A Quantitative Model to Predict a Safe Yield for Well Fields in Kufra and Sarir Basins, Libya     

Moid U. Ahmad 《Ground water》1983,21(1):58-66

  相似文献   

ASSESSMENT OF 17β-ESTRADIOL IN AQUATIC ENVIRONMENTS AROUND KLANG VALLEY, MALAYSIA     

Ahmad Ismail　Syaizwan Zahmir Zulkifli　Ferdius Mohamat Yusuff　Usuki Yasuteru　Kitajima Sachiko　Arizono Koji 《湿地科学》2007,5(4):322-325

This study was conducted to assess the existing concentration of 17β-estradiol(E2)in the surface water samples collected from rivers and lakes around Klang Valley,Malaysia.E2,which is a natural feminizing chemical produced in female organisms,regularly used to compare with other environmental estrogens because they behave similarly and react effectively as a hormone at a very low concentration.It was found that the average concentration of E2 in the aquatic environment of Klang Valley was(14.08 ±3.67)pg/mL,which was 14 times higher than those in the Japanese aquatic environment in this study.The river system had the average concentration of(20.02±5.26)pg/mL while the lake had an average concentration of(5.91±3.39)pg/mL.The E2 concentration was presumed high if the sources occurred nearby the area.Current levels of E2 in the aquatic environment may possess threats to existing aquatic organisms.Since high level of E2 has been discovered in the aquatic environment around Klang Valley,further studies and monitoring of E2 and other EDCs concentrations are needed to determine their levels in Malaysian aquatic environment and help to control these chemicals pollution in the aquatic environment.  相似文献   

An Experiment Using the High Resolution Eta and WRF Models to Forecast Heavy Precipitation over India   总被引：1，自引：0，他引：1  

Y. V. Rama Rao  H. R. Hatwar  Ahmad Kamal Salah  Y. Sudhakar 《Pure and Applied Geophysics》2007,164(8-9):1593-1615

In the present study using the Weather Research and Forecasting (WRF) and Eta models, recent heavy rainfall events that occurred (i) over parts of Maharastra during 26 to 27 July, 2005, (ii) over coastal Tamilnadu and south coastal Andhra Pradesh during 24 to 28 October, 2005, and (iii) the tropical cyclone of 30 September to 3 October, 2004/Monsoon Depression of 2 to 5 October 2004, that developed during the withdrawal phase of the southwest monsoon season of 2004 have been investigated. Also sensitivity experiments have been conducted with the WRF model to test the impact of microphysical and cumulus parameterization schemes in capturing the extreme weather events. The results show that the WRF model with the microphysical process and cumulus parameterization schemes of Ferrier et al. and Betts-Miller-Janjic was able to capture the heavy rainfall events better than the other schemes. It is also observed that the WRF model was able to predict mesoscale rainfall more realistically in comparison to the Eta model of the same resolution.  相似文献   

Influence of surface and vegetation characteristics on C-band radar measurements for soil moisture content   总被引：1，自引：0，他引：1  

Shakil Ahmad Romshoo  Masahiro Koike  Sadayukihir Onaka  Taikan Oki  Katumi Musiake 《Journal of the Indian Society of Remote Sensing》2002,30(4):229-244

Soil moisture estimation using microwave remote sensing faces challenges of the segregation of influences mainly from roughness and vegetation. Under static surface conditions, it was found that Radarsat C-band SAR shows reasonably good correlation and sensitivity with changing soil moisture. Dynamic surface and vegetation conditions are supposed to result in a substantial reduction in radar sensitivity to soil moisture. A C-band scatterometer system (5.2 GHz) with a multi-polarization and multi-angular configuration was used 12 times to sense the soil moisture over a tall vegetated grass field. A score of vegetation and soil parameters were recorded on every occasion of the experiment. Three radar backscattering models Viz., Integral Equation Model (IEM), an empirical model and a volume scattering model, have been used to predict the backscattering phenomena. The volume scattering model, using the Distorted Born Approximation, is found to predict the backscattering phenomena reasonably well. But the surface scattering models are expectedly found to be inadequate for the purpose. The temporal variation of soil moisture does show good empirical relationship with the observed radar backscattering. But as the vegetation biomass increases, the radar shows higher sensitivity to the vegetation parameters compared to surface characteristics. A sensitivity analysis of the volume scattering model for all the parameters also reveals that the radar is more sensitive to plant parameters under high biomass conditions, particularly vegetation water content, but the sensitivity to surface characteristics, particularly to soil moisture, is also appreciable.  相似文献   

Chemical Characteristics of Stream Draining fromDudu Glacier: An Alpine Meltwater Stream inGanga Headwater, Garhwal Himalaya     

Ahmad Sarfaraz Hasnain Syed Iqbal. Glacier Research Group  School of Environmental Sciences  Jawaharlal Nehru University  New Delhi-  India 《中国地质大学学报(英文版)》2001,12(1)

