Document Type : Research Paper
Author
MSc, Agricultural and Natural Resources Research Center, Western Azerbaijan, Iran
Abstract
Computation and estimation of flood discharge is necessary in hydraulic structure planning and flood control projects. The precise estimation of runoff and flood discharge needs comprehensive data of the amount and condition of rainfall and design precipitation. Rainfall Depth-Area-Duration curves (DAD) of each region, are used to estimate the optimal precipitation. In this research, these curves were provided for 1, 3, 6, 9, 12, 18 and 24 hours intervals and their relations were studied for Northern parts of Western Azerbaijan province. Eleven maximum and pervasive storms were selected to draw the cumulative rainfall graph. There are adequate recorded and non-recorded rain gauges in the region. Mass curves were prepared for non-recorded stations using relations between rainfall gradient and altitude in the isohyets maps. Results showed that the maximum rainfall for 1 km2 is related to 18 h rainfall with 42 mm and its minimum is related to 1 h rainfall with 4.29 mm. Also, 9 and 12 h curves indicated no difference in different areas. Comparing 18 and 24 h curves indicated that the amount of precipitations are equal in small areas and 18 h curve is above 24 h curve in wast areas that could be related to the shortage of rainfalls with 24 h duration.
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