Amazonian tropical forests account for 20-50% of global primary productivity and up to 40% of carbon stored in terrestrial biomass (Phillips et al., 1998). The Amazon is also home to the Earth’s largest river system, accounting for approximately 20% of the world’s total river discharge (Richey et al., 1989). Despite the clear global significance of the Amazon basin, substantial uncertainties remain in terms of both aboveground wood biomass and carbon storage within its extensive forests (Houghton et al., 2001), and the functioning of its river systems, particularly in terms of floodplain inundation (Wilson et al., 2007). This thesis addresses the aforementioned uncertainties through providing new insight into the interaction between fluvial processes and Amazonian floodplain varzea forests, for the Beni floodplain in north east Bolivia. Flood inundation dynamics for the Beni floodplain are quantified through application of a 1D-2D hydraulic model code, with topographical forcing provided through bare earth DEMs derived from the SRTM global elevation dataset (Farr and Kobrick, 2000). Subsequently, in the final part of the thesis, aboveground wood biomass estimates are generated for the Beni floodplain, through extrapolation of plot scale inventory measurements with respect to spatially distributed remote sensing datasets. These estimates are subsequently integrated with modelled flood inundation and maps depicting Beni river channel migration, in order to explore the influence which fluvial processes exert upon aboveground wood biomass storage in varzea forest stands. Overall, results presented within this thesis quantitatively demonstrate that fluvial processes, specifically flood inundation and lateral channel migration, exert significant impacts upon aboveground biomass storage within Beni floodplain forests. Furthermore, as a result of these influences, aboveground wood biomass storage within Beni floodplain forests is substantially lower than would be expected based upon published estimates for varzea forests across the Amazon (Baker et al., 2004; Saatchi et al., 2007). This implies that systematic overestimation of aboveground wood biomass storage for Amazonian varzea forests may constitute a significant source of uncertainty in basin scale biomass estimates.

The Water Supply of Byzantine Constantinople is one of the most outstanding achievements of hydraulic engineering from the Roman world. Working entirely as a gravity-fed system, this infrastructure relied on hundreds of kilometres of masonry channels, winding along the hills of Turkish Thrace and carrying water to Constantinople across different watersheds. The Water Supply was built in two main phases: the first in the mid-fourth century, following the foundation of Constantinople in 330 AD; and the second in the early fifth century. It is not clear whether the aqueducts from these two phases worked independently or as a single system, yet the scale of this would have been colossal, reaching lengths of 450 km between the two aqueducts. However, a full and close understanding of its hydraulic design and function has until now been missing. As such, this investigation aims to: (1) establish a clear route for the aqueducts, both in terms of length and gradient (mapping); (2) determine likely volumes of water entering the system at the various intakes (hydrology); and (3) evaluate its hydraulic behaviour and flow characteristics (hydraulics). While previous work on similar Roman aqueducts yielded only estimates of maximum capacity, this work delves into the engineering of the ancient infrastructure to provide a more realistic assessment of theWater Supply discharge to the City. The physical configuration of the aqueducts is reinterpreted based on the latest archaeological records comprising Global Positioning System (GPS) measurements and field observations, and validated against modern satellite terrain data in a Geographic Information System (GIS). Refined estimates of length and gradient are proposed, along with a reassessment of all channel observations, bridges and tunnels along the system. It is found that the total length of the aqueducts would have been around 426 km if they operated as a single system, and up to 565 km if they continued in parallel all the way to Constantinople; the gradient of the system would have been well below 0.1% throughout, decreasing from upstream to downstream, with steeper slopes only at the intakes. To estimate reasoned inflow conditions for the Water Supply intakes at the time of its operation, modern spring flow records are investigated, and climatic changes from the Early Byzantine period are studied by means of Macrophysical Climate Modelling (MCM). Monthly and daily resolutions are addressed: monthly inflow data can capture the extent of the seasonal variations that may have occurred at the springs, accounting for karst hydrogeology; daily inflow data allows the study of flow attenuation in the Water Supply in the short term. Simplified models and engineering judgement are employed to recreate monthly and daily inflow series from limited modern data for karstic springs and weather stations in Thrace. The results from GIS mapping, combined with the proposed inflow scenarios, are used to develop open-channel flow modelling of the Water Supply at a global scale. Aqueduct flow is numerically simulated by means of both steady (monthly) and unsteady (daily) analysis using the river modelling software HEC-RAS. The system capacity and hydraulic performance are studied for the fourth and fifth century aqueducts operating either as parallel lines or joining into a single system. An estimation of water delivered to Constantinople is proposed for typical dry, average and wet years. Results of this work are employed in a parallel research investigation on the management and distribution of water within the ancient city.

