Monitoring and Evaluating the Sedimentation Process in Mosul Dam Reservoir Using Trap Efficiency Approaches

Abstract

Reservoirs are usually exposed to sediment accumulation problems that will lead to reduction in their storage capacity. This problem directly affects the performance of the dams and causes shortage of their useful life. The simplest technique to estimate sediment deposition rate is using sediment rating curve with sediment trapping efficiency (TE) of the reservoir. Many empirical and semi-empirical approaches have been suggested for to determine this term depending on the annual inflow rate, reservoir characteristics and features of the catchments area. In this study six different empirical methods depending on the residence time principle (water retention time) were used. These approaches were reviewed and applied to determine TE of Mosul dam reservoir (MDR) for period 1986 to 2011. The monthly operating data for inflow, outflow and water elevations for MDR were used to determine monthly TE and long-term TE for whole period of MDR using the mentioned methods. Furthermore, the monthly inflow rate for River Tigris upstream MDR, its sediment rating curve and sediment feeding from valleys around MDR were used to estimate the amount sediment coming to the reservoir. The results provided by these methods for TE with sediment coming to MDR were used to compute the amount of sediment deposited in MDR on monthly bases during this period. The results obtained were evaluated using observed bathymetric survey data that had been collected in 2011 after 25 years of the operation of the dam. The results showed all the mentioned methods gave convergent results and they were very close to bathymetric survey results for estimating the volume of sediment deposited especially that proposed by Ward which gave 0.368% percentage error. Furthermore, the result computed using monthly TE gave good agreement if compared with that long-term TE where the percentage error was ranging between −3.229% to 1.674% for monthly adopted data and −4.862% to −2.477% for I. E. Issa et al. 191 whole period data. It is believed that this work will help others to use this procedure on other reservoirs.

Sediment and nutrient budgets are inherently dynamic: evidence from a long-term study of two subtropical reservoirs

“…8), similar to the findings of a long-term study of an arid lake system in Australia (Cook et al, 2010). P retention has been demonstrated in reservoirs throughout the world (Josette et al, 1999;Bosch and Allan, 2008). However TP retention was more variable than TSS retention because P can be transformed via chemical and biological processes into a range of organic and inorganic forms.…”

Siltation and Desilting Practices in A Runoff Reservoir on Heavy Sediment-Laden River

“…For these power plant reservoirs, silt and sediment can be easily deposited, which have negative effects on the normal operations of the power stations. The existing research findings have mainly focused on the siltation processes and treatment measures of large reservoirs [5][6][7][8][9][10] . At the current time, studies regarding the siltation processes and causes of silt accumulations in the runoff power station reservoirs are lacking.…”

Estimating the sediment trap efficiency and lifespan of cascaded reservoirs in the Upper Yangtze River Basin, China

“…Thus, research regarding the sediment trap problem should consider different spatial and temporal scales of the catchments and reservoirs to cover the detailed local characteristics (Xiong, Xu, & Yuan, ). Additionally, sediment trap calculation based on dynamic modelling (Hu, Wu, & Chen, ; Huang et al., ; Tong & Zhou, ), distributed hydrological modelling (Toniolo & Schultz, ; Mueller et al, ), nonlinear prediction (Jothiprakash & Garg, ) and field data analysis (Issa, Al‐Ansari, & Knutsson, ; Jothiprakash & Garg, ) can only provide the sediment trap information for an individual objective, which underestimates the sediment trap efficiency when the accumulative effects of the cascaded reservoirs are not considered (Xu & Yan, ). Considering the complex factors affecting the sediment trap in the UYRB, the trap efficiency (TE) was believed to be the most suitable index to study the sediment trap problem because it can reflect the most informative attributes of the catchment and the reservoir (Gert & Jean, ).…”

“…Issa et al. () applied the time‐dependent change of the TE for a reservoir in Iran, calculated from field data, to study the deposition process. Most of the TE, however, was calculated on the basis of data from individual reservoirs, with the systematic effects of the cascaded reservoirs in the UYRB seldom being considered (Huang et al., ).…”