Sound level produced during rock drilling vis-à-vis rock properties

The process of drilling, in general, always produces sound. Though sound is used as a diagnostic tool in mechanical industry, its application in predicting rock property is not much explored. In this study, an attempt has been made to estimate rock properties such as uniaxial compressive strength, Schmidt rebound number and Young's modulus using sound level produced during rotary drilling. For this purpose, a computer numerical controlled vertical milling centre was used for drilling holes with drill bit diameters ranging from 6 to 20 mm with a shank length of 40 mm. Fourteen different rock types were tested. The study was carried out to develop the empirical relations using multiple regression analysis between sound level produced during drilling and rock properties considering the effects of drill bit diameter, drill bit speed and drill bit penetration rate. The F-test was used to check the validity of the developed models. The measured rock property values and the values calculated from the developed regression model are fairly close, indicating that the developed models could be efficiently used with acceptable accuracy in prediction of rock properties.     

Estimation of Residual Undrained Shear Strength from Gravity Corer Penetration Data

Residual undrained shear strength, s _{u_res} , is an important parameter for analyzing the response of structures buried within potentially unstable soil mass. A framework for estimating s _{u_res} of fine grained sediments from gravity corer penetration has been developed considering viscous drag during free fall of the corer through seawater and cohesive energy loss during sediment penetration. The procedure was used to estimate s _{u_res} using data from a submarine geotechnical investigation in western Canada. Comparison of the results with alternative estimates of s _{u_res} from miniature torvane tests on the gravity core samples and CPTs performed nearby reveals a reasonable agreement.     

Inverse modelling of aquifer parameters in basaltic rock with the help of pumping test method using MODFLOW software

The origin and movement of groundwater are the fundamental questions that address both the temporal and spatial aspects of ground water run and water supply related issues in hydrological systems. As groundwater flows through an aquifer, its composition and temperature may variation dependent on the aquifer condition through which it flows. Thus, hydrologic investigations can also provide useful information about the subsurface geology of a region. But because such studies investigate processes that follow under the Earth's shallow, obtaining the information necessary to answer these questions is not continuously easy. Springs, which discharge groundwater table directly, afford to study subsurface hydrogeological processes.The present study of estimation of aquifer factors such as transmissivity (T) and storativity (S) are vital for the evaluation of groundwater resources. There are several methods to estimate the accurate aquifer parameters (i.e. hydrograph analysis, pumping test, etc.). In initial days, these parameters are projected either by means of in-situ test or execution test on aquifer well samples carried in the laboratory. The simultaneous information on the hydraulic behavior of the well (borehole) that provides on this method, the reservoir and the reservoir boundaries, are important for efficient aquifer and well data management and analysis. The most common in-situ test is pumping test performed on wells, which involves the measurement of the fall and increase of groundwater level with respect to time. The alteration in groundwater level (drawdown/recovery) is caused due to pumping of water from the well. Theis (1935) was first to propose method to evaluate aquifer parameters from the pumping test on a bore well in a confined aquifer. It is essential to know the transmissivity (T = Kb, where b is the aquifer thickness; pumping flow rate, Q = TW (dh/dl) flow through an aquifer) and storativity (confined aquifer: S = bS_s, unconfined: S = S_y), for the characterization of the aquifer parameters in an unknown area so as to predict the rate of drawdown of the groundwater table/potentiometric surface throughout the pumping test of an aquifer. The determination of aquifer's parameters is an important basis for groundwater resources evaluation, numerical simulation, development and protection as well as scientific management. For determining aquifer's parameters, pumping test is a main method. A case study shows that these techniques have been fast speed and high correctness. The results of parameter's determination are optimized so that it has important applied value for scientific research and geology engineering preparation.     

Evaluating water table response to rainfall events in a shallow aquifer and canal system

Shallow aquifers typically have greater hydrologic connectivity and response to recharge and changes in surface water management practices than deeper aquifers and are therefore often managed to reduce the risk of flooding. Quantification of the water table elevation response under different management scenarios provides valuable information in shallow aquifer systems to assess indirect influences of such modifications. The episodic master recession method was applied to the 15‐min water table elevation and NEXRAD rainfall data for 6 wells to identify water table response and individual rainfall events. The objectives of this study were to evaluate the effects of rainfall, water table elevation, canal stage, site‐specific characteristics, and canal structure modification/water management practice on the fluctuations in water table elevations using multiple/stepwise multiple linear regression techniques. With the modification of canal structure and operation adjustment, significant difference existed in water table response in the southern wells due to its relative downstream position regarding the general groundwater flow direction and the structural modification locations. On average, water table response height and flood risk were lower after than before the structure modification to canals. The effect of rainfall event size on the height of water table response was greater than the effect of antecedent water table elevation and canal stage on the height of water table response. Other factors including leakance of the canal bed sediment, specific yield, and rainfall on i  ? 1 day had significant effects on the height of water table response as well. Antecedent water table elevation and canal stage had greater and more linear effects on the height of water table response after the management changes to canals. Variation in water table response height/rainfall event size ratio was attributed to difference in S _y , antecedent soil water content, hydraulic gradient, rainfall size, and run‐off ratio. After the structure modification, water table response height/rainfall event size ratio demonstrated more linear and proportional relationship with antecedent water table elevation and canal stage.     

Redistribution of riverine and rainfall freshwater by the Bay of Bengal circulation

Ocean Dynamics - We use satellite-derived currents and a Lagrangian approach to investigate the redistribution of the precipitation minus evaporation (P-E) and river freshwater inputs into Bay of...     

Drought disaster monitoring and land use dynamics: identification of drought drivers using regression-based algorithms

Natural Hazards - Droughts are particularly disastrous in South Africa and other arid regions that are water-scarce by nature due to low rainfall and water sources. According to some studies,...     

Genetic architecture of three Turbinella pyrum varieties (Linnaeus, 1758) from the southeast coast of India

The genetic diversity and variation of three pseudo‐species of the commercially important Indian conch Turbinella pyrum from the southeast coast of India were studied. A total of 88 individuals was genotyped at 12 loci and differences in the genetic diversity among genetic groups were correlated with known population histories. The study identified 535 alleles and all the studied loci were highly polymorphic. The number of alleles ranged between four and 29 with a global mean of 14.861. The global means of the observed and expected heterozygosities were 0.774 and 0.891, respectively. The estimated within‐population inbreeding value (F_IS = 0.131) indicated a shortfall of heterozygosity in the populations. An analysis of molecular variance showed that 5% of the total variation was due to differences between genetic groups. The Bayesian approach revealed strong distinctiveness in the three genetic groups studied. Overall microsatellite analysis revealed less genetic diversity in all studied genetic groups and significant genetic variation among the three pseudo‐species. The study highlights the significant distinctiveness of the pseudo‐species of T. pyrum and the need for appropriate conservation efforts in order to prevent further losses of their genetic diversity.     

Estimation of Residual Undrained Shear Strength from Gravity Corer Penetration Data

Residual undrained shear strength, s_{u_res}, is an important parameter for analyzing the response of structures buried within potentially unstable soil mass. A framework for estimating s_{u_res} of fine grained sediments from gravity corer penetration has been developed considering viscous drag during free fall of the corer through seawater and cohesive energy loss during sediment penetration. The procedure was used to estimate s_{u_res} using data from a submarine geotechnical investigation in western Canada. Comparison of the results with alternative estimates of s_{u_res} from miniature torvane tests on the gravity core samples and CPTs performed nearby reveals a reasonable agreement.