Dayyer is one of the longest and most important rivers in Bushehr province and carries the sediments annually in Bushehr area. Therefore, due to the presence of Dayyer river which the effect of its generated sediment, is of great importance through the studies, hydrologic and sediment studies of this river have been implemented here.
The aim of hydrologic and dediment studies of Dayyer river, is the estimation of inlet/input sediment toward the sea in the eustariy which inevitably makes us implement basic studies like physiography, geology, meteorological and hydrologic studies of the river.
In order to estimate the input sedimentation to the sea, because of the lack of station for measuring the sediment to have real data, the experimcntal methods which have the most compatibility to Iran southern coastlines conditions and have been evaluated during the previous consulting studies, EPM (Erosion potential Method) have been used.
In this methed, by the assessment of three effective factors on soil erosion and sediment generation of basins which are: the soil erosion charaeteristics (Ф), the ground usage coudition and watershed lithology and geology is calculated where, by using the temperature coefficient, and the average rainfall, the erosion intensity coefficient, will be obtained. The annual WSP and the correspounding relation, determines the erosion versus m3/ km2 / year. There after, for conversion of this value to the generated sediment value, calculating another coefficient namely the sedimentation coefficient of the basin, is needed. This coefficient is computed using physical parameters of the basin like circumference, height and the length of the basin. Finally by multiplication of the result by the sediment value (WSP), special sediment in m3 /km2 / year (GSP) will be estimated. If this value multiply by the basin area, the total sediment rate in m3 / year (GS) will be obtained. The results of the calculations have been summarized in Table 7.1.
Table 7.1 The summary of the results of sediment rate calculations in Dayyer basin.
Due to the reletions used in Dayyer basin sedimentation and erosion studies, the total erosion of the whole basin was determined which results have been presented in table 7.1. As we can see in the table, the average sediment value for the whole of Dayyer basin, is abaut 430564.66 ton per year, and regarding that the basin’s area equals to 103800 Hectare, the special sediment value or in other words, the sediment value versus ton/hec/year equals to 4.14. Also the annual average of erosion for the whole of Dayyer basin, equals to 1197852 ton per year and due to the basin’s area, the special erosion value is 11.54 ton/hec/year. Among the total estimated sediment, 20 percent is the bed load (66241 m3 ) and rest of 80 percent is suspended load (264963 m3) carried by the river, where more than 70% of it is formed by silt and the rest is clay (16 %) and sand (10%).
Dayyer River Site Area