Siting, disassaying and exfilling of the Mamão Dam in Ecuador/RN

Over four decades, there has been silting process of the riverbed that flows into the Mamão Dam, which supplies the water needs of the city of Ecuador-RN. This process has been taking place, caused largely by the receipt of mining tailings upstream of the reservoir. Thus, it became necessary the dredging consisting of removing the debris build-up and the bed debris and the riverbanks, offering a free flow to the waters that are intended for, and the excavation of the waste particles and accumulated sediment in the bed reservoir. For this, it was necessary; there were the necessary techniques for the conservation and proper maintenance so that did not occur obstruction of alluvial channel this spring. The work consisted of advice to the Municipality of the City of Ecuador, state of Rio Grande do Norte, where it made a technical feasibility study to recover the amount of previously existing water in the weir, were recovered to meet the population's consumption demand city and county. The study was conducted in 2013 and thus met the revitalization process and also the awareness of miners and miners, as the appropriate place for deposit of tailings stemmed these activities.

Relative role of sediment entrainments on log-law parameters of longitudinal velocity distributions in mobile bed flows

In alluvial channel, the non-cohesive bed particles are frequently accelerated by the flows and there has been an inconclusive debate on the deviations of logarithmic law parameters that demonstrate the velocity distributions in flows. Present study aims to elucidate the current knowledge of overwhelming theoretical and experimental evidences in this regard within the scope of near-bed turbulent flow characteristics. The study was conducted in two folds collecting instantaneous velocity of flow over a rigid sand bed under clear water flow conditions and compared to those over mobile sand beds under equilibrium bed-load. Results corroborated additional support to confirm the upward shifting of zero-velocity level in mobile bed flows. Most importantly, the conventional value of von Kármán coefficient significantly deviates in mobile bed flows compared to those in rigid sand bed. Also, the frictional velocity obtained from the bed slope consistently differs to those obtained from the Reynolds shear stress (RSS) distributions owing to transfer of stress aliquot to the bed particles. The mechanism is well demonstrated with the energy-momentum transfer within the framework of energy budget concept which shows near-bed negative pressure energy diffusion rates with increasing turbulence production in mobile bed flows.

Application of equilibrium theory on alluvial channel-form adjustment in a large river heavily loaded with sediment

<p>Taking the width/depth ratio of an alluvial channel as an independent variable, a variational analysis of basic flow relationships shows that flow is able to achieve stationary equilibrium by adjusting channel geometry when the condition of maximum flow efficiency (MFE) is satisfied. To examine if this theory of self-adjusting channel morphodynamics can be practically applied to large river systems heavily loaded with sediment, this study examines the degree of correspondence between theoretically determined equilibrium channel geometries and actual measurements along the lower Yellow River. Using the Meyer-Peter and Müller bedload relation <span>modified</span><span> </span><span>on the basis of MFE theory and relations of flow continuity and resistance we present a detailed investigation of the potential physical causes and main factors resulting in the correspondence. </span></p>