Hard Rock Terrain Research Articles

Geospatial Techniques for Efficient Conservation and Management of Surface Water for Irrigation in Joganbedi Village, Khargone District, Madhya Pradesh, India

Abstract. The study aimed at developing improved methods based on remote sensing and GIS techniques to increase cultivated area under irrigation. Landuse / landcover mapping was considered as the key component to prioritize locations for constructing appropriate recharge structures. Joganbedi scheme was proposed for this study. Joganbedi is situated 13 km. from Khargone, district Khargone, Madhya Pradesh, India. Command area of the proposed scheme lies in Beda sub-basin which is a tributary of the Narmada River. This area is of hard rock terrain and is occupied by the Deccan basalt. The main objective of the study was surface water conservation and management via multi-spectral information resulting from remotely sensed data to increase irrigation. High resolution GeoEye1 stereo images were used for generation of DEM, contour, landuse/landcover mapping, lineaments and drainage mapping. DEM was used for canal alignment. and further, contours were used to determine catchment, submergence /FRL, and command areas. Landuse/landcover statistics of submergence area helped to identify different land classes within the study area. These parameters are required for scheme planning. Additionally, rainfall data, maximum drawdown level, and dam height were collected as supporting parameters. The study concludes that landuse/landcover mapping is useful in identification of surface water conservation and management plan for irrigation purpose. It also proves that implementation of Joganbedi scheme will increase the cultivated area under irrigation, facilitate the farmers for multi season cropping and help in improving their economic condition.

Spatio-temporal Identification of Regions with Anomalous Values of 222Rn in Groundwater of Madurai District, Tamilnadu, India

Measurement of dissolved radon (222Rn) activity concentration in groundwater samples from private and public hand pumps, and in bore wells located at Madurai district of Tamilnadu, India, are presented. The study attempts to identify the background value of 222Rn in groundwater of hard rock terrain and the main aquifer contributing 222Rn, and to determine if any correlation exists with observed field parameters. Measured parameters included pH, TDS, Temperature and 222Rn in 42 samples for two seasons (South West Monsoon [SWM] and North East Monsoon [NEM]). The results show that the 222Rn activity concentration of the samples ranged from 0.049 to 59.952 Bq/L in South west monsoon and 0.12 to 211.60 Bq/L in North east monsoon. The higher activity was noted in NEM and the highest 222Rn concentrations were observed in granitic terrains in both seasons. The average values of the parameters studied shows that there is a general decrease of TDS and Temperature, but an increase in 222Rn and pH during NEM. The spatial representation of the activity shows that maximum values are in the north eastern part of the study area. Further, correlations between the measured parameters show that temperature has a negative correlation to the samples of charnockite formation during both seasons; pH and TDS also show negative relationships to 222Rn during SWM.

Regional Appraisal of the Fluoride Occurrence in Groundwaters of Andhra Pradesh

Abstract: Fluoride (F−) is essential for normal bone growth, but higher concentration in the drinking water causes health problems which are reported in many states of India. Andhra Pradesh is one of the states which suffer from excess fluoride in groundwater particularly in the hard rock terrain. In this context, a study was conducted in Andhra Pradesh based on chemical analysis of water samples from hydrograph net work stations (dug wells) and exploratory bore wells. The concentration of fluoride in groundwaters ranges from traces to 9.75 mg/l. The occurrence of fluoride is mostly sporadic, uneven and varies with depth. The highly affected districts include Nalgonda and Warangal in Telangana region, Prakasam in coastal region, Anantapur and Kurnool in Rayalaseema region. In certain areas of Nalgonda district, 85% of wells have fluoride more than permissible limit (> 1.5 mg/l) for drinking water. High F− is present in all the geological formations, predominantly in granitic aquifers, compared to the other formations. The average value of fluoride is high in the deeper zone (1.10 mg/L), compared to the shallow zone (0.69 mg/L). The fluoride-rich minerals present are the main sources for fluoride concentrations in groundwater. Residence time, evapotranspiration and weathering processes are some of the other supplementary factors for high fluoride concentrations in groundwater. Long-term data of hydrograph net work stations (dug wells) reveal that fluoride concentrations do not show any marked change of trend with respect to time. The concentration of fluoride is found to increase with increase of Na+and HCO3−, and decrease with increase of Ca2+. Sodium bicarbonate waters are more effective in releasing fluoride from minerals into groundwater. High fluoride waters are of Na+ type. The paper presents a brief account of the study and its results.

