throughout history dams have been important structures in water storage. to avoid overtopping, damage, and or failure of a dam, adequate spillway is needed to release excess water from upstream floods. researchers found that spillways have to be made nonlinear in order to reach an economic structure with high performance. a piano key weir is one of the best solutions. piano key weirs are the mo...

Weirs, as overflow structures, are extensively used for the measurement of flow, its diversion and control in the open canals. Labyrinth weir due to more effective length than conventional weirs, allows passing more discharge in narrow canals. Determination the design criteria for the practical application of these weirs need more investigation. Weir angle and its position relative to the flow ...

water quality trading is a new approach in pollution control which satisfies water quality standards suggesting minimum cost solutions. this method uses tradable discharge permits based on pollution transfer coefficient in a river. this paper tries to establish a water quality trading program in a river basin according to transfer coefficients between pollution sources and evaluate cost effecti...