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1.
Development of storm hyetographs for flood forecasting in the Kingdom of Saudi Arabia 总被引：1，自引：0，他引：1
This paper presents the derivation of the design storm hyetograph patterns for the Kingdom of Saudi Arabia based on real rainfall events from meteorological stations distributed throughout the Kingdom. Two thousand twenty-seven rainfall storms for a 20–28-year period were collected and analyzed covering 13 regions of the Kingdom. Four distinct dimensionless rainfall hyetograph patterns have been obtained over the Kingdom, while two patterns have been obtained for each individual region because of the lack of data for long-duration storms in individual regions. The resulting dimensionless rainfall patterns for each region can be used to develop storm hyetographs for any design duration, total rainfall depth and return period. It has been shown that the developed storm hyetographs have different features from other storm patterns that are commonly used in arid zones. The study recommends using these curves for the design of hydraulic structures in Kingdom of Saudi Arabia and regions alike. 相似文献
2.
Hatem A. Ewea Amro M. M. Elfeki Jarbou A. Bahrawi Nassir S. Al-Amri 《Arabian Journal of Geosciences》2016,9(5):424
Runoff peak and volume in flood studies are estimated relying on temporal rainfall distribution from various storm patterns. Usually, SCS distributions types (I, II, III, IA) are commonly used. Using these distributions in runoff calculations assume that the in situ temporal rainfall pattern typically behaves as the one described by the SCS-type distribution, which is due to cyclonic frontal storms and actually developed in temperate environment. To what extent such assumption is valid in the arid environment? How much the impacts of rainfall temporal patterns are reflected in runoff volumes and peaks? The aim objectives of the current study are to answer the above two questions and clarify the validity of aforementioned assumption and exemplify such effect. Real rainfall data collected from rain gauges of Makkah Al-Mukkramah region over a period of more than 20 years are utilized. Temporal rainfall patterns and their parameters are deduced. Many hydrological simulations are performed and comparisons, in terms of runoff volume and peak flows, are made to show the effects of the common rainfall storm patterns and the developed rainfall storm patterns in the region based on the current study. Results indicate that major bursts of the design rainfall storm pattern are located in the first time of the storm period in the two quartiles which is mainly due to convective rainfall type in thunderstorms unlike the commonly used by SCS types relying on frontal cyclonic storms. Makkah Al-Mukkramah temporal rainfall pattern does not behave as the “typical pattern” assumed by SCS distributions that are deduced from different environments. The impacts of the temporal pattern reflected as an overestimate in the runoff peak reached to 68 %. The developed hyetographs and tables presented in the current study are recommended to enhance economical and rational design practice in watersheds of Makkah Al-Mukkramah region. 相似文献
3.
The impact of rainfall distribution patterns on hydrological and hydraulic response in arid regions: case study Medina,Saudi Arabia 总被引：1，自引：0，他引：1
Mohamed Abdulrazzak Amro Elfeki Ahmed Samy Kamis Mostafa Kassab Nassir Alamri Kashif Noor Anis Chaabani 《Arabian Journal of Geosciences》2018,11(21):679
Rainfall distribution patterns (RDPs) are crucial for hydrologic design. Hydrologic modeling is based on Soil Conservation Services (SCS) type RDPs (SCS type I, IA, II, and III). SCS type II method is widely used by hydrologists in arid regions. These RDPs were designed for the USA and similar temperate regions. There is no scientific justification for using SCS type II method in arid regions. The consequences of using SCS type II have impacts on the hydrologic and hydraulic modeling studies. The current paper investigates the validity of the SCS type II and in arid regions. New temporal RDPs were applied and compared with SCS type II RDPs. The produced peak discharges, volumes, maximum inundation depths, top widths, and velocities from both approaches were analyzed. An application is made on the protection channel in Taibah and Islamic Universities campuses in Medina, Saudi Arabia. A methodology was followed which included frequency analysis, catchment modeling, hydrological modeling, and hydraulic modeling. Results indicated that there are considerable consequences on infrastructural design, and hydrologic and hydraulic parameters if inappropriate RDPs are used. The investigation confirmed that the SCS type RDPs do not reflect the actual flood features in arid regions. 相似文献
