A Model Study of the Circulation in the Pearl River Estuary (PRE) and Its Adjacent Coastal Waters: 1. Simulations and Comparison with Observations

The Princeton Ocean Model is used to study the circulation features in the Pearl River Estuary and their responses to tide, river discharge, wind, and heat flux in the winter dry and summer wet seasons. The model has an orthogonal curvilinear grid in the horizontal plane with variable spacing from 0.5 km in the estuary to 1 km on the shelf and 15 sigma levels in the vertical direction. The initial conditions and the subtidal open boundary forcing are obtained from an associated larger-scale model of the northern South China Sea. Buoyancy forcing uses the climatological monthly heat fluxes and river discharges, and both the climatological monthly wind and the realistic wind are used in the sensitivity experiments. The tidal forcing is represented by sinusoidal functions with the observed amplitudes and phases. In this paper, the simulated tide is first examined. The simulated seasonal distributions of the salinity, as well as the temporal variations of the salinity and velocity over a tidal cycle are described and then compared with the in situ survey data from July 1999 and January 2000. The model successfully reproduces the main hydrodynamic processes, such as the stratification, mixing, frontal dynamics, summer upwelling, two-layer gravitational circulation, etc., and the distributions of hydrodynamic parameters in the Pearl River Estuary and coastal waters for both the winter and the summer season.

Provenance versus weathering control on the composition of tropical river mud (southern Africa)

This study presents an integrated mineralogical-geochemical data base on fine-grained sediments transported by all major rivers of southern Africa, including the Zambezi, Okavango, Limpopo, Olifants, Orange and Kunene. Clay mineralogy, bulk geochemistry, Sr and Nd isotopic signatures of river mud, considered as proxy of suspended load, are used to investigate the influence of source-rock lithology and weathering intensity on the composition of clay and silt produced in subequatorial to subtropical latitudes. Depletion in mobile alkali and alkaline-earth metals, minor in arid Namibia, is strong in the Okavango, Kwando and Upper Zambezi catchments, where recycling is also extensive. Element removal is most significant for Na, and to a lesser extent for Sr. Depletion in K, Ca and other elements, negligible in Namibia, is moderate elsewhere. The most widespread clay minerals are smectite, dominant in muds derived from Karoo or Etendeka flood basalts, or illite and chlorite, dominant in muds derived from metasedimentary rocks of the Damara Orogen or Zimbabwe Craton. Kaolinite represents 30-40% of clay minerals only in Okavango and Upper Zambezi sediments sourced in humid subequatorial Angola and Zambia. After subtracting the effects of recycling and of local accumulation of authigenic carbonates in soils, the regional distribution of clay minerals and chemical indices consistently reflect weathering intensity primarily controlled by climate. Bulk geochemistry identifies most clearly volcaniclastic sediments and mafic sources in general, but cannot discriminate the other sources of detritus in detail. Instead, Sr and Nd isotopic fingerprints are insensitive to weathering, and thus mirror faithfully the tectonic structure of the southern African continent. Isotopic tools thus represent a much firmer basis than bulk geochemistry or clay mineralogy in the provenance study of mudrocks.

Geomorphology and evolution of the late Pleistocene to Holocene fluvial system in the south-eastern Llanos de Moxos, Bolivian Amazon

In the Bolivian Amazon several paleochannel generations are preserved. Their wide spectrum of morphologies clearly provides crucial information on the type and magnitude of geomorphic and hydrological changes within the drainage network of the Andean foreland. Therefore, in this study we mapped geomorphological characteristics of paleochannels, and applied radiocarbon and optically stimulated luminescence dating. Seven paleochannel generations are identified. Significant changes in sinuosity, channel widths and river pattern are observed for the successive paleochannel generations. Our results clearly reflect at least three different geomorphic and hydrological periods in the evolution of the fluvial system since the late Pleistocene. Changes in discharge and sediment load may be controlled by combinations of two interrelated mechanisms: (i) spatial changes and re-organizations of the drainage network in the upper catchment, and/or (ii) climate changes with their associated local to catchment-scale modifications in vegetation cover, and changes in discharge, inundation frequencies and magnitudes, which have likely affected the evolution of the fluvial system in the Llanos de Moxos. In summary, our study has revealed the enormous potential which geomorphic mapping and analysis combined with luminescence based chronologies hold for the reconstruction of the late Pleistocene to recent fluvial system in a large portion of Amazonia.

