rivers are important water resources for human life, but sometimes cause irreparable damages. the flood plains are fertile terrains which are endangered by flood. flood hazard mapping is one of the basic methods in flood fighting. in order to decline flood damages, the simulation of the hydraulic behavior of the rivers during flood occurrence is very important. in this study, areas that are flo...

The role of terrigenous sediment in controlling the occurrence of coral reef ecosystems is qualitatively understood and has been studied at local scales, but has not been systematically evaluated on a global-to-regional scale. Current concerns about degradation of reef environments and alteration of the hydrologic and sediment cycles place the issue at a focal point of multiple environmental co...

Background: Iran is located in the global arid zone. With an average rainfall of less than 250 mm. 25 percent is Iran of located in hyper-dry area and 40 percent in the arid area. In 2007, the World Bank report declared the annual reduction of freshwater resources in Iran 6 times more than global standards and indicators. Since at present, in Iran most available fresh water enters the water eco...

1. Compared with rivers in more humid, forested ecoregions of eastern and midwestern U.S.A., rivers in semi-arid grassland of the U.S. Great Plains tend to be relatively shallow, more variable in discharge, and characterised by high suspended sediment loads. Although critical life stages of fish in prairie rivers probably depend at least partially on zooplanktonic food, data on community and di...

The Neotropical Ambrysus stali La Rivers species complex is reviewed and includes A. bifidus La Rivers & Nieser, A. scolius La Rivers, A. stali La Rivers, and A. tricuspis La Rivers. Ambrysus oblongulus Montandon is removed as a member of this complex. Features uniting these species are related to male genitalia and associated structures. Ambrysus maya n. sp. is the fifth species in the complex...

Flow variability plays an important role in structuring lotic communities, yet comparatively little is known about processes governing assemblage dynamics in stream ecosystems with stable environmental conditions, such as spring-fed rivers. Volcanic spring-fed rivers (hereafter spring-fed rivers) occur in geologically active landscapes of the western USA and around the globe. We sampled inverte...

 The concentrations of Cd, Pb, Ni and Hg were determined in gill, liver and muscle of Barbus xanthopterus in down streams of Karoon and Dez Rivers during summer 2009. Heavy metal concentrations varied significantly, depending on the types of the tissue in fish species. The levels of heavy metals such as Cd, Pb, Ni and Hg in the Barbus xanthopterus of Karoon River were higher than in Barbus xant...