Journal of Geography, Environment and Earth Science International

Groundwater usage in the world is widely reported to increase because of the uncertainties attached with the availability of surface water. Groundwater resources are looked upon as the alternate source of freshwater on account of its widespread and continuous availability in proximity to the point of use or living place, less vulnerability to contamination and low cost of extraction in both urban and rural area of developed and developing countries of the world. Such a scenario has led to the degradation and depletion of groundwater resources in many parts of the world. The study area, Coimbatore district, is a rapidly urbanizing and industrializing city in the southern part of India which relies upon the groundwater resources for meeting the agricultural, industrial and domestic requirements. In view of this evaluation of groundwater resources and an understanding of the vulnerability of the aquifer to contamination become essential for the effective management of groundwater resources. The vulnerability of the groundwater to contamination is assessed using DRASTIC and Pesticide DRASTIC index in the GIS environment. The study showed that the high vulnerability areas are characterized by shallow water table of less than 4 m, gentle topography, sandy loam soils, thinner vadose zone and underlying geologic formations with well-developed fissures and fractures.

The GFSAD30m cropland extent map has been recently produced at a spatial resolution of 30m as a part of NASA MEaSUREs’ Program Global Food Security Data Analysis (GFSAD) project. Accuracy assessment of this GFSAD30m cropland extent map was initially performed using an assessment strategy involving a simple random sampling (SRS) design and an optimum sample size of 250 for each of 72 different regions around the world. However, while statistically valid, this sampling design was not effective in regions of low cropland proportion (LCP) of less than 15% cropland area proportion (CAP).

The SRS sampling resulted in an insufficient number of samples for the rare cropland class due to low cropland distribution, proportion, and pattern. Therefore, given our objective of effectively assessing the cropland extent map in these LCP regions, the use of an alternate sampling design was necessary. A stratified random sampling design was applied using a predetermined minimum number of samples followed by a proportional distribution (i.e., SMPS) for different cropland proportion regions to achieve sufficient sample size of the rare cropland map class and appropriate accuracy measures.

The SRS and SMPS designs were compared at a common optimum sample size of 250 which was determined using a sample simulation analysis in ten different cropland proportion regions. The results demonstrate that the two sampling designs performed differently in the various cropland proportion regions and therefore, must be selected according to the cropland extent maps to be assessed.

Carbonaceous shales of the Upper Disang Formation of the Inner Paleogene Fold Belt of Assam-Arakan Basin, exposed along the Dimapur-Senapati road section of Nagaland and Manipur states of India have been studied for interpreting hydrocarbon potential. The Upper Disang Formation is mostly composed of alteration of shales, sandstones and siltstones. The shales are black coloured and splintery in nature. The shales and associated sandstones show sedimentary structures like bioturbation, cross bedding and ripple marks indicating shallow water origin. The shales contain appreciable amount of pyrites indicating marine influence in the depositional basin. The average TOC of the carbonaceous shale samples is 0.53% indicating poor generative potential. The poor generative potential of the formation is also supported by low S₁ (average 0.04 mg/gTOC), S₂ (average 0.16 mg/gTOC) and HI (average 36 mg/gTOC). The organic matters are represented dominantly by Type IV kerogens (inertinite) with subordinate amount of Type III kerogens (vitrinite) as shown by both Rock Eval parameters and organic petrography. The dispersed organic matters (DOM) are identified as semifusinite and collotelinite under the microscope. The organic matters are interpreted to be inert/post mature kerogens from the maturity parameters like Rock Eval T_max (average 563°C), and mean vitrinite reflectance (average 2.0% in oil). The study indicates very poor hydrocarbon potential of the Upper Disang Formation of the Dimapur-Senapati road section.

This research aimed to correlate the sedimentary transport with the diagenetic processes in the coastal zone and Amazon Continental Shelf (ACS). Physical and physical-chemical parameters, trace element contents (Cr, Pb, Ni, Zn and Hg), and O₂, CO₂ and iron flux were determined in sediment and pore water. Sedimentary incubation (96 hours) and algorithms were applied to determine the variation of the activity coefficient (ΔI) and ionic strength (F_i) of the predominant chemical species, and to estimate the net production and mineralization of the organic matter (ΔCO_2T) in the system. There are not many studies applying incubation tests to identify the diagenetic processes, especially in fluvial-marines sediments. The results showed a strong zonation associated to the transport and deposition processes, influenced mainly by the grain-size and texture of sediment and fluvial streams. The distribution of trace elements followed the trend of the sedimentary pattern, with higher levels of metals in the deposits of clay minerals and organic matter. A factor of weight (F_w), calculated to establish the degree of importance of each parameter under the distribution and mobility of trace elements, suggests that the mobility of Cr, Ni and Zn is controlled by depth, clay and organic compounds contents, and concentration of dissolved oxygen. The vertical flow of O₂ and CO₂ and the Fe²⁺/Fe³⁺ ratio in the pore water suggest a predominance of organic matter oxidation in the sedimentary layer between 0.0 and 0.2 m, with partially anaerobic mineralization of the sediments below 0.4 m. Increases in trace element concentrations were observed in iron reduction zones, indicating processes of desorption of oxides and hydroxides of Fe and mineralization of organic matter. The extrapolation of the results of the incubation test to the studied system allowed to establish three hypotheses related to the diagenetic processes: 1) the flow of marine currents may be allowing the aerobic oxidation in the sandy sediments, with the nitrification route more accentuated than the ammonification route; 2) in the region of the coastal zone and inner continental shelf the routes of oxidation and reduction may be alternating according to the physical-chemical factors and seasonality; 3) in the coastal zone and inner shelf the net mineralization rate exceeded the net production rate of the organic matter (ΔCO_2T >0).

In spite of its industrial importance, Hugli is one of the leading potato producing districts of West Bengal with momentous productivity. But the productivity has shown considerable variation in its quantity, yield per unit of land and area under the crop over the last few decades. The present study strives to assess the spatio-temporal dynamics, emphasizing on trend, growth and variability as well as inter-Block variations in potato productivity of Hugli District from 1990-91 to 2013-14. The study was primarily based on the secondary data obtained from various sources. Time series analysis (3 year moving average curve), Coppock’s Instability Index and Sahu’s Simple Achieved Variation have been used to analyze the trend, instability and sustainability of the productivity, whereas, Crop Yield and Concentration Indices Ranking Coefficient is employed to identify productivity regions of potato. The result has revealed a unique oscillating nature in area, yield and output over the study period. The area and the output of the crop have been increased almost 51.70% [Exponential R²= 0.751] and 32.75% [Exponential R²= 0.381] respectively, whereas the yield rate has shown an insignificant positive trend of growth [Exponential R²= 0.014] during the same period.  The Blocks have also revealed wide inter-disparity in productivity during the phase with considerable degree of instability and sustainability.