Geology
The geological map of the study area (Fig. 4) shows that it is covered by varied geological formations such as basaltic lava flows (Deccan trap of Upper Cretaceous to Eocene age) covering the northern part of the catchment area which are overlain by Quaternary sediments viz. Piedmont zone (Bazada zone) and the alluvium covering the southern part of the area (Tiwari et al. 2010; Saha and Asthana, 1990). Out of which, the majority of the basin area (61.33%) is covered with a thick pile of alluvial sediments.
Since geology plays a major role in controlling the groundwater as well as surface water resources, the area has been classified by assigning appropriate weights as per groundwater potential. Accordingly, a higher rating of three (3) is given to alluvial plain (older and younger) wherein the groundwater potential is expected to be very good to excellent. While least weightage (1) is given to the Bazada zone due to its poor groundwater potential since it acts as a groundwater run-off zone. The Deccan trap having moderate groundwater potential is allotted with the weightage value of two (2).
Geomorphology
Geomorphological processes reflect inter-relationship amongst the variables like climate, geology, soils, and vegetation; and thus, therefore, are an important aspect of environmental analysis and planning (Buol 1973; Blarzcsynski 1997). The geomorphological set-up of the study area is interpreted from the digitally enhanced satellite image and the results of the same are categorized into four different geomorphological units i.e. alluvial plain younger/lower, alluvial plain older, Piedmont zone (Bazada zone), and the upper basaltic plateau (Fig. 5). The thematic map on geomorphology reflects that the older alluvial plain, formed due to the deposition of river sediments, is widely distributed and has covered an extensive area of 262.15 km2 (50.30% of the total area). The other geomorphological unit i.e. Piedmont zone (Bazada zone) trends from north to south and spreads in a 55.26 km2 area. The least area of the basin is occupied by the younger alluvium plain unit, having about 14.39 km2 spread (3.20% of the total area). The upper plateau developed over the Deccan trap is present exclusively in the northern part. The lowest occurred zone is the younger alluvium plain covering about 14.39 km2 area and incorporating about 3.20% of the total catchment area. Based on their hydrological properties, the highest rating of three (3) is assigned to the alluvial plain (older and younger) whereas the lowest rating of one (1) is assigned to the Piedmont zone (Bazada zone).
Landuse/ Landcover
The existing land use in the area is a key factor to understand the land utilization process which has a direct bearing on groundwater situation and hence forms a base of designing the developmental plan for any region. The map on land use/land cover for the study area is prepared from the IRS-P6 LISS III satellite image data (acquisition in October 2015), by executing the maximum likelihood classification algorithm technique. The entire process of classification of the satellite image is performed in Arc-GIS 9.0 software. The map so obtained shows, five major classes, viz. agriculture, built-up, forest, wastelands, and water bodies (Fig. 6). During the process, the highest rating (3) is assigned to agriculture, whereas the lowest rating (0) is assigned to the built-up land and water bodies due to their lesser possibility of changing the existing land use pattern. The land use/land cover map of the study area shows the dominance of the agricultural area. The high altitude region encompasses the forest area. As agriculture is present over most of the area the need for water for crop cultivation is also demanding which anticipates overexploitation of groundwater.
Cropping Pattern
The thematic map pertaining cropping pattern has been prepared from the digitally enhanced image and analyzed further to obtain the results on the cropping pattern scenario. The results are categorized into nine (9) divisions of crop i.e. citrus plantation, current fallow land, dense closed forest, gullied/ravenous land, Kharif, Kharif + Rabi (double-cropped), land with scrub, land without scrub, and Rabi (Fig. 7). This map on the cropping pattern depicts the growth of dense forest over 96.28 km2 (21.41%) area in the northern hilly region. Because of inadequate water availability, Kharif is the most cultivated crop in the area of 235.61 km2 (52.40%); whereas, Rabi crop is least occurred and found scattered over 1.88 km2 (0.42%) in the near central region. The presence of Kharif + Rabi (double-crop) is also remarkable in its presence and occupies 97.51 km2 (21.69%) of the region. The highest rating (3) is assigned to Citrus along with Kharif + Rabi (double-cropped) as they show the productive lands whereas the lowest (1) rating is assigned to the gullied/ravenous land and scrubland where there is further scope for its development.
