Browsing by Author "Alho, Petteri"

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  • Blueprint conceptualization for a river basin's digital twin
    (2025-03) Pal, Debasish; Marttila, Hannu; Ala-Aho, Pertti; Lotsari, Eliisa; Ronkanen, Anna-Kaisa; Gonzales-Inca, Carlos; Croghan, Danny; Korppoo, Marie; Kamari, Maria; van Rooijen, Erik; Blafield, Linnea; Silander, Jari; Baubekova, Aziza; Bhattacharjee, Joy; Haghighi, Ali Torabi; Uvo, Cintia Bertacchi; Kaartinen, Harri; Rasti, Mehdi; Klove, Bjorn; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    To achieve a good ecological status of water resources, we are exploring new frontiers by envisioning river basin planning through the newly promoted digital twin perspective. In river basin management, a digital twin is an innovative virtual paradigm – a holistic living replica of the river basin achieved by seamless integration of real-time monitoring, historical observations, data analytics, predictive modeling, and high-performance computing within a framework of interoperable software and scalable hardware – leveraging nuanced understanding of complex environmental, social, and economic interactions, discerning uncertainties, and bridging critical knowledge gaps for progressive improvement in system understanding, optimization of operational efficiency, and continuous advancements in decision-making. This perspective paper lays the groundwork in transforming the futuristic vision of a river basin's digital twin into reality. The proposed blueprint outlines the processes for integrating digital twin components, creating dynamic replicas of river basin systems, and conducting virtual what-if analyses. Aligning with digital transformation, this work segments the river basin into distinct systems to effectively manage diverse objectives and ensure adaptability across various river basin types with spatiotemporal scalability. Supporting sustainable management, the digital twin holds immense potential to surpass existing decision-support systems through continuous bi-directional feedback loops with the river basin.
  • Data Processing and Quality Evaluation of a Boat-Based Mobile Laser Scanning System
    (2013) Vaaja, Matti; Kukko, Antero; Kaartinen, Harri; Kurkela, Matti; Kasvi, Elina; Flener, Claude; Hyyppä, Hannu; Hyyppä, Juha; Järvelä, Juha; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Mobile mapping systems (MMSs) are used for mapping topographic and urban features which are difficult and time consuming to measure with other instruments. The benefits of MMSs include efficient data collection and versatile usability. This paper investigates the data processing steps and quality of a boat-based mobile mapping system (BoMMS) data for generating terrain and vegetation points in a river environment. Our aim in data processing was to filter noise points, detect shorelines as well as points below water surface and conduct ground point classification. Previous studies of BoMMS have investigated elevation accuracies and usability in detection of fluvial erosion and deposition areas. The new findings concerning BoMMS data are that the improved data processing approach allows for identification of multipath reflections and shoreline delineation. We demonstrate the possibility to measure bathymetry data in shallow (0–1 m) and clear water. Furthermore, we evaluate for the first time the accuracy of the BoMMS ground points classification compared to manually classified data. We also demonstrate the spatial variations of the ground point density and assess elevation and vertical accuracies of the BoMMS data.
  • Empirical Modeling of Spatial 3D Flow Characteristics Using a Remote-Controlled ADCP System: Monitoring a Spring Flood
    (2015) Flener, Claude; Wang, Yunsheng; Laamanen, Leena; Kasvi, Elina; Vesakoski, Jenni-Mari; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
  • Flow patterns and morphological changes in a sandy meander bend during a flood-spatially and temporally intensive ADCP measurement approach
    (2017) Kasvi, Elina; Laamanen, Leena; Lotsari, Eliisa; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The fluvio-geomorphological processes in meander bends are spatially uneven in distribution. Typically, higher velocities and erosion take place near the outer bank beyond the bend apex, while the inner bend point bar grows laterally towards the outer bank, increasing the bend amplitude. These dynamics maintain the meander evolution. Even though this development is found in meandering rivers independent of soil or environmental characteristics, each river still seems to behave unpredictably. The special mechanisms that determine the rate and occasion of morphological changes remain unclear. The aim of this study is to offer new insights regarding flow-induced morphological changes in meander using a novel study approach. We focused on short-term and small-spatial-scale changes by conducting a spatially and temporally (daily) intensive survey during a flood (a period of nine days) with an ADCP attached to a remotely controlled mini-boat. Based on our analysis, the flood duration and the rate of discharge increase and decrease seems to play key roles in determining channel changes by controlling the flow velocities and depth and the backwater effect may have notable influence on the morphological processes. We discuss themes such as the interaction of inner and outer bend processes and the longer-term development of meander bends.
