Analysis of the active length dynamics on intermittent streams using water presence sensors

2021 ◽  
Author(s):  
Francesca Zanetti ◽  
Nicola Durighetto ◽  
Filippo Vingiani ◽  
Gianluca Botter
Keyword(s):  
Objective Evaluation ◽  
Electrical Signal ◽  
Current Intensity ◽  
Active Network ◽  
Exceedance Probability ◽  
Intermittent Streams ◽  
Stream Network ◽  
Stream Length ◽  
Active Length ◽  
Event Based

<p>Headwater streams are important for their hydrological function and for their significant contribution to the riverine ecosystems. Nevertheless their study has always been challenging because of the ephemeral and intermittent nature of those streams. Maps representing the active part of the river network are usually drawn after field surveys performed under different hydrologic conditions, which enable an objective evaluation of the temporal changes in the length of the active network. This method is useful to describe seasonal variations of the stream length, but has significant limitations when it comes to the description of event-based changes of the flowing network, provided that visual inspections of entire catchments are highly time-consuming. In this work, electrical resistance (ER) sensors were used to analyze event-based active network dynamics along some of the tributaries of an Alpine creek in northern Italy. Current intensity values were collected every 5 minutes by the sensors and a threshold electrical signal was identified to distinguish between wet and dry status of the reaches where the probes were placed. A statistical analysis revealed a good correlation among the mean current intensity recorded, the exceedance probability of the threshold and the persistency of the nodes. Data collected by the sensors were also interpolated in space along the network to obtain a sequence of maps of the active and dry parts of the stream network. From each map the wet length (L) of the watercourse was derived and linked to the corresponding discharge (Q) at the outlet of the catchment. Small and intense precipitation events had different effects on the variations of Q and L: the network length was found to be more sensitive than discharge to small precipitation inputs; relevant stream flow variations were instead observed only during significant events that originated the largest changes in the active network length.  This heterogeneous behaviour negatively affected the quality of the fitting of empirical discharges vs. wet length data through a power law model. Water presence sensors provide an opportunity to study in depth the spatiotemporal dynamics of the active length of intermittent streams and link such dynamics to the relevant hydrological drivers.</p>

Characterizing temporary stream dynamics: the Stream Length Duration Curve

2021 ◽  
Author(s):  
Nicola Durighetto ◽  
Anfonso Senatore ◽  
Gianluca Botter
Keyword(s):  
Network Dynamics ◽  
Catchment Scale ◽  
Stream Length ◽  
Temporary Streams ◽  
Active Length ◽  
Temporary Stream ◽  
Riverine Ecosystems ◽  
Objective Classification ◽  
Event Based

<p>Temporary streams (i.e. streams that temporarily cease to flow) are becoming a hot research topic in hydrology. These streams provide an invaluable contribution to riverine ecosystems, as they host a variety of habitats (from lotic to lentic and terrestrial) which sustain high biodiversity. Temporary streams can be found in different regions of the world and are characterized by strongly heterogeneous flow patterns, from flashy streams that flow only after rainfall events to rivers that episodically experience droughts. Many recent studies investigated temporary streams, originating interesting observational datasets about event-based or seasonal network dynamics. Empirical or conceptual models are usually employed for assessing the main physical drivers of network dynamics in each specific study site.<br>In this contribution, we develop and apply novel theoretical tools to understand how the local statistical properties of each reach of the network affect the catchment-scale variability of the active length. In particular, the Stream Length Duration Curve (SLDC) is proposed to efficiently summarize catchment-scale dynamics of the active length, providing an objective way to quantify network dynamics. The concept of SLDC is applied to a number of Italian headwater catchments, where data about temporal changes in the configuration of the flowing stream are available, providing a clue for the characterization of emergent temporal and spatial patterns of network dynamics. The Stream Length Duration Curve can facilitate comparisons across different catchments an time periods, possibly enabling and objective classification of temporary streams. </p>

scholarly journals Event controls on intermittent streamflow in a temperate climate