Groundwater Quality
The work on groundwater quality in the study area has been attempted earlier by various researchers. The available hydrochemical data generated by Jain and Tambe (2012) is modified and used further by applying the nearest neighbor interpolation technique in a GIS platform to derive the groundwater quality map for the Bordi watershed. Based on the distribution of total dissolved solid (TDS) values, the watershed area is categorized into three divisions, i.e. fresh, brackish, and saline water (Fig. 8). The freshwater (TDS < 1500) has occupied an area of 106.34 km2 (23.67%) primarily in the northern-southern parts and few patches of the north-east region. The brackish water (TDS in between 1500–3000) has the maximum areal extent and is found mainly in the central region of 273.82 km2 area (60.90%). The saline groundwater (TDS > 3000) is found distributed in the north-east and south-west regions and has 69.38 km2 (15.43%) of aerial extent. The highest rating is assigned to freshwater whereas the lowest rating is assigned to the saline water category. This is because fresh water is more considerable over saline water from the geo-environmental point of view.
Groundwater Fluctuation
The studies on groundwater levels and their fluctuations over the period (i.e. pre and post-monsoon periods) are vital to understanding the groundwater regime of any area. The hydrogeological data of 66 inventory wells from the entire watershed were collected pre and post-monsoon season of the year 2012. The total depth of the existing wells ranged from 2.6 and 39.80 m below ground level (bgl). The pre-monsoon and post-monsoon water level vary from 1.4 and 39.60 m (bgl) and 0.9–39.50 m (bgl) respectively. The average seasonal fluctuation is around 0 to 6.90 m. The groundwater fluctuation map for the study area is derived based on water table data of the observation wells (Table 2). As per this, the map is categorized into three classes i.e. high, moderate, and poor (Fig. 9). Poor groundwater fluctuation is the most dominant category over 213.679 sq. km and comprises 47.52% of the total area. The highest rating (3) is assigned to poor fluctuation whereas the lowest rating (1) is assigned to a high fluctuation category according to the groundwater potential.
Table 2
Well inventory details of total sixty six (66) dug wells falling in the Bordi Watershed
Well
No.
|
Location/
Village
|
Total Depth (mbgl)
|
Depth to Water Level (mgbl)
|
Groundwater Fluctuation
(m)
|
Pre-Monsoon
|
Post-Monsoon
|
1.
|
Yeoda
|
9.94
|
6.25
|
4.8
|
1.45
|
2.
|
Yerandgaon
|
11.28
|
6.1
|
5.65
|
0.45
|
3.
|
Bambarda
|
7.84
|
4.27
|
1.2
|
3.07
|
4.
|
Pimplod
|
13.59
|
8.36
|
6.25
|
2.11
|
5.
|
Jainpur
|
8.36
|
8
|
7.4
|
0.6
|
6.
|
Adula
|
7.39
|
6.61
|
4.2
|
2.41
|
7.
|
Sagarvadi
|
7.72
|
5.97
|
2.5
|
3.47
|
8.
|
Jogarvadi
|
6.71
|
4.68
|
2.6
|
2.08
|
9.
|
Warudbedruk
|
7.01
|
7.32
|
5.7
|
1.62
|
10.
|
Warudbedruk
|
8.23
|
7.14
|
5.9
|
1.24
|
11.
|
Rajkheda
|
10.93
|
6.88
|
6.2
|
0.68
|
12.
|
Wadnergangai
|
10.54
|
7.67
|
5.6
|
2.07
|
13.
|
Wadnergangai
|
5.31
|
5.41
|
4.1
|
1.31
|
14.
|
Wadnergangai
|
7.59
|
6.88
|
5.25
|
1.63
|
15.
