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1.
There is little knowledge available about infiltration and evaporation processes in wadi channels in arid regions. This work was conducted to determine the actual evaporation from bare soils in wadi channels in the south-western region of the Kingdom of Saudi Arabia. The estimation of soil evaporation is highly dependent on the availability of moisture in the upper layers of alluvial wadis, in which the areal rainfall, flood hydrograph and soil properties play a significant part. The study was conducted by estimating the actual evaporation using soil moisture data, precipitation and runoff depths in a representative basin. The results are compared with potential rates. The actual rates were 1.5 mm/day immediately after a rainy day and then decreased to 0.42 mm/day. The minimum rate was about 0.1–0.2 mm/day during the dry season. The potential rates were about 9.5 mm/day in June and July, decreasing to 3.5 mm/day in December and January. 相似文献
2.
Sally E. Sutton 《地球表面变化过程与地形》1987,12(5):567-570
The magnitude of groundwater resources is poorly correlated with surface catchment area in a group of wadi bottom alluvial aquifers in Northern Oman. It is suggested that this is due to progressive water gap captures across a limestone ridge. 相似文献
3.
Fresh water resources within the Kingdom of Saudi Arabia are a rare and precious commodity that must be managed within a context of integrated water management. Wadi aquifers contain a high percentage of the naturally occurring fresh groundwater in the Kingdom. This resource is currently overused and has become depleted or contaminated at many locations. One resource that could be used to restore or enhance the fresh water resources within wadi aquifers is treated municipal waste water (reclaimed water). Each year about 80 percent of the country's treated municipal waste water is discharged to waste without any beneficial use. These discharges not only represent a lost water resource, but also create a number of adverse environmental impacts, such as damage to sensitive nearshore marine environments and creation of high-salinity interior surface water areas. An investigation of the hydrogeology of wadi aquifers in Saudi Arabia revealed that these aquifers can be used to develop aquifer recharge and recovery (ARR) systems that will be able to treat the impaired-quality water, store it until needed, and allow recovery of the water for transmittal to areas in demand. Full-engineered ARR systems can be designed at high capacities within wadi aquifer systems that can operate in concert with the natural role of wadis, while providing the required functions of additional treatment, storage and recovery of reclaimed water, while reducing the need to develop additional, energy-intensive desalination to meet new water supply demands. 相似文献
4.
Endorheic basins, filled by a rhythmic stratification of fluvio-lacustrine sediments, are useful archives for studying the interaction of palaeoenvironment and prehistoric development. Archaeological evidence indicates an occupational maximum during the Early to Mid-Holocene humid phase that can be linked to geochronological dates. A wadi has cut these sediments and a wadi profile of about 6 m was sampled for luminescence dating.
Palaeodose estimates are based on single aliquot measurements of the sand-sized quartz fraction using the regenerative dose technique. The comparison of equivalent dose results from different aliquot sizes (<100 and >1000 grains) provides interesting insights into heterogeneous degrees of bleaching. Problems arising from substantial variations in environmental dose rates of such heterogeneous sediments are discussed.
The luminescence ages indicate two major phases of deposition, both of Holocene age. The lower 2 m of sediments were deposited about 9400 years ago. The sedimentation of the upper 2 m started about 7200 and terminated around 6300 years ago. Radiocarbon ages of charcoals contained in the upper part of the section disagree with that OSL dating. This discrepancy is explained by re-deposition of the charcoal fragments. 相似文献
5.
Abstract Groundwater recharge in arid regions is intermittent and usually occurs as a result of flood flow transmission losses in dry wadi channels. Hydrograph characteristics play a dominant role in determining the amount of channel abstraction in relation to the width of the wetted perimeter and the time of inundation, and the subsequent groundwater recharge. Large variations in the magnitude of channel losses result mainly from the diversity in inflow volumes. The magnitude of groundwater recharge in relation to bed transmission losses is dependent on flood volume and duration, soil moisture content and physical soil profile characteristics. Runoff volume and duration are the dominant factors influencing the cumulative infiltrated volume and recharge to shallow water tables. Taking into consideration the influence of various hydrological and channel characteristics, several regression equations are suggested to estimate the transmission losses from a wadi bed and the groundwater recharge. 相似文献
6.
