a challenging task in comparison to surface water (Todd 1980;Ranjan et al. 2017). The subsurface water generally occurs in the weathered, fractured hard-rock aquifer, whose thickness depends on the geological formation and geography of the study area. The GWP zones are a type of water-bearing natural cavity of the earth's crust that acts like channels for transmission and also a reservoir for the storage of subsurface water.
The satellite image helped extensively in the identi cation and evaluation of the GWP zones in a geographical area due to its skill to recognize largeground landscapes easily (Prasad et al. 2006; Adamala et al. 2016). Further, it observed that simulation of various technologies, including Remote Sensing (RS) and Geographical Information System (GIS) for the exploration of the GWP zone, enhanced its ability of predictability (Murasingh et al. 2018). It observed that the researchers used RS and GIS in the demarcation of the GWP zone assessments in their respective study-area located in various geographical and climatic zones of the world (Andualem and Demeke 2019; Murasingh et al. 2018Murasingh et al. , 2013Vijith 2007;Magesh et al. 2012;Biswas et al. 2012). The thematic-layers were prepared and utilized during the assessment of the GWP in this research work. In the study area, most of the regions were suffering from water scarcity due to poor geological conditions and unplanned extraction of groundwater for agriculture activity (Srivastava and Ramanathan 2018a). Hence, it is essential to explain the GWP zone in the study-area to optimize the utilization of groundwater for sustainable development. The traditional groundwater recharge potential was assessed through hydrological eld investigations and modeling with a soil moisture model (Singh et al. 2019; Thorpe and Scott 1999;White et al. 2003). It had observed that in-situ investigation is costly, timeconsuming, di cult at a large scale in comparison to assessment through RS and GIS (Thapa et al. 2018; Srivastava and Ramanathan 2018b).
In this research work, the delineation of the GWP and distributions of subsurface water resources had performed by using RS and GIS data. The RS and GIS technique provides a synoptic view of a large-region. It simpli ed the evaluation process through improved and faster assessment and progress in groundwater management with collateral information. All these studies had based on an indirect calculation through topographical features, lineament density, drainage density, geomorphology, land-use/land-cover, slope, and hydrological characteristics of the study area.
The integrated approach of the RS, GIS, MCDA, and AHP had utilized in this research work for the evaluation and identi cation of suitable GWP zones and favorable arti cial recharge zone in the Guna district. The researchers appreciated this technique and utilized RS, GIS, MCDA, AHP as tools for water resource management and other environmental management (Machiwal et  identi cation of a suitable groundwater recharge zone is an essential pre-requisite for the sustainable management of groundwater resources. Groundwater recharge is a process of water in ltration from the unsaturated zones into the saturated zones (Freeze and Cherry 1979;Srivastava 2019). It occurred only in the conditions when the water has own underneath the ground and in ltrates into the saturated zone (Yeh et al. 2016).
This research work aims to develop the thematic-layers of the GWP zones and the identi cation of suitable GWP zones in the Guna district. This study also identi ed and delineated the groundwater recharge zones through the integration of various modi ed and developed thematic-layers for the Guna district.

Study-area
This study-area has placed in the Madhya Pradesh state of India, geographically located in the NE of the Malwa Plateau between the Parbati River and the Betwa River (latitude N 23 o 53′-N 25 o 06′ and longitude E 76 o 48′-E 78 o 16′) (Fig. 1). The topo-sheet No. 54G, H, and L provided by the Survey of India (SOI) was utilized for the development of the study area map. The study-area inhabited by ~ 1260 villages, resided ~ 13 million peoples as per the Census of Government of India (2011). Almost all peoples are living in the villages and fully dependent on the subsurface water for irrigation, domestic and commercial requirements. The annual rainfall was ~ 108.72cm and received maximum rainfall (~ 86%) through SW monsoon (from June to September). The atmospheric temperature ranged from 4.8°C (in winter) to 46°C (in summer) as per the Indian Meteorological Department (IMD) report (2011-2020).

