UAV Thermal Images for Water Presence Detection in a Mediterranean Headwater Catchment

Remote Sensing, Год журнала: 2021, Номер 14(1), С. 108 - 108

Опубликована: Дек. 27, 2021

As Mediterranean streams are highly dynamic, reconstructing space–time water presence in such systems is particularly important for understanding the expansion and contraction phases of flowing network related hydro–ecological processes. Unmanned aerial vehicles (UAVs) can support monitoring when wide or inaccessible areas investigated. In this study, an innovative method detection river based on UAV thermal infrared remote sensing (TIR) images supported by RGB evaluated using data gathered a representative catchment located Southern Italy. Fourteen flights were performed at different times day three periods, namely, October 2019, February 2020, July two heights leading to ground sample distances (GSD) 2 cm 5 cm. A simple methodology that relies analysis raw without any calibration proposed. The identification signature other land surface elements targeted TIR sensor specific control matrices image. Regardless GSD, proposed allows active stream under weather conditions favor sufficient drying heating surrounding bare soil vegetation. surveys performed, ideal unambiguous found with air–water differences higher than °C accumulated reference evapotranspiration before survey time least 2.4 mm. Such not during cold season surveys, which provided many false pixel detections, even though allowing extraction useful information. results achieved led definition tailored strategies flight scheduling levels complexity, simplest them choosing early afternoon as time. Overall, proved be effective, same simplified only images, avoiding photogrammetric processes, minimizing postprocessing efforts.

Язык: Английский

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Hydrological classification of non‐perennial Mediterranean rivers and streams: A new insight for their management within the water framework directive

River Research and Applications, Год журнала: 2022, Номер 39(4), С. 675 - 691

Опубликована: Дек. 27, 2022

Abstract Classification of natural flow regimes non‐perennial rivers and streams (NPRS) is an incipient field research. NPRS represent approximately 70% the total Mediterranean are expected to increase in next decades as a result climate change. Due ecological importance need improve national assessment methods within scope Water Framework Directive (WFD), this paper aims classify hydrological regime 69 non‐regulated streams, testing several indices related magnitude, frequency, duration, timing, rate change periods cessation. Using daily records, 315 were calculated their relationships examined with Principal Component Analysis (PCA) for different thresholds used define zero‐flow condition (0, 1, 2, 5 L/s). Redundancy analysis identified five that better describe patterns variability NPRS: number days per year without flow, annual percentage months mean coefficient variation Julian date start rise rate. these indices, self‐organizing map (SOM) was trained order categorize into three groups similar features. The results study provide statistically‐based classification environments. We expect will useful insights water authorities assessments status type bodies.

Язык: Английский

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

Remote Sensing, Год журнала: 2020, Номер 12(21), С. 3624 - 3624

Опубликована: Ноя. 4, 2020

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 terrestrial laser scanning (TLS). This study sought to quantitatively relate morphological adjustments in Azohía Rambla, gravel-bed ephemeral southeastern Spain, (ω), critical (ωc), gradients (∂ω/∂s), different reference channel reaches 200 300 m length. High-resolution digital terrain models (HRDTMs), combined with ortophotographs point clouds from 2018, 2019, 2020, ground-based surveys, were used estimate spatial variability sediment budgets assess bed mobility during period at scales: (RCRs), pilot survey areas (PBSAs), representative geomorphic units (RGUs). The optimized complementary role SfM technique allowed generation accurate reliable HRDTMs, upon which 1-D hydrodynamic model was calibrated calculated. resulting high-resolution maps spatially explicit analysis transport efficiency relation volumes erosion deposition RCR PBSA. In addition, net incision or downcutting vertical sedimentary accretion monitored for each flood event bedforms hydraulic variables. Sediment sources sinks armoring processes showed trends according gradient, verified field observations. During flows exceeding bankfull discharges (between 18 24 m3 s−1 reach), significant variations ∂ω/∂s values ω/ωc ratios (e.g., −15 < 15 Wm−3; > 2 peak discharge 31 s−1) associated large amount bedload mobilized upstream middle (average rise height 0.20 0.35 same event). By contrast, more moderate (≤10 only produced minor changes surface washing, selective transport, local scouring.

Язык: Английский

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Changes in stream power and morphological adjustments at the event-scale and high spatial resolution along an ephemeral gravel-bed channel

Geomorphology, Год журнала: 2021, Номер 398, С. 108053 - 108053

Опубликована: Ноя. 26, 2021

Язык: Английский

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Dynamics of Organic Matter Transport, Storage, and Processing in a Non-perennial Mediterranean River Network

Ecosystems, Год журнала: 2024, Номер 27(5), С. 636 - 654

Опубликована: Июль 19, 2024

Язык: Английский

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