Response of the Dupi Tila aquifer to intensive pumping in Dhaka,Bangladesh     

Brian?L.?MorrisEmail author  Ashraf?Ali?Seddique  Kazi?Matin?Ahmed 《Hydrogeology Journal》2003,11(4):496-503

This paper focuses on the water-quantity issues facing Dhaka because of the rapid exploitation of the Dupi Tila aquifer. Dhaka is one of the world's largest groundwater-dependent cities, relying on water withdrawn from this underlying semiconfined sand aquifer. A meteoric rise in well construction in both the private and public sectors in recent years has produced an estimated 1,300 boreholes that tap the aquifer in urban and suburban parts of the city. Analysis of construction records for public-supply wells drilled between 1970 and 2000 shows that water levels are falling in several areas of the city despite apparently favorable recharge conditions. The productivity of boreholes as measured by specific capacity has also declined significantly. Even though the aquifer system is vital to the infrastructure of the city it remains a poorly quantified resource, and until this is resolved by investment in evaluation studies, attempts to efficiently manage the resource in a sustainable way will be frustrated.

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Resumen Este artículo trata de los aspectos cuantitativos relacionados con la sobreexplotación del acuífero de Dupi Tila, que suministra a la ciudad de Dhaka (Bangladesh). Ésta es una de las mayores ciudades del mundo con dependencia de las aguas subterráneas, y se abastece de un acuífero semiconfinado formado por arenas. El aumento meteórico en la construcción de pozos durante los últimos años, tanto en el sector público como en el privado, ha provocado que haya unas 1.300 captaciones del acuífero en las zonas urbana y suburbana de la ciudad. El análisis de los registros constructivos de pozos de abastecimiento público entre 1970 y 2000 muestra que los niveles piezométricos están descendiendo en diversas áreas de la ciudad, a pesar de la existencia de condiciones aparentemente favorables de recarga. La productividad de los pozos, determinada por su capacidad específica, también ha disminuido significativamente. Aunque el sistema acuífero es vital para la infraestructura de la ciudad, los recursos aún no han sido cuantificados adecuadamente. Hasta que este asunto no sea resuelto mediante la inversión en estudios de evaluación, los intentos por gestionar eficientemente los recursos de forma sustentable serán infructuosos.

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Résumé Cet article porte sur les pertes en quantité subies par Dacca du fait de l'exploitation rapide de l'aquifère de Dupi Tila. Dacca est l'une des villes dépendant de l'eau souterraine les plus importantes du monde, prélevant l'eau d'un aquifère sableux sous-jacent semi-captif. On estime à 1,300 forages l'accroissement des creusements de puits aussi bien dans le secteur privé que public dans ces dernières années; ils prélèvent dans l'aquifère dans la partie urbaine et à la périphérie de la ville. L'analyse des déclarations de creusement de puits pour l'AEP forés entre 1970 et 2000 montre que les niveaux d'eau ont chuté dans plusieurs zones de la ville malgré des conditions de recharge apparemment favorables. La productivité des puits mesurée par la capacité spécifique a également diminué significativement. Même si le système aquifère est vital pour l'infrastructure de la ville, il reste une ressource médiocrement quantifiée, et tant que ceci ne sera pas résolu par un investissement dans des études d'évaluation, les tentatives pour gérer efficacement la ressource de façon durable échoueront.

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CHEMICAL CHARACTERISTICS OF WETLAND＇S INFLOW DRY DIFFUSE DUST AND DIRT FROM IMPERVIOUS SURFACE     