Integrated knowledge- and data-driven approaches for groundwater potential zoning using GIS and multi-criteria decision making techniques on hard-rock terrain of Ahar catchment, Rajasthan, India

This study utilizes for the first time integrated knowledge-driven and data-driven methods for groundwater potential zoning in the hard-rock terrain of Ahar River catchment, Rajasthan, India by employing remote sensing, geographical information system, multi-criteria decision making (MCDM), and multiple linear regression (MLR) techniques. Thematic maps of the 11 hydrological/hydrogeological factors i.e., geomorphology, soil, topographic elevation, slope, drainage density, proximity to surface waterbodies, pre- and post-monsoon groundwater depths, net recharge, transmissivity, and land use/land cover, influencing the groundwater occurrence were used. The themes and their features were assigned suitable weights, which were normalized by the MCDM technique. Finally, the knowledge-driven groundwater potential map, generated by weighted linear combination, revealed that the good, moderate and poor groundwater potential zones are spread over 90.94 km2 (26 %), 135 km2 (39 %) and 122.36 km2 (35 %), respectively. Furthermore, the data-driven precise groundwater potential index (GPI) map was computed by MLR technique. The results of both the knowledge- and data-driven approaches were validated from the well yields of 18 sites and were found to be comparable to each other. Moreover, exogenous and endogenous factors affecting the good, moderate and poor groundwater potential were identified by applying principal component analysis. The results of the study are useful to water managers and decision makers for locating appropriate positions of new productive wells in the study area. The novel approach and findings of this study may also be used for developing policies for sustainable utilization of the groundwater resources in other hard-rock regions of the world.

Assessment of groundwater potential based on aquifer properties of hard rock terrain in the Chittar–Uppodai watershed, Tamil Nadu, India

Aquifer performance was tested in 24 locations to assess the groundwater potential of the hard rock terrain in the Chittar–Uppodai watershed of the Tambaraparani River basin. Geologically, the area consists of biotite gneiss, charnockite, and quartzite. The aquifer characteristics, such as transmissivity (T), the storage coefficient, specific capacity, optimum yield, and the recovery rate were calculated. The drawdown transmissivity was determined using Jacob’s straight-line method, while the recovery transmissivity was determined by the Theis method. The drawdown transmissivity was low in the western areas, particularly at Kadayanallur, and was higher in the other areas. The recovery transmissivity was high in the western area, and, with the exception of Gangaikondan, was low at other locations. The assessment indicates that there is groundwater potential in the western part of the study area because of favorable results for recovery drawdown, aquifer thickness, and specific capacity.

Delineation of groundwater potential zone in hard rock terrain of India using remote sensing, geographical information system (GIS) and analytic hierarchy process (AHP) techniques

The present study has been undertaken to delineate the groundwater potential zones in the hard rock terrain of Palamu district, Jharkhand using the advanced applications of remote sensing, geographical information systems and analytic hierarchy process techniques. The integration and analyses of various thematic databases viz., geomorphology, lithology, soil, slope, lineament density, weathered zone thickness, drainage density and rainfall proved useful in the delineation of GWP zones. The study indicates that only 136 km2 of the study area exhibit excellent groundwater potential, 248 km2 has very good groundwater potential, whereas 36.89 and 38.23% are under poor and very poor groundwater potential zones, respectively. Hence, only a total of 11.6% of the area (490 km2) is classified as high to excellent groundwater potential. The final groundwater prospect map obtained was classified as excellent potential, very good potential, good potential, moderate potential, poor potential and very poor potential zone.