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Jaeil Cho Yang-Won Lee Pat J.-F. Yeh Kyung-Soo Han Shinjiro Kanae 《Environmental Earth Sciences》2014,71(9):3935-3944
Arid regions in Asia are commonly characterized by rapidly growing populations with limited land resources and varying rainfall frequencies under climatic change. Despite being one of the most important environmental challenges in Asia, the changing aridity in this region, particularly due to large-scale land cover change, has not been well documented. In this study, we used rainfall data and a new land heterogeneity index to identify recent trend in land cover changes in the Asian arid regions. The result indicates a significant decreasing trend of barren lands and an increasing trend of vegetated lands. Although the potential land cover change is commonly believed to be strongly sensitive to rainfall change, such sensitivity has not been observed during the nine-year period (2001–2009) analyzed. Through the analyses of two separate periods (2001–2005 and 2005–2009), the sensitivity of rainfall to land cover change in arid regions is found to be dependent on the initial spatial heterogeneity of vegetated land cover. The approach used and the findings in this study represent an important step toward better understanding of large-scale land cover change in the Asian arid regions, and have the potential to predict future land cover change under various climate change scenarios. 相似文献
7.
Ayman G. Awadallah Mahmoud S. Farahat Mohammed Haggag 《Arabian Journal of Geosciences》2017,10(9):214
The soil conservation service curve number (SCS-CN) method is one of the most commonly used methods to compute the direct runoff from a rainfall event. Since the method was established, numerous researches were undertaken to improve the method through accurate estimation of its parameter and especially the curve number (CN). However, the essence of the SCS method, as an event-based Hortonian mechanism method, remained unchanged. The main assumption of the method related to the rainfall input is that the rainfall is continuous in time and uniform over the watershed. Mohammad and Adamowski (2015) paper apparently used the SCS method to estimate the annual runoff using the annual rainfall as one cumulative rainfall input value, which is a violation of the event-based principle of the method and of the assumption of the continuity of the rainfall event.To re-estimate the average annual runoff more realistically for the Asir region, Saudi Arabia, daily rainfall data from 14 rainfall stations are used for calculating the resulting runoff depths, on a daily event-by-event rainfall basis, throughout the whole simulation period. The resulting runoff depths are added for each year, and the total cumulative annual runoff values for each year are averaged to get the average annual runoff. The runoff values based on the previously mentioned procedure are an upper limit of the actual average annual runoff as the underlying SCS equations discard evaporation and similar long-term losses. Nevertheless, the average runoff values obtained in the discussion paper are an order of magnitude (at least five to tenfold) lower than the ones of the original paper. An equation is proposed to obtain a more realistic estimate of the average annual runoff, to be used with the average annual rainfall as an input, if the annual value is the only available rainfall information. 相似文献
8.
Zekai Şen 《Arabian Journal of Geosciences》2014,7(4):1627-1636
Previous studies lack proper and quick assessment of sediment yield rates in arid regions. Sediment yield at a point along the main channel of a drainage basin is an integrated result of upland, gully, and channel erosion, transportation, and depositional processes. The external dynamic agents of sediment yield are water, wind, gravity, temperature change, ice, and biological activities. Although each may be important in arid regions, at locations, occasionally present-day hydrological cycle works water are the most widespread agent of erosion and account for the bulk of sediment yield. This paper focuses on sediment yield formulations in arid regions in terms of little morphology in addition to the runoff discharge after a storm rainfall. Among the morphological variables are the drainage basin area, main channel slope, and the drainage density. Hence, the channel head is represented by the combination of drainage area and the slope. The emphasis is given to the determination of simple and straightforward sediment yield rate formulations by dimensional analysis technique. Three simple formulations are derived, and two of them are applied to one of the largest wadis, Wadi Baysh, with its 54 sub-basins, in the southwestern Saudi Arabia. 相似文献
9.
