1 Introduction

Lineaments are any linear or curvilinear mappable features of the earth’s surface with distinct patterns [1, 2]. The lineaments have attracted geologists since the inception of use of aerial photographs and satellite imageries in geological studies. Geological lineaments are manifestation of the sub-surface continuation of faults, fractures, joints, dykes, bedding planes, foliation, streams, and boundaries of litho-contacts between stratigraphic formations and volcanic flows [1]. Geologist such as Hobbs and O’leary [3, 4], were the first to place on record the existence and importance of linear geomorphic features as the expressions of zones of weakness or structural offsets on the earth’s surface. Geological lineaments determine the tectonic architecture of the region and have close association with occurrence of economic minerals, petroleum deposits, groundwater flow as well as yield, marking its significance in their investigations [5,6,7].

The pioneer work of lineament mapping was labour-intensive, relying on aerial photographs to comprehend the structural complexities of regions [8, 9]. However, the advent of remote sensing datasets and GIS software, lineament mapping has become efficient, significantly benefiting hydrological, tectonic, drainage and landslide hazard studies [10,11,12,13,14,15,16,17,18,19,20]. Multispectral-temporal nature and synoptic view of satellite data and GIS software make the lineament mapping time and cost effective with greater accuracy [21,22,23,24,25,26,27]. Recent studies have leveraged data from DEM, Digital Terrain Model, and Landsat 8 OLI data, LISS-III, RISAT-1 SAR for lineament extraction [21, 28,29,30,31,32]. While, automatic lineament extraction methods have been developed, but they often mistakenly identify non-geological linear features, such as utility lineaments-roads, railway lines, power lines, canals etc. Therefore, to ensure accuracy and relevance, manual extraction of lineaments from satellite imageries [33] is preferred for the present study.

In context to groundwater occurrence, especially in igneous and metamorphic terrains which lack primary porosity and permeability, the lineaments have been of paramount importance [34]. Numerous research works have demonstrated a close association between the lineaments and groundwater occurrence [34,35,36,37,38,39,40,41,42,43,44,45]. Sometimes, lineaments are underlain by zones of localized weathering facilitating infiltration of meteoric water and indicates the regions of structural weakness [34]. Specifically, in hard rock terrains, the lineaments induce secondary porosity and permeability, augments infiltration of surface runoff supporting the storage of groundwater. Wherever, these lineaments show consistency, regional continuity and high density, give rise to a good groundwater source of appreciable size [46]. Thus, the identification and mapping of lineaments plays a decisive role in determination of groundwater occurrences, in hard rock terrains [34].

The district Dangs, marks the extension of Western Ghats in Gujarat, with less transmissible basaltic rocks, rugged trappean highlands, and steep slopes [47,48,49]. Despite high average annual rainfall (2000 mm), the terrain conditions cause higher runoff than infiltration, leading to groundwater crisis during the dry season [47, 48, 50]. The basaltic flows of Deccan Volcanic Province (DVP) characterize the aquifer system of the region with groundwater mainly confined to fractured and weathered horizons [35, 46, 51]. Many groundwater structures struggle to sustain through the scorching summers, failing to yield adequate water. To ensure year-round groundwater yield, the extraction structures can be strategically located in areas with the thickest weathered horizons and high fracture/joint density. To address this crisis, it is important to ruminate the spatial distribution of lineaments in the region. The satellite imagery of Dangs reveals that the region is extensively crisscrossed by the lineaments, including joints, fractures, and dykes. Therefore, investigating such lineaments is crucial for understanding their influence on groundwater occurrence of the region. The objective of present study is to investigate the influence of geological lineaments on groundwater occurrence of the Khapri watershed in Dangs district. This is achieved by classifying lineaments into positive and negative categories based on their contribution to water infiltration. Additionally, the study aims to analyse the spatial distribution and concentration of lineaments as well as its orientation in the Khapri watershed.

The novelty of the present study is the use of hill-shades derived from the Carto-DEM at various illumination angles to extract maximum lineaments. This paper classifies the lineaments into positive and negative to investigate their possible influence on groundwater occurrence in the watershed. The positive lineaments due to their exposed bare rock and steeply sloping surfaces will constitute runoff and not contribute to groundwater as effectively as the negative lineaments. This comprehensive approach allows to capture a complete representation of the lineament network and its influence on groundwater occurrence in the Khapri watershed.