Azam Khan　Saadat Ashraf 《湿地科学》2005,3(4):249-257

This paper presented chemical characteristics of wetland inflow diffuse dust and dirt. Single land use impervious areas (parking and roads) were observed and analyzed in commercial and residential areas for organic matters, phosphorus and heavy metals. The buildup data were collected for approximately six months from December to June. The frequency of monitoring was observed daily for the first two months, twice a week for the next two months and once a week for the last two months. The results indicated significant variations in the organic matters and heavy metals strength and total accumulation among the observed areas. High pollutants strength was associated with smaller dust and dirt (DD) particles. Concentrations of phosphorus varied between 5.1 μg/g and 8.3 μg/g in DD particle less than 75 μm and account for 35%-60% of the total phosphorus. The organic matter accumulation rate associated with particles less than 600 μm and greater than 600 μm was 0.1-1 g·(curb-m)-1·d-1 and 0.1-1.5 g·(curb-m)-1·d-1 , respectively. DD particles greater than 600 μm consist of 70%-90% of leaves and other plant residues. The strength of heavy metals was more at road compared to parking areas both in commercial and residential areas. Percentage of Zn, Cu and Pb attached with particles less than 200 μm were in the range of 50%-70% in parking, 45%-90% on smooth roads and 30%-80% on rough roads. All the dust and dirt exhibited rising trend with time. Dust and dirt buildup data follow a non-linear accumulation function and can be presented better either by an exponential or power function.  相似文献   

September 2004 Flood Event in Southwestern Bangladesh: A Study of its Nature,Causes, and Human Perception and Adjustments to a New Hazard     

Abu Muhammad Shajaat Ali 《Natural Hazards》2007,40(1):89-111

This paper examines the nature and causes of September 2004 hazardous flood that affected the dry and drought prone southwestern region of Bangladesh. It also examines human perception of this new hazard and their methods of adjustments to its negative impacts. Field research for this study includes personal interviews of 453 victim families living in four thanas (lowest administrative units) in Jessore and Satkhira districts of southwestern Bangladesh. Findings of the study suggest that all victim respondents viewed this flood event as a natural hazard, which has caused severe damage to standing crops, fish ponds, permanent trees and homesteads, and deteriorated human health and sanitation conditions. Its long-term impacts on fish farming, soil quality degradation, as well as changing land use/land coverage are also noteworthy but yet to be adequately explored. Both perceived and scientific causes of this flood event include high rainfall for a week before the flood, unusual movement of low pressure system into the affected area, cloudy weather and low evaporation, siltation of the regional riverbeds, and rolling back of the Ganges River water through the Ichamati and Bhagirati rivers. These factors also caused hazardous flooding at the same time in the Ichamati and Bhagirati Rivers and their floodplains in the West Bengal province of India. To release the overflow of flood water inside India, the Indian border patrol breached the Ichamati river embankment in several places along Satkhira and Jessore international border which had aggravated the flood situation in the study area.  相似文献   

Adsorption of heavy metals in glacial till soil     

Ashraf Z. Al-Hamdan  Krishna R. Reddy 《Geotechnical and Geological Engineering》2006,24(6):1679-1693

The charged sites on soil particles are important for the retention/adsorption of metals. Metallic counterions can neutralize the intrinsic charges on the surfaces of soil particles by forming complexes. In this study, efforts have been made to determine the effect of surface potential, pH, and ionic strength on the adsorption of four metal ions, hexavalent chromium Cr(VI), trivalent chromium Cr(III), nickel Ni(II) and cadmium Cd(II), in glacial till soil. Batch tests were performed to determine the effect of pH (2–12) and ionic strength (0.001–0.1 M KCl) on zeta potential of the glacial till soil. The point of zero charge (pH _PZC ) of glacial till was found to be 7.0±2.5. Surface charge experiments revealed the high buffering capacity of the glacial till. Batch adsorption experiments were conducted at natural pH (8.2) using various concentrations of selected metals. The adsorption data was described by the Freundlich adsorption model. Overall glacial till shows lower adsorption affinity to Cr(VI) as compared to cationic metals, Cr(III), Ni(II) and Cd(II).  相似文献   

Studies on the transfer of mineral nutrients from feed, water, soil and plants to buffaloes under arid environments     

M.Y. Ashraf  A. Khan  M. Ashraf  S. Zafar 《Journal of Arid Environments》2006,65(4):632-643