This thesis presents a research work on the development of new methodology for near-real-time detection and localisation of pipe bursts in a Water Distribution System (WDS) at the District Meters Area (DMA) level. The methodology makes use of online hydraulic model coupled with a demand forecasting methodology and several statistical techniques to process the hydraulic meters data (i.e., flows and pressures) coming from the field at regular time intervals (i.e. every 15 minutes). Once the detection part of the methodology identifies a potential burst occurrence in a system it raises an alarm. This is followed by the application of the burst localisation methodology to approximately locate the event within the District Metered Area (DMA). The online hydraulic model is based on data assimilation methodology coupled with a short-term Water Demand Forecasting Model (WDFM) based on Multi-Linear Regression. Three data assimilation methods were tested in the thesis, namely the iterative Kalman Filter method, the Ensemble Kalman Filter method and the Particle Filter method. The iterative Kalman Filter (i-KF) method was eventually chosen for the online hydraulic model based on the best overall trade-off between water system state prediction accuracy and computational efficiency. The online hydraulic model created this way was coupled with the Statistical Process Control (SPC) technique and a newly developed burst detection metric based on the moving average residuals between the predicted and observed hydraulic states (flows/pressures). Two new SPC-based charts with associated generic set of control rules for analysing burst detection metric values over consecutive time steps were introduced to raise burst alarms in a reliable and timely fashion. The SPC rules and relevant thresholds were determined offline by performing appropriate statistical analysis of residuals. The above was followed by the development of the new methodology for online burst localisation. The methodology integrates the information on burst detection metric values obtained during the detection stage with the new sensitivity matrix developed offline and hydraulic model runs used to simulate potential bursts to identify the most likely burst location in the pipe network. A new data algorithm for estimating the ‘normal’ DMA demand and burst flow during the burst period is developed and used for localisation. A new data algorithm for statistical analysis of flow and pressure data was also developed and used to determine the approximate burst area by producing a list of top ten suspected burst location nodes. The above novel methodologies for burst detection and localisation were applied to two real-life District Metred Areas in the United Kingdom (UK) with artificially generated flow and pressure observations and assumed bursts. The results obtained this way show that the developed methodology detects pipe bursts in a reliable and timely fashion, provides good estimate of a burst flow and accurately approximately locates the burst within a DMA. In addition, the results obtained show the potential of the methodology described here for online burst detection and localisation in assisting Water Companies (WCs) to conserve water, save energy and money. It can also enhance the UK WCs’ profile customer satisfaction, improve operational efficiency and improve the OFWAT’s Service Incentive Mechanism (SIM) scores.

This master thesis gives an account for the numerous uncertainties that prevail one-dimensional hydraulic models and flood inundation maps, as well as suitable assessment methods for different types of uncertainties. A conducted uncertainty assessment on the river Voxnan in Sweden has been performed. The case study included the calibra-tion uncertainty in the spatially varying roughness coefficient and the boundary condi-tion uncertainty in the magnitude of a 100-year flood, in present and future climate conditions. By combining a scenario analysis, GLUE calibration method and Monte Carlo analysis, the included uncertainties with different natures could be assessed. Significant uncer-tainties regarding the magnitude of a 100-year flood from frequency analysis was found. The largest contribution to the overall uncertainty was given by the variance between the nine global climate models, emphasizing the importance of including projections from an ensemble of models in climate change studies. Furthermore, the study gives a methodological example on how to present uncertainty estimates visually in probabilistic flood inundation maps. The conducted method of how the climate change uncertainties, scenarios and models, were handled in frequency analysis is also suggested to be a relevant result of the study.