This study analyses regional drought characteristics (frequency, severity, and persistence) of meteorological droughts occurred in the northwestern parts falling under arid and semiarid regions of India with mean annual rainfall ranging between 100 and 900 mm. A drought is defined as a season or a year with rainfall less than 75% of corresponding mean at a place. Long-term monthly rainfall records (1901–2013) of 90 districts of north-west India located in the states of Punjab, Haryana, Rajasthan and Gujarat are used in the analysis. The percentage departure of seasonal rainfall from long-term average rainfall has been used for identification of onset, termination, and quantification of drought severity. The average frequency varied from once every 3–4 years. The westerly districts have an average drought return period of 3 years, while districts lying toward the east had droughts once every 4 years. Only four of the 90 districts in the study area experienced droughts once every 5 years. Persistent droughts of 2, 3, and 4 year duration occurred widely. Severe droughts occurred in the years 1904, 1905, 1911, 1918, 1931, 1939, 1985, 1986, 1987, 1993, and 2002, with an average frequency of severe drought events of one in 10 years. The analysis presented in this paper improves understanding of the regional drought characteristics and will inform drought mitigations and strategies in these arid and semiarid areas. 相似文献
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This study aimed at investigating the first flush phenomenon from residential, commercial and industrial catchments. Stormwater was grab sampled and the flow rate was measured during 52 storm events. The dimensionless cumulative pollutant mass and runoff volume were used to determine the runoff volume needed to transport 50 and 80 % of total pollutant mass. Almost all the constituents did not satisfy this first flush definition except for total suspended solids (TSS) in the commercial catchment. The averages first runoff volume required to remove 50 and 80 % of the total pollutant mass were 37 and 67, 35 and 65, and 36 and 64 % for the residential, commercial and industrial catchments, respectively. It seemed that less runoff is required to transport the same amount of pollutant loadings in tropical urban catchments than in temperate regions. BOD, COD, NH3-N, SRP and TP consistently showed strong first flush effects in all catchments. The first flush strengths of TSS, BOD, COD, NH3-N and TP in the commercial catchment were strongly correlated with total rainfall, rainfall duration, max 5 min intensity, runoff volume and peak flow, but not with antecedent dry days. Management of the first 10 mm runoff depth would be able to capture about half of the total pollutant mass in stormwater runoff that would otherwise goes to drains. 相似文献
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文章依据冰芯、树木年轮等自然记录和历史文献记录,分析了中国北方不同地区近2000年的沙尘事件及其与气候变化的关系。结果表明,在干旱区西部,历史时期的沙尘变化主要受温度变化的制约,无论在10年尺度,还是百年尺度上,沙尘事件与温度变化均表现为显著的反相关,即气候寒冷期与沙尘频发事件相对应,气候温暖期与沙尘发生变弱期一致;在半干旱区,在10年尺度上温度和降水序列与沙尘发生频率均显著负相关,但在百年尺度上沙尘与降水变化的关系更为密切;在干旱区东部,沙尘与气候变化的关系具有明显的过渡性特征,气候变化对沙尘事件的作用主要在百年尺度上体现出来,沙尘与温度记录的负相关比降水更好,在10年尺度上气候与沙尘序列尽管也是负相关,但不显著。通过对现代气象记录的气温、降水变化和沙尘事件频数分析,其结果与历史时期情况基本一致。 相似文献
12.
临界雨量是一个关键的山洪灾害预警指标。按其技术原理将临界雨量推求方法划分为数据驱动的统计归纳法和基于灾变物理机制的水文水力学法分别进行评述,并介绍了临界雨量指标的两个拓展:动态临界雨量和暴雨临界曲线,综述了临界雨量不确定性分析的研究进展。通过综述发现:中国目前主要应用的是较简单的统计归纳法;临界雨量推求主要考虑前期降雨量（前期土壤饱和度）和时段累积降雨量两个因素的影响或仅后者一个;临界雨量指标难以反映山洪灾害的规模;考虑临界雨量不确定性有助于提高预警质量,但如何充分考虑其影响仍然是一个挑战。 相似文献
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An impervious surface cover is continuously spreading over the Wu-Tu upstream watershed due to the concentrated population
and raised economical demands, while that area also frequently suffers from heavy storms or typhoons during the summer season.