  • Fluviomorphic trajectories for dryland ephemeral stream channels following extreme flash floods
    (2024-07) Lotsari, Eliisa; House, P. Kyle; Alho, Petteri; Baker, Victor R.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Ephemeral alluvial streams pose globally significant flood hazards to human habitation in drylands, but sparse data for these regions limit understanding of the character and impacts of extreme flooding. In this study, we document decadal changes in dryland ephemeral channel patterns at two sites in the lower Colorado River Basin (southwestern United States) that were ravaged by extraordinary flash floods in the 1970s: Bronco Creek, Arizona (1971), and Eldorado Canyon, Nevada (1974). We refer to these two floods as ‘fluviomorphic erasure events’, because they produced blank slates for the channels that were gradually moulded by more frequent but much smaller flood events. We studied georectified aerial photos that span ~60 years at each site to show that both study sites recovered to their pre-flood condition after ~25 years. We employ channel network metrics: stream-link area (SLA), geometric braiding index and junction-node density. Each metric decreased during the short-duration extreme flood erasure events. Subsequently, a fluviomorphic trajectory at a decadal tempo returned the channels to pre-flood values. The SLA decreased at rates of 3.6%–4.1% per year in the decade following the floods. The extreme flood events decreased the pre-flood geometric braiding index at the two sites by 56%–68%, and it took 15–24 years for this index to recover to pre-flood values. In contrast, it took 30–35 years for the channels to recover to a uniform pre-flood channel form, as indicated by the spatial distribution of bars and junction nodes. Our results document baseline examples of ephemeral stream channel evolution trajectories, as future climatic change will likely accelerate increases in the magnitudes and frequencies of extreme floods and geomorphic erasure events.
  • The impacts of near-bed flow characteristics on river bed sediment transport under ice-covered conditions in 2016–2021
    (2022-12) Lotsari, Eliisa; Lintunen, Karoliina; Kasvi, Elina; Alho, Petteri; Blåfield, Linnea
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Global climate change has been projected to affect hydrology, the ice-covered flow period and river morphology (including changed sediment transport conditions) in northern high-latitude regions. To understand the impact of the expected shortening of the ice-covered period on bedload transport, one needs to understand the present sediment transport in these high-latitude rivers with annually occurring ice cover. Thus, the aims are (1) to define the impacts of ice cover on near-bed flow characteristics during hydrologically varying years, and (2) to analyse the impacts of these mid-winter flow characteristics on the bed sediment transport potential. The analyses are based on Acoustic Doppler Current Profiler (ADCP: 2016–21) and Acoustic Doppler Velocimeter (ADV: 2020–21) measurements performed in mid-winter ice-covered conditions of the sandy and small (circa 20 m wide) Pulmanki River in northern Finnish Lapland. Despite the ice-covered river conditions in winter, sediment transport occurs even during these harshest mid-winter conditions. The critical velocities and shear velocities of mid-winter conditions were exceeded in winters 2016–2021, and bedload transport occurred according to bedload measurements. Three different situations occurred regarding the bed sediment transport and near-bed velocity conditions: (1) high measured mid-winter discharges indicate high velocities throughout the meander bend; (2) low measured mid-winter discharges cause low near-bed velocities throughout the meander bend; (3) winters having intermediate discharges indicate near-bed velocities and sediment transport potential being higher at the upstream inlet and apex sections of the meander bend but clearly lower downstream of the apex. The confinement by the river ice cover, i.e. bottom-fast ice, explains the velocity variation. The near-bed velocities were the highest at the upstream inlet section of a symmetrical meander bend, where the measurement cross-sections were narrower and shallower. The velocities were the lowest downstream of the apex, where the channel changed from relatively narrow to wider and deeper.