In hydrological and hydraulic modelling, river geometry is a crucial input data. Recent investigations have been looking at methods to improve the description of cross sections extracted by DEM derived by satellite images. SRTM derived DEM are often lacking precise information as the sensors cannot detect the submerged river parts, but, on the other hand, it is available on a global scale which makes it very attractive and useful, especially in data scarce regions. This study aims at applying the so called “slope break” method to improve river cross section geometry extracted from SRTM DEM. The report is divided into three parts: a) The making of a Matlab-code to improve cross sections geometry extracted by satellite derived DEM; b) an application of the code to real cross-sections from the river Po in Italy and c) hydraulic simulations with and without SRTM modified cross sections to test the performance of the method, in collaboration with senior colleagues. The Matlab successfully performs the slope break point and finds, when appropriate, the approximated lowest point zmin of the cross section below the water surface. The comparison of the river geometry of the modified SRTM cross sections versus LiDAR available cross sections show the good performance of the method in improving the river geometry description. This code can simplify the work and improve many SRTM river cross sections in an effective way. The hydraulic simulations performed with and without the modified cross sections show how the modified SRTM model improves when compared to LiDAR results

Satellite derived data has become an essential input in hydraulic modelling. Digital ElevationModels (DEMs) derived from different sources through remote sensing techniques have become a powerful tool for poorly gauged regions. This paper analyses the capabilities of DEMS derived from Shuttle Radar Topography Mission (SRTM) and a Light Detection and Ranging (LiDAR) and compares their accuracy against each other in a 1D hydraulic model. The study tests two different methods for inferring the river bathymetry under the water surface level for the SRTM derived DEM in order to enhance its performance, the study further analyze the reliability of remotely sensed altimetry data derived from different satellite missions (TOPEX and ENVISAT) and its suitability to complement spaceborne topographic data in hydraulic modelling.

Detta arbete utreder olika terrängunderlags påverkan på habitatanalyser genom hydraulisk modellering, med fokus på att bestämma de bäst anpassade terrängunderlagen för olika områden nedströms vattenkraftanläggningar. Studien genomför en jämförande analys av olika terrängunderlag, inklusive olika laserskannad data från Lantmäteriet samt fotogrammetrimodeller baserade på drönarbilder, för att avgöra hur dessa metoder påverkar habitatanalyser. Arbetet undersöker även hur habitatanalyser påverkas av andra osäkerheter som introduceras vid hydraulisk modellering av habitat, nämligen Mannings råhetskoefficient och de antagna preferenserna av flödesförhållanden vilka bestämmer de habitabla områdena. Studien inkluderar prognoser för habitabla områden för lax vid olika flödesförhållanden och vid tre olika vattenkraftverk med torrfåror av olika karaktär. Hydraulsik modellering är ett användbart verktyg för att få en förståelse för de ekologiska konsekvenserna av vattenkraftsanläggningar. Representativa terrängdata är avgörande eftersom de direkt påverkar beräkningarna av de hydrauliska variablerna inom modellerna, vilket i sin tur bestämmer lämpligheten av habitat. Resultaten visar på betydande variationer i omfattningen av habitabla områden beroende på vilken typ av terrängunderlag som användes, samt beroende på flödesområdets karaktär. Generellt visade de modifierade versionerna av terrängunderlagen på mer representativa resultat än de omodifierade, och modifieringar baserade på uppmätta värden är att föredra för att generera representativa modifieringar. I områden med mindre vegetation ger terrängmodeller genererade med drönarfotogrammetri de mest representativa resultaten, medan de ger osäkra resultat i områden med mer vegetation. I bevuxna områden visar istället modifierade terrängmodeller baserade på laserskannade data från Lantmäterier på mer representativa resultat. De olika typerna av laserskannade data från Lantmäteriet visar inte på någon betydande skillnad i detta syfte. Vidare genomföordes känslighetsanalyser för Mannings råhetskoefficient och laxens habitatpreferenser. Dessa analyser visade på relativt förväntade resultat, där ett ökat värde på Mannings råhetskoefficient resulterade i reducerade hastigheter och ökade djup, vilket i sin tur resulterade i större beboeliga områden vid högre flödeshastigheter. Motsatta resultat observerades för minskade värden för Mannings råhetskoefficient. Variationerna i Mannings råhetskoefficient visar inga betydande skillnader i vilket flöde som genererar ett ekologiskt maximum. De varierade habitatpreferenserna visade på större variation i optimala flöden, vilket understryker vikten av att ta fram representativa habitatpreferenser baserade på specifika ekologiska förhållanden på platsen. / Introduction This