I-DtjcrONAlpine environment enjoys a distinct set of physicochemical conditions asl compared to other aqueous systems. Thehydrochemical characteristics of meltwater draining from thisenvironment are different from the other aqueous ecosystemsdue to their mountainous nature and extreme cold climatic conditions. The high concentration of various chemical constitu.ents in meltwater shows the intensive chemical weathering inthe basin. The rapid physical weathering due tO grinding actionof the gl…  相似文献   

Hydrogeologic Units Of Lebanon     

Kamal Khair  Nizar Aker  Khalil Zahruddine 《Hydrogeology Journal》1992,1(2):34-49

Based on geomorphologic and hydrogeologic characteristics of its territory, Lebanon is divided into three provinces: the West Lebanon province, the Bekaa province, and the East Anti-Lebanon province. These provinces are subdivided into smaller hydrogeologic units, the basins and subbasins. Significant features used in the subdivision are faults, relief, anticlinal axes, river channels, and water divides. Recharge to groundwater is a percentage of the intake area, the percipitation rate over this area, and the infiltration rate of outcropping rocks. The amounts of recharged water over the three provinces are 1609, 914, and 19 Mm³, respectively. Discharge is surface water from springs and water wells along the Lebanese coast. The discharge from the Lebanese rivers exceeds 3700 Mm³/year, an appreciable amount of which comes from natural springs. The quantity of groundwater pumped by wells or flowing into neighboring countries and to the sea as submarine springs, may exceed 800 Mm³/year.  相似文献   

Investigation on the geological and geotechnical factors leading to a major slope failure at a selected site on a Jordanian highway     

Azm S. Al-homoud  Salah Taqieddin  Safwan Saket 《Natural Hazards》1995,12(3):203-224

During and after the very wet 1991/1992 winter experienced in Jordan, significant slope failures occurred along several sections of the new Irbid-Amman highway in Jordan. The topography over most of the route is hilly, and significant amounts of cut and fill were used to construct the highway. One such slope failure lies at 44+800 km on the highway south of Jerash City at a distance of about 5.0 km from Wadi Zerqa bridge. A landslide occurred downslope of the highway embankment resulting in a collapse of the most of the gabbion wall supporting the embankment. This paper deals with the overall stability of the slope at 44+800 km. It presents the geological and geotechnical studies carried out at this site, identifies the causes and mechanism of instability, and presents appropriate remedial measures. The study concluded that the landslide movement occurred within the colluvium material. It resulted primarily from excess piezometric pressures generated within the slope as a direct consequence of inadequate drainage. It is recommended to reconstruct the entire gabbion wall with its foundation seated on the sandstone that underlies the colluvium and to install a surface drainage system at the site.  相似文献   

Urbanization and urban development in the Muslim World: From the Islamic City Model to megacities     

Bilal Ahmad 《GeoJournal》1995,37(1):113-123

  相似文献   

Geochemical Aspects of Hypogene Hydrothermal Alteration Zones in the Chol-qeshlaghi Area, NW Iran: Constrains on REEs     

Kamal SIAHCHESHM  Mohammad SHAHSAVANI BAMI 《《地质学报》英文版》2020,94(3):777-788

Chol-qeshlaghi altered area lies in the northwestern part of the post-collisional Urumieh-Dokhtar magmatic arc, NW Iran. Pervasive silicic, argillic, phyllic and propylitic altered zones appears to be intimately affiliated to the fluids derivative of upper Oligocene Khankandi granodiorite. This paper is dedicated to the identification of geochemical characteristics of hydrothermal alterations, focusing on the determination of the mass gains and losses of REEs, to gain significant insights regarding the chemical exchanges prevailed between the host rocks and hydrothermal fluids. The low pH and high activity of SO_4~(-2) ligands in silicic alteration fluids, resulting in depletion of entire REEs. Decreasing of LREEs appeared in argillic zone may attributed to reduce in adsorption ability of clay minerals in low pH; whereas HREEs enrichment in phyllic zone was inclined to put it down to the abundance of sericite(± Fe oxides). A significant reduction of Eu/Eu* ratio in silicic zone can be attributed to negligible sulfides and clay minerals as some effective agents in adsorption of released Eu~(+2). Factors such as changes in pH, the abundance of absorptive neomorph mineral phases, activity of ligands play an important role in controlling the distribution and concentration of REEs in Chol-qeshlaghi alteration system.  相似文献   

The isotopic composition of carbon in the Alberta oil sand     

Kamal N. Jha  John Gray  Otto P. Strausz 《Geochimica et cosmochimica acta》1979,43(9):1571-1573

The carbon isotopic ratios obtained from Athabasca bitumen, asphaltene and maltene have the same value $\text{δ}{}^{13}\text{C}\text{= ?29.6}\text{per ml}$. The corresponding values in the Cold Lake deposits are ?30.6, ?30.0 and ?31.6 per ml. The ratios determined for methane collected from the oil sand and its fractions are about 15 per ml lower than the above values. It appears that the Athabasca and Cold Lake Reservoirs have similar histories.  相似文献