2 Study area

The district Dangs marks the southernmost part of trappean highlands of Mainland Gujarat. It is drained by four important rivers viz. Ambica, Purna and their major ephemeral tributaries Khapri and Gira respectively. The river Khapri emerges near village Vanar on the western slope of trappean highlands of district Dangs. The longest stretch of river Khapri lies in northwest direction and continues its journey through villages viz., Galkund, Umbarpada, Ahwa, and merges with river Ambica near village Vati. The Khapri watershed is located between 20° 53′ 27.52′′ N and 20° 35′ 6.91′′ N latitudes and 73° 27′ 12.42′′ E and 73° 50′ 13.53′′ E longitudes and occupies area around 523 km2 and is included in 46H/14, 46H/13, 46H/10, 46H/9 and 46H/5 SOI topographic maps (1:50,000) (Fig. 1). The elevation varies from 1083 m in south-eastern part to 86 m above mean sea level (amsl) in north-west. Geologically, the Khapri watershed is completely underlined by Deccan basalts, overlain by recent alluvium and alluvio-colluvial sediments of Quaternary age. The recent deposits consisting of gravels, sand, silt and clay sized particles are thin and are present in irregular patches along the river and at the confluence of river Khapri with Ambica. Amongst the eleven flows identified in the district, the Khapri watershed is underlined by nine basaltic flows [47]. The flows are intruded by ENE-WSW, WNW-ESE, NW–SE and NE-SW trending dykes and are transacted by numerous regional joints trending NNE-SSW as well as fractures. Megascopically, the flows in Khapri watershed are light to dark grey, fine to coarse grained, non-porphyritic to porphyritic.

Fig. 1
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Location map of the Khapri watershed

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3 Dataset and methodology

The lineaments of the Khapri watershed, are extracted with the help of IRS LISS-III (24 m) (bhuvan.nrsc.gov.in) satellite data of May 2019 and Carto-DEM (bhuvan.nrsc.gov.in). The detailed methodology is graphically represented in Fig. 2. To extract the lineaments from IRS LISS-III satellite data the False Colour Composite (FCC) is prepared by combining Bands 4, 3, 2 i.e., SWIR, NIR and Red respectively. On the other hand, to extract lineaments from Carto-DEM (30 m), shaded relief maps with light illumination angle set at 45° intervals (45°, 90°, 135°, 180°, 225°, 270°, 315°, 360°) are generated in GIS environment by applying “Hill-shade” tool. Upon generation of the FCC and shaded-relief maps, the apparent geological lineaments were digitized using line tool in Arc Map 10.4. To ascertain the mapped lineaments are geological features, these are verified through google earth (https://earth.google.com) and ground-truth verification. The lineaments relating to public utilities such as roads, bridges, powerlines etc. were discarded by overlaying them on topographic maps and google earth data. The comprehensive lineament map of the Khapri watershed is prepared by combining all the lineaments mapped from FCC and eight shaded-relief maps, where all the duplicate lineaments are discarded. The rockworks software is employed to plot the rose diagram for determining dominant orientation of lineaments in the Khapri watershed. Later, the lineaments were categorized as (i) Positive lineaments and (ii) Negative lineaments. The ridges, plateaus and dykes on the satellite data are categorized as positive lineaments [52]. While, offsets, regional and decipherable local joints, straight stream segments are categorized as negative lineaments [52]. Based on this classification, the negative lineament density and positive lineament density maps have been prepared in Arc Map 10.4 and are correlated with seasonal groundwater level data.

Fig. 2
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Flowchart depicting dataset and methodology employed for the study

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4 Lineament architecture of the Khapri watershed

The geological lineaments of the Khapri watershed are mapped on FCC satellite image (Fig. 3) and eight shaded relief maps generated from Carto-DEM at different azimuthal angles (Figs. 4, 5, 6, 7). From these lineament maps, it is observed that maximum lineaments are mapped from the hill-shade with illumination azimuths 45° and 360° (Table 1). While, the minimum number of lineaments are mapped from illumination azimuths 225° and 270° (Table 1). The variation in the number of lineaments mapped from a shaded relief maps generated from same Carto-DEM is due to the False Topographic Perception Phenomenon (FTPP) initially described by [53], and recently substantiated by [21, 54, 55]. The FTPP is governed by the illumination angle and can cause the ridges to appear as valleys and vice versa [53, 56]. In the present case, the hill shades with azimuth angles 45° provides good clarity and is useful to decipher maximum lineaments (Table 1), suggesting little or no influence of FTPP. While, the hill shades with azimuth angles 90°, 225° and 270° are affected by FTPP and depicts the inverse picture of rugged topography of the Khapri watershed, which makes it difficult to map the lineaments (Table 1). These hill shades were carefully examined with google earth imagery as well as during ground-truth verification. These observations are substantiated by the studies of [21, 52, 57, 58], where hill shades prepared at certain illumination angles are effective for mapping lineaments compared to others.

