Study On Adjustment Of Sediment And Water Of Fenjiashan Reversior

In the dried and semi-dried northwest region of China, water that restored in reservoir isthe most important method of water resource utilization. The most important measure to keepthe storage of reservoirs is adjusting water and sediments in the reservoir that located on theYellow River. Fengjiashan Reservoir is a large hydraulic engineering that have 389 million m3total reservoir capacity and irrigates 90.7 thousands hm2, it's tasks are: irrigating agriculturalfields, generating electricity, raising fishes, supplying water to Baoji City for life utilizationand Baoji Second generating electricity plant for industry production utilization. With the measurements and model tests for many years of Fengjaishan Reservoir, thesediment management models have been worked out: The discharging sediment with densitycurrent is an important mode to discharge sediment for deposition reduction as well. Thedeposition of reservoir can be reduced by means of density current to sluice sediment andsave water, it could increase the efficiency of sluicing sediment and prolong the life of thereservoir. This paper utilizes water and sediment data which collected from Qianyang hydrologicstation from 1957~1993 and the administrated model of Fengjaishan Reservoir, the authorconstruct a mathematic model of reservoir deposition. Based on the check of the model, theauthor research on the process, quantities, and distribution of the deposition in 2043 in thefuture. Total deposition in the reservoir is 171 millions m3, bed material is 25.85 millions m3,suspending sediment is 145 millions m3, Effective storage will decrease from 286 millions m3to 143 millions m3, died storage will decrease from 91 millions m3 to 33 millions m3. It willlead to the decrease of coefficient of the reservoir and reduce the capability of adjustmentgreatly. Meanwhile the author built a partial reservoir model to study the sediment deposition ofthe reservoir and sediment flushing with density current .The blending process of the densityof current and the forming process of the turbid water reservoir are observed through buildingthe reservoir before dam, the vertical distribution of sediment before the dam and themaximum suspending are obtained in the experiment. Based on the relation between level and capacity that obtained from mathematiccalculation model, calculated routing of flood between different frequency and differentcapacity. The concrete results what obtained form calculation and experiment are: watersupply of Fengjisshan Reservoir in 2043 year is clean under the condition of the dischargebelow reservoir inflow 560m3/s, quality of water supply is satisfied by Baoji City for lifeutilization and Baoji Second generating electricity plant for industry production utilization;water supply of Fengjisshan Reservoir in 2023 year is useful because sediment content islower than 5kg/m3 under the condition of the discharge below reservoir inflow 1040 m3/s,quality of water supply is satisfied by Baoji City for life utilization and Baoji Secondgenerating electricity plant for industry production utilization; water supply of FengjisshanReservoir in 1993 is useless completely because sediment content is bigger than 5kg/m3 underthe condition of the discharge surpasses reservoir inflow 1650 m3/s, quality of water supply isnot satisfied by Baoji City for life utilization and Baoji Second generating electricity plant forindustry production utilization. Allocation of supply water in 2030 year for different units was obtained to satisfy bywater supply quality that is lower than 5kg/m3. The concrete results are: the quantity of watersupply to Baoji City is 60 millions m3; the quantity of water supply to electric plant is 40millions m3, the percentage of water supply is 97.3%, satisfied the demand of the designedstandard-- 97%; average agriculture irrigation is 149.1 millions m3, percentage of watersupply is 59.5%, surpassing designed standard--50%, water supply to Yangmao...