ABSTRACT A hydrogeological research project was conducted in the arid crystalline province of the Southern Sinai. To gain a better understanding of regional groundwater flow patterns, Landsat images as well as air photos were used. Three main flow systems were investigated: (1) The flow system occurring along longitudinal regional crustal fractures with the direction parallel to the Gulf of Elat Rift; this system captures the flow in the main wadi beds draining eastwards. (2) The flow system found in shallow fractured rocks, capturing the flow in small tributaries in the upper part of the drainage basin. (3) The system of dikes governing the flow regime in wadi beds draining westwards. The preliminary estimate of the recharge into the fractured crystalline aquifers and the interconnected gravel bed aquifers is in the order of magnitude of 10–15% of the total precipitation. 相似文献
7.
At Wadi Sabra (SW Jordan) human occupation dates back to the Palaeolithic and Epipalaeolithic. Although there is stratigraphic correlation based on archaeological finds of Ahmarian origin, numerical age estimates are lacking. We applied single-aliquot optical dating of coarse grained quartz of wadi deposits and investigated the luminescence properties in detail to achieve more accurate age information about the time of human occupation. Weak luminescence signals and scattered dose distributions characterise the multi-grain aliquots. The residual doses of the investigated modern wadi sediment are between 0 and 7 Gy. Moreover, comparison of equivalent dose (De) values of 1 mm and 8 mm aliquots shows higher equivalent doses for the large aliquots. Both experiments indicate that the luminescence signal is partially bleached prior to deposition. The dose distributions of all samples are broadly scattered and have overdispersion values between 25 and 43%, some samples are significantly skewed. The shape of the dose distributions points to other sources of scatter, in addition to partial bleaching. Comparison of 1 mm multi-grain and single-grain data demonstrates that the luminescence signal of one multi-grain aliquot most likely is from a single grain. For this reason, variation in the number of photon counts due to the weak luminescence intensity and variations in beta microdosimetry have a bigger impact on the spread of dose distributions. However, we cannot quantify the particular impact of partial bleaching, weak luminescence intensity and beta microdosimetry. To account for the spread of the dose distribution, we use the central age model to calculate equivalent doses. Age calculations yield results in the range of 30–48 ka. 相似文献
8.
Abstract The Khulais plain lies within a typical arid area in western Saudi Arabia. Groundwater occurs within two aquifers in the area: the alluvium of the wadi system, and the sandy layers of the Cretaceous-Tertiary sedimentary succession. Detailed field investigations and laboratory analysis helped in determining the aquifer properties for each of the water-bearing units. Groundwater movement has been thoroughly studied, and distribution maps prepared to explain the variations in transmissivity, permeability, porosity and specific yield. An attempt has been made to estimate volumes of groundwater flow towards the plain. This study presents a first attempt towards determining groundwater availability in the Cretaceous-Tertiary succession of this part of the world. 相似文献
9.
Norbert Mercier Christine Hatt Michel Fontugne Jean-Louis Reyss Hlne Valladas Luc Wengler Jean-Philip Brugal Abderrahmane Ouammou Andr Weisrock 《Quaternary Geochronology》2009,4(4):326-334
The Sidi Messaoud site provides a 40 m thick sedimentary infilling of great importance for the study of environmental changes and landscape evolution during the Upper Pleistocene in the Western Sahara. In this study, chronological results obtained by the 14C, U-series and optical dating techniques are compared. Each individual age, depositional environment and post-deposition history of the various samples are evaluated, in order to explain the methodological reasons for discordances and concordances. Stratigraphic and palaeoenvironmental implications for the last 120 ka history in southwestern Morocco are also inferred: the wadi Noun gorges had been incised before MIS 5, and later, during MIS 3, the valley has been filled in with a mean sedimentation rate of 1 m/ka. 相似文献
10.