Assessment of Sedimentation in Major Reservoirs of Hard Rock Terrain of India Using RS Technique

Sedimentation in the reservoir reduces the storage capacity and its life. Hence, the periodic investigation is necessary to arrive at a realistic siltation index for planning of future reservoir projects in the basin. The conventional techniques of sediment quantification in a reservoir are cumbersome, costly and time consuming. With the advent of remote sensing techniques, it has become very cheap and convenient to quantify the amount of sedimentation in the reservoir. Therefore, in the present study, the assessment of the sedimentation in major reservoirs of hard rock terrain was carried out using the digital image processing of remotely sensed data of reservoirs in hard rock terrain of India. The remote sensing data acquired for various dates were analysed for estimating the reservoir water spread area as well as computing the capacity of reservoir. The annual rate of sedimentation and further loss in reservoir capacity are found more in case of Tungabhadra reservoir as compare to other reservoirs under study due to its drainage characteristics. The revised Elevation-Area-Capacity (EAC) curves developed for study reservoirs will be helpful to reservoir authority for planning the mitigation measures to enhance the capacity and its operation. The factors related to catchment characteristics influencing reservoir sedimentation were also analysed. Based on the analysis, it can be revealed that the rate of sedimentation is linearly correlated with size of the drainage area. KeywordsReservoir Sedimentation; Reservoir Capacity; Remote Sensing; Digital Image Processing

Geophysical Monitoring for the Prospects of Groundwater in the Hard Rock Terrain Regions along the Thandava River Basin

The occurrence, movement and control of groundwater, particularly in hard-rock areas, are governed by different factors such as topography, lithology, and structures like fractures, faults and nature of weathering. An attempt was made in the present study to investigate the extent of the influence of structures such as fractures and thereby delineate the nature of subsurface lithology with the help of electrical resistivity method. Vertical Electrical Soundings by Schlumberger array configuration were recorded in fifty stations of the study area. The choice of the sampling stations in, around and along the basin made the study the first of its kind in the area. The huge sample number made ease of the interpretations with reliability in establishing the geomorphology of the area around the river basin. Groundwater potential zones were delineated with the present status of the reserves. The lithological segregation of the hard rock terrain stands reference for future studies besides suitability of the area made the study in announcing the challenges to be faced for sustainability.

Delineation of Fractured Aquifer Using Numerical Analysis (Factor) of Resistivity Data in a Granite Terrain

In hard rock terrain, fractured aquifers comprise the major source of groundwater availability where the phreatic aquifer is desaturated. Identification of fracture zones in hard rock terrain and potential groundwater source delineation had been a perennial problem in hydrology. The purpose of this paper is to highlight the study over a small watershed area, in a granite terrain, wherein an attempt was made to delineate and map the fractured aquifer using numerical (factor) analysis of the conventional vertical electrical sounding data, which was obscure in curve matching technique. This numerical approach in concatenation with resistivity imaging or other techniques would prove to be an effective tool in groundwater exploration.

Identification of the Recharge Sites Using Remote Sensing and GIS in Hard Rock Terrain

Upper Yerrakalava river basin, a part of the Kolleru-Upptuteru catchment lies between Krishna and Godavari river delta is experiencing fall in groundwater levels in recent years. It was identified that groundwater fall is more in sandstone terrain than in khondalitic terrain. To improve the groundwater levels, a study on multi layer analysis was conducted to identify the recharge sites. This included the rainfall and groundwater level analysis, preparation and integration of spatial maps like drainage, lithology, structures, geomorphology and land use/land cover. The final integrated layer was prepared by using weighted aggregation method and was classified into areas of high to low recharge using standard deviation as classification parameter. Remote sensing and GIS techniques were used in preparation of the thematic maps. Geologically, the area had three major rock types namely sandstones, khondalites and granite gneisses. Geomorphologically, 80% of the area was occupied by pediment deeply weathered and pediment moderately weathered material. Crop land and cropland mixed with plantation covered 59% of the area. Rainfall registered an increasing trend in most of the area. The final integrated layer had the recharge areas of very good (2.07%), good (7.15%), moderate (22.8%), poor (56.53%) and very poor (11.44%). Very good recharge locations were identified where fractures were available with good drainage in sandstone terrain, pediplain deeply weathered and double cropped lands. Very poor recharge locations were identified where no fractures and no drainage, steep slopes in khondalitic terrain occupied with forested lands.

