International Journal of Economic and Environmental Geology
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Land Subsidence Caused by Groundwater Exploitation in Quetta Valley, Pakistan
Get PDFLand subsidence is affecting several metropolitan cities in developing as well as developed countries around the world such as Nagoya (Japan), Shanghai (China), Venice (Italy) and San Joaquin valley (United States). This phenomenon is attributed to natural as well as anthropogenic activities that include extensive groundwater withdrawals. Quetta is the largest city of Balochistan province in Pakistan. This valley is mostly dry and ground water is the major source for domestic and agricultural consumption. The unplanned use of ground water resources has led to the deterioration of water quality and quantity in the Quetta valley. Water shortage in the region was further aggravated by the drought during (1998-2004) that hit the area forcing people to migrate from rural to urban areas. Refugees from the war torn neighboring Afghanistan also contributed to rapid increase in population of Quetta valley that has increased from 0.26 million in 1975 to 3.0 million in 2016. The objective of this study was to measure the land subsidence in Quetta valley and identify the effects of groundwater withdrawals on land subsidence. To achieve this goal, data from five Global Positioning System (GPS) stations were acquired and processed. Furthermore the groundwater decline data from 41 observation wells during 2010 to 2015 were calculated and compared with the land deformation. The results of this study revealed that the land of Quetta valley is subsiding from 30mm/y on the flanks to 120 mm/y in the central part. 1.5-5.0 m/y of groundwater level drop was recorded in the area where the rate of subsidence is highest. So the extensive groundwater withdrawals in Quetta valley is considered to be the driving force behind land subsidence. Keywords: Land subsidence, water depletion, GPS, Quetta, GIS, Pakista
Regionwide Geodynamic Analyses of the Cenozoic Carbonate Burial in Sri Lanka Related to Climate and Atmospheric CO2
Get PDFAsian tectonism and exhumation are critical components to develop modern icehouse climate. In this study, stratigraphic sections of eight wells in the Mannar and Cauvery basins were considered. The author demonstrated that this local system records a wealth of information to understated regional and global paleoclimatic trends over the Cenozoic era. The lithostratigraphic framework has been generally characterized by deposition of carbonate-rich sediments since the Middle Cenozoic. Geological provenance of carbonate sediments had probably related to local sources from Sri Lankan and Indian land masses. The main controlling factor of carbonate burial is rather questionable. However, this carbonate burial has indicated the possible link to the Middle to Late Cenozoic global climatic transition. This major climatic shift was characterized by long-term reduction of atmospheric carbon dioxide concentration over the Cenozoic era. Consequently, this geological trend (carbonate burial) has a straightforward teleconnection to the global cooling towards the glaciated earth followed by the development of polar ice sheets that persist today. Keywords: Mannar Basin, Cauvery Basin, Sri Lanka, paleoclimate, carbonate burial, Cenozoic era
Spatial and Seasonal Studies of Sedimentological and Neoichnological Characteristics from Mangrove areas of Karachi, Pakistan
Get PDFThe purpose of this study is to appraise the physicochemical properties of mangrove sediments and their influence on neoichnological properties produced by different crab species from Korangi Creek (S1) and Sandspit backwater areas (S2 and S3), Karachi. The significant spatial, seasonal and tidal differences (p <0.05) were examined in %moisture, %porosity and sorting coefficient Φ.The significant spatial and seasonal variations were observed in total organic matter, mean Φ, skewness Φ and kurtosis Φ of sediment. Neoichnological properties (burrow number, diameter and total burrow opening area) were observed with significant differences among the macrohabitat (stations) and microhabitat (tidal levels). The correlation analysis indicated that the neoichnological properties are strongly linked with sedimentological properties such as water contents, total organic matter and textural parameters. This study could be employed to distinguish between different paleoenvironmental controlling factors, predicated on similar paleoichnological features made by similar fossil organisms in a mangrove environment.