2021 ◽  
Author(s):  
Nils Hinrich Kaplan ◽  
Theresa Blume ◽  
Markus Weiler
Keyword(s):  
Soil Moisture ◽  
Soil Layer ◽  
Temperate Climate ◽  
Substantial Part ◽  
Intermittent Streams ◽  
Stream Network ◽  
Deep Soil ◽  
Event Scale ◽  
Precipitation Characteristics ◽  
Event Based

Abstract. Intermittent streams represent a substantial part of the worldwide stream network and their occurrence is expected to increase due to climate change. Thus, it is of high relevance to provide detailed information of the temporal and spatial controls of streamflow intermittency to support management decisions. This study presents an event-based analysis of streamflow responses in intermittent streams in a meso-scale catchment with temperate climate. According to the streamflow responses, events were classified into flow or no-flow classes. Response controls like precipitation, soil moisture, and temperature were used as predictors in a random forest model to identify temporal controls of streamflow intermittency at the event-scale. Soil moisture was revealed as the most important predictor in the catchment. However, different patterns of predictor importance were found among the three dominant geologies in the catchment. Streamflow responses in the slate geology were controlled by soil moisture in the shallow and deep soil layers, while streamflow in the marl geology was primarily controlled by the soil moisture in the upper soil layer. Streamflow responses in catchments covering both marls and sandstone were dependent on soil moisture whereas streamflow in the only catchment with pure sandstone geology depended on precipitation characteristics. In both the slate and marl geology, streamflow intermittency also showed a relationship with seasonal fluctuations of soil temperature, probably as a proxy-variable of seasonal changes in evapotranspiration as well as an indicator of freezing conditions.

scholarly journals SLiX: A GIS Toolbox to Support Along-Stream Knickzones Detection through the Computation and Mapping of the Stream Length-Gradient (SL) Index

2020 ◽  
Vol 9 (2) ◽  
pp. 69 ◽  
Author(s):  
Daniela Piacentini ◽  
Francesco Troiani ◽  
Tommaso Servizi ◽  
Olivia Nesci ◽  
Francesco Veneri
Keyword(s):  
Regional Scale ◽  
Cost Effective ◽  
Stream Channels ◽  
Stream Network ◽  
Stream Length ◽  
Mountainous Catchments ◽  
Digital Elevation ◽  
Longitudinal Profiles ◽  
And Cluster Analysis ◽  
Hillslope Processes

The stream length-gradient (SL) index is widely used in geomorphological studies aimed at detecting knickzones, which are extensive along-stream deviations from the typical concave-up shape assumed for stream longitudinal profiles at steady-state conditions. In particular, SL was practical for identifying anomalous gradients along bedrock stream channels in mountainous catchments. This work presents the GIS toolbox SLiX designed to extract values of the SL index, starting from Digital Elevation Models (DEMs). SLiX is also suitable for the spatial analysis of the SL values, allowing for the identification of landscape portions where anomalous high values of SL occur and, consequently, those catchment sectors where stream channels show peaks in the erosional dynamic. The SLiX main outputs are (i) point shapefiles containing, among stream channels attributes, the extracted values of SL along the stream network analyzed, and (ii) SL anomaly maps in GeoTIFF format, computed through the Hotspot and Cluster Analysis (HCA), that permit the detection of the catchment sectors where the major SL anomalies occur and consequently the principal knickzones. The application of the proposed tool within an experimental catchment located in the Northern Apennines of Italy demonstrated the proper functionality and the potential of its use for different geomorphological and environmental studies. The accurate and cost-effective detection of anomalous changes in stream gradient ensured by SLiX is of great interest and can be useful for studies aimed at unravelling the Earth processes responsible of their formation (e.g., active hillslope processes, such as landslides directly interacting with the streambed, presence of geological structures, and meander cut-off). The applications of SLiX have clear implications for preliminary analyses, at a regional scale in different morpho-climatic contexts, for the hydrological management of river basins and/or to prevent geological hazards related to the fluvial erosional dynamics.

