Fulton), [email protected] (J. Ostrowski)

Summary Forecasting streamflow during extreme hydrologic events such as floods can be problematic. This is particularly true when flow is unsteady, and river forecasts rely on models that require uniform-flow rating curves to route water from one forecast point to another. As a result, alternative methods for measuring streamflow are needed to properly route flood waves and account for inertial and pressure forces in natural channels dominated by nonuniform-flow conditions such as mild water surface slopes, backwater, tributary inflows, and reservoir operations. The objective of the demonstration was to use emerging technologies to measure instantaneous streamflow in open channels at two existing US Geological Survey streamflow-gaging stations in Pennsylvania. Surface-water and instream-point velocities were measured using hand-held radar and hydroacoustics. Streamflow was computed using the probability concept, which requires velocity data from a single vertical containing the maximum instream velocity. The percent difference in streamflow at the Susquehanna River at Bloomsburg, PA ranged from 0% to 8% with an average difference of 4% and standard deviation of 8.81 m 3 /s. The percent difference in streamflow at Chartiers Creek at Carnegie, PA ranged from 0% to 11% with an average difference of 5% and standard deviation of 0.28 m 3 /s. New generation equipment is being tested and developed to advance the use of radar-derived surface-water velocity and instantaneous streamflow to facilitate the collection and transmission of real-time streamflow that can be used to parameterize hydraulic routing models. Published by Elsevier B.V

Estimating continental river basin discharges using multiple remote sensing data sets

AbstractRivers act as a source of fresh water for terrestrial life, yet the discharges are poorly documented since the existing direct observations are inadequate and some observation stations have been interrupted or discontinued. Discharge estimates using remote sensing thus have a great potential to supplement ground observations. There are remote sensing methods established to estimate discharge based on single parameter derived relationships; however, they are limited to specific sections due to their empirical nature. In this study, we propose an innovative method to estimate daily discharges for continental rivers (with river channel widths >800m (Birkett and Beckley, 2010)) using two satellite derived parameters. Multiple satellite altimetry data and Moderate Resolution Imaging Spectroradiometer (MODIS) data are used to provide a time series of river stages and effective river width. The derived MODIS and altimetry data are then used to optimize unknown parameters in a modified Manning's equation. In situ measurements are used to derive rating curves and to provide assessments of the estimated results. The Nash–Sutcliffe efficiency values for the estimates are between 0.60 and 0.97, indicating the power of the method and accuracy of the estimations. A comparison with a previously developed empirical multivariate equation for estimating river discharge shows that our method produces superior results, especially for large rivers. Furthermore, we found that discharge estimates using both effective river width and stage information consistently outperform those that only use stage data

Microwave backscattering from surf zone waves

The microwave backscatter properties of surf zone waves are analyzed using field observations. By utilizing a preexisting, independent, water surface discrimination technique, the microwave returns were extracted along individual waveforms and the data from shoaling (steepening) waves, surf zone breaking waves, and remnant foam were separated and quantified. In addition, a wave tracking analysis technique allows the returns to be examined on a wave-by-wave basis as individual waves progress through the shoaling zone and break on a nearshore sand bar. Normalized radar cross sections (NRCS), polarization ratios, Doppler spectra, and scatterer velocities were collected using a dual-polarized, X-band radar operating at lower grazing angles than previously reported (1°–3.5°). The results indicate that the maximum NRCS levels are from the active breaking portions of the wave and were consistently about -20 dB, regardless of radar polarization, azimuth angle, wave height, or wind speed. In addition, breaking waves induce broadening of the Doppler spectra and mean scatterer velocities that correlate well with the carrier wave celerity. Analysis of the polarization ratios suggest that the active breaking portions of the wave are depolarized but that higher polarization ratios (>0 dB) are found on the leading edges shoreward of the active breaking portions of the waves, which indicates a clear distinction between two scattering regimes. These results are consistent with scattering from a very rough surface that is being mechanically generated by the breaking process, showing a good agreement with the expected grazing angle dependency of a Lambertian scatterer.Keywords: microwave backscattering, wave breaking, nearshore, remote sensin

