Trends Detection and Characteristics of Hydrological Time Series of Rivers in North of Iraq

Hydrological systems are potentially sensitive to climate changes. This paper aims at detecting possible changes in the stream flow regime of Balikian and Rawanduz rivers in the north of Iraq over the period 1958-1984. The methodology is based on the analysis of some characteristics of monthly maximum, minimum and average and annual mean flow, as well as on the non-parametric Mann-Kendall statistical test. The analysis of hydrological time series shows that the total yearly amount yield of Balikian and Rawanduz river are 820 and 473 million cubic meter respectively. Most of the variations in discharge coincides with the variations in precipitation. The maximum average runoff occurs in March for Balikian and in April for Rawanduz and the minimum average runoff occurs in August and September for both rivers. The wide variety in values of Non-uniformity coefficient (NUC) between the two rivers indicates the difference in the sources of water resources and its distribution during the year. For the annual flow series of both rivers there is no obvious trend displayed. The trends in most of the months for the flow of both rivers are not significant, however, for Rawanduz river there is obvious downward trend in March, April, May, Jun and September.