Multisite disaggregation of monthly to daily streamflows: Case study of Kizilirmak basin (Turkey)

The thesis presents a comprehensive study in the applicability of existing disaggregation methods on streamflow data in Kızılırmak Basin (Turkey). The Parametric and non-parametric approaches were utilized to disaggregate the streamflow temporally from annual to monthly data as well as spatially by assuming a set of aggregated streamflow at a key station is available and it is desired for disaggregation to substations that are statistically similar to observed ones. The purpose of performing non-parametric and deterministic approaches is to show the effects of the drawbacks of the parametric one such as the normality assumption. The utility and limitation of these approaches were discussed how these approaches preserve a variety of the statistical characteristics of the historical data. The results showed that the non-parametric disaggregation approach was better than the parametric approach to capture the statistical characteristics of historical data for the tested sites. The main advantage of deterministic approach is to allow for disaggregation directly from annual to daily data. These simulated lower-level time scales (monthly, daily, or hourly) data can be used for determination of river basin management policies as well as completing streamflow time series.