The Survey of Surface Water Collecting Channels Performance in the Flood Crisis (Case Study: Sub-Basin Channels Of South Safarabad in Zanjan City)

Flood is one of the natural disasters which creates much finical and damage in the world every year. Iran is located in the arid part of the world. Because of this, water resource especially water flow is the main effective factor in the farming's of cities and villages. So we can say that core of most big cities of Iran like Isfahan is located at the sides of the rivers. Zanjan is located and developed at the side of Zanjanroud and the development of the city has located various ravines of this river in the area of the city. In some cases, ravine beds are changed into underground or open channels. And natural channels are combined. On the other hand, in most of the created channels, short- term, mind- term, and long- term floods are not calculated. With the development of city, the lands are often changed into impermeability surfaces and runoff is increased. At the time of intensive rains, in most parts of Zanjan city, we will face with city flood and water logged which will crenate intensive damages. In this research, the researcher has investigated the surface water disposal channels in Zanjan city which are created on south Safarabad ravine. At first, the evaluation of the maximum discharge volume in the floods with high return period is done by using Zanjan metrological station statistics. Then, the disposal performance of this channel is compared with the maximum discharge volume. The result showed that the made channels in the subbasin of south Safarabad is not made based on the maximum discharge. In flood time, the additional discharge is changed into crisis and will have created much damage.