Rain-runoff Frequency Analysis for Designing Reservoirs in order to Collect Surface Water for the Development of Urban Green Space (Case Study: city of Tabriz)

Rain water harvesting methods is the include of management methods in order to encounter and compatibility with the conditions of the lack of water. Base of these methods, is allocating surfaces of the earth in order to collecting, storing and reusing rain water for designing goals at the times needed. The necessity of the implementation of the plan is that Were seeing that in any relatively intense rainfall occurs, The Eclipse occurs on roads and utilities and the damage to the House, that is required to a big city like Tabriz to have a macro system to reduce any damages caused by the floods and also be able to take maximum advantage of this current of water. In present research, In order to increase accuracy in using the methods of estimating runoff, facilitate the access and reduce the cost of transferring, the study area was divided to 4 sub drainage basin. Runoff derived of the four zones was computed with the SCS method. The volume of the reservoirs were designed with the use of the method of runoff frequency analysis for different seasons and with different return periods. Comparing green landscape monthly water requirement with rain water of Tabriz, clears that reservoirs are able to provide about 48 percent of the need for green landscape and the rest of the need, can be provided through the underground water and the incoming water supply to the city.