Analisis Hidrolika Bangunan Krib Permeabel pada Saluran Tanah (Uji Model Laboratorium)

One of the structures to protect river bank erosion is groyne. Groyne can serve and control water flow, reducing flow velocity and scour of river bank. The purposes of this study is to analyze the changes in the river bed elevation (morphology) and the depth of scour in the upstream groyne caused by the permeable groyne installed at the river meanders. The experiment was conducted at Fluid Mechanics and Hydraulics Laboratory, Sriwijaya University. The study tested the hydraulics models, a trapezoidal channel, meanders angle of 90˚, five permeable groynes at meanders, and the water flowing in the channels was clear water. The observations were carried out with a flow rate was 63,32 Lt / min, three variations of permeable groynes angle were 45˚, 90˚ and 135˚ to the upstream within 1 hour, 2,5 hours and 4 hours for each angle variations . The results of this study showed that the flow velocity of meanders was decreasing to the end of the meanders, and the changes of channel only occurred at the riverbed. Maximum riverbed changes (Bt / Bo) for permeable groyne angle of 45˚, 90˚ and 135 ˚ were 1,376 cm, 1,346 cm dan 1,452 cm. The maximum depth of scour (ds/y) for permeable groyne angle of 45˚, 90˚ and 135˚ were 1,05 cm, 0,95 cm dan 1,17 cm. Thus, permeable groyne with angle of 90 proved to be the best with the smallest riverbed changes (Bt /Bo) was 1,346 cm and the coefficient of determination (R2) was 0,9384, and also the smallest scour depth (ds/y) was 0,95 cm and the coefficient of determination (R2) was 0,8317 compared to other groyne permeable angles

The Ectoprocta (Bryozoa) of Scammon's Lagoon, Baja California, Mexico. American Museum novitates ; no. 2199

56 p. : ill., 2 maps ; 24 cm.Includes bibliographical references (p. 50-56)."Thirty-seven species of Ectoprocta representing 17 families are reported in the present collection from Scammon's Lagoon, Baja California, the first bryozoan collection reported from this region. Seventeen of the species had not previously been recorded from the Pacific coast of Baja California. One new species, Schizoporella occidentalae, is described. One new genus is erected, Alismittina, for Smittia californiensis Robertson, 1908, which has been rediscovered on the Pacific coast after having been unreported for more than 50 years. (Smittia is preoccupied.) The generic description of Hippopodinella Barroso, 1924, is emended to include: occasional small avicularia on the frontal or around the aperture. These are present on the type species of Lepralia adpressa Busk, 1854, now Hippopodinella adpressa. Rhynchozoon tumulosum has been synonymized under Rhynchozoon rostratum, and Holoporella quadrispinosa has been placed in synonymy with Holoporella brunnea. Clarification of the status of Hippoporella gorgonensis and Aimulosia uvulifera is undertaken. The distributional pattern of the species represented in the collection indicates that 48.6 per cent are tropical in occurrence, 37.1 per cent are also found in warm temperate waters, and 14.3 per cent also occur in cool temperate waters. Since many of the species are found in more than one zone, these figures should not be interpreted as indicating species that are restricted specifically to each area. This pattern is closely comparable to that of the ectoprocts found between Cabo San Lucas and Magdalena Bay on the west coast of Baja California, rather than to the assemblages immediately adjacent to Scammon's Lagoon"--P. 50