Evaluation of groundwater potential zones using GIS and remote sensing in Noyyal Basin, Tamil Nadu, India

Groundwater is a dynamic and replenishable natural resource but in hard rock terrain the availability of groundwater is of limited extent. The occurrence and movement of groundwater in an area is governed by several factors. It is therefore, necessary to integrate several factors on these terrain characteristics. This can be best achieved by geographical information system (GIS). River Noyyal was perennial with good flow till early 70s. In recent years, the scenario has changed drastically and the river has become practically seasonal. River Noyyal receives copious water during northeast monsoon from September to November. The rest of the year it remains more or less dry. While the surface water resources in the area are inadequate to meet the local needs and the groundwater resources also not properly explored. So, various thematic maps have been used for the preparation of groundwater prospective map by integrating geology, geomorphology, slope, drainage and lineament of the study area. The interpretation shows that the entire study area is predominant in moderate to good category for groundwater potential.

Geophysical investigations for groundwater in a hard rock terrain, Salem district, Tamil Nadu, India

The main aim of a geophysical investigation in a hard rock region is to solve different hydrogeological problems like depth of water table, basement rock, thickness of weathered zone/formation, structural and stratigraphic conditions relevant to groundwater conditions, and permeability of aquifers. A total of 54 vertical electrode soundings were carried out by Schlumberger electrode arrangement to signify complete lithology of the study area and interpretation was carried out by using curve matching techniques. From the study, 65 % of area is dominated by ‘A’ type curve indicating increasing resistivity with depth and 17 % by ‘K’ type representing a high-resistivity layer sandwiched between two low-resistivity layers. Four layer cases were also noted in 12 % of the study area indicating gradation between the weathered and fractured layers as a semi-weathered zone. Greater thickness has been identified in the weathered zone at the contact of peninsular gneiss and charnockite regions. The maximum, minimum, mean, and arithmetic mean were plotted and identified higher background resistivity values in charnockite. The overlay of maximum and minimum curves for different layers signifies variation of weathering intensity with depth or the presence of weaker zones. In general, lithology plays a significant control over weathering of rocks and groundwater potential.

Geochemical Modelling of Fluoride Concentration in Hard Rock Terrain of Madhya Pradesh, India

Abstract:The aim of the present study is to locate and decipher the groundwater quality, types, and hydrogeochemical reactions, which are responsible for elevated concentration of fluoride in the Chhindwara district in Madhya Pradesh, India. Groundwater samples, quality data and other ancillary information were collected for 26 villages in the Chhindwara District, M.P. India during May 2006. The saturation index was computed for the selected samples in the region, which suggest that generally most of the minerals are saturated with respect to water. The concentration of fluoride in the region varies from 0.6 to 4.74 mg/l, which is much higher as per the national and international water quality standards. The study also reveals that the fluoride bearing rock formations are the main source of the higher concentration of fluoride in groundwater along with the conjuncture of land use change. Moreover, the area is a hard rock terrain and consists of fractured granites and amygdaloidal and highly jointed compact basalt acting as good aquifer, which is probably enriching the high content of fluoride in groundwater. High concentration of fluoride is found in deeper level of groundwater and it is possible due to rock‐water interaction, which requires further detailed investigation. The highly alkaline conditions indicate fluorite dissolution, which works as a major process for higher concentration of fluoride in the study area. The results of this study will ultimately help in the identification of risk areas and taking measures to mitigate negative impacts related to fluoride pollution and toxicity.

A practical solution in delineating thin conducting structures and suppression problem in direct current resistivity sounding

In hard rock areas, conventional apparent resistivity measurement using Schlumberger resistivity sounding fails to detect thin conducting structures (2-D and 3-D fractures filled with groundwater and mineral aggregate) concealed at a large depth. In the present study, an attempt is made to way-out the detection problem of deep seated thin conducting layer. It is proposed to study the apparent conductance simultaneously with resistivity sounding to detect such conductive zones qualitatively. Apparent conductance is defined as the magnitude of current flowing in the subsurface for a unit applied voltage through current electrodes. Even though such measurement is of qualitative importance, it gives extremely valuable information for the presence of conductive zones at depth in challenging hard rock terrain. It has been observed that apparent conductance increases significantly when groundwater bearing fractures and conductive bodies are encountered in the subsurface. Field data from different locations are presented to demonstrate the efficacy of such measurement. The measurement assists to the conventional resistivity sounding for successful prediction of groundwater zones at large depth in different hard rock areas and is of enormous importance. The approach is also used for possible solution of suppression problem in the DC resistivity sounding when intermediate layer is not reflected in the resistivity sounding curve. Finally, the approach can be used together with resistivity sounding to solve many practical problems.