Hanen Jarray Mounira Zammouri Mohamed Ouessar Ammar Zerrim Houcine Yahyaoui 《Water Resources》2017,44(4):595-603
Groundwater is the main source of water in arid regions. Thus, groundwater pollution becomes a major issue due to the increasing contamination, which poses serious and harmful risk to the environment. Groundwater vulnerability maps can be used as a tool to help decision makers to protect groundwater resources from contamination. The vulnerability of the Mio-Plio-Quaternary shallow aquifer (Southeast Tunisia) has been assessed using a DRASTIC model based on Geographic Information System (GIS). The different parameters of the model were collected from several sources and converted into thematic maps using ArcGis©. Each DRASTIC parameter was assigned a weight and rating based on a range of information within the parameter. Groundwater vulnerability map shows a large area (48%) with high risk of pollution. It indicates that the Southern part of the aquifer and the wadi beds are the most susceptible to contamination. The measured nitrate concentration is coherent with the DRASTIC model results. 相似文献
11.
Shallow sloping drainage tunnels dug into the hillsides to intercept water tables are an important source of water supply in many semi-arid countries. This paper deals with the modelling of such drainage tunnels, with particular reference to the aflaj (singular falaj) of Oman; factors affecting their flow, their response to recharge and their imposition on the surrounding aquifer are investigated. The equations governing groundwater flow in unconfined aquifers are modified to realistically reproduce the observed flow response. In this way the effect of falaj flow can be incorporated into the strategy for the management of scarce water resources. The modelling results show that the falaj flow follows an exponential recession and its rate is related to aquifer geometry and parameters. The results have been used to estimate the contributing length of aflaj under various hydrological conditions and to indicate the most likely recharge mechanism for a falaj situated in wadi gravels. Furthermore, the close resemblance between the predicted falaj flow and field flow measurements, from Oman, is a measure of the model's applicability. 相似文献
12.
The dry wadis ‘ephemeral channel’ constituting the main tributaries to the Nile River in Kom Ombo are structurally and tectonically controlled and exhibit complex drainage pattern. This complicated drainage pattern is inherited from the morpho‐tectonic evolution of the ancestral Nile River (‘Protonile’), which drained the Eastern Desert during the Middle Pleistocene. A digital elevation model derived from Shuttle Radar Topography Mission data is used to delineate the contemporary drainage networks and their catchments. Satellite images acquired during a flash flood event were used to validate the delineated watershed divides and flow pathways, particularly where the courses of dry wadis are interlocked. Currently, the westward flow of Wadi Abu‐Suberah is derived from a small area in the Eastern Desert, as the palaeo‐upper reaches of this wadi were captured due to tectonic movements along NW/SE and N/S faults by wadis in the Kharit and Elewa areas. The influence of these tectonic movements on groundwater distribution is also shown where the deep Nubian aquifer discharges its water into the Quaternary aquifer through fault planes. The northward flowing ‘Protonile’ main course has tectonically shifted from the Gallaba plain in the Western Desert, eastward to the current Nile River course. This shift has produced several cut‐off segments of the palaeo‐tributary drainage that was originally flowing westward towards the old ‘Protonile’ main course in the Gallaba plain. However, these segments have reversed their surface run‐off flow directions eastward towards the current Nile course; they could include potential groundwater resources, as their alluvium may be still recharged by the Nile River. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
13.
