EXPERIMENTAL STUDY ON BED SCOUR IN A 90°CHANNEL BEND     

Masoud GHODSIAN  S. Kamal MOUSAVI 《国际泥沙研究》2006,21(4)

The special feature of bend flow leads to scouring of the bed and bank. Various parameters like flow depth, flow velocity or discharge, geometry of bend and characteristics of bed material may affect the scour process. Experiments were carried out to study the effect of some important parameters on bend scour under clear water condition. Experiments were conducted in a 0.6m wide and 0.7m high flume with 90 degree bend. The lateral variations of bed slope were studied. The maximum depth of scour was correlated to densimetric Froude number, relative bend radius and relative depth of flow.  相似文献   

Impact of flash flood recharge on groundwater quality and its suitability in the Wadi Baysh Basin,Western Saudi Arabia: an integrated approach     

Milad H. Z. Masoud  Jalal M. Basahi  Natarajan Rajmohan 《Environmental Earth Sciences》2018,77(10):395

An integrated approach was used to evaluate the impact of flash flood recharge on groundwater quality and its suitability for drinking, irrigation, livestock and poultry uses in the Wadi Baysh Basin, Western Saudi Arabia. Analyses of 182 groundwater samples, collected from the study area before and after a flash flood (FF) event, show that the average concentrations of TDS, Mg, Na, Cl, NO₃ and EC decreased significantly after the event. The major water types (mixed CaMgCl, NaCl and CaCl) indicate that the infiltration of surface water from FF recharge has a great influence on groundwater chemistry. Drinking water suitability maps, created using WHO standards, indicate that wells located in the upstream region are suitable for drinking despite their high TDS and total hardness (TH) values. Groundwater in the coastal region is unsuitable due to its high salinity, high TH and high concentrations of major ions. The suitability of groundwater for irrigational use was assessed using salinity, sodium adsorption ratio, bicarbonate hazard, residual sodium carbonate, Kelly’s ratio, magnesium hazard, sodium percentage and permeability index values, which indicated that groundwater in the study region is suitable for most soils and crops. After FF, groundwater quality is improved by dilution, especially in the downstream region. USSL classification shows that the majority of the water samples are in the C3S1, C4S2, and C3S2 classes and are therefore suitable for the irrigation of salt-tolerant crops. Irrigational suitability maps suggest that wells in the upstream region are suitable for irrigation, whereas wells located near to the coast are unfit for irrigation. This study implies that construction of check dams in the dry valleys (wadies) may improve the groundwater quality in the area.  相似文献   

Seismic interaction of underground RC ducts and neighboring bridge piers in liquefiable soil foundation     

Saeed Moshirabadi  Masoud Soltani  Koichi Maekawa 《Acta Geotechnica》2015,10(6):761-780

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Rainfall-runoff modeling of ungauged Wadis in arid environments (case study Wadi Rabigh—Saudi Arabia)     

M. Masoud 《Arabian Journal of Geosciences》2015,8(5):2587-2606

Flash flood forecasting of catchment systems is one of the challenges especially in the arid ungauged basins. This study is attempted to estimate the relationship between rainfall and runoff and also to provide flash flood hazard warnings for ungauged basins based on the hydrological characteristics using geographic information system (GIS). Morphometric characteristics of drainage basins provide a means for describing the hydrological behavior of a basin. The study examined the morphometric parameters of Wadi Rabigh with emphasis on its implication for hydrologic processes through the integration analysis between morphometric parameters and GIS techniques. Data for this study were obtained from ASTER data for digital elevation model (DEM) with 30-m resolution, topographic map (1:50,000), and geological maps (1,250,000) which were subject to field confirmation. About 36 morphometric parameters were measured and calculated, and interlinked to produce nine effective parameters for the evaluation of the flash flood hazard degree of the study area. Based on nine effective morphometric parameters that directly influence on the hydrologic behavior of the Wadi through time of concentration, the flash flood hazard of the Rabigh basin and its subbasins was identified and classified into three groups (High, medium, and low hazard degree). The present work proved that the physiographic features of drainage basin contribute to the possibility of a flash flood hazard evaluation for any particular drainage area. The study provides details on the flash flood prone subbasins and the mitigation measures. This study also helps to plan rainwater harvesting and watershed management in the flash flood alert zones. Based on two historical data events of rainfall and the corresponding maximum flow rate, morphometric parameters and Stormwater Management and Design Aid software (SMADA 6), it could be to generate the hydrograph of Wadi Rabigh basin. As a result of the model applied to Wadi Rabigh basin, a rainfall event of a total of 22 mm with a duration of 5 h at the station nearby the study area, which has an exceedance probability of 50 % and return period around 2 years, produces a discharge volume of 15.2?×?10⁶ m³ at the delta, outlet of the basin, as 12.5 mm of the rainfall infiltrates (recharge).  相似文献   

Geotechnical Mapping of Najran Soils for Safe Urban Expansion,Najran Region,Saudi Arabia     

Ahmed Abd El Aal  Alaa A. Masoud 《Geotechnical and Geological Engineering》2018,36(4):2003-2020

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Seismic hazard analysis and local site effect of the 2017 Mw 7.3 Sarpol-e Zahab,Iran, earthquake     

Zafarani  Hamid  Jafarian  Yaser  Eskandarinejad  Alireza  Lashgari  Ali  Soghrat  Mohammad Reza  Sharafi  Hassan  Afraz-e Haji-Saraei  Masoud 《Natural Hazards》2020,103(2):1783-1805

Natural Hazards - A strong earthquake occurred on November 12, 2017, in Sarpol-e Zahab city, western Iran, with the moment magnitude ( $$M_{{\text{w}}}$$ ) of 7.3 and a focal depth of...  相似文献   

