Papers by Rolland Andrade
International Journal of Geophysics, 2014
In hard rock terrain, fractured aquifers comprise the major source of groundwater availability wh... more 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.
Earth Resources, 2013
ABSTRACT Physical properties of the unsaturated zone during percolation are subjected to temporal... more ABSTRACT Physical properties of the unsaturated zone during percolation are subjected to temporal variations. An attempt is made to understand the changes through electrical resistivity modulation. A pilot scale experiment was conducted over medium textured sandy-gravel soil intercalated with regolith cover of considerable thickness. Wenner (alpha) electrical profiling with electrode spacing"s of 2 & 5 m was adopted over a grid area of 4 m x 4m, with inter-station interval of 0.5m. The apparent resistivity was measured at each stations of alternate profile lines during different time periods of infiltration test conducted at the centre of the grid area. Prominent changes in apparent resistivity are observed due to influence of infiltrating moisture flux. The analysis on changes in apparent resistivity at depth (D~1.0m) between pre and post infiltration test helped in identifying the area of influence due to saturation. A significant rise in apparent resistivity at the bottom of wetting front at depth (D~2.5m) was noticed, attributable to the migration and displacement of air from the moisture occupied pore spaces. The inferred depth of moisture migration from the resistivity profile results concurred with the depth evolved through tritium injected tracer stu-dies. The resistivity investigations also indicated preferred flow direction of the percolating moisture at deeper levels confirmed by the tracer movement. The results demonstrate the utility of electrical profiling in mapping the subsurface for better under-standing of the moisture migration pathways and its associated processes.
Sustainable Water Resources Management, 2017
wells, etc. The percentage of area influenced by canal irrigation to the total irrigated area in ... more wells, etc. The percentage of area influenced by canal irrigation to the total irrigated area in India has fallen from about 39.77 to 29% over the last few decades. Apart from the arrival of bore well in irrigation sector, seepage losses from irrigation canals also hampered the efficiency of canal and irrigation system significantly, in terms of water logging, salinization, natural groundwater balance, etc. Apart from unlined canals, significant seepage losses were noticed and reported in lined canals, probably because canal lining deteriorates with time (Singh 2013). The canal seepage is assessed either by direct measurements (Inflow-Outflow method, seepage meter method, resistivity method and filtration meter method) or by indirect measurements (tracer techniques, physical and analog modeling technique, electrical analog, mathematical modeling and remote sensing technique) (Kaufmann 2009; Hoffmann and Sander 2007; Watt and Khan 2007; Flury and Wai 2003; Aeby et al. 2001, Moser 1995). Several physical and onsite constraints like stopping of normal canal activity (Ponding tests, inflow-outflow method), presence of excessive canal flow (non-suitable for seepage meter method) and absence of steady flow (non-suitable for Water balance method) pose hindrance in the application of direct method. Sometimes excessive time requirement for testing [analytical methods, Acoustic Doppler Current Profilers (ADCP)] or application of more than one technique (geophysical techniques) prevents in selection of different techniques (Alam and Butha 2004; Kinzli et al. 2010). Tracer techniques are economic and one of the fastest, method in terms of detection of seepage prone zones, identification of seepage path without interrupting canal's day-today normal activity. Here in this paper, the authors highlight the utility of Tracer techniques and also reported the two different aspects, which are qualitatively in identifying maximum Abstract Canal irrigation is well developed in several provinces of India since independence. With the increase in demand and irregular rainfall, several areas are covered using canal network to suffice agricultural and drinking water needs. Besides its utility and functioning, several problems are associated with canal irrigation, such as seepage losses and water logging. Apart from geophysical and geological methods, tracer is a tool which can be used to study canal seepage. It facilitates in identifying maximum seepage zones and expected seepage path qualitatively and quantitatively without interrupting normal activity of the canal. In this paper, identification of canal seepage in detail with two case studies namely Indira Gandhi Main Canal (IGMC), Rajasthan, and canals in Kakrapar network, Gujarat, from Indian subcontinent is reported. Tracer studies revealed the vulnerable zone, i.e., fractures or cracks in the canal lining with excessive seepage in both the cases. Tracer technique is a definite, reliable and cost effective tool, which provides unique insight into canal seepage investigation.
Any mining activity results into generation of disintegrated waste materials “Tailings”. Tailings... more Any mining activity results into generation of disintegrated waste materials “Tailings”. Tailings are also known as slimes or leach residue which are the left over materials after the process of separating the valuable fraction of radioactive as U3O8 in Uranium mining. Mine tailings are usually produced from the mill in slurry form, which demands proper disposable sites, as it generally consists of trace quantities of metals/radioactive elements. Hence, surface waste disposal site has to be characterized for its sub-surface nature to understand its role in environmental impact due to the loading of waste materials. The objective of this article is to provide a description of the site investigation techniques and approaches that can be used to characterize the flow of subsurface water, map the lithology at near surface disposal facilities. Surface geophysical techniques like ERT (2D resistivity tomography), ground magnetic and borehole seismic studies in integration with each other can be an ideal tool in mapping the geophysical characteristics of sub-surface formations in and around the disposal site.
