Using fluorescein and bromide tracers to investigate the role of baseflow in a small suburban watershed in Iowa,USA          下载免费PDF全文

S. Rai  M. Z. Iqbal 《水文研究》2015,29(2):173-186

Fluorescein and bromide tracers were used to study baseflow mechanisms of a small suburban watershed in northeast Iowa, USA. The tracers were applied to ten injection holes ranging from 1.3 to 3.0 ft in depth in two phases. Separately, two PVC wells (15 and 16 ft deep) were used to investigate tracer movement in a deeper flow system. Over 30 days of phase 1, none of the tracers was detected in the creek water. In phase 2, fluorescein was irregularly detected in the creek at two sites, whereas bromide was detected at one site only. Meanwhile, soil analysis detected measurable diffusion of bromide and fluorescein at four sites. At each of these sites, the tracer was found to be diffusing toward the creek. None of the tracers applied to the deeper PVC wells showed any movement toward the creek over 1 month of continuous sampling. Isotopic composition of water samples varied spatially as well as temporally going from the deep well (δ¹⁸O = ?8.89‰) to the injection holes (average δ¹⁸O = ?8.42‰), to the creek (average δ¹⁸O = ?7.86‰), and further to the rain samples (average δ¹⁸O = ?4.68‰). The analytical error margin is ±0.09‰. Samples from the injection holes were generally heavier than the deep well sample and lighter than the creek samples, indicating that there was no significant connection between the surface and the subsurface systems. Furthermore, the sporadic appearance of bromide and fluorescein both spatially and temporally points to the fact that baseflow does not constitute a significant part of the area's stream discharge. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Discovery of antler from a new site in the Pinjor Formation (Pleistocene) of Pakistan     

Abdul Ghaffar  Muhammad Akhtar  Muhammad Akbar Khan  Abdul Majid Khan  Khizar Samiullah  Mehboob Iqbal 《Journal of the Geological Society of India》2012,80(1):119-122

Partially complete right antler from the Pinjor Formation (Pleistocene) of the Upper Siwalik Subgroup is identified, described and its phylogenetic relationship is discussed. The fossil antler is compared with other known fossil records of family Cervidae as well as with the extant species, on the basis of which it can be attributed to Axis punjabiensis. This species has not been reported previously from this fossil site.  相似文献   

Spatial analysis of a historical phenomenon: using GIS to demonstrate the strategic placement of Umayyad desert palaces   总被引：1，自引：0，他引：1  

Mahmoud Bashir Alhasanat  Shahid Kabir  Wan Muhd Aminuddin Wan Hussin  Erin Addison 《GeoJournal》2012,77(3):343-359

The Umayyad qusour (desert palaces) are monumental structures built during the reign of the first caliphate of Islam. Usually dismissed as “pleasure palaces” or “hunting lodges,” some scholars are beginning to argue that these prominent structures were strategic interventions in the landscape. Until now, historians have relied mainly on textual, architectural and art-historical analyses of the qusour in order to understand Umayyad state architecture. This research proposes the use of spatial analysis through GIS to lend a new dimension to the discussion. The results of the analysis show that Umayyad qusour are carefully situated at routes of transhumance and water sources. The distribution pattern of the Umayyad qusour is clustered at the outlet of Wadi Sarhan, and there is actually line-of-sight communication between Azraq, Amra, Haranah, Muwaqqar, Umm al Walid, Mushatta, and Qastal. There is also a positive association between Umayyad qusour and their water sources. These results support the argument that the Umayyad qusour were built strategically at perennial water sources in order to monitor routes of transhumance amongst the socio-political centers of the period.  相似文献   

The inner ramp facies of the Thanetian Lockhart Formation,western Salt Range,Indus Basin,Pakistan   总被引：1，自引：1，他引：0  

Muhammad Hanif  Muhammad Imraz  Fahad Ali  Muhammad Haneef  Abdus Saboor  Shahid Iqbal  Sajjad Ahmad Jr 《Arabian Journal of Geosciences》2014,7(11):4911-4926

The Lockhart Formation from a major carbonate unit of the Paleocene Charrat Group in Upper Indus Basin, Pakistan represents a larger foraminiferal–algal build up deposited in a cyclic sequence of the carbonate ramp. The foraminiferal–algal assemblages of the Lockhart Formation are correlated here to larger foraminiferal biostratigraphic zone, i.e. Shallow Benthic Zone (SBZ3) of the Thanetian Age. Inner ramp lagoon, shoal and fore shoal open marine are three main facies associations represented by wackstone and packstone foraminiferal–algal deposits. These facies are present in a cyclic order and displayed a retrograding carbonate ramp indicating the Thanetian transgressive deposits associated with eustatic sea level rise. The correlation of the microfacies of the Lockhart Formation (Upper Indus Basin) and facies of the Dungan Formation (Lower Indus Basin) provide detailed configuration of the depositional setting of the Indus Basin during the time interval represented by the Thanetian Zone SBZ3.  相似文献   

Using stable isotopes of nitrogen to study its source and transformation in a heavily farmed watershed     