Scour and flow field around a spur dike in a 90° bend   总被引：2，自引：1，他引：1  

Majid FAZLI  Masoud GHODSIAN  Seyed Ali Akbar Salehi NEYSHABOURI 《国际泥沙研究》2008,(1)

Spur dike is an important element in river training that creates rapid variations in flow field, sediment transport and bed topography. The mechanism of flow and sediment transport in a channel bend is very complex, especially when a spur dike is constructed in a bend. Most of previous investigations on flow behavior and scour around spur dike were carried out in straight channels. In this paper results of experiments on flow field and scour around a spur dike in a 90 degree channel bend are presented. Sand with uniform grain size was used as the bed material. Experiments were conducted for different locations and different lengths of spur dikes at the bend with different values of discharge. The three dimensional flow fields around a spur dike were investigated. The maximum depth of scour was correlated to the Froude numbers, lengths and the locations of spur dike in the bend.  相似文献   

Different Irrigation Methods and Their Comparisons Based on the Parametric Evaluation Method in Khosouyeh Dam Subbasin,Iran     

Masoud MASOUDI  Reza ZARE 《资源与生态学报(英文版)》2019,10(5):504-510

Today, the world's population is rising dramatically, and in line with this increase in the population of food and agricultural products, there must be an increasing in the number of problems associated with this process of agricultural land. Then it is necessary to use the maximum potential of this lands that product maximum yield without any damage. To reach this objective, land suitability evaluation is the most important way that can reach human to this objective. The main objective of this research was to compare different irrigation methods based on a parametric evaluation system in an area of 221402 ha in the Khosouyeh Subbasin of the Fars province, in the south of Iran. After preparing land unit map, 37 points were selected for sampling. Soil properties were evaluated and analyzed. Suitability maps for drop and gravity irrigation were generated using GIS technique. The results revealed land suitability of 98.42% of the case study was classified as permanently not suitable (N₂) and 1.52% currently not suitable (N₁) for gravity irrigation. On the other hand, land suitability of 77.73% of the case study was classified as permanently not suitability (N₂), 6.05% currently not suitable (N₁), 12.43% marginally suitable (S₃) and 3.79% moderately suitable (S₂) for drop irrigation. The limiting factors for both kinds of drop and gravity irrigation are soil depth and slope of land.  相似文献   

Skill Assessment of Copernicus Climate Change Service Seasonal Ensemble Precipitation Forecasts over Iran     

Masoud NOBAKHT  Bahram SAGHAFIAN  Saleh AMINYAVARI 《大气科学进展》2021,38(3):504-521

Medium to long-term precipitation forecasting plays a pivotal role in water resource management and development of warning systems.Recently,the Copernicus Climate Change Service(C3S)database has been releasing monthly forecasts for lead times of up to three months for public use.This study evaluated the ensemble forecasts of three C3S models over the period 1993-2017 in Iran’s eight classified precipitation clusters for one-to three-month lead times.Probabilistic and non-probabilistic criteria were used for evaluation.Furthermore,the skill of selected models was analyzed in dry and wet periods in different precipitation clusters.The results indicated that the models performed best in western precipitation clusters,while in the northern humid cluster the models had negative skill scores.All models were better at forecasting upper-tercile events in dry seasons and lower-tercile events in wet seasons.Moreover,with increasing lead time,the forecast skill of the models worsened.In terms of forecasting in dry and wet years,the forecasts of the models were generally close to observations,albeit they underestimated several severe dry periods and overestimated a few wet periods.Moreover,the multi-model forecasts generated via multivariate regression of the forecasts of the three models yielded better results compared with those of individual models.In general,the ECMWF and UKMO models were found to be appropriate for one-month-ahead precipitation forecasting in most clusters of Iran.For the clusters considered in Iran and for the long-range system versions considered,the Météo France model had lower skill than the other models.  相似文献   

Assessing issues associated with a time‐integrated fluvial fine sediment sampler     

Masoud Goharrokhi  Hoda Pahlavan  David A. Lobb  Philip N. Owens  Shawn P. Clark 《水文研究》2019,33(15):2048-2056

Collecting a representative time‐integrated sample of fluvial fine‐grained suspended sediment (<63 μm) is an important requirement for the understanding of environmental, geomorphological, and hydrological processes operating within watersheds. This study (a) characterized the hydrodynamic behaviour of a commonly used time‐integrated fine sediment sampler (TIFSS) using an acoustic Doppler velocimeter (ADV) in controlled laboratory conditions and (b) measured the mass collection efficiency (MCE) of the sampler by an acoustic Doppler current profiler under field conditions. The laboratory results indicated that the hydrodynamic evaluations associated with the original development of the TIFSS involved an underestimation of the inlet flow velocity of the sampler that results in a significant overestimation of the theoretical MCE. The ADV data illustrated that the ratio of the inlet flow velocity of the sampler to the ambient velocity was 87% and consequently, it can be assumed that a representative sample of the ambient fine suspended particles entered into the sampler. The field results showed that the particle size distribution of the sediment collected by the TIFSS was statistically similar to that for the ambient sediment in the Red River, Manitoba, Canada. The MCE of the TIFSS in the field trials appeared to be as low as 10%. Collecting a representative sample in the field was consistent with the previous findings that the TIFSS is a suitable sampler for the collection of a representative sample of sufficient mass (e.g., >1 g) for the investigation of the properties of fluvial fine‐grained suspended sediment. Hydrodynamic evaluation of the TIFSS under a wider range of hydraulic conditions is suggested to assess the performance of the sampler during high run‐off events.  相似文献