Journal of Geosciences and Geomatics

A severe hailstorm, with hail stones estimated at 1 kg, at the city of Pokhara, 800m asl in the Nepal Himalayas, on May 18, 2005 is investigated in this paper. Upper air data obtained from Gorakhpur combined with Department of Hydrology and Meteorology (DHM) surface data at Pokhara provided the basis for stability index calculations, such as convective available potential energy (CAPE). Strong updrafts in which large hail is formed are directly related to CAPE. This paper attempts to calculate CAPE values in complex terrain, where data for low tropospheric levels is not available. Temperatures and dewpoint temperatures above the surface were estimated from the DHM observations of cumulus cloud base heights at Pokhara. This proved to be a valid technique for providing essential weather data at 850hPa. The Pokhara area is a known location of moisture convergence. This, plus exceptionally cold air aloft from the northwest on May 17 and 18, resulted in extreme instability, with CAPE values reaching and possibly exceeding 6800J/Kg.

Journal of Geosciences and Geomatics. 2015, 3(5), 142-153. DOI: 10.12691/jgg-3-5-5
Pub. Date: February 27, 2016

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Modeling Urban Sprawls in Northeastern Illinois

by T. Friehat, G. Mulugeta and T. S. Gala

Original Research

Like many metropolitan regions Chicago area characterized by Urban Sprawl. The ability to manage this Urban Sprawl for a sustainable future presents numerous challenges for geographers and planners. Nowadays remotely sensed data are inherently suited to provide information on urban land cover (LC) characteristics, change over time, and modeling. This paper has attempted to investigate Urban Sprawl in northeastern Illinois, and analyze its impact on the agricultural land and nature over time. The satellite images were acquired and classified to prepare the base maps, change detection was employed to analyze changes overtime. The Land Change modeler was used to predict the future urban growth of the area in 2020 and 2030. The results indicated that between (1989 and 2010) the built up area increased by 82.2%, which associated with a loss of 25.8% of the valuable agricultural lands and a decline in the urban open spaces and other landscape categories by 32.5%. The predicted maps showed an increase of built up land, which will cause further loss of agricultural lands mainly in the suburbs.

Journal of Geosciences and Geomatics. 2015, 3(5), 133-141. DOI: 10.12691/jgg-3-5-4
Pub. Date: November 02, 2015

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Assessing Chloride Distribution and Concentrations in the Aquifer Systems of the Niger Delta

by H.O Nwankwoala and S.A Ngah

Original Research

This study aims at assessing the distribution of chloride in the aquifer systems and evaluating its occurrence in the different geomorphologic zones of the Niger Delta. The chloride values range from 3mg/l – 810mg/l. 68% of the samples have chloride concentration less than 48mg/l, 24% with chloride concentration between 48mg/l and 250 mg/l while 8% with chloride concentration greater than 250mg/l. The highest concentration of 801mg/l was obtained from a borehole at Oloma. The chloride content in groundwater appears generally to decrease from north to south i.e. from the hinterland to the coast. The localized chloride enrichment around the Old GRA, Borokiri, Moscow road and Central Police Station in Port Harcourt could be as a result of brackish water invasion from nearby creeks and tidal channels. The study revealed that chloride is a major quality issue especially in groundwater in these areas as well as in the mangrove swamps and the coastal beaches and ridges.

Journal of Geosciences and Geomatics. 2015, 3(5), 128-132. DOI: 10.12691/jgg-3-5-3
Pub. Date: November 02, 2015

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Competitiveness of Inverse Distance Weighting Method for the Evaluation of Gold Resources in Fluvial Sedimentary Deposits: A Case Study

by Al-Hassan Sulemana and Adjei David

Original Research

Gold mineralisation at Pepe occurs in a sedimentary sequence known as the Banket Series formation. Due to cut-back, further exploration has been done to obtain credible resource estimates for pragmatic mine planning and design. There is therefore, the need for the application of an appropriate, accurate and cost effective estimation method. The selection of the method used for any particular deposit depends on several factors including ease–of-use, robustness, accuracy and precision. Although the mine employs Ordinary Kriging (OK), which has gained much recognition and proven to be a very good estimator, it is complex and time consuming. This calls for effective alternatives. Inverse Distance Weighting (IDW) is another reliable method of estimation as it is simple, accurate and fast, and has proven to be effective for some deposits. This study seeks to verify the propriety and applicability of IDW to the estimation of the orebody by comparing the estimates obtained from Inverse Distance Weighting (IDW) and Ordinary Kriging methods. Correlation analysis performed on ID2W and OK model grades indicated a near perfect correlation coefficient of 0.93; an indication that ID2W can be used as a good alternative to OK at Pepe.

Journal of Geosciences and Geomatics. 2015, 3(5), 122-127. DOI: 10.12691/jgg-3-5-2
Pub. Date: October 22, 2015

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Ore Grade Reconciliation Techniques – A Review

by Amoako Richard and Al-Hassan Sulemana

Review Article

The essence of ore grade reconciliation is to identify, analyse and manage variance between planned and actual results in a way that highlights opportunities. A consistent record of poor reconciliation is an indication that this variance has not been adequately managed. This would inevitably result in significant economic impact on mining companies. Unfortunately, the issue of poor reconciliation has been an age-old one most mining companies have been battling with and resulting in failure of several mining companies to estimate ore grade accurately, despite good grade control sampling and geological control. This paper reviews various practical and theoretical approaches to ore grade reconciliation, and further reveals inefficiencies in the mining value chain that contribute to poor reconciliation. Key recommendations, pertinent to observations and findings of the study, are thus made towards improving ore grade reconciliation.

Journal of Geosciences and Geomatics. 2015, 3(5), 116-121. DOI: 10.12691/jgg-3-5-1
Pub. Date: October 22, 2015

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