Combining SfM Photogrammetry and Terrestrial Laser Scanning to Assess Event-Scale Sediment Budgets Along a Gravel-Bed Ephemeral Stream

Remote Sensing

卷:12

JoséL. Pastor¹  MiguelCano Gonzalez¹  Roberto Tomás¹  Adrián Riquelme¹  Pedro Pérez-Cutillas²  Carmelo Conesa-García²  Rafael García-Lorenzo²  Carlos Puig-Mengual³  Francisco Martínez-Capel³ 

[1] Department of Civil Engineering, University of Alicante, 03080 Alicante, Spain;

[2] Department of Physical Geography, University of Murcia, 30001 Murcia, Spain;

[3] Institut d’Investigació per a la Gestió Integrada de Zones Costaneres (IGIC), Universitat Politècnica de València (UPV), 46730 Gandia, Spain;

关键词: SfM photogrammetry;    terrestrial laser scanning;    stream power;    morphological sediment budget;    bedforms;    gravel-bed ephemeral channel;   

DOI  :  10.3390/rs12213624

来源: DOAJ

【 摘 要 】

Stream power represents the rate of energy expenditure along a stream reach and can be calculated using topographic data acquired via structure-from-motion (SfM) photogrammetry and terrestrial laser scanning (TLS). This study sought to quantitatively relate morphological adjustments in the Azohía Rambla, a gravel-bed ephemeral stream in southeastern Spain, to stream power (ω), critical power (ω_c), and energy gradients (∂ω/∂s), along different reference channel reaches of 200 to 300 m in length. High-resolution digital terrain models (HRDTMs), combined with ortophotographs and point clouds from 2018, 2019, and 2020, and ground-based surveys, were used to estimate the spatial variability of morphological sediment budgets and to assess channel bed mobility during the study period at different spatial scales: reference channel reaches (RCRs), pilot bed survey areas (PBSAs), and representative geomorphic units (RGUs). The optimized complementary role of the SfM technique and terrestrial laser scanning allowed the generation of accurate and reliable HRDTMs, upon which a 1-D hydrodynamic model was calibrated and sediment budgets calculated. The resulting high-resolution maps allowed a spatially explicit analysis of stream power and transport efficiency in relation to volumes of erosion and deposition in the RCR and PBSA. In addition, net incision or downcutting and vertical sedimentary accretion were monitored for each flood event in relation to bedforms and hydraulic variables. Sediment sources and sinks and bed armoring processes showed different trends according to the critical energy and stream power gradient, which were verified from field observations. During flows exceeding bankfull discharges (between 18 and 24 m³s⁻¹ according to channel reach), significant variations in ∂ω/∂s values and ω/ω_c ratios (e.g., −15< ∂ω/∂s <15 Wm⁻³; ω/ω_c >2 for a peak discharge of 31 m³s⁻¹) were associated with a large amount of bedload mobilized upstream and vertical accretion along the middle reach (average rise height of 0.20 to 0.35 m for the same event). By contrast, more moderate peak flows (≤10 m³s⁻¹) only produced minor changes resulting in surface washing, selective transport, and local bed scouring.

【 授权许可】

Unknown