Using noncontact measurement of water surface dynamics to estimate river discharge

Estimating river discharge requires simultaneous measurement of velocity and flow depth. While surface velocities are relatively easy to measure using noncontact techniques, depth measurement usually requires physically intrusive instrumentation. This limits our capability to remotely monitor discharge in natural rivers subject to bed level variations. This work tests the potential to estimate the surface velocity, the water depth, the depth average velocity, and then discharge of a river using only a sequence of images of the dynamic water surface. The method is based on a comparison between the spatiotemporal Fourier spectra of the pixel intensities of these images and the theoretical dispersion relations of turbulence-generated surface fluctuations and gravity-capillary waves. The method is validated through the analysis of water surface videos obtained with fixed cameras from two river sections equipped with conventional discharge gauging. The applicability of the approach is demonstrated and the measurement uncertainties are quantified. The method is affected by two main sources of uncertainty: one derives from the estimation of the velocity index and the other from the obtainable resolution of the Fourier analysis. This resolution strongly controls the observation of depth and/or velocity variations in space and in time. The technique has advantages over current approaches: it has clear physical foundations; the equipment is low cost and is highly mobile; it does not need artificial tracers or physical equipment to measure depth; and it can directly provide estimates of the key flow parameters just from time series of images of the water surface

Sea surface wave reconstruction from marine radar images

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 103-105).The X-band marine radar is one type of remote sensing technology which is being increasingly used to measure sea surface waves nowadays. In this thesis, how to reconstruct sea surface wave elevation maps from X-band marine radar images and do wave field prediction over short term in real time are discussed. The key idea of reconstruction is using dispersion relation based on the linear wave theory to separate the wave-related signal from non-wave signal in radar images. The reconstruction process involves three-dimensional Fourier analysis and some radar imaging mechanism. In this thesis, an improved shadowing simulation model combined with wave field simulation models for the study of the correction function in the reconstruction process and an improved wave scale estimation model using non-coherent radar data are proposed, which are of great importance in the reconstruction process. A radar image calibration method based on wave field simulation is put forward in order to improve the quality of reconstructed sea surface wave. Besides, a theoretical wave scale estimation model using Doppler spectra of the coherent radar is put forward, which is proposed to be a good alternative to the current wave scale estimation model. The reconstructed sea surface wave can be used for wave field simulation in order to predict the wave field, which is not only an application of this reconstruction process, but also a parameter optimizing tool for the reconstruction process.by Yusheng Qi.S.M

Análisis y comparación de metodologías de aforo de caudal en lámina libre mediante curva de gasto y perfilador acústico Doppler. aplicación en ríos de la región de Quebec (Canadá)