thesis investigates the influence of various terrain data on habitat analyses through hydraulic modelling, aiming to identify the most suitable terrain models for different areas downstream of hydropower plants in Sweden. The study aims to evaluate the utility of different advanced and costly measurement techniques by adressing the following research questions; How significant is the difference in estimated habitable area for salmon downstream of hydropower plants using terrain data of varying levels of detail? What causes the differences in habitable area and what characterizes the watercourses where terrain models with different levels of detail are best suited? How much do variations in Manning’s roughness coefficient and the hydraulic preferences for salmon impact the estimated habitable areas? Methodology The study conducts a comparative analysis of various terrain data, including different laser-scanned datasets from Lantm¨ateriet and photogrammetry models based on drone footage, to determine how these methods affect predictions in habitable areas in streams donstream of hydropower plants. The habitat analyses were performed using hydraulic modeling in the HEC-RAS software, analysing three different models with varying terrain data and flow rates. The simulation results were then used to estimate the extent of areas with suitable habitat based on calculated water depths and velocities. Hydraulic modelling is a useful tool for understanding the ecological impacts of hydropower installations. Accurate terrain data is crucial as they directly influence the calculation of hydraulic variables within the models, which in turn determines the predicted suitability of habitats for various aquatic species. Results and Discussion The results show significant variations in the extent of habitable areas depending on the type of terrain data used and the characteristics of the flow area. Generally, modified versions of the terrain showed more representative resultes than unmodified versions, with modigfications based on measured values being the preferable. In areas with less vegetation, terrain models generated from drone photogrammetry provided the most representative results, while these models produced uncertain results in more vegetated areas. In vegetated areas, modified terrain models based on laser-scanned data from Lantm¨ateriet showed more representative results. No significant difference was observed between different types of laser-scanned data from Lantm¨ateriet within the purpose of the study. Additionally, sensitivity analyses were conducted for Manning’s roughness coefficient and hydraulic habitat preferences for salmon. These analyses showed that increased Manning’s roughness coefficient values resulted in reduced velocities and increased depths, leading to larger habitable areas at higher flow rates. Opposite results were observed for decreased values of Manning’s roughness coefficient. Variations in Manning’s roughness coefficient showed no significant differences in the flow rates generating an ecological maximum. However, varying habitate oreferences showed greater variation in optimal flow rates, underlining the importance of deriving accurate habitate preferences based on specific ecological conditions at site. Conclusions The analysis results emphasise the importance of a thorough understanding of the mothods and tools used in habitate analyses. This involves ensuring the quality of terrain data and making precise choices of habitate preferences based on species presence. Creating accurate models is complex, and simplied models can lead to misleading results.

Växande städer leder till att naturmark omvandlas till stadsmiljöer. Det skapar mer hårdgjorda ytor och därmed ökade volymer dagvatten som behöver hanteras. Modellering av dagvattennätet används ofta för att bedöma kapaciteten och risk för översvämningar. Avrinningsområdets storlek är en avgörande parameter för att bedöma hur mycket vatten som kommer till en viss ledning. Traditionellt har automatisk bestämning av avrinningsområden gjorts enbart utifrån topografin. I områden med dagvattennät styr däremot ledningarnas sträckning i första hand hur vattnet rinner, och de följer inte nödvändigtvis terrängen. ArcHydro Tools, som är ett tilläggsprogram till ArcMap, har utvecklats för att beräkna topografiska avrinningsområden. Genom att programmera en tilläggsfunktion i Python har processen i ArcHydro Tools anpassats för att kunna ta hänsyn till dagvattennätet. Dagvattennätet approximerades som vattendrag. Tryckledningar och tunnlar tillåter inte något inflöde av vatten. Därför beskrevs dessa som ändpunkter i ledningsnätet, varifrån vattnet inte rann vidare. Funktionen som skapades i det här examensarbetet tillät att vattnet stannade i dessa punkter, till skillnad från i den ursprungliga metoden. Den utgick istället från att vattnet rann till kanten av det undersökta området, vilket i de här fallen skulle ha resulterat i felaktigt avgränsade avrinningsområden. Tilläggsfunktionen anpassades för att användas som övriga funktioner i ArcMap och testades på data över Lidingö stad. Resultatet visade att det var möjligt att utnyttja topografiskt baserade