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21.
Sarva Mangala Praveena Mohd Harun Abdullah Kawi Bidin Ahmad Zaharin Aris 《Environmental Earth Sciences》2012,66(3):719-728
Numerical models are capable of simulating various groundwater scenarios and relate it towards groundwater management. This
paper focuses on numerical modeling and water balance approaches in the search for a sustainable management plan in Manukan
Island. The impacts of pumping and recharge rates represented by groundwater scenarios were investigated by means of hydraulic
heads, chloride concentrations and water balance components. Overpumping and inconsistency in recharge rate are the stresses
shown in Scenario A. Scenario B involved with reduction pumping rate by 25% has shown an increase in groundwater levels, chloride
concentration and groundwater storage. Scenario C showed the most promising finding compared with Scenarios A and B. Highest
hydraulic heads, lowest chloride concentration (1,552.2 mg/L) and positive groundwater storage (254.3 m3/day) were obtained in Scenario C. Chloride concentration in pumping wells still exceeds World Health Organization International
Standard limit in Scenario C which illustrates an additional water treatment is needed. Nevertheless, in view of a compromise
groundwater management plan in study area, Scenario C is the best plan so far to protect the groundwater resources in the
study area. More understanding of the artificial recharge method (percolation tank) and study site by means of modeling studies
is needed. Additionally, further progress is needed in obtaining the water usage data from each part to determine the best
pumping rate. A sustainable groundwater management plan is crucial to maintain the natural resources and social benefits as
well as to protect the ecological balance of Manukan Island. 相似文献
22.
In the catchment area of Scopia, Central Greece, a lumped applied approach of water balance was accomplished, by applying the Zygos model, which delineates an essential water balance forms. The model is in view of Thornthwaite model, in its modified version. It can be adjusted automatically, with the evolutionary annealing-simplex technique for nonlinear optimization, or manually and the input data are precipitation and the potential evapotranspiration. In the present study, both programmed and manual calibration occurred. Programmed calibration took place, utilizing a specimen of measured runoff values from October 2009 to March 2011. Despite the fact that the Nash–Sutcliffe coefficient (NSC) value was high (0.87), the simulated parameters of water balance had abnormal significance for Scopia catchment area. On the contrary, manual calibration uncovered that the actual evapotranspiration constitutes 64.6% (450.1 mm) of the precipitation. Runoff and percolation represent 20.6% (143.6 mm) and 14.8% (102.9 mm) of the precipitation, respectively. The NSC (0.70) and the validation criteria exhibit an ideal adjustment of simulated to measured runoff, while the hydrological parameters appeared to have a physical significance for the study site. Zygos model connects the emergence of springs with the development of the karstification in the carbonate rocks of the region and affirms the predominance of runoff versus percolation due to the hydrolithological structure of the Scopia catchment. This is related to the presence of episodic floods in the area. The yearly precipitation values were found with an error of 0.2% and are viewed as insignificant. 相似文献
23.
Hydrochemical changes in a small tropical island’s aquifer: Manukan Island, Sabah, Malaysia 总被引：1，自引：0，他引：1
Small islands groundwater are often exposed to heavy pumpings as a result of high demand for freshwater consumption. Intensive
exploitation of groundwater from Manukan Island’s aquifer has disturbed the natural equilibrium between fresh and saline water,
and has resulted increase the groundwater salinity and leap to the hydrochemical complexities of freshwater–seawater contact.
An attempt was made to identify the hydrochemical processes that accompany current intrusion of seawater using ionic changes
and saturation indices. It was observed that the mixing between freshwater–seawater created diversity in geochemical processes
of the Manukan Island’s aquifer and altered the freshwater and seawater mixture away from the theoretical composition line.
This explained the most visible processes taking place during the displacement. 相似文献
24.
Lintang Nur Fadlillah Widyastuti M. Geottongsong Tanita Sunarto Marfai Muh Aris 《Water Resources》2019,46(6):832-843
Water Resources - Understanding estuarine characteristics is crucial for managing aquatic ecosystem and aquaculture. A delta is a dynamic area that influence by both sea and river. Research on a... 相似文献
25.
Aris Karastergiou Simon Johnston 《Monthly notices of the Royal Astronomical Society》2007,380(4):1678-1684
Motivated by recent results on the location of the radio emission in pulsar magnetospheres, we have developed a model which can account for the large diversity found in the average profile shapes of pulsars. At the centre of our model lies the idea that radio emission at a particular frequency arises from a wide range of altitudes above the surface of the star, and that it is confined to a region close to the last open field lines. We assert that the radial height range over which emission occurs is responsible for the complex average pulse shapes rather than the transverse (longitudinal) range proposed in most current models. By implementing an abrupt change in the height range to discriminate between young, short-period, highly energetic pulsars and their older counterparts, we obtain the observed transition between the simple and complex average pulse profiles observed in each group respectively. Monte Carlo simulations are used to demonstrate the match of our model to real observations. 相似文献
26.
Lucas J. Lourens 《《幕》》2008,31(2):239-242
A proposed resolution to the current Neogene-Quaternary debate involves independent, non-overlapping status for the two units and harks back to Lyell＇s original denotation of the terms Older and Newer Pliocene. 相似文献
27.
