B. Ghahraman; K. Davary
Abstract
Due to inadequate flood data it is not always possible to fit a frequency analysis to at-site stations. Reliable results are not always guaranteed by a single clustering algorithm, so a combination of methods may be used. In this research, we considered three clustering algorithms: single linkge, complete ...
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Due to inadequate flood data it is not always possible to fit a frequency analysis to at-site stations. Reliable results are not always guaranteed by a single clustering algorithm, so a combination of methods may be used. In this research, we considered three clustering algorithms: single linkge, complete linkage and Ward (as hierarchial clustering methods), and K-mean (as partitional clustering analysis). Hybrid cluster analysis was tested for up-to-dated of floods data in 68 hydrometric stations in East and NE of Iran. Four cluster validity indices were used to find the optimum number of clusters. Based on the Cophenetic coefficient and average Silhouette width, single linkge, and complete linkage methods were performed well, yet they produced non-consistent clusters (one large and numerous small clusters) which are not amenable for flood frequency analysis. It was shown that hybridization was efficient to form homogeneous regions, however, the usefulness was dependent to the number of classes. Heterogeneity measure of Hosking was negative, due to inter-correlation of floods in the clusters. The hybrid of Ward and K-mean was shown to be the best combination for the region under study. Four homogeneous regions were delineated.
R. Ghafourian; A. Bagherian kalat; A. Gord Noushahri
Abstract
Part of water flowing downstream in rivers, infiltrates into the bed river. Infiltrated water depends on morphologic and hydraulic characteristic of the rivers. Planners and managers want to know the amount of water infiltrates into the bed and consequently recharges ground water. In this study three ...
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Part of water flowing downstream in rivers, infiltrates into the bed river. Infiltrated water depends on morphologic and hydraulic characteristic of the rivers. Planners and managers want to know the amount of water infiltrates into the bed and consequently recharges ground water. In this study three rivers of Kashaf rud river basin, namely Ferizi, shandiz (Zoshk) and Golestan, were selected and their discharges were measured during period of 2009-2011 at the beginning and the end of a selected reach in each of the mentioned rivers by a current meter. Then transmission losses (TL) of the reaches were computed by subtracting the measured discharges. By surveying longitudinal profile and cross sections of the reaches and running the Hec-Ras model, wetted perimeter was determined for every discharge measurement for three selected reaches. Analysis of data showed that there is a significant exponential relationship between TL and the measured discharge at the beginning of the reach and wetted perimeter for one kilometer of the reach. The results showed that the percentage of TL decreases with increasing of the discharge in each river. As well as TL rate decreases from west to east; on the other hands in Ferizi river is the most and in Golestsn river is least. Developing an exponential model which is independent of the wetted perimeter, is one of the other results of the research.