Methodology
This study was performed with well-planned and adopted an integrated approach methodology, which included the collection of data, analysis, interpretation, and validation of results. The geospatial technique, MCDA, and AHP were utilized in this research work to delineate the GWP of the study-area. Seven thematic-layer had used in this research work for the delineating GWP zone through MCDA and AHP methods. The summary of the methodologies adopted for the delineations of GWP zones has given in Fig. 2.
At the initial stage published maps, remote sensing data, and groundwater data has collected through various Government of India agencies. These agencies are the Central Pollution Control Board (CPCB), Madhya Pradesh Pollution Control Board (MPCB), Survey of India (SOI), Madhya Pradesh Council of Science and Technology (MPCST), IRS Bhuwan portal, etc. The groundwater water-table data was collected in-situ during eld observation through pumping test by using monitoring wells identi ed within the study area. The remote sensing data had collected for image enhancement and classi cation through ArcGIS software.
The thematic map was developed by using the published-map (after digitization and recti cations), remote sensing data, and monitoring well data. The published-map that utilized during the delineation of GWP are hydrogeology, soil texture, lineament density, drainage density, land-use, and slope of the topography. The MCDA had utilized in this research for assigning the weightage to all variables used during calculations. Ranking of themes and AHP has used during the evaluation of the normalized weight of individual theme and their diverse layers. The methodology suggested by Saaty (1990) had used in this research work for the calculation of the consistency ratio (CR) and the consistency index (CI).
The statistical calculation has performed during the assessment of the groundwater potential index (GWPI) and further these data were used for the delineation GWP zone in the project study area. The validation of the GWP map has performed by using primary data collected from the eld through the pumping test. The Receiver Operating Characteristic Curve (ROC) and the Area Under the Curve (AUC) have developed during the validation of the GWP map of the study area.

Development of Thematic Maps
The development of the thematic maps is a primary step for the delineation and identi cation of the suitable GWP zone in the projected study-area.
These maps were collected for the development of thematic maps through various sources like IRS-Bhuwan, India, CPCB, MPCB, literature, and annual reports of MPCST, Bhopal, etc. The land-cover thematic-map has also been formulated by categorizing the satellite image and validating it with actual information or experimental data available on the ground. The software available for the development of thematic maps had utilized in this research work.

Geology
Vindhyan sandstone, shales, and limestone were available in surplus proportions in the geology of the study area. The natural aquifer identi ed within the weathered fractured jointed Deccan-traps, the shale, and the Vindhyan sandstone (CGWB, 2013-20). Around 66% portion of the study-area possessed Deccan-trap basalt of the Malawa Group, which indicated a long-period of geological developments (Fig. 3). The statistics of the geology of the study-area have shown in table 1. The statistical assessment of the lithology of the study area indicated that the Deccan-trap occupied ~ 4830.4 km 2 (~ 74.49%) of the study area (Table 1). Laterite dominating lithology occupied ~ 55.12 km 2 (~ 0.85%) of the study area. Vindhyan sandstone and the shale dominating geology distributed in ~ 1538.15 km 2 (~ 23.72%) of the study area. The geology of the study-area indicated ~ 60.96 km 2 (~ 0.94%) of the study area (Table 1).  Subsurface water occurred under the phreatic condition with signi cant yields. Bamori and Guna blocks exposed with the Vindhyan sandstone, which has been inserted with shale. Srivastava and Ramanathan (2018a) reported in their study that hard-rock was cracked and inter-connected at a different depth, further developed, and adopted it as a potential aquifer at a deeper level. The peoples are extracting surface water through a motorpump to ful ll the water requirement for irrigation, industrial and domestic. The eld observation showed that the yield of bore-wells in the studyarea ranged between 2-10 liters/second. The unit-draft ranged from 0.005-0.017 mcm/year in case of tube-wells and 0.001-0.008 mcm/year observed in the case of dug-wells (CGWB 2013-20).

Geomorphology
Geomorphology showed the EW alignment of the Vindhyan-range possess the Sindh-valley, Malwa-plateau, and the Parbati river-valley. Binaganj and the Chachoda hills occupied the rest of the study area. The study of physiography indicated that it possessed the low-level plateau, ood-plains through the river, and the plain of extrusive origin with rocky-bench. The rest of the landforms was a low structural plateau, a plain of the Proterozoic rocks. The eld study indicated the elevations ranged between 324-561m. The projected area in this research work falls under the Yamuna riverdrainage system supported with few seasonal rivers. The Parbati River and Kumo River are tributaries of the Chambal River drain that occupied most of the Guna district. The Eastern zone of the study-area drained through the Sindh River, and the ow direction of the river is towards the north with a low-gradient.
It possessed ~ 15.55% forest and ~ 50.68% sown-area. Approximately 62.25% of the study-area was arable land (CGWB 2013-20). It reported that ~ 66.02% area under agricultural-activities created stress over subsurface water due to over-exploitation of groundwater for irrigation, the domestic and industrial requirement (Srivastava 2019). The study-area was also suffering from poor-quality and scarcity of water because these regions possessed fractured hard-rock aquifer, and further over-exploitation of subsurface water created anxiety over groundwater.