Extreme River Floods in Western Switzerland and the Lake of Constance Region in the Period Prior to Instrumental Measurements

The floods that occurred on the Aare and Rhine rivers in May 2015 and the mostly successful handling of this event in terms of flood protection measures are a good reminder of how important it is to comprehend the causes and processes involved in such natural hazards. While the needed data series of gauge measurements and peak discharge calculations reach back to the 19th century, historical records dating further back in time can provide additional and useful information to help understanding extreme flood events and to evaluate prevention measures such as river dams and corrections undertaken prior to instrumental measurements. In my PhD project I will use a wide range of historical sources to assess and quantify past extreme flood events. It is part of the SNF-funded project “Reconstruction of the Genesis, Process and Impact of Major Pre-instrumental Flood Events of Major Swiss Rivers Including a Peak Discharge Quantification” and will cover the research locations Fribourg (Saane R.), Burgdorf (Emme R.), Thun, Bern (both Aare R.), and the Lake of Constance at the locations Lindau, Constance and Rorschach. My main goals are to provide a long time series of quantitative data for extreme flood events, to discuss the occurring changes in these data, and to evaluate the impact of the aforementioned human influences on the drainage system. Extracting information given in account books from the towns of Basel and Solothurn may also enable me to assess the frequency and seasonality of less severe river floods. Finally, historical information will be used for remodeling the historical hydrological regime to homogenize the historical data series to modern day conditions and thus make it comparable to the data provided by instrumental measurements. The method I will apply for processing all information provided by historical sources such as chronicles, newspapers, institutional records, as well as flood marks, paintings and archeological evidence has been developed and successfully applied to the site of Basel by Wetter et al. (2011). They have also shown that data homogenization is possible by reconstructing previous stream flow conditions using historical river profiles and by carefully observing and re-constructing human changes of the river bed and its surroundings. Taken all information into account, peak discharges for past extreme flood events will be calculated with a one-dimensional hydrological model.

Accuracy of tidal breathing measurement of FloRight compared to an ultrasonic flowmeter in infants.

INTRODUCTION Monitoring breathing pattern is especially relevant in infants with lung disease. Recently, a vest-based inductive plethysmograph system (FloRight®) has been developed for tidal breathing measurement in infants. We investigated the accuracy of tidal breathing flow volume loop (TBFVL) measurements in healthy term-born infants and infants with lung disease by the vest-based system in comparison to an ultrasonic flowmeter (USFM) with a face mask. We also investigated whether the system discriminates between healthy infants and those with lung disease. METHODS Floright® measures changes in thoracoabdominal volume during tidal breathing through magnetic field changes generated by current-carrying conductor coils in an elastic vest. Simultaneous TBFVL measurements by the vest-based system and the USFM were performed at 44 weeks corrected postmenstrual age during quiet unsedated sleep. TBFVL parameters derived by both techniques and within both groups were compared. RESULTS We included 19 healthy infants and 18 infants with lung disease. Tidal volume per body weight derived by the vest-based system was significantly lower with a mean difference (95% CI) of -1.33 ml/kg (-1.73; -0.92), P < 0.001. Respiratory rate and ratio of time to peak tidal expiratory flow over total expiratory time (tPTEF/tE) did not differ between the two techniques. Both systems were able to discriminate between healthy infants and those with lung disease using tPTEF/tE. CONCLUSION FloRight® accurately measures time indices and may discriminate between healthy infants and those with lung disease, but demonstrates differences in tidal volume measurements. It may be better suited to monitor breathing pattern than for TBFVL measurements.

Summer Abundance of Fishes in a Maine Tidal Cove with Special Reference to Temperature

The daytime abundance and localized distribution of fishes in relation to temperature were studied in a small tidal cove by beach seining on seven dates in the Back River estuary, Maine, during the summers of 1971 and 1972. Temperatures on the seven dates ranged from 15.1–26.2 C, and salinities ranged from 17.3–24.7‰. Eighteen species of fishes were captured, with mummichogs, smooth flounders, Atlantic silversides and Atlantic herring together comprising over 98% of the catch. Mummichogs and Atlantic silversides were captured primarily near the inner end of the cove, while other abundant species were caught mainly at the outer end of the cove. Several species seem well adapted to naturally warm cove temperatures. Others seem now virtually excluded because of warm temperatures. Winter flounder, Atlantic herring, and Atlantic tomcod might be excluded from the cove during daytime in summer if artificial warming of the cove were permitted.

A Jewel in Our Midst: a photo essay of the Connecticut River

Its unique tidal marshes, ecology, geology, scenic areas, and fascinating history make the Connecticut River a treasure to residents and visitors alike. It is one of the 1,713 “Wetlands of International Importance” designated throughout the world by the International Ramsar Convention. This photo essay also describes the education efforts underway by Connecticut Sea Grant and its partners to assist educators with resource materials.

Ansicht des Landungsplatzes zu Paramaribo, eines holländischen Kauffarteischiffes das Buschmann und River zugehörte, worin Frau von Panhuys gekommen war

Louise von Panhuys