3,059 research outputs found
Automated estimation and analyses of meteorological drought characteristics from monthly rainfall data
The paper describes a new software package for automated estimation, display and analyses of various drought indices – continuous functions of precipitation that allow quantitative assessment of meteorological drought events to be made. The software at present allows up to five different drought indices to be estimated. They include the Decile Index (DI), the Effective Drought Index (EDI), the Standardized Precipitation Index (SPI) and deviations from the long-term mean and median value. Each index can be estimated from point and spatially averaged rainfall data and a number of options are provided for months' selection and the type of the analysis, including a running mean, single value or multiple annual values. The software also allows spell/run analysis to be performed and maps of a specific index to be constructed. The software forms part of the comprehensive computer package, developed earlier and designed to perform the multitude of water resources analyses and hydro-meteorological data processing. The 7-step procedure of setting up and running a typical drought assessment application is described in detail. The examples of applications are given primarily in the specific context of South Asia where the software has been used
Indexing the Environmental Vulnerability of Mountain Streams in Azerbaijan
A simple environmental vulnerability assessment scheme is developed and illustrated using several streams in Azerbaijan as examples. Vulnerability of a river ecosystem is defined in terms of a combined impact of pressure factors such as water withdrawals, pollution, climate change impact on flow variability, and land use. These factors are used to measure the sensitivity of various elements/components of the system to impacts. The choice of these indicators may vary from area to area and depends on the nature of man-made and natural conditions. Each factor is characterized and quantified using a specific indicator and score. The total vulnerability score is estimated as a sum of the scores of all indicators. Most of the streams studied in Azerbaijan were found to be very vulnerable or extremely vulnerable, according to the developed scheme. The overall approach is straightforward and transparent. Conclusions are made about the vulnerability and/or resiliency of streams, to be taken into consideration when planning for water-sources development for the future
ЛЕДОВЫЙ РЕЖИМ ОЗЁР ЗАБАЙКАЛЬЯ В УСЛОВИЯХ СОВРЕМЕННОГО ПОТЕПЛЕНИЯ
The problem of the climate change impact on the ice regime of lakes has become topical in view of the revealed (observed) shortening of the freeze-up duration and a decrease in the ice thickness for many years. The relationship between timing and duration of the ice events and climate characteristics had been found. The influence of climate change on the ice regime in the Transbaikalia was previously estimated by the example of the Ivano-Arakhley lakes. In this work we determined the trends of changes of the following parameters: air temperature, the duration of freeze-up and the maximal ice thickness as well as the reliability of these trends on lakes Arakhley, Shakshinsky, Bolshoy Leprindo, Gusinoye, Baunt, Sosnovoye. The least-squares method was used to determine the long-term trends; consistency of the changes in the studied characteristics was evaluated by means of the correlation analysis. The significance of the trends and correlation coefficients was evaluated using Student's t-statistics.Оценено влияние изменений климата на ледовый режим озёр Забайкалья с 1975 по2012 г. Современная тенденция повышения температуры воздуха влияет на даты начала и окончания ледостава, формирование максимальной толщины льда и его прирост. Продолжительность ледостава и максимальная толщина льда за многолетний период уменьшились
Environmental Flow Assessment: Recent Examples from Sri Lanka
Abstract Assessment and provision of Environmental Flows (EF) is important for the protection of aquatic ecosystems. EF are a set of discharges of a particular magnitude, frequency and timing that are necessary to ensure a certain range of benefits from a river. Such flows need to be scientifically determined and economically justified. Limited exposure to the concept of EF exists in developing countries. This paper gives two recent relevant example studies, which were conducted by IWMI, with foci on EF Assessment (EFA) and valuation of EF benefits in the Walawe and Menik Ganga river basins located in a semi-arid zone of southern Sri Lanka. The Walawe example illustrates the simple method for estimation of EF. The EF are approximated at two sites along the main stream of the Walawe River, which are located below the two main reservoirs. A desktop method is used, which is based on simulated, unregulated daily flow time series and their flow duration curves. The study also illustrates how the required hydrological information can be generated for the locations where EF assessment is intendedquickly and in conditions of limited observed data. The second Menik Ganga example is used as a case study to evaluate the costs and benefits of environmental water allocations. The EF components evaluated include the water needs for religious festivals, and the requirements of the Yala National Park, the Pilinnawa coastal wetland and grasslands, and the Yala Fisheries Management Area (YFMA) off the coast. Almost all estimates are based on use values of EF such as marketed goods and recreation. The paper intends to stimulate discussion and further research in the fields of EF assessment and economic valuation
Global Environmental Flow Information for the Sustainable Development Goals
Environmental flows (EF) are an important component of Goal 6 (the ‘water goal’) of the Sustainable Development Goals (SDGs). Yet, many countries still do not have well-defined criteria on how to define EF. In this study, we bring together the International Water Management Institute’s (IWMI’s) expertise and previous research in this area to develop a new methodology to quantify EF at a global scale. EF are developed for grids (0.1 degree spatial resolution) for different levels of health (defined as environmental management classes [EMCs]) of river sections. Additionally, EF have been separated into surface water and groundwater components, which also helps in developing sustainable groundwater abstraction (SGWA) limits. An online tool has been developed to calculate EF and SGWA in any area of interest
The Certification of ATLAS Thin Gap Chambers Produced in Israel and China
Thin gap chambers (TGCs) are used for the muon trigger system in the forward
region of the LHC experiment ATLAS. A TGC consists of a plane of closely spaced
wires maintained at positive high voltage, sandwiched between resistive
grounded cathode planes with an anode wire to cathode plane gap distance
smaller than the wire-to-wire spacing. The TGCs are expected to provide a
trigger signal within 25 ns of the bunch spacing of the LHC accelerator, with
an efficiency exceeding 95%, while exposed to an effective photon and neutron
background ranging from 30 to 500 Hz/cm2. About 2,500 out of the 3,600 ATLAS
TGCs are being produced at the Weizmann institute in Israel, and in Shandong
University in China. Once installed in the ATLAS detector the TGCs will be
inaccessible. A vigorous production quality control program is therefore
implemented at the production sites. Furthermore, after chamber completion, a
thorough program of quality assurance is implemented to ensure the efficient
performance of the chambers during more than ten years of operation in the LHC
high rate environment. This program consists of a detailed mapping of the
detectors response using cosmic rays, as well as checking the chambers behavior
using a high rate radiation source. An aging test performed on five chambers in
a serial gas connection is presented. Finally the results of the chambers
certification tests performed at CERN before the installation in ATLAS are
described.Comment: Presented at 2004 IEEE Nuclear Science Symposium 2004, Rome, Oct 200
Measurement of the Pion Form Factor in the Energy Range 1.04-1.38 GeV with the CMD-2 Detector
The cross section for the process is measured in the
c.m. energy range 1.04-1.38 GeV from 995 000 selected collinear events
including 860000 events, 82000 events, and 33000
events. The systematic and statistical errors of measuring the
pion form factor are equal to 1.2-4.2 and 5-13%, respectively.Comment: 5 pages, 2 figure
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