Glaisdale Beck diversion scheme - channel change and suspended sediment response

This paper describes the implementation of a novel mitigation approach and subsequent adaptive management, designed to reduce the transfer of fine sediment in Glaisdale Beck; a small upland catchment in the UK. Hydro-meteorological and suspended sediment datasets are collected over a two year period spanning pre- and post-diversion periods in order to assess the impact of the channel reconfiguration scheme on the fluvial suspended sediment dynamics. Analysis of the river response demonstrates that the fluvial sediment system has become more restrictive with reduced fine sediment transfer. This is characterised by reductions in flow-weighted mean suspended sediment concentrations from 77.93 mg/l prior to mitigation, to 74.36 mg/l following the diversion. A Mann-Whitney U test found statistically significant differences (p < 0.001) between the pre- and post-monitoring median SSCs. Whilst application of one-way analysis of covariance (ANCOVA) on the coefficients of sediment rating curves developed before and after the diversion found statistically significant differences (p < 0.001), with both Log a and b coefficients becoming smaller following the diversion. Non-parametric analysis indicates a reduction in residuals through time (p < 0.001), with the developed LOWESS model over-predicting sediment concentrations as the channel stabilises. However, the channel is continuing to adjust to the reconfigured morphology, with evidence of a headward propagating knickpoint which has migrated 120 m at an exponentially decreasing rate over the last 7 years since diversion. The study demonstrates that channel reconfiguration can be effective in mitigating fine sediment flux in upland streams but the full value of this may take many years to achieve whilst the fluvial system, slowly readjusts.

The new DGFI-TUM realization of the ITRS: DTRF2014 (data)

The DTRF2014 is a realization of the the fundamental Earth-fixed coordinate system, the International Terrestrial Reference System (ITRS). It has been computed by the Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM). The DTRF2014 consists of station positions and velocities of 1712 globally distributed geodetic observing stations of the observation techniques VLBI, SLR, GNSS and DORIS. Additionally, for the first time, non-tidal atmospheric and hydrological loading is considered in the solution. The DTRF2014 was released in August 2016 and incorporates observation data of the four techniques up 2014. The observation data were processed and submitted by the corresponding technique services: IGS (International GNSS Service, http://igscb.jpl.nasa.gov) IVS (International VLBI Service, http://ivscc.gsfc.nasa.gov) ILRS (International Laser Ranging Service, http://ilrs.gsfc.nasa.gov) IDS (International DORIS Service, http://ids-doris.org). The DTRF2014 is an independent ITRS realization. It is computed on the basis of the same input data as the realizations JTRF2014 (JPL, Pasadena) and ITRF2014 (IGN, Paris). The three realizations of the ITRS differ conceptually. While DTRF2014 and ITRF2014 are based on station positions at a reference epoch and velocities, the JTRF2014 is based on time series of station positions. DTRF2014 and ITRF2014 result from different combination strategies: The ITRF2014 is based on the combination of solutions, the DTRF2014 is computed by the combination of normal equations. The DTRF2014 comprises 3D coordinates and coordinate changes of 1347 GNSS-, 113 VLBI-, 99 SLR- and 153 DORIS-stations. The reference epoch is 1.1.2005, 0h UTC. The Earth Orientation Parameters (EOP) - that means the coordinates of the terrestrial and the celestial pole, UT1-UTC and the Length of Day (LOD) - were simultaneously estimated with the station coordinates. The EOP time series cover the period from 1979.7 to 2015.0. The station names are the official IERS identifiers: CDP numbers or 4-character IDs and DOMES numbers (http://itrf.ensg.ign.fr/doc_ITRF/iers_sta_list.txt). The DTRF2014 solution is available in one comprehensive SINEX file and four technique-specific SINEX files, see below. A detailed description of the solution is given on the website of DGFI-TUM (http://www.dgfi.tum.de/en/science-data-products/dtrf2014/). More information can be made available by request.

Tsunami simulation and detection using global navigation satellite system reflectometry

