نتایج جستجو برای: rivers

تعداد نتایج: 19001  

1998
John D. Wehr Louis Calder Jean-Pierre Descy

Historically, rivers have served as sources of drinking water, fisheries resources, transportation routes, irrigation supplies, and waste removal systems. Human civilization has had many major effects on rivers, dating back more than 5000 years when Egyptians built dams on the Nile to supply water for crops and human consumption. Today, management of large rivers requires a balance between huma...

2001
JASON L. WHITE BRET C. HARVEY

1. We used field surveys to compare the density and mesohabitat-scale distribution of the native coastrange sculpin (Cottus aleuticus) and the prickly sculpin (C. asper) in coastal rivers in north-western California, U.S.A., with and without an introduced piscivorous fish, the Sacramento pikeminnow, Ptychocheilus grandis. We also measured mortality of tethered prickly sculpin in a field experim...

Journal: :Computers & Geosciences 2006
Jorge D. Abad Marcelo H. García

RVR Meander was developed as a toolbox for modeling restoration and naturalization processes in rivers. This model includes Windows-based and Geographical Information System-based programs for analyzing and modeling planform migration of streams. In the past, several rivers have been channelized causing environmental and ecological problems. Restoration techniques evolve as natural solutions to...

2005
G. J. Chakrapani

Sediment transfer from continents to oceans via rivers is one of the important processes regulating river-bank stabilization, soil formation, biogeochemical cycling of elements, crust evolution and many other earth-related processes. Due to changes in continental positions during the geologic past, water flow and sediment loads in rivers have also shown variations during different time periods....

2004
ROBERT L. SINSABAUGH GEORGE W. KLING

1. We examined the influence of hydrologic seasonality on temporal variation of planktonic bacterial production (BP) in relatively undisturbed lowland rivers of the middle Orinoco basin, Venezuela. We sampled two clearwater and two blackwater rivers over 2 years for dissolved organic carbon (DOC), chlorophyll, phosphorus and bacterial abundance to determine their relationship to temporal variat...

2003
Peter J Crawford

Preface The Healthy Rivers Commission has completed investigations of the coastal catchments of rivers and lakes as referred to it by the NSW Government since 1995. Lessons learnt from those Inquiries have led the Commission to establish a number of key principles and strategies, which it believes are essential to achieving healthy rivers, lakes and catchments. This document advances a vision f...

Journal: :The Iowa Review 2009

2016
Amy E Peden Richard C Franklin Peter A Leggat

OBJECTIVE(S) Describe unintentional drowning deaths in rivers, creeks and streams (rivers) in Australia and identify risk factors to inform prevention. DESIGN & SETTING This study is a cross-sectional, total population audit of all unintentional fatal drownings in Australian rivers between 1-July-2002 and 30-June-2012 using Australian coronial data. A modified Bonferroni test has been applied...

ژورنال: بوم شناسی آبزیان 2014
Elahe , Amoeei khozani, Kolangi Miandare, Hamed , Shabani, Ali ,

Paraschistur anielseni is one of the main species of Paraschistura genus that is distributed in freshwater rivers which drain into the Persian Gulf. There has not been any study on genetic diversity of this species yet. In this investigation, 90 samples were collected from the rivers Shapour, Dalaki (Fars province) and Mand (Bushehr province) (30 samples per river) to investigate their populati...

2014
Dominika Saniewska Magdalena Bełdowska Jacek Bełdowski Michał Saniewski Marta Szubska Andrzej Romanowski Lucyna Falkowska

In Mediterranean seas and coastal zones, rivers can be the main source of mercury (Hg). Catchment management therefore affects the load of Hg reaching the sea with surface runoff. The major freshwater inflows to the Baltic Sea consist of large rivers. However, their systems are complex and identification of factors affecting the outflow of Hg from its catchments is difficult. For this reason, a...

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