[ES] La determinación del caudal en lámina libre es un ejercicio complejo, pero indispensable para la resolución de varios problemas a los que los técnicos se enfrentan a menudo, sea en el campo de los recursos hídricos o en redes de saneamiento para conocer mejor y predecir los caudales que son generalmente utilizados para fines económicos, sociales o medioambientales. Para ello, es indispensable disponer de instrumentos adecuados capaces de medir de manera precisa, detallada y con coste inferior, los distintos parámetros necesarios para los estudios a realizar. Afortunadamente, durante los últimos 20 años, la posibilidad de disponer de sistemas informáticos y electrónicos muy sofisticados a precios reducidos, ha conducido al desarrollo de instrumentos electrónicos para la medición de la velocidad, el nivel de la lámina de agua y el caudal, con mucha precisión y fiabilidad, lo que ha evolucionado la hidrometría. Hoy en día, los medidores electrónicos de velocidad que utilizan técnicas acústicas, de radar o por imagen están revolucionando la medida de caudales en los cauces. Cada vez más, estos sistemas están remplazando a los instrumentos mecánicos, convirtiéndose así en los instrumentos predilectos para medir el caudal. Estos instrumentos ofrecen unas prestaciones superiores en términos de eficacia, rendimiento y seguridad. Un enfoque relativamente reciente para el aforo de caudal en lámina libre, consiste en medir la velocidad y la profundidad del flujo mediante el perfilador acústico Doppler (Acoustic Doppler Current Profiler, ADCP) para calcular el caudal, un instrumento de medida muy preciso en condiciones ideales de utilización. Para ello, en el siguiente trabajo se analiza el funcionamiento del ADCP en diferentes contextos, comparándolo con el método clásico: la curva de gasto, que consiste en llevar una campaña de medidas puntuales, permitiendo establecer simultáneamente el caudal y la profundidad, por lo medios más precisos posible, con el fin de calibrar una relación que mediante una única medida de profundidad, permite obtener el caudal. Este enfoque clásico tiene una base teórica bastante solida y se basa sobre tecnologías probadas para medir la velocidad y la profundidad. Desgraciadamente, es difícil obtener medidas nivel-caudal en situaciones extremas, ya que generalmente no suele haber equipos de medida en terreno cuando se produce un evento extremo. Asimismo, el ADCP tiene la ventaja de proporcionar de manera segura gran cantidad de medidas que cubren toda la gama de valores necesarios para calibrar una curva de gasto, que a su vez resulta más ventajosa en el plan económico y operacional, para proporcionar medidas con menos fluctuaciones que el ADCP, por lo que claramente se puede deducir que existe una sinergia entre los dos métodos.[EN] Determination of the open channel flow is a complex exercise but it is essential in order to solve the problems that technicians often face to better understand and predict discharges which are generally used for commercial, social or environmental purposes, whether in the field of water resources or in sewerage networks. For this aim, it is essential to have adequate instruments which are able to measure accurately, detailed and with a reasonable cost, the different parameters needed for studies to be performed. Nowadays, electronic speed meters using acoustic techniques, radar or imaging are revolutionizing the flow measurement in open channels. Increasingly, these systems are replacing mechanical instruments and they are becoming reference instruments to measure flows. These instruments offer superior performance in terms of efficiency, performance and security. A relatively recent approach to obtain the open channel flow is to measure the speed and flow¿s depth using acoustic Doppler profiler (Acoustic Doppler Current Profiler, ADCP) to calculate the discharge, a very precise measuring instrument when used in ideal conditions. In this way, the following paper analyzes the performance of the ADCP in different contexts, comparing it with the classical method: the stage-discharge curves. This classical method consists in doing a campaign of one-off measures, allowing the determination of flow and depth simultaneously as precise as possible, in order to calibrate a relationship that, using a single measure of depth, enables to calculate the corresponding flow. Furthermore, firstly a pilot phase is developed in order to learn and use properly the new technologies and associated instrumentation to measure the instantaneous velocities in open channel flow: the ADCP. Its configuration, commissioning and procurement data will be done. Then their operation will be validated, first by comparing the flow channel obtained in a laboratory with those obtained using a calibrated electromagnetic flow meter and a gage, and secondly performing an experimental theoretical contrast between the ADCP and the stage-discharge curve obtained in the classical formulas of hydraulics. Secondly, we analyze data from three rivers in the region of Quebec (Canada), assess the discrepancies between the estimated flow rating curve and flow measured by ADCP and finally, determine whether the stage-discharge curve is able to reproduce the measurements obtained by the ADCP.Lahkim Jelloul, A. (2012). Análisis y comparación de metodologías de aforo de caudal en lámina libre mediante curva de gasto y perfilador acústico Doppler. aplicación en ríos de la región de Quebec (Canadá). http://hdl.handle.net/10251/27536Archivo delegad

Application of Techologies Based on Hydroacoustics, Radar and Pressure Sensors in Monitoring and Analysis of Water Movement in Karst : Doctoral Thesis