|
Wadnergangai
|
6.48
|
6.76
|
5.1
|
1.66
|
16.
|
Wadnergangai
|
11.25
|
8.18
|
6
|
2.18
|
17.
|
Wadnergangai
|
13.03
|
9.25
|
7.1
|
2.15
|
18.
|
Gavandgaon
|
11.91
|
12.29
|
8.5
|
3.79
|
19.
|
Hingani
|
12.1
|
9.58
|
6.5
|
3.08
|
20.
|
Kalgavan
|
28.23
|
20.48
|
17.6
|
2.88
|
21.
|
Kalgavan
|
20.7
|
21
|
20.45
|
0.55
|
22.
|
WadaliDeshmukh
|
20.25
|
20.9
|
20.5
|
0.4
|
23.
|
Bhuraskheda
|
18.25
|
18.55
|
18.55
|
0
|
24.
|
Nimkhed
|
39.62
|
35.05
|
35.05
|
0
|
25.
|
Nimkhed
|
28.66
|
24.38
|
24.38
|
0
|
26.
|
Karla
|
32.2
|
29.1
|
28
|
1.1
|
27.
|
Bhandaraj
|
32.39
|
30.25
|
28.9
|
1.35
|
28.
|
Gavandgaon Bk.
|
7.48
|
10.2
|
7.6
|
2.6
|
29.
|
Sategaon
|
17.85
|
17.65
|
17.1
|
0.55
|
30.
|
Sategaon
|
21.92
|
22.37
|
22
|
0.37
|
31.
|
Rajapur
|
22.09
|
22.24
|
19.1
|
3.14
|
32.
|
Rajapur
|
15.4
|
15.9
|
15.25
|
0.65
|
33.
|
Jawardi
|
26.8
|
21.76
|
20
|
1.76
|
34.
|
Dhanwadi
|
30
|
30
|
29.5
|
0.5
|
35.
|
Adgaon
|
39.7
|
39
|
38.8
|
0.2
|
36.
|
Murtijapur
|
41
|
39.6
|
39.5
|
0.1
|
37.
|
Malkapur
|
28.95
|
25.7
|
25.4
|
0.3
|
38.
|
Malkapur
|
25.18
|
25.5
|
25.3
|
0.2
|
39.
|
Adgaon
|
39.8
|
38.5
|
38.3
|
0.2
|
40.
|
Karla
|
30.7
|
28.35
|
26.4
|
1.95
|
41.
|
Panaj
|
29.7
|
30
|
27.35
|
2.65
|
42.
|
WadaliDeshmukh
|
33.63
|
26.9
|
20
|
6.9
|
43.
|
Ruikhed
|
26.1
|
19.1
|
13.8
|
5.3
|
44.
|
Mahagaon (Gadhi)
|
6
|
4.9
|
3
|
1.9
|
45.
|
Mahagaon (Gadhi)
|
2.6
|
1.4
|
0.9
|
0.5
|
46.
|
Rajura
|
7.95
|
5.7
|
2.9
|
2.8
|
47.
|
Vastapur
|
7.78
|
3.2
|
1.4
|
1.8
|
48.
|
JanunaBedruk
|
5.4
|
4.5
|
1.5
|
3
|
49.
|
Jhingapur
|
12.35
|
12.6
|
6.4
|
6.2
|
50.
|
Menghat
|
6.4
|
6
|
1.4
|
4.6
|
51.
|
Khirkundkhurd
|
4.9
|
3.2
|
2.35
|
0.85
|
52.
|
Mardi
|
8.8
|
5.6
|
1.85
|
3.75
|
53.
|
Ruikhed
|
31.7
|
21.5
|
18.7
|
2.8
|
54.
|
Chausala
|
35.6
|
35
|
34.8
|
0.2
|
55.
|
Chinchona
|
29.2
|
20
|
17.2
|
2.8
|
56.
|
Nimkhed Bazar
|
24.35
|
21.5
|
18.8
|
2.7
|
57.