NEW FINDINGS ON RIVER NETWORK ORGANIZATION: LAW OF EIGENAREA AND RELATIONSHIPS AMONG HORTONIAN SCALING RATIOS

Fractals ◽  
2017 ◽  
Vol 25 (03) ◽  
pp. 1750029 ◽  
Author(s):  
SOOHYUN YANG ◽  
KYUNGROCK PAIK
Keyword(s):  
Drainage Basin ◽  
River Network ◽  
Length Ratio ◽  
Network Organization ◽  
Stream Network ◽  
Stream Length ◽  
Fractal Organization ◽  
New Findings ◽  
The Law

Horton’s laws have long served as fundamental principles for fractal organization of a drainage basin. Scaling ratios of stream number, length, area, and side tributary have been proposed but the definitions of these basic variables are inconsistent. The concept of eigenarea can be utilized to resolve this issue. Here, we investigated the relationships among Hortonian scaling ratios using the concept of eigenarea. We found that the eigenarea ratio, likewise other scaling ratios, is invariant within a stream network, the law of eigenarea. We analytically revealed that the eigenarea ratio is equivalent to the stream length ratio. Our examination implies that Horton’s original two ratios of stream number and length can represent most Hortonian scaling ratios except Tokunaga ratio.

scholarly journals The Response of Stream Competence to Topographic and Seasonal Variations in The Bamenda-Menchum Drainage Basin, North West Region, Cameroon

2019 ◽  
Vol 11 (2) ◽  
pp. 21 ◽  
Author(s):  
Kang Edwin Mua ◽  
Kometa Sunday Shende
Keyword(s):  
Drainage Basin ◽  
Flow Direction ◽  
Control Policy ◽  
Slope Instability ◽  
River Channels ◽  
Stream Network ◽  
Stream Length ◽  
Alluvial Deposits ◽  
North West ◽  
Development Prospects

The flow direction of streams remains an establishing mechanism in understanding drainage basin function and stream competence. The ability of streams to erode, transport and deposit loads in fluvial geomorphology exert a benchmark precursor for slope dynamics given the differential geological outcrop of the Bamenda-Menchum basin. Such competence in stream network generates slope instability as materials continuously move down slope from the volcanic escarpment face of Bamenda highlands to the sedimentary lowland area of Lower Bafut-Menchum basin. This paper investigate the influence of stream flow direction and stream competence on slope dynamics and how such dynamism affects the development prospects of the drainage basin. Slope range was obtained from AVL/EBI.JHO measurement. Stream length, density and flow direction were gotten from GIS Arc 21. Stream depth, channel width, flow rate and sedimentation levels were measured. Gully depth on slopes and landslide angles were measured using 30m tape and a graduated pole. Questionnaires were used to collect information on the vulnerability of households to slope dynamics orchestrated by stream competence. Findings revealed that stream competence varies from the two geological basements and that the escarpment face respond to high flow gravity and hydraulic action contributing to rapid erosion and transportation of loads. The results equally showed that the Bamenda escarpment face that is linked to the crystalline rocks produce differential erosion and landslide. 76.7% of slope instability is explained by geological structure and seasonality effect in the basin while 23.3% of slope dynamics is explained by other variables not specified in the study. The lower basin remains liable to deposition of materials on river channels and flood plain. The accumulation of sand, stones and alluvial deposits are extracted and exploited for the development prospects of the basin. The study recommends channel and slope management by integrating slope development control policy in drainage basin management and development.

scholarly journals Analysing river network dynamics and active length - discharge relationship using water presence sensors

2021 ◽  
Author(s):  
Francesca Zanetti ◽  
Nicola Durighetto ◽  
Filippo Vingiani ◽  
Gianluca Botter
Keyword(s):  
Power Law ◽  
Cross Sections ◽  
Temporal Dynamics ◽  
River Network ◽  
Low Flow ◽  
Stream Network ◽  
Entire Study ◽  
Temporary Streams ◽  
Active Length ◽  
Spatio Temporal

