On the North American Great Plains, several snake species reach their northern range limit where they rely on sparsely distributed hibernacula located in major river valleys. Independent colonization histories for the river valleys and barriers to gene flow caused by the lack of suitable habitat between them may have produced genetically differentiated snake populations. To test this hypothesis...

The issues of loss of quality of life and functional disruption of the river valleys are very important. In the present settlement system, the river valleys should not be places for reproducing poverty. To link the environmental values with urban development, the research is to answer the following question: How can the results of the integrated development of urban valleys be achieved via urba...

One of the most important natural factors and critical facilities in Tehran is presence of AlborzSlopes River-Valleys which have been considered as natural tourist places for citizens since a long time ago, especiallyin hot summers and play effective role in creating a balance between manmade and natural spaces. Importance ofthese river-valleys as ecological pathways is enhanced with the increa...

tehran city has been subject of critical environmental challenges during the course of 20th. century namely: massive population growth, broad expansion, reduction in urban open/green spaces, increasing in energy consumption and waste production. releasing industrial wastewater into river valleys have led to considerable changes in structure of city's natural landscape. the natural structur...

intra-city natural structures have always had a key role in creating sustainable urban greenspaces. adapting to natural features and relating the intra-city greenspaces to such natural structures as river-valleys, hillsides, lakes and forests, guarantee the endurance, sustainability and longevity of the natural quality of city. this paper looks at intra-city natural structures which have underg...

one of the most important natural factors and critical facilities in tehran is presence of alborzslopes river-valleys which have been considered as natural tourist places for citizens since a long time ago, especiallyin hot summers and play effective role in creating a balance between manmade and natural spaces. importance ofthese river-valleys as ecological pathways is enhanced with the increa...

urban landscape structural analysis; focused on the remnant patch mosaic network as the component with closest interdependency with air and water related processes was undertaken to find and propose environmental planning suggestions.assessments demonstrate that remnant patch mosaic network structure of tehran is still restorable. with appropriate corrective measures based on the natural lay ou...

abstract a mountain glacier, when it occupies a river valley, immediately begins to change the cross-section and profile of that valley. river valleys in mountain areas tends to have v-shaped profiles. glaciers work to widen as well as deepen their valleys and the typical cross-section of a glacial valley is u-shaped. the u-shaped glacial valley is one of the most characteristic of glacial land...