Studies were conducted at a Livestock Farm in an arid region of Pakistan, to determine the uptake of mineral nutrients from the food of buffaloes. Samples of feed, water, forage, soil as well as blood, milk, urine, and faeces of the animals were collected and analysed for K⁺, Ca²⁺, and Fe²⁺ during summer and winter. The results showed that the concentrations of K⁺ and Ca²⁺ in plants were low, whereas that of Fe²⁺ was high. In animals, K⁺ was not found in the milk in significant amounts, rather it was excreted in the urine. The calcium taken in by the animals was used for the synthesis of milk, as a result of which low Ca²⁺ concentrations were detected in urine. Mineral nutrient concentrations (K⁺ and Ca²⁺) in forage plants and water were lower than the optimum requirement of the animals, as a result of which blood plasma contained lower amounts of minerals (K⁺ and Fe²⁺) than that of the normal animals or critical limits. From the findings of the present study, it can be concluded that the buffaloes raised at the livestock farm had a severe deficiency of mineral nutrients, particularly K⁺ in lactating and Fe²⁺ in both lactating and non-lactating animals. Feed supplements, that can overcome these deficiencies, should be used for the optimum growth, milk production and resistance to diseases.  相似文献   

Data-Driven Modeling Approach to Predict the Recovery Performance of Low-Salinity Waterfloods     

Kalam  Shams  Khan  Rizwan Ahmed  Khan  Shahnawaz  Faizan  Muhammad  Amin  Muhammad  Ajaib  Rameez  Abu-Khamsin  Sidqi A. 《Natural Resources Research》2021,30(2):1697-1717

Natural Resources Research - Low-salinity waterflooding (LSWF) has, in the past decade, attained a lot of attention to enhance oil recovery. In LSWF, diluted water is injected into an oil reservoir...  相似文献   

Modeling the impact of groundwater harvesting on the hydro-salinity of a saline catchment in southeastern Australia     

Shahbaz Khan  Muhammad Nadeem Asghar  Tariq Rana 《Hydrogeology Journal》2008,16(4):713-726

Recharge to a saline, unconfined shallow-water-table aquifer is normally considered as an irrecoverable loss of water, but such thinking could be reviewed empirically. The use of an appropriate groundwater harvesting system does not only provide an opportunity to recover this lost water, but can also help in catchment salinity management and improvement. Agricultural-based land-drainage systems such as those that use serial biological concentration (SBC) of salts, provide examples of such harvesting methods. The impact of groundwater harvesting has been assessed on the hydro-salinity of a saline catchment in southeastern Australia through modeling. For both the below average rainfall and very wet years, the “do nothing” scenario resulted in increasing salinization in the catchment. However, after introducing a SBC system, groundwater salinity showed a decreasing trend while hydraulic heads tended to stabilize around the depth of subsurface collector wells. However, for a successful groundwater harvesting system, proper understanding of the groundwater flows and salt mobilization associated with a catchment is necessary. The outcomes of this modelling study have the potential to address similar issues (salinization) and/or needs (water harvesting) existing elsewhere in the world, particularly in semi-arid regions.

Muhammad Nadeem AsgharEmail:

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Applicability of an ultra-long-range terrestrial laser scanner to monitor the mass balance of Muz Taw Glacier, Sawir Mountains, China     

FeiTeng Wang  ChunHai Xu  ZhongQin Li  Muhammad Naveed Anjum  Lin Wang 《寒旱区科学》2018,10(1):47-54

Glacier mass balance is a key component of glacier monitoring programs. Information on the mass balance of Sawir Mountains is poor due to a dearth of in-situ measurements. This paper introduces the applicability of an ultra-long-range terrestrial laser scanner(TLS) to monitor the mass balance of Muz Taw Glacier, Sawir Mountains, China. The Riegl VZ?-6000 TLS is exceptionally well-suited for measuring snowy and icy terrain. Here, we use TLS to create repeated high spatiotemporal resolution DEMs, focusing on the annual mass balance(June 2, 2015 to July 25, 2016). According to TLS-derived high spatial resolution point clouds, the front variation(glacier retreat) of Muz Taw Glacier was 9.3 m. The mean geodetic elevation change was 4.55 m at the ablation area. By comparing with glaciological measurements, the glaciological elevation change of individual stakes and the TLS-derived geodetic elevation change of corresponding points matched closely, and the calculated balance was-3.864±0.378 m w.e.. This data indicates that TLS provides accurate results and is therefore suitable to monitor mass balance evolution of Muz Taw Glacier.  相似文献   

