Hydrological Study and Analysis of Two Farm Dams in Erbil Governorate

Abstract

This research presents hydrological study and analysis for two proposed farm dams (Chaluk and Zurgazraw) located in Erbil Governorate - Iraqi Kurdistan Region. Many site visits were made to the Chaluk and Zurgazraw areas to select the most suitable site for the farm dams. The area and properties of the catchment area for both farm dams were measured by arc GIS software and were equal to 1.99, and 3.97 km2 for Chaluk and Zurgazraw farm dams, respectively. The topographic study and surveying of the selected sites aimed to construct the contour maps of the sites, determine the capacity of the reservoir for different heights of the farm dam embankment, and locate the centerline of the dam and spillway. In the hydrological analysis, as the proposed farm dam’s streams are ungauged streams with no runoff data records, the U.S. Soil Conservation Service (SCS) method was used to find the annual runoff yield. This method depends on physical parameters of the catchment area and daily rainfall depth data taken from Erbil Meteorological station; the calculated minimum, maximum, and average runoff yield were equal to 16556, 233407, and 103957 m3 for Chaluk, and 33030, 456641, and, 207393 m3 , Zurgazraw farm dam. The Australian (ARR) organization method was used to determine the 50 year return period peak discharge for the farm dams catchment area, which were equal to 14.71, and 24.07 m3 /sec for Chaluk, and Zurgazraw farm dams, respectively. Based on the calculated average annual inflow and calculated annual sediment inflow into farm dams by Universal Soil Loss Equation, the dead, and live storages elevations, and volumes were fixed to be equal to 411, and 418 m.a.s.l. (meters above sea level) and 7741, and 103425 m3 for Chaluk, and 404, and 412 m.a.s.l 20863, and 293822m3 for Zurgazraw farm dam.