Fig. 3
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Extraction of geological lineaments from IRS LISS-III FCC satellite data

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Fig. 4
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Extraction of lineaments from shaded relief map having a 45° azimuth angle b 90° azimuth angle. Inset rosette diagram represents the trend of lineaments

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Fig. 5
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Extraction of lineaments from shaded relief map having a 135° azimuth angle b 180° azimuth angle. Inset rosette diagram represents the trend of lineaments

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Fig. 6
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Extraction of lineaments from shaded relief map having a 225° azimuth angle b 270° azimuth angle. Inset rosette diagram represents the trend of lineaments

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Fig. 7
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Extraction of lineaments from shaded relief map having a 315° azimuth angle b 360° azimuth angle. Inset rosette diagram represents the trend of lineaments

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Table 1 Number and length of lineaments extracted from different hill-shade angles in the Khapri watershed
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The total length of lineaments mapped from azimuths 45° to 360° is 1682.66 km (Table 1). The lineaments of maximum length are mapped from the hill shade illuminating at 45°, while the minimum length is mapped at 270° (Table 1). The total length of lineaments in comprehensive lineament map (Fig. 8) is 503.98 km. This total length in the comprehensive lineament map (Table 2) is far less than the lengths of lineaments mapped from individual hill shades, due to elimination of the duplicate lineaments. This clearly suggests that hill shade viewed from single illumination angle is not enough to extract the maximum lineaments present in a region. Therefore, the hill shades viewed from more than one illumination angle is important. The similar observations were recently made by [57]. To ascertain the mapped lineaments are geological features, these are validated through google earth and ground-truth verification (Fig. 9). The comprehensive lineaments are further classified into two categories viz. (i) Positive lineaments and (ii) Negative lineaments (Fig. 10). The ridges, plateaus and dykes on the satellite data are categorized as positive lineaments [52]. While, offsets, regional and decipherable local joints, straight stream segments are categorized as negative lineaments. The primary reason of categorization of lineaments is due to their influence on water infiltration capacity.

Fig. 8
figure 8

Comprehensive lineament map of the Khapri watershed, prepared by combining all the lineaments mapped on IRS LISS-III FCC satellite data and eight shaded-relief maps. Inset rosette diagram represents the prominent trend of lineaments

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Table 2 Number and length of positive, negative and comprehensive lineaments in the Khapri watershed
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Fig. 9
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Ground truth verification and measuement lineament trend

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Fig. 10
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a Positive and b Negative lineamens of the Khpari watershed. Inset rosette diagram represents the prominent trend of lineaments

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The total length of positive lineaments is 117.84 km. The longest positive lineament (5.4 km) and the shortest positive lineament (0.24 km) in the Khapri watershed are probably marked by dykes (Table 2). The positive lineaments dominantly trend in ENE-WSW, WNW-ESE, NNE-SSW and NE-SW (Fig. 10), while the negative lineaments dominantly show NNE-SSW, NNW-SSE, N-S, NE-SW and ENE-WSW trends (Fig. 10). The total length of negative lineaments is 383.61 km. The longest negative lineament (7.32 km) in the Khapri watershed is marked by a major hydro geo-fracture and engulfs number of lower order streams, while, the shortest negative lineament (0.24 km) (Table 2) is located in central part of the watershed near village Gaurya and is marked by a first order stream. The positive lineaments due to their exposed bare rock and steeply sloping surfaces will constitute runoff and not contribute to groundwater as effectively as the negative lineaments [52]. Moreover, prominent zones of localized weathering occur along the negative lineaments which give rise to secondary porosity and permeability resulting into good groundwater repository.

Rose diagrams are plotted in rock-works software for lineaments extracted from individual shaded relief maps (Figs. 4, 5, 6, 7) and the comprehensive lineament map (Fig. 8), to understand their orientation in the Khapri watershed. The rose diagrams indicate NNE-SSW and ENE-WSW are dominant lineaments directions for all azimuthal shaded relief maps. However, a minor shift from predominant direction is observed for the azimuth angle 180° and 225° due to FTPP (Figs. 5d, 6e). The orientation of lineaments in the Khapri watershed are following the regional trends of Narmada son lineament and N-S Cambay graben [59].