|
Hirapur
|
26.3
|
24.7
|
21.7
|
3
|
58.
|
Palaskhed
|
9.35
|
6.7
|
3.5
|
3.2
|
59.
|
Khirada
|
23.6
|
24
|
22.2
|
1.8
|
60.
|
Lakhar
|
36.45
|
35.2
|
35
|
0.2
|
61.
|
Hasnapur
|
29.1
|
28.15
|
27
|
1.15
|
62.
|
Anjangaon
|
24.9
|
24.5
|
22.5
|
2
|
63.
|
Selgaon
|
28.95
|
27.15
|
24.4
|
2.75
|
64.
|
Dhari
|
11.95
|
9.3
|
5.9
|
3.4
|
65.
|
Dahigaon
|
28.8
|
24
|
18.2
|
5.8
|
66.
|
Garajdari
|
6.0
|
5.0
|
1.5
|
3.5
|
Range
|
2.6–39.80
|
1.4–39.60
|
0.9–39.50
|
0-6.90
|
Soil Depth
The soil formed in topographic sequence under specific geo-pedological environmental conditions has great influence of different geomorphic features in conjunction with the type of parent materials (Kantor and Schwertmann 1974). For digital soil depth database creation, the soil map developed by the National Bureau of Soil Sciences & Land Use Pattern (NBSS & LUP) is used in this study and the obtained results are categorized into three classes i.e. deep, moderate, and shallow depths (Fig. 10). The soils of the Bordi watershed show a wide variation in their depths because of their physiographical set-up. The soils on hills and slopes are having shallow to medium depth while in the low lying areas and river valleys deep soils are observed. Soil depth map depicts shallow soil (< 25cm) at the high altitude regions particularly in the northern part, moderate soil (25-50cm) mostly in the valley fills around the shallow depth region, and deep soil (> 50cm) in the central and entire southern region of the watershed. The ratings are assigned according to the importance of soil depth as per its erodable nature, in which, the highest rating (3) is assigned to the deep soil which is least prone to erosion, whereas, the lowest rating (1) is assigned to shallow soil that is highly susceptible to erosion.
Soil Texture
Soil texture is one of the important factors in development planning as it governs the infiltration characteristic of soil (Varade et al. 2013). The soil map depicted mainly three types of soil textural classes i.e. gravelly clay loam, gravelly sandy clay loam, and silty loam (Fig. 11). The major portion of the study area is occupied by gravelly clay loam 325.68 km2 (72.43% of the total area) as apparent from the map. The poorly drained clay soils have a high runoff, while sandy soils generate less runoff (Aller et al. 1987). Considering this, the highest weightage of three (3) is given to silty loam, while weightage of two (2) is given to gravelly sandy clay loam and one (1) weightage is provided to gravelly clay loam.
Slope
The slope or topographic features of an area are important as they affect the run-off process, soil erosion, and land use planning. By considering it, the slope map of the watershed was generated by using the Cartosat-1 DEM and Survey of India topographical maps. The topography of the area is distributed as the low slope (less than 5%) over the entire alluvial region towards the mid-lower portion, moderate slope (5–15%) occurs in a piedmont zone in the northern side, and high slope (> 15%) seen in the extreme northern boundary (Fig. 12). It is found that the majority of the study area falls under the low slope class (Table-1). The highest rating of three (3) is assigned to the low slope category due to its favorable situation for agricultural, plantation, and developmental activities. All land with low to moderate topographical location was rated high for sustainable geo-environmental protection and development.
Soil Erosion
Soil erosion is a process of removing the earth material (both rock debris and soil) and its further transportation to a longer distance by the various erosive agents (Singh 1998). The studies on soil erosion are essential to predict soil erosion rates under land-use conditions vis-à-vis geo-environmental situation. The soil erosion data extracted from the soil map of NBSS & LUP depicts three divisions viz. slight, moderate, and severe erosion types (Fig. 13). Because of the planer topography, slight erosion is observed in most of the central and lower reaches covering 316.207 sq. km area (70.33%). Moderate erosion is observed mostly in the highlands of the Deccan trap region due to its resistive nature, whereas severe erosion is remarkably observed only along the stream channels and a few places in the highlands of weathered nature. The highest rating is assigned to slight erosion whereas the lowest rating is assigned to severely eroded areas. This is because slight erosion is much considerable over severe erosion from the geo-environmental point of view.