metoder för bestämning av avrinningsområden så att avgränsningen istället skedde med utgångspunkt i dagvattennätet. Det är ett steg mot att effektivisera processen för bestämning av avrinningsområden för användning vid hydrologisk modellering av dagvattennätet. Behovet av manuell bearbetning minskas. Ett försök att i ArcMap implementera en funktion för efterbehandling av avrinningsområden gjordes också. Funktionen letar upp avrinningsområden som bedöms som för små och lägger ihop dem med ett närliggande område. Avrinningsområden som beräknats med den modifierade metoden har senare använts vid modellering av dagvattennätet i Molkom, Värmland. / Growing populations result in expanding cities. An increase in the amount of impervious surfaces in the area will follow and thereby generate more storm water. The capacity of the drainage system can be evaluated using hydraulic modelling. The model highly depends on the catchment areas, which will determine the water volume each pipe section receive. Watershed delineation is usually done based on the topography. However, if a storm water drainage system is present, it may route the water in a different direction than the slope indicates. ArcHydro Tools is an extension to ArcMap and is commonly used to delineate catchment areas. The method heavily relies on topography during this process. A function has been developed during the course of this project to allow for the drainage system to be the primary source of information for watershed delineation. This function made sure that outlets in the model were to be evaluated as such, even if they happen to be located in the middle of the area of interest. The water is therefore not necessarily routed to the edge of the elevation model, but can be allowed to stay at the appropriate position. In order to do this, the drainage system was represented as a stream network. The new method was applied to test data supplied by Lidingö city, Stockholm, Sweden, and included elevation data and information about the drainage system. The result implies that it is indeed possible to use the drainage system as a base for delineation of catchment areas. A more efficient method of calculating catchment areas will reduce the required amount of manual processing, thereby saving time and resources. Another function, for finishing up the resulting catchment areas, is proposed but not fully implemented. The whole process was used to delineate catchment areas for Molkom, County of Värmland, Sweden. The resulting watersheds were later successfully used for modelling the storm water drains in the area.

Climate change results to more extreme and frequent flood events that induce extra risk to flood protection structures such as levees. Thus, estimation of the probability of levee failure is of utmost importance when it comes to structural safety and flood risk assessment. This master thesis focuses on the estimation of the probability of levee failure owing to backward erosion at the foundation of the levee. For the estimation of the probability of failure three breach models of different complexity were developed and site-specified data were used from the Paglia river area and an assessment of the results followed. Besides the breach models, a 2-D hydraulic model was also built where breach scenarios were used to assess the associated flood risk. The results showed that the complexity of the breach model plays significant role to the estimated probability of failure. The simplest model estimated the lowest probability, while the complex the highest. Consequently, the associated to the complex model flood risk was higher than the other two. / Klimatförändringarna är ett allmänt problem som bland annat resulterar i ökad risk för extrema hydrologiska händelser. Av dessa extrema händelser är översvämningar bland de mest förekommande. För att tackla problemen med översvämningsriskerna används skyddsvallar som en av de vanligaste anläggningarna bland olika översvämningsskydd. Vid ett tillräckligt högt flöde kan dock den ökade belastningen på skyddsvallen orsaka att skyddsvallen havererar. En skyddsvall kan haverera på grund av flera fysikaliska fenomen, varav de vanligaste är inre erosion, otillräcklig släntstabilitet samt överspolning. Risken för att en skyddsvall havererar, det vill säga brottrisken, kan beräknas med olika metoder. Sannolikhetsbaserade metoder har nyligen växt fram som ett allt viktigare tillvägagångssätt. Det här examensarbetet handlar om brottsannolikhetsberäkningar för skyddsvallar i syfte att kartlägga översvämningsrisker. Arbetet fokuserar på fenomenet med inre erosion i skyddsvallars grundläggning. Det praktiska exemplet i examensarbetet studerar nybyggda skyddsvallar utmed den italienska floden Paglia längs en flodsträcka om 4,5 km mellan städerna Ciconia och Orvieto Scalo i regionen Umbria i centrala Italien. Ur ett hydrogeologiskt perspektiv karaktäriseras regionen av fint jordmaterial, med inslag av slutna akviferer. Sannolikhetsberäkningar med hjälp av ramverket för Monte Carlo-analys genomfördes för tre olika modeller för att beskriva inre erosion i skyddsvallarna till följd av ett 200-årsflöde. De tre olika numeriska modellerna