The increased flood volume due to this extended imperviousness causes a greater potential hazard than that of the past. In
order to evaluate the urbanized impacts on the watershed, a set of methods were used to estimate the changes of the watershed
storage. This research chose 51 observed events from three raingauges on the Wu-Tu upstream watershed, Taiwan, to study the
volume characteristic of abstracted rainwater. In the study, the block Kriging method was used to estimate the area rainfall
and the hourly excess was derived through the non-linear programing (NLP). A total of 40 samples were calibrated through the
hydrological model and the Soil Conservation Service (SCS) model using the optimum seeking method in order to search out and
establish the best parameters that illustrate the hydrological and geomorphic conditions at that time. Eleven cases were used
to examine the established relationship of the parameters and the impervious coverings. A design storm approach was used to
view the changes of the volume for various scale storms/typhoons because of the different degrees of urbanization. Then, a
diagram was designed to show the relationships that exist among the runoff coefficient, return period, and impervious surface.
The satisfactory results show that storage capability of rainwater for various scale storms on the Wu-Tu watershed would be
respectively reduced about 42–156 cms in different decrements up to now. 相似文献
15.
Slope failures in the tropical regions, particularly Malaysia are commonly triggered by frequent rainfall. The tropical rainfall can be characterized as short and intense throughout the year, and prolonged and less intense during monsoon seasons. Under such circumstances, various rainfall patterns should be included in the analysis of rainfall-induced slope failure in the tropical regions. This paper is aimed to demonstrate a simple model for preliminary evaluation of rainfall-induced slope failure. The critical rainfall patterns for four typical types of soil were first determined. Seepage finite element analyses were conducted using the extreme rainfall of ten-year return period for Johor Bahru, Malaysia. The results showed that the ratio of rainfall intensity to soil saturated permeability (i.e., I/ksat) plays an important role in determining the critical rainfall pattern. Two critical combinations of antecedent rainfall and major rainfall, 1-day, 2-day, 3-day, 5-day, 7-day, 14-day, and 30-day antecedent rainfalls and the redistribution of the critical combination of antecedent rainfall and 1-day major rainfall were responsible for the formation of suction envelope in soil. The suction envelope, representing the worst suction distribution in soil, was used for the computation of factor of safety of soil slope through the modified infinite-slope–limit-equilibrium method. A model, PERISI, was developed based on the findings from numerical simulation. The suction envelope and factor of safety computed from the PERISI model showed good agreements with the results obtained from Seep/W and Slope/W computer programs and the results derived from the model of Rahardjo et al. developed in 1995. 相似文献
16.
《Atmósfera》2014,27(4):411-427
Daily extreme precipitation values are among environmental events with the most disastrous consequences for human society. Information on the magnitudes and frequencies of extreme precipitations is essential for sustainable water resources management, planning for weather-related emergencies, and design of hydraulic structures. In the present study, regional frequency analysis of maximum daily rainfalls was investigated for Golestan province located in the northeastern Iran. This study aimed to find appropriate regional frequency distributions for maximum daily rainfalls and predict the return values of extreme rainfall events (design rainfall depths) for the future. L-moment regionalization procedures coupled with an index rainfall method were applied to maximum rainfall records of 47 stations across the study area. Due to complex geographic and hydro-climatological characteristics of the region, an important research issue focused on breaking down the large area into homogeneous and coherent sub-regions. The study area was divided into five homogeneous regions, based on the cluster analysis of site characteristics and tests for the regional homogeneity. The goodness-of-fit results indicated that the best fitting distribution is different for individual homogeneous regions. The difference may be a result of the distinctive climatic and geographic conditions. The estimated regional quantiles and their accuracy measures produced by Monte Carlo simulations demonstrate that the estimation uncertainty as measured by the RMSE values and 90% error bounds is relatively low when return periods are less than 100 years. But, for higher return periods, rainfall estimates should be treated with caution. More station years, either from longer records or more stations in the regions, would be required for rainfall estimates above T=100 years. It was found from the analyses that, the index rainfall (at-site average maximum rainfall) can be estimated reasonably well as a function of mean annual precipitation in Golestan province. Index rainfalls combined with the regional growth curves, can be used to estimate design rainfalls at ungauged sites. Overall, it was found that cluster analysis together with the L-moments based regional frequency analysis technique could be applied successfully in deriving design rainfall estimates for northeastern Iran. The approach utilized in this study and the findings are of great scientific and practical merit, particularly for the purpose of planning for weather-related emergencies and design of hydraulic engineering structures. 相似文献
17.