Integrated Regional Geo-environmental Quality Evaluation
The status of the physical environmental condition discussed above reveals the environmental quality scenario, thus indicate towards limited choices of land use/land cover, soil erosion, infertility of soils, and paucity of potable water, etc. Similarly, the long-term use of improper agricultural practices has exploited land and water resources in the basin and poses the problems of sensitivity, fragility, and environmental changes. The geo-environmental potential index (GPI) of the Bordi River basin is calculated based on the above ten factors. The GPI values of the basin range between 3 to 30. Subsequently, these values are reclassified into four classes as follows: (a) poor resources (< 9), (b) low resources (9–16), (c) moderate resources (16–23), (d) high resources (> 23) (Table-3) and the spatial distributions of regional geo-environmental resources are given in Fig. 14. The categorization of geo-environmental resources in the study area is discussed below;
Area with high geo-environmental resources
The areas with the high geo-environmental resources are distributed in the southern part of the Bordi watershed. The geo-environmental potential index map shows that approximately 48.30% of the study area is classified under high geo-environmental quality with GPI index values ranging between 23 to 30. The region shows good vegetation cover, a weak and slight intensity of soil erosion. The sound quality of the geo-environment in this portion is due to high vegetation cover, rich nutrients in the soil, fewer disturbances by human beings, and good soil penetrability. The high geo-potential of the area indicates that this area is very suitable for development through agricultural practices and thus is likely to be overexploited which may lead to degradation of the environment. Therefore the area needs the implementation of conservation measures on a large scale mainly to retain sustainability.
Area with moderate geo-environmental resources
The moderately geo-environmental resources zone accounts for 25.75% of the whole study area with its values ranging between 16 and 23. It is distributed in the north and south-west of the study area (The landform is characterized by high mountains and leveled lands), of which the ecosystem is composed of dense forest in the uplands. Areas with moderate eco-environmental quality have strong eco-sensitivity, less human interferences, and important ecosystem service included the whole of Chikhaldara, mid, western, and northern parts of the Bordi basin. The major region is occupied by farmland, forest, along with some grassland. The human activities are relatively less, thus making the environment quality of this part better. This area is also likely to deteriorate due to the exploitation of forest resources as well as high erosion due to steep slopes and thin soil cover. To protect the area from further deterioration it is necessary to implement soil and forest conservation techniques in this area.
Area with low geo-environmental resources
The low geo-environmental resources zone is mainly concentrated in the northern part of the Bordi watershed. It constitutes 23.98% of the basin area with GPI index values ranging between 9 and 16. The major land-use types in this area are agriculture and forestland. The eco-environment of the area appears to be affected by human activity more seriously, and the eco-environment quality is only generic.
Area with poor geo-environmental resources
The areas with poor geo-environmental resources are located in the northern area in the form of scattered patches of 8.88 km2 only accounted for a very small proportion (2%) of the study area. The areas are in the vicinity of small towns with a hard surface and limited vegetation cover (Schotten et al. 2001). The GPI index has values is below nine (< 9). This area since located close to human settlement is more prone to degradation due to their activities thus requires measures for restoration of soil and vegetation cover.
Table 3
Geo-environmental quality categories of study area
Class
|
GPI Index
|
Area (km2)
|
Area (%)
|
High resources
|
> 23
|
217.18
|
48.30
|
Moderate resources
|
16–23
|
115.79
|
25.75
|
Low resources
|
9–16
|
107.84
|
23.98
|
Poor resources
|
< 9
|
8.88
|
2
|
|
|
449.608
|
100%
|