Natural Hazards - The present work focuses on using remote sensing techniques and geographical information system (GIS) to automatically extract lineaments in the southeast of Morocco, which is one... 相似文献
In the context of major outcomes of a steadily changing climate, extreme climatic conditions and the associated events in various forms of weather-related natural disasters, e.g. droughts, floods, and heat waves, are more frequently experienced on the global scale in recent years. In support of this argument, there are adequate numbers of explicit signals over such a persistent outlook, which is greatly illustrated by historical data and observations. This study, which is mainly oriented to investigating the drought behaviour in Thracian, Aegean and Mediterranean transects of Turkey's major river basins, is actually inspired by the foreseen potential of using annual maximum drought severity series (based on drought definition through the standardized precipitation index (SPI)) within a framework that resembles the use of flood discharge directly from flow measurements in a river basin. To this end, a series of spatial analyses were employed to identify different aspects of flood appearance in the study extent, including trend views on annual average drought severity series, shifts in the starting time of the annually most severe flood periods, and changes in spatial coverage views of average drought conditions under different drought severity categories. The framework of the analytical approaches depends greatly on validated international datasets and open-source computational algorithms. The results from the analyses that were conducted in two consecutive periods of 1958–1980 and 1981–2004 revealed that Turkey's western and southern river basin systems seemed to have experienced quite different behaviours between the two periods in terms of drought severity magnitudes, drought durations and annual occurrence times.
Geotechnical and Geological Engineering - This paper presents a study on Chlef sand to examine the effect of fines content (Fc), relative density (RD) and initial conditions on the compressibility... 相似文献
As a result of climate change and unsustainable land use management in the recent past, droughts have become one of the most devastating climatic hazards whose impacts may prolong from months to years. This study presents analysis of droughts for two major cropping seasons, i.e., Kharif (May–September) and Rabi (October–April), over the Potwar Plateau of Pakistan. The analysis is performed using various datasets viz. observational, reanalysis, and Regional Climate Models (RCMs), for the past (1981–2010) and future (2011–2100) time periods. The following two methods for the identification of dry and wet years, also referred to as drought and wetness, are applied: (1) the percentile rank approach and (2) the drought indices, Standardized Precipitation Index (SPI) and Reconnaissance Drought Index (RDI). Future projections of droughts are investigated using RCM (RegCM4.4 and RCA4) outputs from CORDEX South Asia domain under two Representative Concentration Pathway (RCP) scenarios, RCP4.5 and RCP8.5. Generally, the indices show non-significant decreasing trends of drought severity in the recent past for all cases; however, significant increasing trends are observed for annual (0.006) and Kharif (0.007) cases under RCP4.5 scenario. The analysis of large-scale atmospheric dynamics suggests the significant role of low-level geopotential height anomalies over Tibetan Plateau (northwest of Pakistan) during Kharif (Rabi) season in controlling drought occurrence by transporting moisture from the Bay of Bengal (Arabian Sea). Moreover, composites of vertically integrated moisture transport, moisture flux convergence/divergence, and precipitable water anomalies show their marked contribution in maintaining the drought/wetness conditions over the Potwar region. 相似文献
The study evaluated CORDEX RCMs’ ability to project future rainfall and extreme events in the Mzingwane catchment using an ensemble average of three RCMs (RCA4, REMO2009 and CRCM5). Model validation employed the statistical mean and Pearson correlation, while trends in projected rainfall and number of rainy days were computed using the Mann-Kendall trend test and the magnitudes of trends were determined by Sen’s slope estimator. Temporal and spatial distribution of future extreme dryness and wetness was established by using the Standard Precipitation Index (SPI). The results show that RCMs adequately represented annual and inter-annual rainfall variability and the ensemble average outperformed individual models. Trend results for the projected rainfall suggest a significant decreasing trend in future rainfall (2016–2100) for all stations at p < 0.05. In addition, a general decreasing trend in the number of rainy days is projected for future climate, although the significance and magnitude varied with station location. Model results suggest an increased occurrence of future extreme events, particularly towards the end of the century. The findings are important for developing proactive sustainable strategies for future climate change adaption and mitigation. 相似文献
Abstract Further ratification of the Kyoto Protocol by non-Annex 1 countries such as the State of Qatar will not affect the entrance into force of the Treaty; however, ratification remains an important decision due to other considerations, primarily the economic costs and benefits associated with ratification. As a member of the Organization of Petroleum Exporting Countries (OPEC), Qatar's economic position is closely allied with revenue generated from its oil and natural gas resources. Qatar expects adverse impacts from implementing the Kyoto Protocol, though the estimated magnitude varies enormously with different models. Also, the impacts depend significantly on how the implementation is done; for example, the kind of policies that other countries use. Qatar is able to counter adverse impacts by exploiting its greater share of natural gas and developing energy-intensive industries that produce nonenergy goods such as steel, petrochemicals, and chemicals. Furthermore, it is clear that clauses in the Protocol can be developed to protect OPEC interests, and if Qatar does not ratify the Protocol, it will be excluded from the subsequent rule-making processes. On balance, there are benefits to ratifying the Treaty, and there is also a strong need for extensive further research. 相似文献
Taking into account of ion temperature effect, existence conditions of arbitrary amplitude solitary Kinetic Alfvén Waves (KAWs) in a plasma with q-nonextensive electrons are investigated by the conventional Sagdeev pseudo potential method. It is found that only solitons with density hump can exist, the amplitude of which depends sensitively on the parameter q, ion temperature (\(\sigma= \frac{T_{i}}{T_{e}}\)) and plasma β. There is an upper limit of solitary wave amplitude which decreases with increase of q, σ and β. The amplitude of solitary KAWs is found to increase with increase in ion temperature. The results obtained in the framework of Maxwellian distribution are reproduced when q→1. 相似文献