Topography and Slope
The topography of the study-area was varying signi cantly and also in uenced the rate of recharge of the aquifer (Fig. 4). Those regions of the study-area have possessed a low slope (or plain-area) exposed to the possibility of high recharge in aquifers due to high residence times. While those areas have possessed a high-slope reduced the chance of recharge due to high surface runoff. In the study-area, the slope was ranging between 1-35% ( Table 2). The statistics indicated that ~ 5506.10 km 2 (~ 84.91%) of study-area possessed slope in between 0-1%; ~383.89 km 2 (~ 5.92%) of study-area possessed 1-3% slope; ~267.82 km 2 (~ 4.13%) of study-area possessed 3-5% slope; ~171.84 km 2 (~ 2.65%) of study-area possessed slope in between 5-10%; ~103.75 km 2 (~ 1.60%) of study-area possessed slope in between 10-15% and ~ 51.23 km 2 (~ 0.79%) of study-area possessed slope between 15-35% ( Table 2). The slope of the topography in the projected study-area has given in Fig. 4. The high slope of topography has also increased the soil weathering and caused the loss of fertility of the soil. While, the plain regions (low slope topography) comparatively had improved the possibility of water holding capacity, recharge of the aquifer, development of the soils, upgradation of water-table, etc. The spatial distribution of the slope percentage of topography in the study area has shown in Fig. 4. It had observed that the projected study area possessed a moderate inclination of topography towards the north direction.

Soils
The soil of the study area had divided into three major types. The rst classi cation indicated clay-rich soils mixed with small size stone, obtained in low depth. This type of clay-rich soil had observed in the zone that possesses low-plateau in the study area. The formation or development of such soils has occurred in the well-drained zone possessing heavy erosions. In the second classi cation obtained loamy soil in the well-drained zones that were possessed a moderate slope of topography within the study area. Such types of soils were also observed at a low depth and formed in those areas possessing intense erosion. The third category of ne soils had observed in moderate deep to deep-depth. It had developed through natural weathering in that topography possessed a gentle slope and shown a good drain area (Fig. 5).
The statistics on the soil types of the study-area have summarized in table 3 (Table 3). The map of the soil distribution in the study-area has given in Fig. 5.   Table 4. The lineament-density of the study area had assessed by using the map, collected from the BHUWAN portal of the Indian Government (Fig. 7). The lineament-density of the study area was calculated in this research work by using the following formulae as suggested by various researchers Where Li indicated the lineament length in the study-area and A is the unit area for the respective zone.
The study-area had classi ed into three major ranges/classi cation of lineament-density. It observed that the lineament-density ranged between 0-0.10 km/km 2 for ~ 42.54% (~ 2758.39 km 2 ) area of the district, lineament-density ranged between 0.10-0.20 km/km 2 for ~ 28.36% (~ 1838.92 km 2 ) area of the district and 0.20-0.35 km/km 2 for ~ 29.10% (1887.32 km 2 ) of total study-area of the district ( Table 5). The high lineament-density increased the possibility of plum recharge of the groundwater aquifer and hence supports the better GWP zone. The study-area has a lineamentdensity between 0.20-0.35 km/km 2 was considered an excellent GWP zone, which enclosed ~ 29.10% of the study area (Fig. 7).  Details of observation well and sampling well are given in Fig. 1 and Fig. 3. The secondary data also collected from the annual report of the CPCB, MCDA was utilized in this research work to assign the relative weights to all variables. These variables are geology, the slope of topography, geomorphology, lineament-density, drainage-density, soil types, land-cover, and land-use, which were utilized during the GWP assessment in this research work (Table 6) . In this research work, the weight assignment has been carried out based on the literature reviews and an understanding of the soil, geology, physiography, lineament-density, drainage-density, land-use, and land-cover in the study area. In this research work relative weight is assigned between 1 to 9 as explained under the Saaty's Scale (1990). The maximum weight has given 9 and suggests extreme importance, while weight assigned 1 for the least important accordingly. The details of pair-wise comparisons of the assigned weight of these variables thematic layers have given in table 7. AHP was utilized in this research work during the evaluation of the normalized weight of the individual themes and their diverse layers. In AHP each variable is divided into a set of criteria, and further criteria are divided into sub-criteria. It has organized in certain preference order, to perform pairwise comparisons to nd the normalized weights. The comparisons between these thematic-layers adopted the similar methodology in this research work as suggested or adopted by the other researchers in their respective research work ( Table 7). The details of pairwise comparison and further normalized weight as the AHP process has given in table 7. The consistency ratio (CR) had calculated in this research work with the help of the consistency index (CI) and standard random index (RI) for all seven variables (Table 8). It had observed that the consistency index was around 0.0106, while the RI for seven variables considered from standard tables is 1.32. The calculated CR for this study was around 0.0080 much lower than 0.1000 (Table 8). This low CR indicated moderate consistency in the results of the pair-wise comparisons among the thematic layer assigned weight analysis. Hence, the AHP model used for this research work has shown reasonably good accuracy in geospatial prediction of the GWP zone in this study. Soil possessing poor-drainage property mostly observed high water holding or high water-storage capacity. While those soils having better drainage, property shows mostly poor water storage or poor-water holding capacity. Hence, clay textured vertisols soils available in the study-area ~ 18% area was considered excellent for water storage prospects (Fig. 5). The details of normal weight and normalized weight for the various soils type have given in Table 9. due to its wobbly and friable character. It supports the high in ltration ability of rainwater (or recharge of the aquifer through rainwater). Igneous and metamorphic rock dominating lithology having columnar, massive, and dense character, which are mainly responsible for the poor recharge of the aquifer through rainwater. It showed a poor GWP zone in these areas due to low recharge through rainwater (Table 10). zone has given low weight, and low-slope topography to the plain-areas had given higher weight due to the availability of surplus time for the recharge of the aquifer in the plain-areas.

