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51.
Quantifying the uncertainty of semiarid flash floods using generalized likelihood uncertainty estimation 总被引：1，自引：0，他引：1
This paper aims to address the question of how the parameter uncertainty associated with a mixed conceptual and physical based rainfall-runoff model (AFFDEF) has influences on flood simulation of the semiarid Abolabbas catchment (284 km2), in Iran. AFFDEF was modified and coupled with the generalized likelihood uncertainty estimation (GLUE) algorithm to simulate four flash flood events. Analysis suggests that AFFDEF parameters showed non-unique posterior distributions depending on the magnitudes and duration of flash flood events. Model predictive uncertainty was heavily dominated by error and bias in soil antecedent moisture condition that led to large storage effect in simulation. Overall, multiplying parameter for the infiltration reservoir capacity and multiplying parameter for the interception reservoir capacity along with potential runoff contributing areas were identified the key model parameters and more influential on flood simulation. Results further revealed that uncertainty was satisfactorily quantified for the event with low to moderate flood magnitudes while high magnitude event exhibited unsatisfactory result. 相似文献
52.
Data inadequacy is a common problem in designing or updating groundwater monitoring systems. The developed methodologies for the optimal design of groundwater monitoring systems usually assume that there is a complete set of data obtained from existing monitoring wells and provide a revised configuration for the system by analyzing the current data. These methodologies are not usually applicable when the current groundwater quantity and quality data are highly sparse. In this paper, a new simulation–optimization approach based on Bayesian maximum entropy theory (BME) is proposed for revising spatial and temporal monitoring frequencies in a sparsely monitored aquifer. The BME is used to simulate the spatial and spatiotemporal variations of groundwater indicators, incorporating the space/time uncertainties due to insufficient data. Comparing the obtained estimations with observations, the best BME model was selected to be linked with an optimization model. The main goal of optimization was to find out the spatial and temporal sampling characteristics of the monitoring stations using the concepts of Entropy theory and a groundwater vulnerability index. The results show the BME estimations are less biased and more accurate than Ordinary Kriging in both spatial and spatiotemporal analysis. The improvements in the BME estimates are mostly related to incorporating hard (accurate) and soft (uncertain) data in the estimation process. The applicability and efficiency of the proposed methodology have been evaluated by applying it to the Tehran aquifer in Iran which is suffering from high groundwater table fluctuations and nitrate pollution. Based on the results, in addition to the existing monitoring wells, seven new monitoring stations have been proposed. Few stations which potentially can be removed or combined with other stations have been identified and a monthly sampling frequency has been suggested. 相似文献
53.
Ali Mahaqi Moheghy Mohammad Anvar Moheghi Mohammad Mehdi Mehiqi Marzieh Zandvakili Zahra 《Water Resources》2020,47(2):325-335
Water Resources - Water in Central Asia is a precious resource in the semiarid and arid environments in which people live in the region. Understanding the groundwater quality is important as it is... 相似文献
54.
Zahra Karimi Mossadegh Justin Parker Eberhard Gischler Wolfgang Oschmann David Blakeway Anton Eisenhauer 《International Journal of Earth Sciences》2013,102(2):545-570
Major changes in community structure and depositional relief of high-latitude coral communities in the southern Persian Gulf between marine isotope stage (MIS) 7 and the present day suggest that the area has become increasingly restricted. Corals and bivalves from outcrops on Kish Island, Iran, were identified in order to interpret the Late Pleistocene palaeoenvironmental setting. U/Th disequilibrium dating was used to constrain the ages of the stratigraphic units. During MIS 7, two coral-bearing sequences were deposited on what is now Kish Island. The lower sequence is dated as MIS 7.5 and changes laterally from an assemblage dominated by Cyphastrea sp. and Platygyra daedalea in the west to one characterized by branching Montipora in the east. By contrast, the upper sequence, dated as MIS 7.1, transitions from an assemblage dominated by platy Montipora in the west to a diverse assemblage of Platygyra and other faviids in the east. The assemblages of both sequences are within a marl matrix and bounded by thin lithified mollusc-rich layers. Corals and bivalves indicate that the sequences were deposited on gentle slopes in sheltered environments less than 20 m deep. The MIS 7 deposits may be classified as coral carpets or biostromes that developed a low-relief framework. During MIS 5, coral communities were no longer framework building and are now limited to an Acropora-rich layer of coral rubble that covers large parts of the island, and two small incipient reefs with sparse faviids. Similarities between the MIS 5 and modern nearshore coral communities suggest that the environmental conditions during MIS 5 were comparable to those of today. The late Pleistocene coral carpets and non-framework coral communities of the southern Persian Gulf may serve as models for coral biostromes in the fossil record, which formed under restricted environmental conditions such as elevated terrigenous input, high turbidity, and strong seasonal changes in temperature and/or salinity. 相似文献
55.
In August 2001, the worst flash flooding event of the Caspian Sea regions in over two centuries claimed over 300 lives after
a weekend of heavy rainfall and brought about a devastating disaster in the Mother-Soo catchment, province of Golestan, Iran.
