Monitoring and Modeling Drainage Network Contraction and Dry Down in Mediterranean Headwater Catchments

Senatore, Alfonso; Micieli, Massimo; Liotti, Alessio; Durighetto, Nicola; Mendicino, Giuseppe; Botter, Gianluca

doi:10.1029/2020wr028741

Cited by 22 publications

(40 citation statements)

References 92 publications

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“…However, the influence of hydroclimatic drivers on the active fraction of the network is not fully understood. Notwithstanding the variability of across the study catchments (attributed to their geological diversity), our results confirm that the extent of active channel length is linked to the amount of excess precipitation in the contributing catchment, as previously proposed in the literature 12 , 31 . This suggests the emergence of distinctive ecohydrological patterns within different climatic regions of the world.…”

Section: Implications For Large-scale Studiessupporting

confidence: 90%

“…Conversely, in the wettest site (Coweeta, where P t − ET > 160mm/month), the mean network persistency approached unity and network dynamics are smoothed, with CV D → 0 . This result offers novel insight on the impact of climate on the active stream length variability 44 , and nicely complements existing modeling and empirical approaches for the characterization of the spatial patterns of flow persistency across a landscape 21,31,45 . Therefore, we believe that the proposed framework can provide useful insight into the impact of climate on the temporal changes of the active drainage density.…”

Section: Quantifying the Mean Active Drainage Density And Its Temporal Variationsmentioning

confidence: 57%

“…In perfectly hierarchical networks, the adoption of ad-hoc monitoring strategies that exploit information available from previous surveys www.nature.com/scientificreports/ can reduce the number of nodes to monitor during a long-term field campaign with at least 10 surveys by 40 to 75%, depending on the exact number of surveys and the mean network persistency (Supplementary Information). Although several initial surveys that include most of the network are needed to establish the hierarchy among the nodes, the saving in terms of number of surveys becomes particularly significant when the number of surveys exceeds 20-as typically needed to capture event-based variations of the active length, see Table 1 in 31 . This indicates that the hierarchical nature of stream dynamics could significantly facilitate the observational mapping of flowing streams in a broad range of settings, especially in large river basins.…”

Section: Hierarchical Activation Of Temporary Streamsmentioning

confidence: 99%

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Hierarchical climate-driven dynamics of the active channel length in temporary streams

Botter

Vingiani

Senatore

et al. 2021

Sci Rep

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Looking across a landscape, river networks appear deceptively static. However, flowing streams expand and contract following ever-changing hydrological conditions of the surrounding environment. Despite the ecological and biogeochemical value of rivers with discontinuous flow, deciphering the temporary nature of streams and quantifying their extent remains challenging. Using a unique observational dataset spanning diverse geomorphoclimatic settings, we demonstrate the existence of a general hierarchical structuring of river network dynamics. Specifically, temporary stream activation follows a fixed and repeatable sequence, in which the least persistent sections activate only when the most persistent ones are already flowing. This hierarchical phenomenon not only facilitates monitoring activities, but enables the development of a general mathematical framework that elucidates how climate drives temporal variations in the active stream length. As the climate gets drier, the average fraction of the flowing network decreases while its relative variability increases. Our study provides a novel conceptual basis for characterizing temporary streams and quantifying their ecological and biogeochemical impacts.

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Section: Implications For Large-scale Studiessupporting

confidence: 90%

Section: Quantifying the Mean Active Drainage Density And Its Temporal Variationsmentioning

confidence: 57%

Section: Hierarchical Activation Of Temporary Streamsmentioning

confidence: 99%

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Hierarchical climate-driven dynamics of the active channel length in temporary streams

Botter

Vingiani

Senatore

et al. 2021

Sci Rep

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“…The surveys were carried out along a river reach some tens of meters long located approximately 550 m upstream of the outlet of the Upper Turbolo catchment [23] (Figure 1), Southern Italy. The catchment is 7 km 2 wide, with altitudes ranging from 183 m a.s.l.…”

Section: Study Sitementioning

confidence: 99%

“…The topic is experiencing a renewed interest of the scientific community owing to the influence of stream dynamics on hydrology, freshwater ecology, and biogeochemistry (e.g., [20][21][22]). In this context, the Mediterranean region is particularly challenging, owing to the enhanced variability of the active length in arid and semiarid regions [23,24]. Borg Galea et al [16] showed the usefulness of drones for monitoring intermittent Mediterranean rivers using RGB images.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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

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Measuring zero water level in stream reaches: A comparison of an image‐based versus a conventional method

Herzog

Stahl

Blauhut

et al. 2022

Hydrological Processes

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A limited number of gauging stations, especially for nested catchments, hampers a process understanding of the interaction between streamflow, groundwater and water usage during drought. Non-commercial measurement devices can help overcome this lack of monitoring, but they need to be thoroughly tested. The Dreisam River in the South-West of Germany was affected by several hydrological drought events from 2015 to 2020 during which parts of the main stream and tributaries fell dry. Therefore it provided a useful case study area for a flexible longitudinal water quality and quantity monitoring network. Among other measurements the setup employs an image-based method with QR codes as fiducial marker. In order to assess under which conditions the QR-code based water level loggers (WLL) deliver data according to scientific standards, we compared its performance to conventional capacitive based WLL. The results from 20 monitoring stations reveal that the riverbed was dry for >50% at several locations and even for >70% at most severely affected locations during July and August 2020, with the north western parts of the catchment being especially concerned. Highly variable longitudinal drying patterns of the stream reaches emerged from the monitoring. The image-based method was found valuable for identification and validation of zero level occurrences. Nevertheless, a simple image processing approach (based on an automatic thresholding algorithm) did not compensate for errors due to natural conditions and technical setup.Our findings highlight that the complexity of measurement environments is a major challenge when working with image-based methods.

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Monitoring and Modeling Drainage Network Contraction and Dry Down in Mediterranean Headwater Catchments

Abstract: Virtually all watercourses experience discontinuous flows along their drainage network. Nonpermanent streams can be observed not only in dry regions but also in most low-order channels of the network, representing more than 89% of the global river network (G. H.

Cited by 22 publications

References 92 publications

Hierarchical climate-driven dynamics of the active channel length in temporary streams

Hierarchical climate-driven dynamics of the active channel length in temporary streams

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

Measuring zero water level in stream reaches: A comparison of an image‐based versus a conventional method

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