Mining activities results into generation of disintegrated waste materials attaining increased mo... more Mining activities results into generation of disintegrated waste materials attaining increased mobilization status and requires a safe disposal mechanism through back filling process or secluded storage on surface with prevention of its interaction with environment cycle. The surface disposal of waste materials will become more critical in case of mined minerals having toxic or radioactive elements. In such cases, the
spgindia.org
ABSTRACT: Significant changes in water levels of shallow and deep wells before and after earthqua... more ABSTRACT: Significant changes in water levels of shallow and deep wells before and after earthquake events were observed in the Thar Desert of India and reported for the first time. Rise in water level of the deep well (165-m depth) was of the order of 5 to 50 cms and was ...
RefDoc Bienvenue - Welcome. Refdoc est un service / is powered by. ...
While the problem is enormous in the industrialized countries for which the statistics are most r... more While the problem is enormous in the industrialized countries for which the statistics are most readily available, in proportion to population, the problem is undoubtedly of similar magnitude or more in most developing countries of the world like India…………… The concept of artificial recharge structure can be extended in pollution mitigation studies under favorable site criterions, as it requires no addition of artificial chemicals or processing plant.
Multi-beam and single-beam bathymetric, gravity and magnetic data, across seven ridge segments (l... more Multi-beam and single-beam bathymetric, gravity and magnetic data, across seven ridge segments (length varying between 37 and 84 km), offset by six transform discontinuities (ranging in dislocation length between 48 and 344 km) of the Northern Central Indian Ridge (NCIR) were collected. Four Transform Faults (TF, viz. Sealark, Vityaz, Ehrlich and Vema) have been mapped in detail; while studies on geological, biological and water sampling were carried out at the last three transform faults. The ridge segments are characterized by along-axis depth variation: deepening at segment ends and shallowing at the centre. Both the ridge axis and TF areas are complex with intra-and inter-segmental morphotectonic and magnetic variations. Basalts collected from axial valley, Ridge-Transform Intersection (RTI) and from near-axis seamount, exhibit pillow and columnar structures. Samples from the RTI yielded ferromanganese crust, nodules and intensely bioturbated calcareous sediments hosting nannoplanktons. The characteristics of the RTI, axial valley and transform and the presence of neo-volcanic zones along ridgenormal profiles suggest predominance of tectonomagmatic activities in the Vityaz and Vema regions. In the Sealark region, tectonic activities dominate.
Natural recharge is an important parameter to be known for groundwater budgeting and management. ... more Natural recharge is an important parameter to be known for groundwater budgeting and management. Principal source of recharge to the groundwater aquifer system is the percolation of a fraction of rainfall during the monsoon season through the vadose zone. Rainfall recharge is highly variable at a given place and the variability is essentially due to rainfall pattern, soil characteristics remaining the same. Estimation of recharge to an unconfined granite aquifer was made by studying the groundwater response to various rainfall pulses of 2004 monsoon through analysis of continuous hydrograph data, after filtering out extraneous noises like tidal effects. Water-level fluctuation was utilized with precipitation events to evaluate transient recharge rate and cumulative recharge rate was found to be in good agreement with the estimates made by tritium injection method over the monsoon period.
Emergence of springs at surface or in shallow pits reported from discrete locations during the mo... more Emergence of springs at surface or in shallow pits reported from discrete locations during the month of January 2005 in the southern Indian peninsular shield area had been an interesting post geo-hydrological phenomenon to investigate. Such freak incidences at places in the interior parts of a continental shield area were reported for the first time. Its connectivity with the 2004 mega thrust great (Mw 9.3) Sumatra earthquake and its multiple aftershocks are studied and analyzed. Resistivity 2D imaging and its hydrogeological modulations revealed perched aquifer conditions at shallow depth (<10 m). There is no geological or geophysical evidence of structurally controlled upward rise of deep groundwater in the area. Electrical conductivity of the emergent spring water and that of deeper (depth >50 m) groundwater support that the spring water is originated due to local effect by the 2004 mega thrust earthquake. The emergence of spring is attributed to ground movement and squeezing of pores in the saturated zone at shallow depth due the mega thrust Sumatra earthquake.
In a case history from the Mahanadi basin (India), we demonstrate the use of resistivity data fro... more In a case history from the Mahanadi basin (India), we demonstrate the use of resistivity data from electric-log soundings and from borehole logs to discriminate between saltwater and freshwater aquifers. We use interpreted data from eight surface-based vertical electrical soundings (VES) and electric well logs from three boreholes in this study. We establish a quantitative relation among longitudinal unit conductance S (obtained from VES), water resistivity R w , and layer thickness h. We show that ambiguities in resistivity data interpretation limit its ability to distinguish between freshwater and saltwater aquifers. Electric well-log data interpretation is much more accurate but requires boreholes, which are not cost effective when exploring for groundwater. Integrating well-log-based estimates of R w into resistivity interpretation of surface-based soundings improves its ability to discriminate freshwater aquifers while maintaining cost-effective exploration.
