Characteristics and quality of reservoir sediments, Mujib Dam, Central Jordan, as a case study

This paper focuses on characterizing the current status of physiochemical properties of Mujib Dam sediments. Five types of granulometric textural facies were observed for the bottom sediments of Mujib reservoir bed; these are clayey facies, clayey-silt facies, sand-silt-clay facies, sand facies, and granule facies. This average grain size will likely play a vital role in adsorption-desorption of the majority trace metals to the reservoir lake. Other sediment parameters including the total averages were 5.9% (total organic matter (TOM)), 7.5 (pH), 25.8% (CaCO3), and 88.0 meq/100 g (cation exchange capacity), with dominant mineralogical constituents of quartz, calcite, dolomite, and minor feldspar and with variability in clay mineral types. The vast majority of trace metals in sediment exhibited values in the range or near the upper limit of the normal worldwide soil ranges. TOM and grain size of sediment are major factors governing the trace metal concentrations. The calculated geoaccumulation index (I-geo) and enrichment factor (EF) of metals in sediments of Mujib Dam were ranked as follows: cadmium (Cd) > copper (Cu) > zinc (Zn) > lead (Pb) > cobalt (Co) > iron (Fe) > chromium (Cr) > nickel (Ni) > manganese (Mn) > Sr based on the I-geo and Cd > Zn > Pb > Co > Cr > Cu > Sr > Ni > Mn according to the EF values. The estimated percentage loss in volumetric capacity of the reservoir due to sedimentation was 1.55% per year, indicating that the sediment currently occupied 18.63% of the original reservoir storage capacity. The maximum life span of reservoir is about 64.46 years.