Keywords: Mangrove sediment, grain size composition, ichnology, Karachi, Pakista
Comparative Analysis of Water Quantity and Quality in Relation to Vegetation Cover in Himalayan Moist Temperate Forests of Galliyat
Get PDFThe aim of this work was to study the impact of deforestation on water quality and quantity in and around Ayubia National Park-Galliyat, Pakistan. Streams from three vegetation zones (HDZ high density vegetation zones, MDZ moderate density vegetation zones, LDZ low density vegetation zones) were selected for comparative analysis. Altitude, slope and aspects (southern and northern) of three sites were kept constant, whereas deforestation was taken as the only variable. Average discharge rates determined during winter and summer of 2010-11 were found highest for HDZ streams [QBR (0.011 and 0. 1241 m3/sec) and QAR (0.0128 and 0.1287 m3/sec)] followed by MDZ streams [QBR (0.0106 and 0. 1218 m3/sec) and QAR (0.0126 and 0.1284 m3/sec)] and lowest [QBR (0.0045 and 0.0157 m3/sec) and QAR (0.0140 and 0.01284 m3/sec)] for LDZ streams. Similarly, pre- and post-rainfall variations in discharge rates were recorded the highest in LDZ (0.06 m3/sec), moderate in MDZ (0.0045 m3/sec) and the lowest in HDZ (0.0032 m3/sec). Analysis of variance for water quality parameters (pH, NO2, NO3) revealed insignificant variations in relation to vegetation cover, whereas significant variations in alkalinity, total dissolved solids, conductivity and hardness were observed. In the light of these results, we concluded that the vegetation cover has close correlation with water and deforestation has significantly influenced water quantity and quality in the study area.
Keywords: Deforestation, water quantity, water quality, vegetation zone, watershed, moist temperate forests
Assessment of Groundwater Resources in Kirana Hills Region, Rabwah, District Chiniot, Pakistan
Get PDFThis study was planned to assess the groundwater quality of the area adjacent to Precambrian Kirana Hills, Pakistan. The majority of the people in the area use groundwater from private wells for drinking and domestic use. Therefore, it is important to provide an overview of the groundwater quality. This information would be beneficial to local people and the administration for selecting suitable water treatment methods. Samples were collected from different wells of Rabwah town, close to the Kirana Hills. Parameters like EC, pH, alkalinity and total dissolved solids (TDS) were determined for 142 samples. While 40 samples were analyzed for hardness, Ca, Mg, Cl, SO4, NO3, and F. standards set by the World Health Organization (WHO) were considered to evaluate the quality of groundwater. Geographic Information System (GIS) was used to interpolate analyzed physicochemical parameters. The results showed that EC, TDS, hardness, Cl, SO4, and Ca were very high in the water samples of the area. Fifty-two percent of samples had pH values lower than the permissible limits. Results suggest that the water quality is extremely adverse close to the hills. The poor water quality in the area near the hills may be due to the limited recharge of aquifers because of the hills and shallow basement, which may act as a barrier to subsurface water movement. Some physical and chemical parameters indicated that the quality of water at deeper levels (i.e. >150 ft) is relatively better. This may be due to limited exploitation of water from deeper aquifers as compared to shallow aquifers. Hence, proper aquifer management is required to prevent water quality deterioration due to over exploiataion. NO3 was found within the acceptable limits and all water samples were found free of any significant contamination by human activities.
Keywords: Kirana hills, GIS, water analysis
Impact of Rain Water Infiltration on the Stability of Earth Slopes
Get PDFSlope failure occurs very often in natural and man-made slopes which are subjected to frequent changes in ground water level, rapid drawdown, rainfall and earthquakes. The current study discusses the significance of water infiltration, pore water pressure and degree of saturation that affect the stability of earth slopes. Rainwater infiltration not only mechanically reduces the shear strength of a slope material, but also chemically alters the mineral composition of the soil matrix. It results in the alteration of macro structures which in turn decreases the factor of safety. A few case studies are discussed in this paper to quantitatively observe the variation in factor of safety (FOS) of various earth slopes by changing the degree of saturation. The results showed that most of the earth slopes get failed or become critical when the degree of saturation approaches to 50 % or more.