Zbog svoje iznimne ranjivosti, krški vodonosnik predstavlja izazov u pogledu zaštite, praćenja, održavanja kvalitete vode i eksploatacije. Hidrološki i hidrogeološki procesi kod krša su ekstremno nepredvidivi zbog anizotropnosti i heterogenosti samog vodonosnika. Procjena regionalne hidrodinamike podzemlja krških terena je često iznimno teška zadaća. Svaki krški vodonosnik ima specifična hidrogeološkai hidrološka svojstva što u konačnici zahtjeva regionalna mjerenja i inkorporaciju prikupljenih saznanja u daljnje modeliranje i upravljanje istim. Razvoj novih tehnologija mjerenja i praćenja vodonosnika u poljima hidroakustike, radara, mjernih senzora i računalne tehnologije, nastaje potreba za implementacijom iste i generiranja novih protokola i metoda mjerenja. Nadalje, nova tehnologija pruža daleko veće mogućnosti te samim time otvara prostor za nove spoznaje vezane za krški vodonosnik te preispituje stare. Vremenska i prostorna rezolucija mjerenja se povećavaju, a računalna tehnologija nudi izvrstan alat za analizu i uspostavljanje modela procesa u prirodi koji vode do boljeg razumijevanja. Glavni pokretač pri izradi ovog rada je stjecanje novih i poboljšavanje starih saznanja o dinamici vode unutar krškog vodonosnika i na površini proučavajući podzemnu dinamiku vode u špiljama i jamama kao i površinsku na primjeru krških jezera i otvorenih vodotoka. Nove spoznaje vezane za prirodu kretanja vode u krškom terenu rezultiraju upravo eksperimentalnim pristupom i mjerenju različitih hidroloških epizoda unutar izrazito heterogenog sustava. U ovom radu se prikazuju kontinuirana hidrološka mjerenja izvedena u dubokoj krškoj jami te se uspostavljaju modeli mjerenih parametara. Nadalje, primjenjuje se probabilistički koncept mjerenja protoka na otvorenom vodotoku kod nepravilnih profila te se pritom uvode novi protokoli mjerenja. Po prvi puta detaljno su snimljena morfometrijska mjerenja Crvenog i Modrog jezera kod Imotskog s najnovijim dostupnim tehnologijama te kontinuirana hidrološka mjerenja Modrog jezera. Prezentiran je također i uspostavljeni hidrološki model za Modro jezero.Because of its extreme vulnerability karst aquifer is a challenge in terms of protection, monitoring, maintenance of water quality and exploitation. Hydrologic and hydrogeological processes in karst are extremely unpredictable because of anisotropy and heterogeneity of the aquifer. Assessment of regional hydrodynamics of underground karst terrain is often extremely difficult task. Each karst aquifer has specific hydrogeological and hydrologic properties, which ultimately require a regional measurement and incorporation of gathered data in further modelling and management. The development of new technology based measurement and monitoring of aquifers in the fields of hydro acoustics, radar measurement, sensors and computer technology creates a need to implement theexisting and generate the new protocols and methods of measurement. Furthermore, the new technology provides far greater opportunities and thus they open up new insights related to karst aquifer and revise the old ones. Temporal and spatial resolution of measurements increase whereas computer technology offers an excellent tool for analyzing and establishing a models of processes in nature that lead to a better understanding. The main motivation for this dissertation is the gaining of new knowledge in the dynamics of water within the karstaquifer and on the karst surface, as well as improvement and validation of old findings by studying the dynamics of underground water in the caves and in the case of surface karst lakesand open streams taking into account. Experimental approach and measurement of hydrological episodes within a highly heterogeneous system result with a new insight in the nature of water movement in the karst terrain. The continuous hydrological measurements in a deep karst cave and established models of the measured parameters are presented in this work. Furthermore, the probabilistic concept of discharge measurement in open water course with irregular profile was carried out which led to introduction of new measurement protocols. For the first time, the detailed morphometric measurements using available emerging technologies were conducted for Red Lake and Blue Lake near Imotski. Continuous hydrological measurements of Blue Lake resulted with a hydrological model which is also presented in this work