S. Gautam  M. Z. Iqbal 《Environmental Earth Sciences》2010,60(1):11-20

Twenty private wells and ten stream locations were sampled to assess the source and fate of dissolved nitrate in the Cedar River watershed of Iowa, USA. The average levels of nitrate in groundwater decreased from 39.5 mg/L in May, to 38 mg/L in July, to 30 mg/L in September. Although several surface water samples exceeded MCL in May, most values dropped to below 20 mg/L by July and September. The decreasing N levels were attributed to the gradual uptake of nitrate by growing crops as well as the cyanobacterial growth in the aquatic systems. The δ¹⁵N values of dissolved nitrate in groundwater ranged from +0.45 to +5.35‰, whereas those in surface water ranged from +1.48 to +5.16‰. The results suggested that commercial fertilizers and soil organic nitrogen were probably mixed up in their transport pathways. A fertilizer-only source would provide much lower delta values, whereas soil nitrogen would provide higher than observed delta values. Denitrification was considered unlikely because of the low δ¹⁵N values, high nitrate concentrations, and moderately high DO content in groundwater. Animal wastes were not found as a possible source of nitrate in the water. This is supported by the low chloride concentrations and lower than 10‰ delta values in the water samples. The study demonstrates that nitrogen isotope data in coordination with the dissolved nitrate levels and land use can be effectively used in nitrogen source identification and its transformation studies.  相似文献   

Trends in extreme rainfall events of Bangladesh   总被引：1，自引：0，他引：1  

Shamsuddin Shahid 《Theoretical and Applied Climatology》2011,103(3-4):489-499

Previous studies have shown that urbanization in the Pearl River Delta (PRD) region in southern China can have significant effect on the land-sea breeze circulation in the region. In this study, some characteristics of this urban heat island (UHI) effect are further investigated by some idealized numerical experiments. This study focuses on three aspects of the UHI effects. Firstly, the interaction of UHI effects associated with different city clusters in the PRD region. Secondly, the UHI effect and the strength of the background wind field. Thirdly, seasonal variation of the UHI effect. Experiment results suggest that the interaction of the UHI effects due to the closely distributed city clusters in the PRD region is not significant, while the UHI effect in the region may depend on the strength of the background wind. The seasonal-mean UHI effect in the region shows a significant variation associated with the change of seasons.  相似文献   

Impact of Siberian High on rainfall variability over Northern part of Indo-Pak region     

M. J. Iqbal  S. M. Fahad Riaz  Badar M. K. Ghauri 《Arabian Journal of Geosciences》2013,6(8):3087-3092

Anticyclones dominate the weather over most of the eastern and the southern Asia during the winter season. This study examines the impact of Siberian High on winter rainfall variability over South Asia. In this paper, the teleconnections between the Siberian High and winter precipitation that cover the northern part of Indo-Pak region have been discussed. The objective indices of area-weighted pressure and area-weighted latitudinal and longitudinal movements high are used to find out the linkage between the winter rainfall in the mentioned region and the Siberian High. The analysis shows that rainfall pattern is significantly correlated with latitudinal displacement of the Siberian High. We have constructed a linear model of the winter rainfall using Siberian High latitude and Nino34 which explains 27 % variance of the winter precipitation for the region under study. The article also explains the physical mechanisms to establish the relationships between the Siberian High and regional rainfall.  相似文献   

Screening Indian Mustard Genotypes for Phytoremediating Arsenic‐Contaminated Soils     

Mohd Kafeel Ahmad Ansari  Shahid Umar  Altaf Ahmad  Shahid Hussain Ansari  Muhammad Iqbal  Gary Owens  Hong‐Bo Shao 《洁净——土壤、空气、水》2013,41(3):313-314

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Spatio‐Temporal Variability and Pollution Assessment of Selected Metals in Freshwater Sediments,Pakistan          下载免费PDF全文

Muhammad Saleem  Javed Iqbal  Munir H. Shah 《洁净——土壤、空气、水》2016,44(4):402-410

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GIS integration of hydrogeological and geoelectrical data for groundwater potential modeling in the western part of greater Kushtia district of Bangladesh     

M. Nozibul Haque  Shamsuddin Shahid  Mumnunul Keramat  Morteza Mohsenipour 《Water Resources》2016,43(2):283-291

Geographical Information System (GIS) has been used in this paper to delineate groundwater resources potential in the western part of greater Kushtia district of Bangladesh, where urgent attention for augmentation of irrigation water supply is required. Thematic maps of transmissivity, hydraulic conductivity, specific yield, net recharge, aquifer thickness, surface water bodies, aquifer resistivity, overburden aquitard thickness and its resistivity have been prepared and assigned weight according to their relative importance using Analytical Hierarchical Process for the preparation of groundwater potential model. Since the values within each thematic map vary significantly, they are classified into various ranges or types and assigned ratings. Finally, the thematic maps are integrated using GIS to prepare the groundwater potential map for the study area in terms of Ground Water Potential Index (GWPI). The evolved map indicates that 22.51% of the study area have GWPI more than 0.70 and therefore, have excellent prospective for exploitation. About 69.12% of the area with GWPI ranging from 0.50 to 0.70 is also quite promising for groundwater abstraction, while the rest 8.37% area having GWPI below 0.50 indicates moderate potential. The obtained map of groundwater potential is found in good agreement with the yields of available pumping test data.  相似文献