Combined ground-penetrating radar (GPR) and electrical resistivity applications exploring groundwater potential zones in granitic terrain

Frequent failures of monsoons have forced to opt the groundwater as the only source of irrigation in non- command areas. Groundwater exploration in granitic terrain of dry land agriculture has been a major concern for farmers and water resource authorities. The hydrogeological com- plexities and lack of understanding of the aquifer systems have resulted in the failure of a majority of the borehole drillings in India. Hence, a combination of geophysical tools comprising ground-penetrating radar (GPR), multielectrode resistivity imaging (MERI), and vertical electrical sounding (VES) has been employed for pinpointing the groundwater potential zones in dry land agricultural of granitic terrain in India. Results obtained and verified with each other led to the detection of a saturated fracture within the environs. In GPR scanning, a 40-MHz antenna is used with specifications of 5 dielectric constant, 600 scans/nS, and 40 m depth. The anomalies acquired on GPR scans at various depths are confirmed with low-resistivity ranges of 27-50Ω ma t 23 and 27 m depths obtained from the MERI. Further, drilling with a down-the-hole hammer was carried out at two recom- mended sites down to 50-70 m depth, which were compli- mentary of VES results. The integrated geophysical anoma- lies have good agreement with the drilling lithologs validat- ing the MERI and GPR data. The yields of these bore wells varied from 83 to 130 l/min. This approach is possible and can be replicated by water resource authorities in thrust areas of dry land environs of hard rock terrain around the world.

Combined surface and borehole seismic imaging in a hard rock terrain: A field test of seismic interferometry

Seismic images are inherently directionally biased by the source-receiver geometry. This directional bias is particularly problematic for seismic imaging in hard rock terrains where structural dips may have any orientation with respect to the surface. We tested a technique for partially mitigating directional bias by combining surface and borehole seismic data and evaluated the results of a first field test of the technique. In this technique, surface data acquired using standard 2D acquisition procedures were combined with borehole data derived from a walk-away vertical seismic profile (VSP). The VSP data were transformed into the borehole datum using seismic interferometry. The interferometry created virtual shot records comprising sources and receivers in the borehole. The virtual shot records were then processed, using standard common midpoint techniques, resulting in an image from the borehole datum. The combination of the surface and borehole data increased the range of illumination angles resulting in seismic images that included reflections from structures with a wider range of dips than is available to surface profiling alone. The field test demonstrated that the surface and borehole data provide complementary information, which is more than either data set alone can provide. The test also verified the robustness of the virtual source technique even when the original VSP data are highly contaminated by high-amplitude tube waves. These results demonstrated that the combined imaging approach has significant potential for application in the polydeformed hard rock domains often encountered in minerals exploration.

Geometrical considerations in the acquisition of borehole interferometric data for imaging near-vertical features: Design of field experiments

Seismic interferometry applied to walkaway vertical seismic profile data has significant potential for imaging the steeply dipping structures often encountered in hard-rock minerals exploration. Using the interferometry process, surface shots can be redatumed to the borehole receivers resulting in virtual shot gathers. The virtual shot gathers can then be processed using a standard common midpoint (CMP) processing flow. Carrying out this procedure for a subvertical borehole results in a geometry that is optimal for imaging structures that are near vertical. Field acquisition parameters play a critical role in recovering reliable virtual source images. We evaluated the major factors that play a role in designing a field acquisition program with the objective of providing guidance to field practitioners. The major issue to be considered is insuring that correlation gathers created in the interferometry process have a stationary phase component that when summed produces events with correct timing and cancellation of nonstationary components. Consistent with previous work, the ray-tracing-based analysis identified the surface source spacing, surface source aperture, and dominant frequency as the most critical parameters. The analysis indicated that because of the high apparent velocities typically encountered in hard rock terrains, a surface source spacing of 20 m and an aperture of 1000 m will result in stationary phase components and avoid spatial alias in the correlation gathers for frequencies as high as 80 Hz. However, closer spacing of the surface sources provided more traces in the correlation gathers resulting in fewer artifacts during summation. These results were further verified by acoustic wave modeling that provided data from more complex targets that were processed through a complete interferometry and CMP flow. The analysis indicated that with care in designing field acquisition parameters, seismic interferometry is realizable within the terrain and access restrictions imposed by many mining camps.

