Flow information is necessary in many diverse applications including water supply management, pollution control, irrigation, flood control, energy generation, and industrial use. New technologies have been developed for the establishment of stage-discharge relationships due to concerns about costs, accuracy, and safety of traditional discharge estimation methods. One emerging technology for measuring open-channel flow is Large-Scale Particle Image Velocimetry (LSPIV). LSPIV is a system capable of measuring surface velocity by collecting and analyzing recorded images of the stream surface. LSPIV has several advantages over conventional discharge measurement techniques: LSPIV is safer, could be automated to reduce labor, and could produce "real-time" discharge measurements. Therefore, the overall goal of this study was to evaluate the accuracy and feasibility of using LSPIV to measure discharge in low-order streams. The specific goals were to develop and test a prototype under varying conditions in a laboratory flume, adapt the prototype for field conditions, test the accuracy of the prototype in the field, and assess and recommend improvements for LSPIV operation as a stream discharge measuring device. The laboratory experiments results indicated that LSPIV accuracy was influenced by camera angle, surface disturbances and flow regime (Froude number), and particle seeding density. Camera angle was optimum around 15 degrees, with larger camera angles producing more error due to image distortion. Conditions at high Froude numbers likely produced out-of-plane displacement losses due to surface disturbances. Low Froude numbers also showed under-predictions, which were likely due to agglomeration of the tracer particles at low velocities. Finally, the laboratory results demonstrated that tracer seeding density should be maximized and that densities below three particles per interrogation window should significantly reduce LSPIV accuracy. The LSPIV prototype was tested at two low-order streams after developing a field prototype and operating procedures. Under field conditions, the prototype acquired consistent images, performed the necessary image processing, and established rules for estimating input parameters. The accuracy of LSPIV was evaluated using a Flo-Mate 2000 current meter and a permanent weir. Overall, twenty discharge measurements were taken with each measuring device at Stroubles Creek and Crab Creek. The discharges measured ranged from 0.12 to 63 cfs, which corresponded to a large range of velocities, with both simple and complex flow patterns. Problems were encountered from surface glare reducing image quality at both sites. The LSPIV prototype was accurate for most measuring conditions with a mean error of -1.7%, compared to the weir measurements. The LSPIV measurements tended to under-predict discharge at high stages and had greater error at moderate flows (up to 39%) compared to the weir. However, at low flow conditions LSPIV showed improved discharge accuracy over the current meter, in comparison to the weir measurements. The LSPIV discharge measurements were not statistically different from either the current meter or weir (á = 0.05). Finally, the LSPIV discharge measurements had an uncertainty of approximately ±14% (at a 95% confidence interval). In conclusion, LSPIV accuracy can be degraded by surface disturbances, inadequate illumination, and poor seeding densities. However, LSPIV showed adequate accuracy with the potential to become competitive with conventional discharge measurement techniques and therefore, has the potential to reduce costs and increase the geographic extent of surface water monitoring networks. / Master of Science

The objective of this study is to compare Large-Scale Particle Image Velocimetry (LSPIV) to conventional methods for measuring discharge. Furthermore, to use the discharge data to create a rating curve at Islandsfallet in Uppsala. To measure discharge, on-site measurements have conventionally been done. Particle tracking allows flow velocimetry measurements without contact with the water. LSPIV works by measuring displacement of tracers through analysing image sequences. Using the free software Fudaa-LSPIV, flow velocity was measured and referenced to ADCP. The ADCP data were additionally used to construct the rating curve allowing to predict the water level/discharge correlation. Particle tracking was found to hold great potential in the Fyris river, and the possibility for setting up LSPIV for continuous discharge measurements should be investigated going forward. Constructing the new rating curve with discharge measurements from ADCP implied the current rating curve not being sufficient by underestimating the discharge levels necessary for a raise in water level implying the need for an updated rating curve. Concluding, does the LSPIV show promising result compared to the ADCP and the rating curve points out a big discrepancy, in higher discharge, between the new and the old rating curve. The rating curve would however need discharge data points in a greater range. / Syftet med detta arbete var att jämföra partikelspårning med mer traditionella metoder för att mäta vattenflöde. Vidare, att använda data för vattenflöde till att skapa en avbördningskurva vid Islandsfallet i Uppsala. För att mäta avrinning, är fältmätningar det konventionella sättet. Partikelspårning tillåter flödesmätningar utan krav på närvarande tekniker på plats. LSPIV fungerar genom att mäta förflyttning av spårelement på ytan genom att analysera sekvenser. Genom att använda gratisprogrammet FudaaLSPIV, mättes vattenflöde och data från ADCP användes som referensdata. Data från ADCP metoden användes också för att skapa en avbördningskurva som tillåter projicering och korrelation av vattennivå samt vattenflöde. Partikelspårning visade sig ha stor potential för Fyrisån och möjligheten att använda LSPIV för kontinuerliga mätningar bör undersökas vidare. Skapandet av den nya avbördningskurvan visade att den nuvarande avbördningskurvan underskattar vattenflödet mot vattennivån och vidare mätningar är nödvändiga för att utveckla avbördningskurvan vidare. Sammanfattningsvis visar LSPIV på positiva resultat i jämförelse med ADCP och avbördningskurvan visar på en stor diskrepans, i högre flöden, mellan den nya och den gamla avbördningskurvan. Avbördningskurvan skulle behöva ett större antal datapunkter för större flödesintervall.