Keywords: Seepage, slope failure, infiltration, factor of safety, unsaturated soi
Evaluation of Reservoir Characteristics of Well Kot-Sarang-2, Potwar Plateau, Pakistan Using Geophysical Logs
Get PDFPresent study deals with reservoir characterization of Kot-Sarang-2 well, located in central part of Potwar plateau of Upper Indus Basin, District Chakwal. The geological structure of the Potwar Basin is the product of the Tertiary Himalayan orogeny, which resulted in the formation of complex fold and thrust belt in this region. In the present work, an attempt has been made to delineate zones having fair shows of hydrocarbons accumulation. In addition to this, estimation of reservoir properties and formation evaluation using wireline logs is also the foremost objective of this study. Based on the wireline logging results, three zones have been marked. Paleocene Lockhart Limestone (3967m to 4045m), Permian Wargal Limestone (4160m to 4245m) and Permian Amb Formation (4246m to 4285m) are possible reservoirs encountered. Physical properties i.e. total porosity (Øt), effective porosity (ØE), resistivity of water (Rw), saturation of water (Sw) and saturation of hydrocarbons (Sh) are calculated. For the calculation of saturation of water (Sw) both Archie’s equation (Swa) and Indonesian equation (Swi) are applied. Results show that Amb and Wargal formations are showing fair to good saturation of Hydrocarbons (Sh) i.e.73% and 88% respectively, but this is due to high resistivity values of these formations and porosity log also giving very low values. Effective porosity for zones Lockhart, Wargal and Amb are 2.56%, 3.5% and 1.32% respectively. Based on these results it is inferred that these formations have low potential for an economically feasible production of hydrocarbons. Keywords: Kot-Sarang, fold and thrust belt, wireline logs, porosity, Archie equation, Indonesian equation
Sedimentology, Sequence Stratigraphy and Reservoir Characterization of Samana Suk Formation Exposed in Namal Gorge Section, Salt Range, Mianwali, Punjab, Pakistan
Get PDFSamana Suk Formation of Bathonian-callovain age, exposed in Nammal Gorge Salt Range, has been studied for microfacies and sequence stratigraphic investigation. The formation is mainly composed of limestone, with minor beds of sandstone and marl. The limestone is grey, yellowish and purple in color. Limestone is fine grained, thin to medium bedded and inter-bedded with algal laminations. The sandstone is light yellowish brown, brick red in color, calcareous and quartzose. Within Samana Suk Formation one 2ndorder sequence and two 3rdorder sequences have been identified. Their regional correlation through fine-tuned dating helped to develop basin fill model and to understand facies dynamics. A facie belt comprising a wide belt of carbonate facies characterized by Peloidal Packstone microfacies represents inner ramp setting and Pelletal/ Peloidal Wackstone, Mud-Wackstone and Mudstone microfacies represent the low energy lagoonal environment. The sandstone lithofacies represents high energy beach environment which indicates aggrading to pro-grading pattern. The porosity analysis has been done on different samples of limestone and sandstone. For the porosity analysis the Image J software is used. In limestone the porosity ranges up to 6% while in sandstone the porosity ranging up to 18%. From the field and porosity analysis it is concluded that Samana Suk Formation in study area is good reservoir.