Groundwater Potential (GWP) Map Development
The GWP map in this research work was created through the overlapping of the various variables thematic-layers. Groundwater potential index (GWPI) helped in classify the projected study-area into several GWP zones. GWPI was calculated by the weighted overlay analysis tool by using the following Malczewski (1999) equation.
Where Wi de ned as the normalized weight of the i th thematic-layers and W j is de ned as the normalized weight of the j th features of thematiclayers, m is the total number of thematic-layers, and n is the total number of features within a theme.  (Table 10).
The spatial distribution of the GWP zone in the Guna district has given in Fig. 9. It indicated that the excellent condition of subsurface water observed in the northern part of the Guna district may be due to the dominance of forest and at surface. This research work also supported by the report of CGWB (2016) shows 172.14 MCM water available in this zone of the Guna district is much higher than in another region.

Conclusions
This study had performed in a well-planned and systematic manner in a study area located in the semi-arid sub-tropical climatic zone of India. The poor-availability of water is a concern in this projected zone. Further, the availability of freshwater for drinking, agriculture, and other industrial activities is a challenging task in the study area. In this research work, an attempt has been taken to delineate the GWP in the Guna district through geospatial techniques, MCDA, and AHP. The seven types of the thematic-layers (geology, lineament-density, drainage-density, slope, soil, geomorphology, land-use, and land-cover) had used in this research work for the delineation of the GWP zone.
It observed that the CI is ~ 0.0106, while the RI for seven variables considered from standard tables is 1.32. The calculated CR for this research work was ~ 0.0080, much lower than 0.1000. This low CR indicated moderate consistency in the results of the pair-wise comparisons among the thematic layer assigned weight for the analysis. Hence, the AHP model used in this research work has shown reasonably good accuracy in geospatial prediction of the GWP zone in this study.
The statistical analysis of the GWPI was used in the classi cation of the study-area into ve-zone like very-high, high, moderate, low, and poor The summary of deleniation of GWP in the Guna district Groundwater Potential map of Guna district Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. This map has been provided by the authors.  ROC Curve