نتایج جستجو برای: year patterns of monthly environmental and river flow
تعداد نتایج: 24145451 فیلتر نتایج به سال:
A river flow regime describes an average seasonal behaviour of flow and reflects the climatic and physiographic conditions in a basin. Differences in the regularity (stability) of the seasonal patterns reflect different dimensionality of the flow regimes, which can change subject to changes in climate conditions. The empirical orthogonal functions (EOF) approach can be used to describe the intr...
Recent research has suggested that changes in temperature and precipitation events due to climate change have had a significant impact on the availability and timing of streamflow. In this study, monthly temperature and precipitation data collected over 29 climate divisions covering the entire Colorado River basin and monthly natural flow data from 29 U.S. Geological Survey (USGS) gauge locatio...
چکیده با توسعه شهر نشینی و دخل و تصرف غیر مجاز در حریم رودخانه ها خسارات زیادی به رودخانه و محیط زیست اطراف آن وارده می شود. در حال حاضر بر اساس آئین نامه اصلاح شده بستر و حریم رودخانه ها، حریم کمی رودخانه که بلافاصله پس از بستر قرار می گیرد از 1 تا20 متر از منتهی الیه طرفین بستر رودخانه تعیین، که مقدار دقیق آن در هر بازه از رودخانه مشخص نیست. در کشورهای دیگر روشهای متفاوتی من جمله: درصد ریسک...
Awareness of the level of river flow and its fluctuations at different times is one of the significant factor to achieve sustainable development for water resource issues. Therefore, the present study two hybrid models, Wavelet- Adaptive Neural Fuzzy Interference System (WANFIS) and Wavelet- Artificial Neural Network (WANN) are used for flow prediction of Gamasyab River (Nahavand, Hamedan, Iran...
In this paper trends of precipitation and stream flow are analyzed in the Atrak River basin in the North Khorasan province. Normal score linear regression, Mann-Kendall, and Seasonal Kendall trend tests were adopted. Three precipitation variables and two stream flow variables including total precipitation, maximum daily precipitation, and number of rainy days, mean discharge and peak discharge ...
Heavy metal pollution dispersion simulation in rivers and predicting spatial and temporal variations of pollutants can be used to determine the precise place and to schedule water withdrawal time for drinking, agriculture, aquaculture and ecosystem studies. To study the movement of heavy metal pollution through Karoon flow model, MIKE 11 was employed fpr simulation of the flow model of Karoon R...
This paper investigates the relationship between river flow, rainfall and groundwater pumpage in the Mikkes stream during the period 1968-2009. The Mikkes basin is located in the north center of Morocco and consists of three different zones that represent diversified geologies. This basin includes a phreatic and confined aquifer in Saïs basin and a shallow aquifer in the Tabular Middle Atlas. A...
Sustaining environmental flows to preserve biodiversity of aquatic plant and animal species, as well as constancy of water for human communities, is essential in many river ecosystems. On the other hand, hydrological changes caused by the dam and its related environmental problems have provoked many concerns for hydrologists, ecologists and policymakers. Therefore, the main aim of this research...
Today, increase in flood frequency and intensity, and flash flood events have caused environmental issues and increased human and economic losses. As a result, numerous tools and new programs for flood forecasting systems and risk management programs are being used in the relevant period. There are models that make it easy to be used for this purpose. In this research, MISDc model was applied t...
hydrograph analysis is a complex problem in a variety of water resources investigations and its estimate is critical in the assessment of low flow characteristics of river for use in water supply, water management and pollution assessment. the paper describes different methods of base flow separation based recession analysis from daily river flow records and distinguishes the most suitable meth...
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