Keywords: Salt Range, microfacies, sequence stratigraphy, reservoir characteristics
Diagenetic setting, dolomitization and reservoir characterization of Late Cretaceous Kawagarh Formation, Khanpur Dam section, Hazara, Pakistan
Get PDFThe Kawagarh Formation is well exposed in Hazara basin in different sections. Due to deep depositional settings, the Kawagarh Formation is least appealing to geologists to investigate it as a hydrocarbon reservoir. In the present study, the diagenetic settings of Kawagarh Formation were chronologically studied to interpret its diagenetic history and the effect of different diagenetic phases on the reservoir potential. The dolomitization is also studied in depth to use it as a key for its reservoir potential. Kawagarh Formation is sampled at Khanpur Dam Section for porosity analysis. The samples were taken from limestone and dolomite facies randomly. The dolomites are in the form of veins and well developed thick size beds. These dolomites are secondary in nature which is hosted by fractures and joints of limestone, which affect about 25% of limestone facies. At outcrop scale different types of dolomites are recognised on the basis of color and texture, yellowish fine-grained, brown blackish coarse-grained in the top portion and saddle dolomites. In petrographic study partial and complete dolomitization are observed. On the basis of crystal sizes and geometry different types of dolomites are recognized which are; (1) fine crystalline planar-euhedral dolomite, (2) medium crystalline planar-subhedral dolomite, (3) medium crystalline non-planar-anhedral dolomite, (4) coarse crystalline planar-subhedral dolomite, (5) coarse crystalline, non-planar-anhedral dolomite and (6) saddle dolomites (SD1). In petrographic study, high inclusions and disturbance are observed at the surfaces of dolomitic rhombs which indicate low Mg replacement or dedolomitization phenomena. On image J porosity analysis, the porosity is found of limestone and dolomitic samples. In limestone facies which is mostly, non-laminated mudstone has very low up to 2 to 3% in the form of vugs and fractures. In dolomitic facies, the porosity is ranging from 5% to 14%. In most of the dolomitic samples, the porosity is round about 5%. From the structural analysis and the study of other carbonate formations, it is concluded that this dolomitization occurs in the Kawagarh Formation along the Khui da Maira fault. Near the fault, the dolomites occur in the irregular pattern, but as we move away from faulted section, the dolomites are converted into horizontal veins and beds. The dolomitization model has been evaluated for better understanding of the phenomenon of dolomitization.
Keywords: Kawagarh Formation, diagenesis, dolomitization and reservoir characterization
Petrogenesis of Bir Madi Gabbro-Diorite and Tonalite-Granodiorite Intrusions in Southeastern Desert, Egypt: Implications for Tectono-Magmatic Processes at theNeoproterozoic Shield
Get PDFThe Neoproterozoic rocks of Bir Madi area, south eastern desert, comprises of Metagabbro-Diorite Complex (GCD) and Tonalite-Granodiorite Suite (TGrS). The GDC has a weak tonalitic to strong calc-alkaline character and is made up of olivine gabbro, hornblende gabbro, dionite and monzodiorite. The olivine gabbro is characterized by abundance of augite and labradorite with psuedomorphic serpentine. The hornblende gabbro is mainly composed of hornblende, labradorite, andesine and minor amounts of quartz with or without augite. The diorite consists essentially of andesine, hornblende, biotite and quartz. TheGDC is compositionally broad.,with a wide range of SiO2, (46-57 %) and pronounced enichment in the LILE (Ba and Sr) relative to the HFSE (Nb,Y and Z).The GDC rocks exhibit petrological and geochemical characteristics of arc-related mafic magmas, derived possibly from partial melting of a mantle wedgeabove an early Pan-African subduction zone of the Neoproterozoic Shield. The tonalite and granodiorite have a calcalkaline affinity and show the geochemical signatures of I-type granitoids. The TGrS contains amphibolite enclaves and foliated gabbroic xenoliths. Based on the field evidence and geochemical data, the GDC and TGrS are not related to a single magma type through fractional crystallization. The prcsence of microgranular amphibolite enclavcs in the tonalitic rocks suggest against their generation by partial melting of a mantle-derived basaltic source. The (tonalitic magma originated from partial melting of an amphibolitic lower crust by anatexis process at a volcanic arc regime during construction of Arabian-Nubian Shield. Fractional crystalization of K-feldspar and biotite gave more developed granodiorite variety from the tonalitic magma. The gabbroic xenoliths are similar in the chemical composition to theinvestigated metagabbros. They are incompletely digested segments from the adjacent metagabbro rocks incorporatedinto the granitic magma through an assimilation process