In this thesis, research for tsunami remote sensing using the Global Navigation Satellite System-Reflectometry (GNSS-R) delay-Doppler maps (DDMs) is presented. Firstly, a process for simulating GNSS-R DDMs of a tsunami-dominated sea sur- face is described. In this method, the bistatic scattering Zavorotny-Voronovich (Z-V) model, the sea surface mean square slope model of Cox and Munk, and the tsunami- induced wind perturbation model are employed. The feasibility of the Cox and Munk model under a tsunami scenario is examined by comparing the Cox and Munk model- based scattering coefficient with the Jason-1 measurement. A good consistency be- tween these two results is obtained with a correlation coefficient of 0.93. After con- firming the applicability of the Cox and Munk model for a tsunami-dominated sea, this work provides the simulations of the scattering coefficient distribution and the corresponding DDMs of a fixed region of interest before and during the tsunami. Fur- thermore, by subtracting the simulation results that are free of tsunami from those with presence of tsunami, the tsunami-induced variations in scattering coefficients and DDMs can be clearly observed. Secondly, a scheme to detect tsunamis and estimate tsunami parameters from such tsunami-dominant sea surface DDMs is developed. As a first step, a procedure to de- termine tsunami-induced sea surface height anomalies (SSHAs) from DDMs is demon- strated and a tsunami detection precept is proposed. Subsequently, the tsunami parameters (wave amplitude, direction and speed of propagation, wavelength, and the tsunami source location) are estimated based upon the detected tsunami-induced SSHAs. In application, the sea surface scattering coefficients are unambiguously re- trieved by employing the spatial integration approach (SIA) and the dual-antenna technique. Next, the effective wind speed distribution can be restored from the scat- tering coefficients. Assuming all DDMs are of a tsunami-dominated sea surface, the tsunami-induced SSHAs can be derived with the knowledge of background wind speed distribution. In addition, the SSHA distribution resulting from the tsunami-free DDM (which is supposed to be zero) is considered as an error map introduced during the overall retrieving stage and is utilized to mitigate such errors from influencing sub- sequent SSHA results. In particular, a tsunami detection procedure is conducted to judge the SSHAs to be truly tsunami-induced or not through a fitting process, which makes it possible to decrease the false alarm. After this step, tsunami parameter estimation is proceeded based upon the fitted results in the former tsunami detec- tion procedure. Moreover, an additional method is proposed for estimating tsunami propagation velocity and is believed to be more desirable in real-world scenarios. The above-mentioned tsunami-dominated sea surface DDM simulation, tsunami detection precept and parameter estimation have been tested with simulated data based on the 2004 Sumatra-Andaman tsunami event.

Rilevamento satellitare di cicli in percorsi urbani

Lo scopo di questo lavoro è sperimentare l’impiego di ricevitori a basso costo per il posizionamento di cicli in ambito urbano. Questo tipo di rilievo trova ampio impiego nello studio e verifica delle funzionalità del reticolo delle piste ciclabili. Il rilievo effettuato in condizioni di scarsa visibilità verso la costellazione satellitare e in presenza di riflessioni multiple indotte da superfici verticali, quali quelle degli edifici in ambito urbano, risulta affetto da specifiche problematiche che si è cercato di affrontare nella presente tesi. In particolare si è analizzato l’effetto del “multipath”, nel posizionamento GPS, di un ciclista in movimento su percorsi caratterizzati da “canyon urbano”, nel centrostorico di Bologna. La strumentazione sperimentata è consistita da un tablet Smasung Note 10.1, uno smartphone Samsung S4 e un ricevitore GNSS (U-blox Neo-7P) collegato ad una Raspberry Pi 2. Anche a livello software è stato sperimentato per le unità Samsung sia il software Strava, che il Blackcountry Navigator. Mentre l’acquisizione del sensore U-blox è avvenuta direttamente tramite connessione seriale in un file di testo. Nel primo capitolo verrà presentato il sistema GPS nella sua generalità. Nel secondo, invece, verrà descritta la parte del sistema GPS, che si è utilizzato per questo lavoro. Nel terzo si mostreranno gli strumenti e le apparecchiature utilizzate durante il lavoro. Nel quarto si procederà alla presentazione del caso di studio. Nell’ultimo capitolo verranno riportate le conclusioni di tutto il lavoro svolto.

Monitoreo de movimientos de terreno en el sector del cerro Tamuga del cantón Paute mediante técnicas DGPS

vulnerabilidad a deslizamientos ubicado en el Cerro Tamuga del cantón Paute, provincia del Azuay, la metodología empleada consiste en utilizar la técnica DGPS (Differential Global Positioning System), la misma que incluye el uso simultaneo de dos o más receptores, el método de medida empleado para las observaciones DGPS es el estático rápido con un tiempo de medida de diez minutos para cada hito, los resultados fueron comparados con mediciones realizadas con estación total, para lo que se aplicó el método de medida y cálculo de triangulación; que consiste en observar desde dos bases diferentes al mismo hito para realizar la triangulación y procesamiento de los datos. Durante la etapa de muestreo se realizó 20 campañas de medición con técnicas DGPS, monitoreando un total de 14 hitos, con técnicas convencionales (Topográficas) se realizó 7 campañas y se monitoreó 14 hitos. De estos datos se obtiene la diferencia entre la última y la primera medición tanto para valores de X, Y y Z, y por tanto se obtiene la variación de precisión para los dos métodos de medición (DGPS y Estación Total). Con los resultados (∆X, ∆Y, ∆Z) se realiza el análisis de la direccionalidad de los vectores de desplazamiento mediante la diferencia entre el promedio de todas las mediciones con el primer punto medido. Los resultados DGPS presentan menor variabilidad de los datos, por lo que se sugiere emplear esta técnica en la medición de desplazamiento en extensiones grandes. Con relación al caso de estudio del Cerro Tamuga, se determinó que mediante las mediciones con DGPS, éste no presenta movimientos, pero se deben continuar las campañas de monitoreo para analizar la situación a largo plazo.