kännetecknades av olika grad av komplexitet. Den enklaste modellen baserades på en metod av Mazzoleni et al. (2015) och tog endast hänsyn till skyddsvallens porositet. Den mellankomplexa modellen var baserad på metoden ifrån Khilar et al. (1985). Den mest komplexa modellen var tidsberoende och baserades på metoderna från Sellmeijer et al. (2011) och Scheuermann (2005), för att ta hänsyn till de två ömsesidigt beroende fenomenen bakåterosion, så kallad ”piping” och läckage, så kallat ”seepage”, vilka tillsammans ger upphov till inre erosion. Resultaten visar att graden av komplexitet i den numeriska modellen spelar en viktig roll när det gäller brottsannolikheten för skyddsvallars grundläggning. Den enklaste modellen beräknade en lägre brottsannolikhet än de andra två modellerna, och den mest komplexa modellen beräknade högst brottsannolikhet av de tre modellerna. Vidare visar resultaten på att några parametrar har en stor inverkan på brottsannolikheten. Dessa är bland annat partikeldiametern som påverkar skjuvhållfastheten i materialet, permeabiliteten, jordlagrets tjocklek under skyddsvallen samt strömningsvaraktigheten. Parametern strömningsvaraktighet kan endast beaktas i tidsberoende modeller, vilket är en av fördelarna med den mest komplexa modellen i denna studie. Förutom de numeriska brottsannolikhetsmodellerna byggdes en tvådimensionell hydraulisk modell upp för att kartlägga de resulterande översvämningsriskerna. Tre olika haveriscenarier studerades för att representera de tre brottsannolikhetsmodellerna. Dock visade det sig att den enklaste av de tre modellerna beräknade så låg brottsannolikhet att det inte var meningsfullt att studera de resulterande översvämningsriskerna enligt den enklaste brottsannolikhetsmodellen i den hydrauliska modellen. Av de två mer komplexa brottsannolikhetsmodellerna visade det sig att den mest komplexa av de två gav mer omfattande haverier i skyddsvallarna och dessutom haverier i flera av skyddsvallarna. Vidare gav den mest komplexa modellen upphov till högst vattennivåer bakom de havererade skyddsvallarna. Slutligen kan det nämnas att staden Scalo Orvieto är utsatt för en högre översvämningsrisk än staden Ciconia enligt resultaten i denna studie.

In civil and environmental engineering numerous are the applications that require prior collection of data on the ground. When it comes to hydraulic modelling, valuable topographic and morphology features of the region are one of the most useful of them, yet often unavailable, expensive or difficult to obtain. In the last few years UAVs entered the scene of remote sensing tools used to deliver such information and their applications connected to various photo-analysis techniques have been tested in specific engineering fields, with promising results. The content of this thesis aims contribute to the growing literature on the topic, assessing the potentialities of UAV and SfM photogrammetry analysis in developing terrain elevation models to be used as input data for numerical flood modelling. This thesis covered all phases of the engineering process, from the survey to the implementation of a 1D hydraulic model based on the photogrammetry derived topography The area chosen for the study was the Limpopo river. The challenging environment of the Mozambican inland showed the great advantages of this technology, which allowed a precise and fast survey easily overcoming risks and difficulties. The test on the field was also useful to expose the current limits of the drone tool in its high susceptibility to weather conditions, wind and temperatures and the restricted battery capacity which did not allow flight longer than 20 minutes. The subsequent photogrammetry analysis showed a high degree of dependency on a number of ground control points and the need of laborious post-processing manipulations in order to obtain a reliable DEM and avoid the insurgence of dooming effects. It revealed, this way, the importance of understanding the drone and the photogrammetry software as a single instrument to deliver a quality DEM and consequently the importance of planning a survey photogrammetry-oriented by the adoption of specific precautions. Nevertheless, the DEM we produced presented a degree of spatial resolution comparable to the one high precision topography sources. Finally, considering four different topography sources (SRTM DEM 30 m, lidar DEM 1 m, drone DEM 0.6 m, total station&RTK bathymetric cross sections o.5 m) the relationship between spatial accuracy and water depth estimation was tested through 1D, steady flow models on HECRAS. The performances of each model were expressed in terms of mean absolute error (MAE) in water depth estimations of the considered model compared to the one based on the bathymetric cross-sections. The result confirmed the potentialities of the drone for hydraulic engineering applications, with MAE differences between lidar, bathymetry and drone included within 1 m. The calibration of SRTM, Lidar and Drone based models to the bathymetry one demonstrated the relationship between geometry detail and roughness of the cross-sections, with a global improvement in the MAE, but more pronounced for the coarse geometry of SRTM.