  • Improving distribution models of riparian vegetation with mobile laser scanning and hydraulic modelling
    (2019-01-01) Nylén, Tua; Kasvi, Elina; Salmela, Jouni; Kaartinen, Harri; Kukko, Antero; Jaakkola, Anttoni; Hyyppä, Juha; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This study aimed at illustrating how direct measurements, mobile laser scanning and hydraulic modelling can be combined to quantify environmental drivers, improve vegetation models and increase our understanding of vegetation patterns in a sub-arctic river valley. Our results indicate that the resultant vegetation models successfully predict riparian vegetation patterns (Rho = 0.8 for total species richness, AUC = 0.97 for distribution) and highlight differences between eight functional species groups (Rho 0.46–0.84; AUC 0.79–0.93; functional group-specific effects). In our study setting, replacing the laser scanning-based and hydraulic modelling-based variables with a proxy variable elevation did not significantly weaken the models. However, using directly measured and modelled variables allows relating species patterns to e.g. stream power or the length of the flood-free period. Substituting these biologically relevant variables with proxies mask important processes and may reduce the transferability of the results into other sites. At the local scale, the amount of litter is a highly important driver of total species richness, distribution and abundance patterns (relative influences 49, 72 and 83%, respectively) and across all functional groups (13–57%; excluding lichen species richness) in the sub-arctic river valley. Moreover, soil organic matter and soil water content shape vegetation patterns (on average 16 and 7%, respectively). Fluvial disturbance is a key limiting factor only for lichen, bryophyte and dwarf shrub species in this environment (on average 37, 6 and 10%, respectively). Fluvial disturbance intensity is the most important component of disturbance for most functional groups while the length of the disturbance-free period is more relevant for lichens. We conclude that striving for as accurate quantifications of environmental drivers as possible may reveal important processes and functional group differences and help anticipate future changes in vegetation. Mobile laser scanning, high-resolution digital elevation models and hydraulic modelling offer useful methodology for improving correlative vegetation models.
  • Laserkeilausmenetelmien soveltuvuus jokiympäristöjen mallinnukseen
    (2016) Vaaja, Matti; Kurkela, Matti; Hyyppä, Hannu; Kukko, Antero; Kaartinen, Harri; Jaakkola, Anttoni; Kasvi, Elina; Lotsari, Eliisa; Virtanen, Juho-Pekka; Saarinen, Ninni; Ahlavuo, Marika; Vastaranta, Mikko; Holopainen, Markus; Jalonen, Johanna; Järvelä, Juha; Alho, Petteri; Hyyppä, Juha
     A3 Kirjan tai muun kokoomateoksen osa
    Laserkeilausaineistojen käyttö virtavesien tutkimuksessa on lisääntynyt nopeasti viime vuosina. Perinteisesti virtavesiin liittyviä prosesseja on mallinnettu maastonmuotojen poikkileikkauksien ja virtausmittausten avulla. Laserkeilausmenetelmät ovat tuoneet mahdollisuuden kerätä alueellisia aineistoja entistä suuremmalla resoluutiolla ja tehokkuudella. Laserkeilauksella tuotettuja maanpinnan korkeusmalleja, muutostulkintamalleja ja kasvillisuuden kohdemalleja käytetään muun muassa tulva-alueiden ja -riskien kartoitukseen, jokidynamiikan ja geomorfologian tutkimuksiin sekä sedimentti- ja habitaattimallinnuksiin.