E.J. Rohling T.R. CaneS. Cooke M. SprovieriI. Bouloubassi K.C. EmeisR. Schiebel D. KroonF.J. Jorissen A. LorreA.E.S. Kemp 《Earth and Planetary Science Letters》2002,202(1):61-75
Little is known about centennial- to millennial-scale climate variability during interglacial times, other than the Holocene. We here present high-resolution evidence from anoxic (unbioturbated) sediments in the eastern Mediterranean Sea that demonstrates a sustained ∼800-yr climate disturbance in the monsoonal latitudes during the Eemian interglacial maximum (∼125 ka BP). Results imply that before and after this event, the Intertropical Convergence Zone (ITCZ) penetrated sufficiently beyond the central Saharan watershed (∼21°N) during the summer monsoon to fuel flooding into the Mediterranean along the wider North African margin, through fossil river/wadi systems that to date have been considered only within a Holocene context. Relaxation in the ITCZ penetration during the intra-Eemian event curtailed this flux, but flow from the Nile - with its vast catchment area - was not affected. Previous work suggests a concomitant Eurasian cooling event, with intensified impact of the higher-latitude climate on the Mediterranean basin. The combined signals are very similar to those described for the Holocene cooling event around 8 ka BP. The apparent type of concurrent changes in the monsoon and higher-latitude climate may reflect a fundamental mechanism for variability in the transfer of energy (latent heat) between the tropics and higher latitudes. 相似文献
14.
Frequency analysis of annual maximum suspended sediment concentrations in Abiod wadi,Biskra (Algeria) 
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下载免费PDF全文 Sediment transport processes in the Mediterranean semi‐arid areas have interested a great number of hydrologists and statisticians. Frequency analysis (FA) procedures are commonly applied for several hydrological events such as floods and droughts. However, in general, FA is not widely applied to treat suspended sediment concentration (SSC), especially in semi‐arid regions. In the present study, an FA was performed on SSC data from 1979 to 1991 observed upstream from the Foum El Gherza dam, which is located at Biskra in the South–East of Algeria. This dam is problematic in terms of silting. Therefore, this study is mainly motivated by providing an FA model and risk evaluation in order to assist dam managers to better evaluate the potential of silting resulting from SSC transport to the reservoir. Probability distributions commonly used in hydrology were tested to SSC data recorded at the M'chounech station on Abiod wadi located upstream the dam. All the FA steps were considered; including classical techniques (e.g. goodness‐of‐fit tests, statistical criteria) as well as recently developed tools (tail distribution classification). Their application led to the selection of the lognormal distribution (LN2) to fit the considered data, and hence an accurate risk assessment could be obtained. Because of the presence of a slight trend, non‐stationary models are also considered in the present study. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
15.
Real data on wadi flood flows from Saudi Arabia, Yemen, Oman, Kuwait, UAE, Bahrain and Qatar were used to develop methodologies for the prediction of annual maximum flows and average monthly flows in the Arabian Gulf states. For the prediction of annual maximum floods, three methods have been investigated. In the first method, regional curves were developed and used together with the mean annual flood flow, estimated from the characteristics of the drainage basin, to estimate flood flows at a location in the basin. The second method fits data to various probability distribution functions, with a developed methodology introduced to account for floods generated by more than one system of climate, and the best fitted function was used for flood estimates. In the third method, only floods over a threshold, which depends on characteristics of the drainage basin, were considered and modelled. For the prediction of average monthly flows, stochastic simulation approaches of flood frequency analysis were used. Each of the prediction methods was verified by being applied in 40 different drainage basins. Based on the results obtained, recommendations were made on the best method to be applied (at present) by design engineers in the Arabian Gulf states. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
16.
In arid and hyper-arid zones, groundwater exploration is one of the most significant ways to locate potential new water supplies. Geophysical prospecting is currently the most successfully used method for locating new supplies, but it is rather costly. Satellite remote sensing (RS) detection, however, with its integration of Geographic Information Systems (GIS) provides the best chance for identifying and initially evaluating water-bearing formations. In the western part of Saudi Arabia, Wadi Na'man has for centuries been one of the major water sources for the city of Makkah Al-Mukarramah. It is therefore very important to find appropriate groundwater potential (GP) zones in this wadi for water supply. This study utilizes RS and GIS techniques, and also studies the hydrogeological, geological, and geomorphological characteristics that have significant impact on groundwater occurrence in Wadi Na'man. Representative layers are generated for each component and each given a weight ratio that depends on the level of influence. The overlay and integration of these thematic layers was used to produce a map that shows the most promising potential groundwater areas and classifies local potentials as either low, medium, or high. The results also reveal that the areas overall-rated as “promising” (i.e., classified as medium or high) represent approximately 17-25% of the total basin area and consist mainly of Quaternary sediments and connected fractured rock areas. 相似文献
17.