As a result of this event, a series of site investigation were carried out to identify the pertinent factors that led to a
flood of this magnitude. This paper identifies the fundamental causes of the frequent floods and debris flow occurrence in
the area prone to flooding and analyzes the main runoff mechanism of these events. The maximum observed 24-h rainfall depths
and maximum peak discharges at the existing gauges were compared with the depths of rainfall and the peak values corresponding
to the August 2001 flood respectively. For the majority of the rain gauges, the rainfall depth exceeded those of historical
recorded events. In Golestan dam, an increase of 7.5 times the maximum value observed in the past 20 years was noted. The
flood height was 10–15 m while passing through the middle subcatchment area of Golestan National Park. The preliminary evaluation
indicates the existence of bare soil in the catchment, movable material, steep slopes, high rainfall intensity, deterioration
of pasture and forest land, and inappropriate agriculture and development practices as well as climate change were the main
factors for the occurrence and the extent of the August 2001 disaster. Finally, due to the likelihood of flooding and debris
flow events in future, some countermeasures are proposed. 相似文献
56.
Neda?Yousefi Saeed?Reza?KhodashenasEmail author Saeid?Eslamian Zahra?Askari 《Arabian Journal of Geosciences》2016,9(4):321
Predicting behavior and the geometry of the channels and alluvial rivers in which the erosion and sediment transport are in equilibrium is one of the most important topics in river engineering. Various researchers have proposed empirical equations to estimate stable river width (W). In this research, empirical equations were examined and tested with a comprehensive available data set consisting of 1644 points collected from 29 stable rivers in various parts of the world. The data set covers a wide range of flow conditions, river geometry, and bed sediments. This data set is classified in two groups (W < 600 m and W ≥ 600 m) for presenting the new models. The new linear and nonlinear multivariable equations were fitted to these two groups, and the best models were selected by preliminary tests and diagnostic determined for each group. The determination coefficient of these models ranged from 0.87 to 0.96. The results show that the models presented in this paper are more accurate with respect to the previously presented models. In the second part, “Artificial neural networks,” perceptron was used and a new methodology for estimating stable channel width was developed. Comparison of the statistical methods presented in this paper and the results of perceptron neural network revealed preferential recent method. 相似文献
57.
58.
This paper investigates the annual cycle in aerosol optical thickness (AOT) and Angstrom exponent in Darwin, Australia, a coastal site in the Tropical Warm Pool where the major aerosol sources are biomass burning and sea salt. We have used radiometer measurements from the Tropical Western Pacific Atmospheric Radiation Measurement facility for the period March 2002–June 2003. Strong seasonal cycles in AOT and Angstrom exponent were observed, peaking during the burning season (May–November). Investigation of the spectral dependence of optical thickness showed that the Angstrom formula can be satisfactorily fitted to the AOT data during the burning season but not on summer and autumn afternoons due to the presence of sea salt aerosols. 相似文献
59.
Zahra Asadolahi Abdolrassoul Salmanmahiny Yousef Sakieh 《Environmental Earth Sciences》2017,76(10):365
Lush Hyrcanian mixed temperate forests are globally important ecosystems with considerable ecological and economic values and high variety of ecosystem services (ES). In this study, an ES-based approach is adopted to develop a spatial conservation framework for Gorganrood Watershed, northeastern Iran. In doing so, the integrated valuation of ecosystem services and trade-offs modeling tool was implemented to spatially quantify a collection of five ES including soil retention, habitat quality (as a proxy for biodiversity), water yield, food supply and carbon storage. These services were integrated into a single layer based on the Total Ecosystem Services (TES) index. By performing correlation analyses, the type and the strength of relationships between ES, TES index values and different land features were analyzed to reveal which land-use categories at what locations are more capable to provide bundles of ES. Accordingly, Hyrcanian mixed temperate forests in the southern sub-watersheds of the area were detected to have higher potential for simultaneous provisioning of multiple ES. In addition, we show that biodiversity hotspots and provision of other ES are highly correlated and thus that conservation of one group can be beneficial for the other. Our findings are particularly applicable in areas where complex network of land-uses and limited resources are major barriers against effective conservation of Hyrcanian mixed temperate forests. 相似文献
60.
Zahra?Sharafi Naeimehossadat?AsmarianEmail author Saeed?Hoorang Amin?Mousavi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(10):2943-2950
Stomach cancer is the second most common cancer in Iranian men and the fourth most common cancer in Iranian women. The incidence rate of this cancer in Iranian men is almost 2.5 times that in women. The objective of this study was to investigate the trend of stomach cancer incidence rate in Iran in an 8-year time period (2003–2010) and also update the incidence estimates of stomach cancer. Data from a total number of 41,830 patients diagnosed with stomach cancer according to the International Classification of Diseases (C16) in 2003–2010 were analyzed. We used Bayesian spatial and Bayesian spatio-temporal models to study the relative risk and trend of stomach cancer incidence rate in Iran. Out of 41,830 stomach cancer registered patients, 72% were male. The average smoothed SIRs were 0.79, 0.82 and 0.78 for the general, female and male population, respectively. This shows a nearly stable incidence rate. The northwest of Iran had the highest incidence rate of stomach cancer. The trend of this rate was declining to the lowest rate in the southeast of the country. The estimated values of coefficient of the trend term for general, female and male population in this model were 0.0085, ? 0.018 and 0.0041, which indicate almost a stable fixed trend. The map of temporal trends also showed that although the incidence rate of this cancer is to some extent stable, in general, in the central and in the east of the country the incidence relative risk has increased over time. The prevalence of Helicobacter pylori infection, Lower socioeconomic status and Iodine deficiency were speculated to be relevant factors for the high incidence rates of stomach cancer in the northwest of Iran. Preventive measures in the north and northwest of Iran could have an effect on controlling this cancer in these areas. 相似文献