La crue de 1910 de la Seine a eu une incidence directe sur le fonctionnement des différents réseaux (réseau électrique, assainissement des eaux usées, transport, eau potable). Le réseau RATP a été particulièrement atteint dans son fonctionnement. Les dommages qu’une crue centennale pourrait engendrer aujourd’hui risquent d’être plus importants encore car le réseau actuel est plus vulnérable du fait des nombreux équipements électriques et informatiques qu’il comporte. La majorité des émergences (les entrées d’eau) de la RATP est située en zone inondable. Lors d’une crue majeure de la Seine, les écoulements dus aux inondations se propagent directement dans la partie souterraine et centrale du réseau (Métro et RER) par le biais de ces émergences. Cette thèse s'intéresse à la simulation hydrodynamique des écoulements dans le réseau RATP en utilisant le logiciel MIKE URBAN dédié à la modélisation des réseaux d’assainissement. Cette modélisation nécessite une bonne connaissance de l’origine des écoulements pour mieux les prendre en compte. En effet, le réseau RATP est inondé par les eaux superficielles et les eaux d’infiltration. Afin de mieux quantifier les volumes entrants dans le réseau, un modèle physique d’une bouche de métro type a été réalisé. Les résultats des essais physiques ont permis de valider un modèle numérique qui caractérise les écoulements autour d’une bouche de métro et quantifie les volumes entrants. Cela a permis également de proposer une formule théorique de débit tenant compte de la géométrie d’une bouche de métro. Les écoulements par infiltration sont quant à eux modélisés en fonction de la charge de la nappe et validés avec des mesures in situ. Ce travail de recherche a comme objectif d’améliorer et valider un modèle de simulation. Il s’agit de mettre en œuvre un outil opérationnel d’aide à la décision qui permettra à la cellule inondation de la RATP de bien comprendre le fonctionnement de son réseau afin d’améliorer son plan de protection contre le risque inondation. / The 1910 flood of the Seine had a direct impact on the functioning of the different networks (Electricity network, sewerage, transport, water distribution). The RATP network was particularly affected in its functioning. The damage that centennial flood could cause today may be even greater because the current network is more vulnerable because of the numerous electrical and computer equipment that it comprises. The majority of the emergences (The water ingress) of the RATP is located in flood areas. During a major flooding of the Seine, the flows due to the floods propagate directly into the underground and central part of the network (Metro and RER) through these emergences. This thesis is interested in a hydrodynamic simulation by MIKE URBAN, Model used to model the RATP network due to its MOUSE engine developed by DHI for the sewerage networks. This work also presents the results obtained on a physical model of a subway station. The experimental data were used to model water ingress within the RATP network from the subway station. Network protection against infiltration requires a thorough knowledge of underground flow conditions. Infiltrations through the tunnels are estimated numerically. The aim of this research is to improve and validate a simulation model. It is a question of implementing an operational decision support tool which will allow the flood cell of the RATP to understand the functioning of its network in order to improve its flood risk protection plan.