Abstract. Despite the importance of temporary streams for the provision of key ecosystem services, their experimental monitoring remains challenging because of the practical difficulties in performing accurate high-frequency surveys of the flowing portion of river networks. In this study, about 30 electrical resistance (ER) sensors were deployed in a high relief 2.6 km2 catchment of the Italian Alps to monitor the spatio-temporal dynamics of the active river network during the fall of 2019. The set-up of the ER sensors was personalized to make them more flexible for the deployment in the field and more accurate under low flow conditions. Available ER data were analyzed, compared to field based estimates of the nodes' persistency and then used to generate a sequence of maps representing the active reaches of the stream network with a sub-daily temporal resolution. This allowed a proper estimate of the joint variations of active river network length (L) and catchment discharge (Q) during the entire study period. Our analysis revealed a high cross-correlation between the statistics of individual ER signals and the flow persistencies of the cross sections where the sensors were placed. The observed spatial and temporal dynamics of the actively flowing channels also revealed the diversity of the hydrological behaviour of distinct zones of the study catchment, which was attributed to differences in the catchment geology and stream-bed composition. The more pronounced responsiveness of the total active length to small precipitation events as compared to the catchment discharge led to important hysteresis in the L vs. Q relationship, thereby impairing the performances of a power-law model frequently used in the literature to relate these two quantities. Consequently, in our study site the adoption of a unique power-law L-Q relationship to infer flowing length variability from observed discharges would underestimate the actual variations of L by 40%. Our work emphasizes the potential of ER sensors for analysing spatio-temporal dynamics of active channels in temporary streams, discussing the major limitations of this type of technology emerging from the specific application presented herein.

scholarly journals Assessing the hydrological impacts of coal resource development: a case study from Australia

2021 ◽  
Vol 66 (1) ◽  
Author(s):  
David A. Post ◽  
Keyword(s):  
Water Resources ◽  
Regional Scale ◽  
Resource Development ◽  
Stream Network ◽  
Stream Length ◽  
Near Surface ◽  
Hydrological Change ◽  
Planning Decisions ◽  
Groundwater Drawdown ◽  
Coal Resource

The objective of this study is to predict regional-scale cumulative impacts on water resources caused by coal resource developments in the Gloucester subregion of New South Wales (NSW), Australia. A key outcome of the assessment is identifying areas where water resources are very unlikely to be impacted (with a less than 5% chance) from those where water resources are potentially impacted (at least a 5% chance). Governments, industry and the community can then focus on areas that are potentially impacted when making regulatory, water management and planning decisions. Potential impacts were ruled out using a zone of potential hydrological change. This zone was defined based on at least a 5% chance of exceeding defined thresholds in multiple hydrological response variables including groundwater drawdown and eight streamflow metrics (only reductions in annual streamflow are reported here). The zone of potential hydrological change in the Gloucester subregion covers 250 km2 and includes 242 km of stream network. This represents 52% of the area and 70% of the stream length assessed. Groundwater drawdown exceeding 0.2 m in the near surface aquifer due to additional coal resource development is very likely (>95% chance) for an area of 20 km2 but is very unlikely (<5% chance) to exceed an area of 100 km2. Although 242 km of streams are identified as being potentially impacted, changes in streamflow are small, with a little over 5% reduction in annual flow in some streams close to the coal mines, and reductions in annual flow in the major rivers not exceeding 1 - 5%.

scholarly journals Impact of changing DOC concentrations on the potential distribution of acid sensitive biota in a boreal stream network

2007 ◽  
Vol 4 (5) ◽  
pp. 3145-3173 ◽  
Author(s):  
H. Laudon ◽  
I. Buffam
Keyword(s):  
Stream Water ◽  
Base Flow ◽  
Spring Flood ◽  
Stream Network ◽  
Stream Length ◽  
Marginal Change ◽  
Sampling Locations ◽  
Doc Concentration ◽  
Aquatic Landscape

Abstract. DOC concentrations have increased in many surface waters in Europe and North America over the past few decades. As DOC exerts a strong influence on pH this DOC increase could have detrimental effects on acid sensitive biota in many streams and lakes. To investigate the potential implications of changes in the DOC concentration on stream water biota, we have used a mesoscale boreal stream network in northern Sweden as a case study. The network was sampled for stream water chemistry at 60 locations during both winter base flow and spring flood periods, representing the extremes experienced annually in these streams both in terms of discharge and acidity. The effect of changing DOC on pH was modeled for all sampling locations using an organic acid model, with input DOC concentrations for different scenarios adjusted by between –30% and +50% from measured present concentrations. The resulting effect on pH was then used to quantify the proportion of stream length in the catchment with pH below the acid thresholds of pH 5.5 and pH 5.0. The results suggest that a change in stream water DOC during base flow would have only a limited effect on pH and hence on the stream length with pH below the acid thresholds. During the spring flood on the other hand a change in DOC would strongly influence pH and the stream length with pH below the acid thresholds. For example an increase in DOC concentration of 30% at all sites would increase the proportion of stream length with pH below 5.5 from 37% to 65%, and the proportion of stream length with pH below 5.0 would increase from 18% to 27%. The results suggest that in poorly-buffered high DOC waters, even a marginal change in the DOC concentration could impact acid sensitive biota in a large portion of the aquatic landscape.