Lineament density is the total length of lineaments in per unit area [60]. It is one of the most significant geo-environmental parameters to understand the intensity of tectonic deformation, permeability characteristics of the region, and demarcate the groundwater potential zones. The areas with high lineament density shows presence of prominent zones of localized weathering that give rise to secondary porosity and permeability and thus forming a good groundwater repository [46]. The comprehensive lineament density of Khapri watershed ranges from 0.1 km/km2 to 8.81 km/km2. It is classified into three categories viz., low (0.1–1.7 km/km2), medium (1.8–3.9 km/km2) and high (4.0–8.8 km/km2) (Fig. 11). The positive lineament density ranges between 0.1 and 1.2 km/km2 and is classified into three categories viz. low (0.1 to 0.48 km/km2), medium (0.49–1.5 km2) and high (1.6–3.3 km2) (Fig. 12). The high positive lineament density is observed in upper reaches (near villages Ukhatiya, Sinbandh and Galkund), in the central part (to the north of villages Nilsakiya, Gaurya and Pimpri), and lower reaches (near village Koylipada). The negative lineament density varies from 0.1 to 8.8 km/km2 and is directly related to infiltration. It is classified into three categories viz., low (0.1–1.5 km/km2), medium (1.6–3.8 km/km2) and high (3.9–8.8 km/km2) (Fig. 12). The high negative lineament density is observed near villages Sinbandh, Galkund, Pipalpada, and Isdar in upper reaches while, in the central part it is observed to the south of village Khapri. In lower reaches, it is observed near villages Ghodi, Dhodhalpada, Kusmal, Koylipada and Raygadh.

Fig. 11
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Comprehensive lineament density map of the Khapri watershed

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Fig. 12
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a Positive and b negative lineament density maps of the Khapri watershed

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4.1 Influence of lineaments on groundwater regime of the Khapri watershed

To understand the influence of lineaments on groundwater regime, the seasonal groundwater fluctuation is correlated with positive and negative lineament density. The groundwater fluctuation is obtained through groundwater depth data, collected in pre- (May, 2022) and post- (November, 2022) monsoon seasons from dug-wells falling in positive and negative lineament density classes. The seasonal groundwater fluctuation of representative wells and corresponding lineament density category is given in Table 3 and Table 4. The lowest total groundwater fluctuation (0.4 m) is observed in the category of high negative lineament density (Table 4). The higher groundwater fluctuation (6.5 m) is encountered for the category, high positive lineament density (Table 3). The scatter plots of positive lineament density v/s groundwater fluctuation (R = 0.69) (R2 = 0.48) and the negative lineament density v/s groundwater fluctuation (Fig. 13) shows moderate correlation (R = − 0.7) (R2 = 0.5). This indicates that in general the regions with high positive lineament density shows higher groundwater fluctuation while the regions with high negative lineament density shows lower groundwater fluctuation. Thus, 48% and 50% variation in groundwater fluctuation can be explained by positive and negative lineament density respectively. Similar, controls on groundwater occurrences were also observed by [34,35,36,37,38,39,40,41,42,43,44,45].

Table 3 Positive lineament density class and corresponding groundwater fluctuation
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Table 4 Negative lineament density class and corresponding groundwater fluctuation
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Fig. 13
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Scatter plots representing a positive correlation between groundwater fluctuation and positive lineament density and b negative correlation between groundwater fluctuation and negative lineament density

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5 Conclusions

  1. 1)

    The integrated use of IRS LISS-III satellite data and Carto-DEM with GIS techniques are effective in accurately mapping and validating geological lineaments, highlighting the necessity of multi-angle illumination to overcome False Topographic Perception Phenomenon (FTPP).

  2. 2)

    The comprehensive lineament analysis of the Khapri watershed reveals that the dominant lineament orientations are NNE-SSW and ENE-WSW, consistent with regional geological trends. The analysis aids in understanding the influence of geological lineaments on groundwater occurrences.

  3. 3)

    The approach of classifying geological lineaments into positive and negative categories, demonstrates that negative lineaments, characterized by regional joints and fractures, relatively enhance groundwater infiltration and storage, while positive lineaments contribute less due to their runoff-inducing characteristics.

  4. 4)

    The investigation indicates a moderate correlation between positive–negative lineament densities and groundwater regime. Regions with high negative lineament density exhibit relatively lower groundwater fluctuation, indicating better groundwater occurrences, while high positive lineament density areas show greater fluctuation, implying comparatively lesser groundwater occurrence.

  5. 5)

    As per the linear regression analysis, around 48% and 50% variation in groundwater fluctuation is explained by the positive and negative lineaments respectively. However, more precise correlation can be obtained, if the analysis is supplemented with field based geophysical data, which is not expensive but exhaustive.

  6. 6)

    The analysis emphasizes the importance of identifying and mapping negative lineaments for targeting groundwater resources in hard rock terrains, such as the Khapri watershed, with limited primary porosity and permeability.