An attempt is made to identify and delineate the groundwater flow direction and rate in a fractur... more An attempt is made to identify and delineate the groundwater flow direction and rate in a fractured hard rock aquifer in Maheshwaram granite watershed in Andhra Pradesh using multiple tracers such as bromide, iodide and rhodamine-B under both natural and induced conditions. A main well in the center and three observation wells at 25 m in north-northwest, southeast and southwest directions respectively were constructed based on 222 Rn anomalies and 4 He measurements. Streaming potential survey was also carried out in the area before, during and after pumping test. The tracer tests indicated preferential groundwater flow in N-S direction. The groundwater flow velocity estimated based on arrival of tracer under natural and induced conditions are 0.52 m/d and 375 m/d respectively.
Any mining activity results into generation of disintegrated waste materials “Tailings”.
Tailing... more Any mining activity results into generation of disintegrated waste materials “Tailings”.
Tailings are also known as slimes or leach residue which are the left over materials after
the process of separating the valuable fraction of radioactive as U3O8 in Uranium mining.
Mine tailings are usually produced from the mill in slurry form, which demands proper
disposable sites, as it generally consists of trace quantities of metals/radioactive elements.
Hence, surface waste disposal site has to be characterized for its sub-surface nature to
understand its role in environmental impact due to the loading of waste materials. The
objective of this article is to provide a description of the site investigation techniques and
approaches that can be used to characterize the flow of subsurface water, map the lithology
at near surface disposal facilities. Surface geophysical techniques like ERT (2D resistivity
tomography), ground magnetic and borehole seismic studies in integration with each other
can be an ideal tool in mapping the geophysical characteristics of sub-surface formations
in and around the disposal site.
Physical properties of the unsaturated zone during percolation are subjected to temporal variatio... more Physical properties of the unsaturated zone during percolation are subjected to temporal variations. An attempt is made to understand the changes through electrical resistivity modulation. A pilot scale experiment was conducted over medium textured sandy-gravel soil intercalated with regolith cover of considerable thickness. Wenner (alpha) electrical profiling with electrode spacing"s of 2 & 5 m was adopted over a grid area of 4 m x 4m, with inter-station interval of 0.5m. The apparent resistivity was measured at each stations of alternate profile lines during different time periods of infiltration test conducted at the centre of the grid area. Prominent changes in apparent resistivity are observed due to influence of infiltrating moisture flux. The analysis on changes in apparent resistivity at depth (D~1.0m) between pre and post infiltration test helped in identifying the area of influence due to saturation. A significant rise in apparent resistivity at the bottom of wetting front at depth (D~2.5m) was noticed, attributable to the migration and displacement of air from the moisture occupied pore spaces. The inferred depth of moisture migration from the resistivity profile results concurred with the depth evolved through tritium injected tracer studies. The resistivity investigations also indicated preferred flow direction of the percolating moisture at deeper levels confirmed by the tracer movement. The results demonstrate the utility of electrical profiling in mapping the subsurface for better understanding of the moisture migration pathways and its associated processes.
In hard rock terrain, fractured aquifers comprise the major source of groundwater availability wh... more 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.
Uploads
Papers by Rolland Andrade
Tailings are also known as slimes or leach residue which are the left over materials after
the process of separating the valuable fraction of radioactive as U3O8 in Uranium mining.
Mine tailings are usually produced from the mill in slurry form, which demands proper
disposable sites, as it generally consists of trace quantities of metals/radioactive elements.
Hence, surface waste disposal site has to be characterized for its sub-surface nature to
understand its role in environmental impact due to the loading of waste materials. The
objective of this article is to provide a description of the site investigation techniques and
approaches that can be used to characterize the flow of subsurface water, map the lithology
at near surface disposal facilities. Surface geophysical techniques like ERT (2D resistivity
tomography), ground magnetic and borehole seismic studies in integration with each other
can be an ideal tool in mapping the geophysical characteristics of sub-surface formations
in and around the disposal site.
Tailings are also known as slimes or leach residue which are the left over materials after
the process of separating the valuable fraction of radioactive as U3O8 in Uranium mining.
Mine tailings are usually produced from the mill in slurry form, which demands proper
disposable sites, as it generally consists of trace quantities of metals/radioactive elements.
Hence, surface waste disposal site has to be characterized for its sub-surface nature to
understand its role in environmental impact due to the loading of waste materials. The
objective of this article is to provide a description of the site investigation techniques and
approaches that can be used to characterize the flow of subsurface water, map the lithology
at near surface disposal facilities. Surface geophysical techniques like ERT (2D resistivity
tomography), ground magnetic and borehole seismic studies in integration with each other
can be an ideal tool in mapping the geophysical characteristics of sub-surface formations
in and around the disposal site.