Sensitivity of pH in a boreal stream network to a potential decrease in base cations caused by forest harvest

2010 ◽  
Vol 67 (7) ◽  
pp. 1116-1125 ◽  
Author(s):  
Anneli Ågren ◽  
Ishi Buffam ◽  
Kevin Bishop ◽  
Hjalmar Laudon
Keyword(s):  
Forest Cover ◽  
Stream Water ◽  
Base Cations ◽  
Forest Harvest ◽  
Stream Network ◽  
Stream Length ◽  
Forestry Practices ◽  
Long Term Effect ◽  
Spring Snowmelt

Increased forest harvest with more whole-tree utilization can decrease base cations (BC) in soils and stream runoff. This paper analyses how reducing stream BC changes the capacity of a boreal stream network to buffer pH changes. We estimated change in stream pH during spring snowmelt in 60 locations throughout a 68 km2 boreal catchment in northern Sweden with different scenarios of BC removal from stream water ranging from 10 to 50 µequiv.·L–1. The pH decreased in all scenarios, and if BC decreased by 50 µequiv.·L–1, stream length with pH above the acid threshold pH 5 during spring snowmelt decreased from 82% to 44% of the stream network, whereas the stream length with pH above 5.5 decreased from 60% to 10%. The pH sensitivity of different stream reaches to reductions in BC was positively related to the slope of the catchment, forest cover, and forested mires, whereas it was negatively related to the percentage of agricultural fields. Because the long-term effect of different forestry practices on stream BC is unclear, there is all the more reason to evaluate BC sensitivity before, rather than after, eventual problems arise.

scholarly journals Impact of changing DOC concentrations on the potential distribution of acid sensitive biota in a boreal stream network

2008 ◽  
Vol 12 (2) ◽  
pp. 425-435 ◽  
Author(s):  
H. Laudon ◽  
I. Buffam
Keyword(s):  
Stream Water ◽  
Base Flow ◽  
Spring Flood ◽  
Stream Network ◽  
Stream Length ◽  
Marginal Change ◽  
Sampling Locations ◽  
Doc Concentration ◽  
Aquatic Landscape

Abstract. DOC concentrations have increased in many surface waters in Europe and North America over the past few decades. As DOC exudes a strong influence on pH this DOC increase could have detrimental effects on acid sensitive biota in many streams and lakes. To investigate the potential implications of changes in the DOC concentration on stream water biota, we have used a mesoscale boreal stream network in northern Sweden as a case study. The network was sampled for stream water chemistry at 60 locations during both winter base flow and spring flood periods, representing the extremes experienced annually in these streams both in terms of discharge and acidity. The effect of changing DOC on pH was modeled for all sampling locations using an organic acid model, with input DOC concentrations for different scenarios adjusted by between −30% and +50% from measured present concentrations. The resulting effect on pH was then used to quantify the proportion of stream length in the catchment with pH below the acid thresholds of pH 5.5 and pH 5.0. The results suggest that a change in stream water DOC during base flow would have only a limited effect on pH and hence on the stream length with pH below the acid thresholds. During the spring flood on the other hand a change in DOC would strongly influence pH and the stream length with pH below the acid thresholds. For example an increase in DOC concentration of 30% at all sites would increase the proportion of stream length with pH below 5.5 from 37% to 65%, and the proportion of stream length with pH below 5.0 would increase from 18% to 27%. The results suggest that in high DOC waters, even a marginal change in the DOC concentration could impact acid sensitive biota in a large portion of the aquatic landscape.

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