  • Mapping Topography Changes and Elevation Accuracies Using a Mobile Laser Scanner
    (2011) Vaaja, Matti; Hyyppä, Juha; Kukko, Antero; Kaartinen, Harri; Hyyppä, Hannu; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Laser measurements have been used in a fluvial context since 1984, but the change detection possibilities of mobile laser scanning (MLS) for riverine topography have been lacking. This paper demonstrates the capability of MLS in erosion change mapping on a test site located in a 58 km-long tributary of the River Tenojoki (Tana) in the sub-arctic. We used point bars and river banks as example cases, which were measured with the mobile laser scanner ROAMER mounted on a boat and on a cart. Static terrestrial laser scanner data were used as reference and we exploited a difference elevation model technique for describing erosion and deposition areas. The measurements were based on data acquisitions during the late summer in 2008 and 2009. The coefficient of determination (R2) of 0.93 and a standard deviation of error 3.4 cm were obtained as metrics for change mapping based on MLS. The root mean square error (RMSE) of MLS‑based digital elevation models (DEM) for non-vegetated point bars ranged between 2.3 and 7.6 cm after correction of the systematic error. For densely vegetated bank areas, the ground point determination was more difficult resulting in an RMSE between 15.7 and 28.4 cm.
  • Morphological changes and riffle-pool dynamics related to flow in a meandering river channel based on a 5-year monitoring period using close-range remote sensing
    (2020-03-01) Salmela, Jouni; Kasvi, Elina; Vaaja, Matti Tapio; Kaartinen, Harri; Kukko, Antero; Jaakkola, Anttoni; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The maintenance of riffle-pool sequences and morphological changes in the long-term have received little attention in the literature. The aims of this study are to determine morphological changes and riffle-pool maintenance in relation to flow conditions in a meandering river channel over a 5-yr period. Change detection was focused on riffle and pool maintenance in a river reach covering three successive meander bends. Changes in a meandering river channel were studied utilizing detailed digital terrain models and flow data. The results indicated that riffle-pool sequences are maintained by high discharge events and the development of pools and riffles was linked. During high discharges, the riverbed eroded on the concave sides and the inflexion points aggraded, causing riffle–pool sequences, whereas during low discharges, concave sides aggraded and inflexion points eroded, causing pool filling and riffle erosion. While discharge increased, near-bed flow velocities increased faster on the concave sides of the bends than at the inflexion points, becoming higher at a discharge of 8 m3/s, ~20% of the bankfull discharge. Changes in the three successive meander bends were mainly similar, and the geometry of meandering rivers contributed to the locations of riffles and pools. Pools and riffles were not stable in size and shape, but their longitudinal location remained the same, instead of migrating up and down the channel. Morphological changes occurred in meander bends year-round, but they were non-linear. Annual channel change was not similar from year to year owing to different flow regimes and morphological changes during the previous year. However, seasonal detection revealed similarities between high and low discharge periods between the years. Concave sides of meander bends may act to temporarily store sediment; however, storage is preserved only under the effective hydrological discharge.
  • Nationwide Digital Terrain Models for Topographic Depression Modelling in Detection of Flood Detention Areas
    (2014) Vesakoski, Jenni-Mari; Alho, Petteri; Hyyppä, Juha; Holopainen, Markus; Flener, Claude; Hyyppä, Hannu
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Topographic depressions have an important role in hydrological processes as they affect the water balance and runoff response of a watershed. Nevertheless, research has focused in detail neither on the effects of acquisition and processing methods nor on the effects of resolution of nationwide grid digital terrain models (DTMs) on topographic depressions or the hydrological impacts of depressions. Here, we quantify the variation of hydrological depression variables between DTMs with different acquisition methods, processing methods and grid sizes based on nationwide 25 m × 25 m and 10 m × 10 m DTMs and 2 m × 2 m ALS-DTM in Finland. The variables considered are the mean depth of the depression, the number of its pixels, and its area and volume. Shallow and single-pixel depressions and the effect of mean filtering on ALS-DTM were also studied. Quantitative methods and error models were employed. In our study, the depression variables were dependent on the scale, area and acquisition method. When the depths of depression pixels were compared with the most accurate DTM, the maximum errors were found to create the largest differences between DTMs and hence dominated the amount and statistical distribution of the depth error. On the whole, the ability of a DTM to accurately represent depressions varied uniquely according to each depression, although DTMs also displayed certain typical characteristics. Thus, a DTM’s higher resolution is no guarantee of a more accurate representation of topographic depressions, even though acquisition and processing methods have an important bearing on the accuracy.