Geophysical signatures resolving hydrogeological complexities over hard rock terrain—a study from Southern India

A series of geophysical parameters have been applied with geological perception to resolve the hydrogeological complexities over granitic terrain at Hyderabad, India. Frequent failure of borehole drillings and the thrust conditions of community have prompted a noninvasive suitable tool, applied at small scale for pinpointing potential well site. Geophysical scanning, viz. electrical resistivity tomography (ERT), spontaneous potential (SP), and electrical gradient profiling (GP) were employed within the restricted space of housing complex to obtain the true characteristics of the subsurface lithology, where anomalies by the underground utility structures have been nullified. Results showed, in ERT, the low order of resistivity range 123 to 200 Ωm showing a plume like weathered zone underlain by sudden slip of massive granite (>217 Ωm) was of great interest to proceed further in the process. Here, the switchover in SP value from +18 mV to −17 mV and GP from mean value 10 to 90 mV/m was recorded. The anomalies in SP and GP were precisely coincided with the ERT where upcoming of subsurface massive granite next to the inferred fracture was noted. Drilling core logs satisfies the geophysical signatures ensuring the inferred saturated fracture with the total yield 1,302 gal/h.

Geoelectrical Schlumberger investigation for characterizing the hydrogeological conditions using GIS in Omalur Taluk, Salem District, Tamil Nadu, India

The increasing demand for freshwater has necessitated the exploration for new sources of groundwater, particularly in hard rock terrain, where groundwater is a vital source of freshwater. A fast, cost effective, and economical way of exploration is to study and analyze geophysical resistivity survey data. The present study area Omalur taluk, Salem District, Tamil Nadu, India, is overlain by Archaean crystalline metamorphic complex. The study area is a characteristic region of unconfined aquifer system. The potential for occurrence of groundwater in the study areas was classified as very good, good, moderate, and poor by interpreting the subsurface geophysical investigations, namely vertical electrical soundings, were carried out to delineate potential water-bearing zones. The studies reveal that the groundwater potential of shallow aquifers is due to weathered zone very low resistivity and very high thickness and the potential of deeper aquifers is determined by fracture zone very low resistivity and very high thickness area. By using conventional GIS method, the spatial distribution maps for different layer (top soil, weathered zone, first fracture zone, and second fracture zone) thicknesses were prepared. The geoelectrical approach was successfully applied in the study area and can be therefore easily adopted for similar environments.

A study on the significance of lithology in groundwater quality of Madurai district, Tamil Nadu (India)

The groundwater occurs in hard rock aquifers, which is more predominant in India. It is more common in the southern peninsula especially Tamil Nadu. Madurai district is located in the central part of Tamil Nadu, underlain predominantly by crystalline formations and alluvium along the river course. The study area being a hard rock terrain, the groundwater is stored in cracks, fissures, joints, etc., and hence the quantity is lesser. The frequent failure of monsoon also aggravates the scarcity of this commodity. In this scenario, the quality and hydrogeochemistry of the available quantum of water plays a significant role for the determination of its utility and in tracing out the hydrogeochemical evaluation. Fifty-four groundwater samples were collected representing the entire study area. The samples collected were representative covering all the major litho units of the study area (charnockite -21, fissile hornblende biotite gneiss-21, granite-4, quartzite-3, and 5 samples from flood plain alluvium). The samples collected were analyzed for major ions and were classified for different purposes like drinking, domestic, and agriculture, with respect to lithology. The comparison of the groundwater samples with the drinking water standards shows that few samples fall above the drinking water limit irrespective of lithology. The samples were classified with sodium absorption ratio, electrical conductivity, residual sodium carbonate, sodium percentage (Na %), Kellys ratio, and magnesium hazard, and permeability index for irrigation purpose found that most of the samples were suitable for irrigation purpose irrespective of lithology. Total hardness and corrosivity index were studied for the domestic purpose and found that the samples of the granitic terrain are safe. Apart from this, index of base exchange, Schoellers water type, Stuyfzands classification were attempted along with Gibbs plot to determine the major geochemical activity of the region. The study reveals that the samples collected from granitic and quartzitic terrains are comparatively better for the domestic and drinking purpose due to the presence of resistant minerals to weathering.