نتایج جستجو برای: year patterns of monthly environmental and river flow

تعداد نتایج: 24145451  

Journal: :international journal of environmental research 2013
w. huang s. yano j.m. zhang y.r. wang

the environmental and ecological issues in the flow-reduced river reach are very serious and arereceiving increasingly attention. in this study, we investigate the temporal and spatial changes in δ13c and δ15n of periphyton and isotopic relationship between periphyton and the endangered fish (ayu, plecoglossusaltivelis) in a flow-reduced river reach in japan. much of the spatial and temporal va...

Journal: :international journal of environmental research 2011
d.k. kim k.s. jeong r.i.b. mckay t.s. chon g.j. joo

in the regulated nakdong river, algal proliferations are annually observed in some seasons, with cyanobacteria (microcystis aeruginosa) appearing in summer and diatom blooms (stephanodiscus hantzschii) in winter. this study aims to develop two ecological models forecasting future chlorophyll a at two time-steps (one-week and one-year forecasts), using recurrent neural networks tuned by genetic...

Environmental flow requirements, to maintain the functioning of freshwater-dependent ecosystems and restore rivers in ecologically acceptable conditions, depend upon the present water quality status of the river. Various stretches of Vishwamitri River vary in quality and quantity. Water quality index is a tool to converse information regarding water quality of various stretches of river and can...

According to recent Studies, about 60 percent of surface waters and 57 Percent ground waters are located in snowy zones in Iran. In most areas of northern hemisphere and alpine environment areas, snow melt lead to the maximum instantaneous flow rate and is an important part of annual discharge. The present study investigated the effect of snowmelt on the surface waters and ground waters in B...

2007
P. R. LIND B. J. ROBSON B. D. MITCHELL

The aim of this study was to identify whether environmental flows released into two lowland rivers (the Glenelg and Wimmera Rivers, western Victoria, Australia) during the spring to autumn period had successfully ameliorated the negative effects of multiple human impacts. Macroinvertebrates and a range of physico-chemical variables were sampled from three reaches in each river. Both rivers were...

2006
Yonas Gebeyehu Tesfaye Mark M. Meerschaert Paul L. Anderson

[1] The generation of synthetic river flow samples that can reproduce the essential statistical features of historical river flows is useful for the planning, design, and operation of water resource systems. Most river flow series are periodically stationary; that is, their mean and covariance functions are periodic with respect to time. This article develops model identification and simulation...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علامه طباطبایی - دانشکده اقتصاد 1389

abstract: about 60% of total premium of insurance industry is pertained?to life policies in the world; while the life insurance total premium in iran is less than 6% of total premium in insurance industry in 2008 (sigma, no 3/2009). among the reasons that discourage the life insurance industry is the problem of adverse selection. adverse selection theory describes a situation where the inf...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده مهندسی عمران 1388

چکیده روش های متعددی برای برآورد رواناب حاصل از بارش در حوضه های آبریز وجود دارد. یکی از این روش ها استفاده از مدل های هیدرولوژیکی است. با استفاده از مدل های هیدرولوژیکی و شبیه سازی فرآیندهای هیدرولوژیکی می توان با صرف کمترین زمان و هزینه، رواناب و مولفه های دیگر چرخ? هیدرولوژیکی را برآورد کرد. از آنجا که در حوضه های آبریز اندازه گیری تمام کمیت های مورد نیاز برای تحلیل رواناب ممکن نیست، انتخاب...

2015
DAVID M. MARTIN JOHN W. LABADIE

1. River management involves satisfying societal preferences alongside environmental needs for a healthy river ecosystem. Environmental flows is a discipline that aims to define streamflow requirements that achieve desired social and ecological conditions in rivers. 2. The ecological limits of hydrologic alteration (ELOHA) framework takes a regional approach towards assessing relationships betw...

ژورنال: علوم آب و خاک 2007
هانی رضائی, , همایون فرهنگ‌فر, ,

A total of 179,460 monthly test-day milk records (thrice a day milking) obtained from 17,946 Iranian Holstein heifers distributed in 287 herds and calved from 1986 to 2001 were used to predict breeding value of animals. Monthly test-day milk production was analysed by applying a covariance function in which the effects of herd-year-season of production (HYSOP), age at test day (covariate), addi...

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