  • Rapid prototyping a tool for presenting 3-dimensional digital models produced by terrestrial laser scanning
    (2014) Virtanen, Juho-Pekka; Hyyppä, Hannu; Kurkela, Matti; Vaaja, Matti; Alho, Petteri; Hyyppä, Juha
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Rapid prototyping has received considerable interest with the introduction of affordable rapid prototyping machines. These machines can be used to manufacture physical models from three-dimensional digital mesh models. In this paper, we compare the results obtained with a new, affordable, rapid prototyping machine, and a traditional professional machine. Two separate data sets are used for this, both of which were acquired using terrestrial laser scanning. Both of the machines were able to produce complex and highly detailed geometries in plastic material from models based on terrestrial laser scanning. The dimensional accuracies and detail levels of the machines were comparable, and the physical artifacts caused by the fused deposition modeling (FDM) technique used in the rapid prototyping machines could be found in both models. The accuracy of terrestrial laser scanning exceeded the requirements for manufacturing physical models of large statues and building segments at a 1:40 scale
  • Sparse Density, Leaf-Off Airborne Laser Scanning Data in Aboveground Biomass Component Prediction
    (2015) Kankare, Ville; Vauhkonen, Jari; Holopainen, Markus; Vastaranta, Mikko; Hyyppa, Juha; Hyyppa, Hannu; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
  • Topographical change caused by moderate and small floods in a gravel bed ephemeral river - A depth-averaged morphodynamic simulation approach
    (2018-03-05) Lotsari, Eliisa S.; Calle, Mikel; Benito, Gerardo; Kukko, Antero; Kaartinen, Harri; Hyyppä, Juha; Hyyppä, Hannu; Alho, Petteri
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In ephemeral rivers, channel morphology represents a snapshot at the end of a succession of geomorphic changes caused by floods. In most cases, the channel shape and bedform migration during different phases of a flood hydrograph cannot be identified from field evidence. This paper analyses the timing of riverbed erosion and deposition of a gravel bed ephemeral river channel (Rambla de la Viuda, Spain) during consecutive and moderate- (March 2013) and low-magnitude (May 2013) discharge events, by applying a morphodynamic model (Delft3D) calibrated with pre- and post-event surveys by RTK-GPS points and mobile laser scanning. The study reach is mainly depositional and all bedload sediment supplied from adjacent upstream areas is trapped in the study segment forming gravel lobes. Therefore, estimates of total bedload sediment mass balance can be obtained from pre- and post-field survey for each flood event. The spatially varying grain size data and transport equations were the most important factors for model calibration, in addition to flow discharge. The channel acted as a braided channel during the lower flows of the two discharge events, but when bars were submerged in the high discharges of May 2013, the high fluid forces followed a meandering river planform. The model results showed that erosion and deposition were in total greater during the long-lasting receding phase than during the rising phase of the flood hydrographs. In the case of the moderate-magnitude discharge event, deposition and erosion peaks were predicted to occur at the beginning of the hydrograph, whereas deposition dominated throughout the event. Conversely, the low-magnitude discharge event only experienced the peak of channel changes after the discharge peak. Thus, both type of discharge events highlight the importance of receding phase for this type of gravel bed ephemeral river channel.