Reservoir Bottom Sediments Research Articles

Effect of impervious members and reservoir bottom sediment on dynamic response of embankment dams

In this paper, a systematic investigation into the effect of both the type of impervious members and the reservoir bottom sediment on the dynamic response of embankment dams has been carried out using the finite and infinite element coupled method. It has been demonstrated from the numerical results that: (1) the resonant frequencies of an embankment dam—foundation system with an upstream inclined concrete apron are different from those with a central clay core; (2) the type of impervious members has a significant influence on the amplification factors of the system in the low frequency range of excitation, but has little effect in the high frequency range of excitation; (3) the foundation material of an embankment dam affects the dynamic response of the dam drastically; (4) the inclusion of the reservoir bottom sediment has a considerable effect on amplification factors of embankment dams in the case of P-wave incidences, but has little influence in the case of SV-wave vertical incidences; and (5) the reservoir bottom sediment also has a profound effect on the deformed shape of the embankment dam for both P-wave and SV-wave incidences.

Simplified Earthquake Analysis of Concrete Gravity Dams

A two‐stage procedure was proposed in 1978 for the analysis phase of elastic design and safety evaluation of concrete gravity dams: (1) A simplified analysis procedure in which the response due only to the fundamental vibration mode is estimated directly from the earthquake design spectrum; and (2) a refined response history analysis procedure for finite element idealizations of the dam monolith. The former was recommended for the preliminary design and safety evaluation of dams, and the latter for accurately computing the dynamic response and checking the adequacy of the preliminary evaluation. In this paper, the simplified analysis procedure has been extended to include the effects of dam‐foundation rock interaction and of reservoir bottom sediments, in addition to the effects of dam‐water interaction and water compressibility included in the earlier procedure. Also included now in the simplified procedure is a “static correction” method to consider the response contributions of the higher vibration mod...

Mutagenicity of bottom sediment from a water reservoir

AbstractThe bottom sediment of an earthen water reservoir was found to cause elevated somatic mutation frequencies in the stamen hair system of Tradescantia and a decrease in the transient chlorophyll fluorescence yield in leaves of Tradescantia and Zea mays. The mutation frequencies varied only slightly over time, and remained elevated for 91 d of chronic treatment when compared with controls. Chemodynamic modeling indicates that chemicals, including mutagens, can be transferred effectively from reservoir bottom sediment to water.

MUTAGENICITY OF BOTTOM SEDIMENT FROM A WATER RESERVOIR

The bottom sediment of an earthen water reservoir was found to cause elevated somatic mutation frequencies in the stamen hair system of Tradescantia and a decrease in the transient chlorophyll fluorescence yield in leaves of Tradescantia and Zea mays. The mutation frequencies varied only slightly over time, and remained elevated for 91 d of chronic treatment when compared with controls. Chemodynamic modeling indicates that chemicals, including mutagens, can be transferred effectively from reservoir bottom sediment to water.

The depositional environment of zinc, lead and cadmium in reservoir sediments

Despite low water retention dams and intervening reservoirs, reservoirs located downstream from a lead-zinc mining and milling area contain relatively higher concentrations of zinc, lead and cadmium than reservoirs in other areas. These metals are also concentrated in reservoir bottom sediments relative to surrounding soils. The zinc and lead content closely correlates to depth of water, organic content and percentage of clay-sized sediments. Zinc is preferentially weathered and transported from its source relative to lead. A model is developed in which the zinc and lead are transported by ionic and/or organo-metallic solution into reservoirs. Because of the relatively long residency time of water in reservoirs, the zinc and lead in the water is removed by clay minerals. Most of the zinc and lead content of the sediments is shown to be associated with sediments of specific gravity between 2·0 and 2·9. The efficiency of these reservoirs as a sink for zinc and lead results in the removal of an average 0·3 ppm zinc and 0·04 ppm lead from waters passing through Fort Gibson Reservoir.