Comparative study of probable maximum precipitation and isohyetal maps for mountainous regions, Pakistan     

Muhammad Waseem Boot  Ghulam Nabi  Tanveer Abbas  HuiJun Jin  Ayesha Yousaf  Muhammad Azeem Boota 《寒旱区科学》2018,10(1):55-68

Probable maximum precipitation (PMP) is widely used by hydrologists for appraisal of probable maximum flood (PMF) used for soil and water conservation structures, and design of dam spillways. A number of methods such as empirical, statistical and dynamic are used to estimate PMP, the most favored being statistical and hydro-meteorological. In this paper, PMP estimation in mountainous regions of Pakistan is studied using statistical as well as physically based hydro-meteorological approaches. Daily precipitation, dew point, wind speed and temperature data is processed to estimate PMP for a one-day duration. Maximum precipitation for different return periods is estimated by using statistical approaches such as Gumble and Log-Pearson type-III (LP-III) distribution. Goodness of fit (GOF) test, chi-square test, correlation coefficient and coefficient of determination were applied to Gumble and LP-III distributions. Results reveal that among statistical approaches, Gumble distribution performed the best result compared to LP-III distribution. Isohyetal maps of the study area at different return periods are produced by using the GIS tool, and PMP in mountainous regions varies from 150 to 320 mm at an average value of 230.83 mm. The ratio of PMP for one-day duration to highest observed rainfall (HOR) varied from 1.08 to 1.29 with an average value of 1.18. An appropriate frequency factor (K_m) is very important which is a function of mean for observed precipitation and PMP for 1-day duration, and K_m values varies from 2.54 to 4.68. The coefficient of variability (C_v) varies from minimum value of 28% to maximum value of 43.35%. It was concluded that the statistical approach gives higher results compared to moisture maximization (MM) approach. In the hydro-meteorological approach, moisture maximization (MM) and wind moisture maximization (WMM) techniques were applied and it was concluded that wind moisture maximization approach gives higher results of PMP as compared to moisture maximization approach as well as for Hershfield technique. Therefore, it is suggested that MM approach is the most favored in the study area for PMP estimation, which leads to acceptable results, compared to WMM and statistical approaches.  相似文献   

Large scale mass movements triggered by the Kashmir earthquake 2005, Pakistan   总被引：2，自引：1，他引：1  

Muhammad BASHARAT  Joachim ROHN  Mirza Shahid BAIG  Muhammad Rustam KHAN  Markus SCHLEIER 《山地科学学报》2014,11(1):19-30

The SPOT image analysis in Muzaffarabad Azad Kashmir,northwest Himalayas,Pakistan reveals that the Kashmir earthquake 2005 triggered a number of coseismic mass movements along the hanging wall block of the Muzaffarabad Fault.The Neelidandi and Langarpura rock falls have been identified as two major reactivated mass movements with an estimated volume of 3.1 × 106m3and 5.76 × 106m3,respectively.The Neelidandi and Langarpura mass movements were initiated during earthquake in the direction of northwest-southeast extension and northeastsouthwest directed thrusting,respectively.The Neelidandi rock fall occurred in sheared cherty dolomites and limestones of the Cambrian Muzaffarabad Formation,whereas the Langarpura rock fall occurred in alternating clays,shales,claystones,siltstones and sandstones of the Miocene Murree Formation.These rock units along the fault are highly fractured and jointed.The geotechnical maps and geological longitudinal profiles show the relationship between the geometrical characteristics and mechanism of these mass movements.Their characteristics were analyzed according to the role of topographic,seismic,geological and tectonic factors.The steep topography,sheared rocks,lithology,coseismic uplift and strong ground shaking of the hanging wall block along Muzaffarabad Fault facilitated the gravity collapse of these mass movements.  相似文献