There is a real need for more research on regionalization of flood estimation methods in arid zones. Such estimations are important because reliable long‐term storm rainfall and corresponding runoff measurements are commonly unavailable. This is the situation in many parts of the Kingdom of Saudi Arabia. Hence, it is necessary to develop a new approach, one that suits the conditions found in the Kingdom, which depend on available, but incomplete measurements and catchment morphological features. In this paper, a modified methodology based on the classical Snyder approach is proposed and it is referred to as the Saudi Geological Survey (SGS) approach in order to reflect works of this kind within the Survey. The basis of the methodology has two phases, namely, logical and empirical. The former phase is valid for any part of the world whether humid or arid, but the latter phase is location specific, which in the case of this paper, is the Arabian Peninsula. The application of the methodology is presented for Wadi Baysh, a major wadi in the south‐western part of the Kingdom. Furthermore, a synthetic unit hydrograph (UH) methodology based on a Gamma distribution function is also presented with applications to some of the Wadi Baysh sub‐basins. For this purpose, a dimensionless UH has been obtained, which is special for the area. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
18.
Stable and radio-isotope results (C, H, O) for groundwaters from the Sirte and northern Kufra basins are used to determine the recharge history during the Holocene and late Pleistocene. Radiocarbon ages have been corrected on the basis of their stable carbon isotope ratios and on environmental samples from the areas, and two groups may be recognised: (1) low 14C activity groundwaters (13000–34000 yr. BP) with δ 13C-5.6 to −11.7‰; and (2) higher 14C activity groundwaters (5000–7800 yr. BP) enriched in 13C up to δ 13C = −3.2‰. There is a general correlation of age with depth.
A well defined freshwater (< 50 mg/l Cl−) channel can be traced within the aquifer for some 130 km through the region, which is considered to represent recharge from a former wadi. This water with an age of ± 7800 yr. BP is chemically and isotopically distinct from the regional groundwaters and provides direct evidence of a significant recharge event during the Holocene.
The stable isotope (O and H) composition of groundwater from the Kufra and Sirte basins are all related by an evaporative line with slope δ D = 4.5δ 13O − 35 with an intercept on the meteoric line of -11‰. This suggests a recharge source continuing into the Holocene from air masses, analogous to current heavy monsoon rain derived from south of the Sahara. The spatial and temporal distribution of groundwaters in relation to the evaporative line suggests a progressive change in character of the recharge which is controlled by a shift towards strongly convective rainfall during the Holocene.
The direct hydrogeological and geochemical evidence supports climatic models proposed by several workers in which discrete humid episodes during the Holocene are inferred. 相似文献
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20.
石油与天然气的成因问题关系到我国乃至世界各国能源结构的配置及其能源在社会与经济发展中的地位和导向.自从17世纪展开对石油的有机与无机成因的争论以来,至今已有约300~400年的历史.尽管有机成因论占据了统治地位,但是无机成因论亦不断地在兴起!通过对这二者的理解和研究,从理论上讲他们都具有一定的物质基础和论据.基于对国内、外一些特异油田的生储环境,原油中所富含的微量金属元素的聚集与散失,某些油田中并未找到卟啉分子这样的生物标志物,碳、氢、氧化学合成实验等方面取得了一定的成效,故全盘否定无机生油的论点和论据确尚感为时过早或欠妥!显然,在以有机物成油为主体的前提下,无机物亦可生成部分石油,并通过运移、渗透到各油田的储集层中应是完全可能的.基于这样的分析、研究和探索,现提出石油的双机(a有机+b无机)混合成因的新理念.诚希能在今后的石油工业发展中,从理论、技术、实验和实践中强化对双机混合成因新理念的深化研究与探索,以达深切理解和扩展石油生、储空间环境等是不无裨益的! 相似文献