Wan Ying Lim Ahmad Zaharin Aris Sarva Mangala Praveena 《Arabian Journal of Geosciences》2013,6(12):4891-4901
The current study presents the application of selected chemometric techniques—hierarchical cluster analysis (HCA) and principal component analysis (PCA)—to evaluate the spatial variation of the water chemistry and to classify the pollution sources in the Langat River. The HCA rendered the sampling stations into two clusters (group 1 and group 2) and identified the vulnerable stations that are under threat. Group1 (LY 1 to LY 14) is associated with seawater intrusion, while group 2 (LY 15 to LY 30) is associated with agricultural and industrial pollution. PCA analysis was applied to the water datasets for group 1 resulting in four components, which explained 85 % of the total variance while group 2 extracted six components, explaining 88 % of the variance. The components obtained from PCA indicated that seawater intrusion, agricultural and industrial pollution, and geological weathering were potential sources of pollution to the study area. This study demonstrated the usefulness of the chemometric techniques on the interpretation of large complex datasets for the effective management of water resources. 相似文献
28.
Nur Aliaa Shafie Ahmad Zaharin Aris Nadzhratul Husna Ahmad Puad 《Arabian Journal of Geosciences》2013,6(8):3049-3058
An exploratory study was carried out at 22 sampling stations along the Langat River, Selangor in order to investigate on the vitality of cation exchange capacity (CEC) in sediment (0–5 cm). Parameters such as pH, Eh, salinity, and electrical conductivity (EC) were determined. The CEC in sediment has been calculated by the determination of Ca2+, Na+, Mg2+, and K+ using the flame atomic absorption spectrophotometer, while the organic matter content in sediment was ascertained using the loss on ignition method. The characteristic of the sediment shows that pH (3.09–7.46), salinity (0.02–10.71 ppt), EC (3.39–517 μS/cm) and Eh (?16.20–253.10 mV) were substantially high in variation. This study also revealed that exchangeable Ca2+ and Mg2+ were controlled by organic matter contents, while exchangeable Na+ and K+ were influenced by salinity. Salinity was observed to play a major part in controlling all the exchangeable cations, as it gives strong significant correlations with Na+, K+, Mg2+, CEC, and organic matter at p?<?0.01. The presence of seawater, clay mineralogy, and organic matter proves that it does play an important role in determining the CEC and soon relates to the pollution magnitude in the sediment. 相似文献
29.
A rapid increase in the number of tourists has placed a heavy demand for freshwater on Manukan Island, a small island located
offcoast of Kota Kinabalu, Sabah. Hydrochemical and numerical approaches have been applied in this study to evaluate the groundwater
quality of unconfined aquifer lying in Manukan Island, Sabah, East Malaysia. This is vital to enhance better understanding
about groundwater management. Hydrochemical analysis output indicated NaCl water type in sampling locations. Seawater intrusion
is marked by its relatively high Na+, Mg2+, Cl− and SO4
2− concentrations. Hydrochemical analysis output clearly showed the influence of seawater in groundwater of Manukan Island.
The numerical model output proved the influence of seawater in groundwater of Manukan Island by indicating the upconing process
at the beneath of the pumping well. Current status of seawater intrusion in Manukan Island is about 14.6% of freshwater and
seawater mixing ratio in low lying area of Manukan Island as simulated by SEAWAT-2000 model output. Numerical model SEAWAT-2000
output showed clearly that the upconing process is the possible route of seawater to influence the fresh groundwater aquifer
chemistry in Manukan Island. The results have enhanced the current understanding of seawater intrusion in the study area.
Future studies will focus on using numerical models to simulate and suggest suitable groundwater management plans in Manukan
Island. 相似文献
30.
Some observations from radiometric ‘8 bit’ data of sediment thin sections based on alternative petrographic image analysis method 总被引：1，自引：0，他引：1
Sudip Dey Suvendu Ghosh Chandrani Debbarma Prasamita Sarkar Mhu Aris Marfai Sabyasachi Maiti 《Journal of Earth System Science》2009,118(2):163-173
This paper deals with the experiment of sediment microstructure analysis especially microfabric mapping by digital imaging.
For that purpose the greyscale images (Red band from RGB combination) of the thin sections have been prepared from the selected
12 samples. The basis of this mapping is the reflectance capacity of different sediments which is influenced by the physical
parameters like grain size and colour. The reflectances of different sediments are represented in digital format by different
DN values from 0–255 within the radiometric ranges of ‘8 bit’ data. Density slicing has been chosen as the method of microstructure
mapping in this research. This study shows that lower DN values normally present dark coloured coarser sand and clay while
higher DN values present light coloured finer sediment samples. In the selected samples for this study the maximum DN value
has been found from micaceous materials. Another remarkable thing observed from the microfabric mapping is that the presence
of coarser sediments forms complex microfabric pattern than the finer sediments in the study area. Though this method have
some demerits, still its simple technique can be very useful for accurate microstructure analysis. 相似文献