In this study, an approach for runoff and recharge estimations that can be applied in arid regions which suffer from lack of data is presented. Estimating groundwater recharge in arid regions is an extremely important but difficult task, the main reason is the scarcity of data in arid regions. This is true for the Eastern Egyptian Desert where groundwater is used for irrigation purposes in agricultural reclamation along the Red Sea coast line. As a result of the scarcity of hydrologic information, the relation between rainfall and runoff was calculated depending on the paleo-flood hydrology information. Two models were used to calculate the rainfall–runoff relationships for El Hawashyia basin and Ghazala sub-basin. Two computer programs known as Gerinne (meaning channel in German) and SMADA6 (Stormwater Management and Design Aid, version 6) were conjunctively used for this purpose. As a result of the model applied to El Hawashyia basin, a rainfall event of a total of 18.3 mm with duration 3 h at the station of Hurghada, which has an exceedance probability of 5–10 %, produces a discharge volume of 10.2 × 106 m3 at the delta, outlet of the basin, as 4.7 mm of the rainfall infiltrates (recharge). For the Ghazala sub-basin, the model yields a runoff volume of 3.16 × 106 m3 transferred from a total rainfall of 25 mm over a period of 3 h, as 3.2 mm of it was lost as infiltration. 相似文献
18.
为研究降雨过程雨强随历时的变化关系,利用中国14个气象站近40年逐分钟降雨资料,采用动态K均值聚类法并根据雨峰在降雨过程中出现的位置,将中国10256次降雨过程分为4种类型,即降雨前期集中型（Ⅰ型）、降雨中期集中型（Ⅱ型）、降雨后期集中型（Ⅲ型）和降雨均匀分布型（IV型）。结果表明:中国Ⅰ型降雨出现频次最高,占47.1%;Ⅱ型次之,占21.2%;Ⅲ型和IV型出现频次相当,分别占15.3%和16.4%。夏季Ⅰ型降雨发生频次占绝对优势,为夏季总降水过程的52.2%;冬季各类雨型发生频次相差不大。Ⅰ型多为短历时高强度降雨,而IV型多为长历时低强度降雨,Ⅱ型和Ⅲ型居中。历时越短时,Ⅰ型降雨的比重越大;随着降雨历时的增加,Ⅰ型降雨的比重明显下降,IV型降雨的比重增加。 相似文献
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An ice core which is 5 annual layers contained was drilled at Dongkemadi branch glacier, middle of Tanggula Mis. The chemical analysis shows the obviously similar variations of the concentrations of major canons and anions versus depth. The similarities are ascribed to the same types of aerosols that most of the ions concentrate and coexist. For instant, the aerosols transported from the arid regions outsides north of the Tibetan Plateau as well as the high-mineralized saline lakes on the plateau are probably the main sources of the major ions. However, profile of nitrate is unique compared with other species. The maximum of the concentrations of the major ions, i. e. Na+, Mg2+, Ca2+, and K+, coincides well with the depths of dirty layers, which correspond the accumulation of snowfalls from the end of ablation season to late spring, the concentration peaks of these layers are possibly due to dry deposition during the "rare precipitation and dust storm" season. The contrast between the profiles of chemical species and stratigraphy of ice core suggests that the disturbance of meltwater to the chemical records of ice core is not negligible. we are confirmed therefore by the records of ice core, that the continental air masses prevailingly controlling atmospheric environment over Tibetan Plateau may reach somewhere south of Tanggula Mountain. 相似文献