Monitoring and modelling drainage network dynamics of a Mediterranean catchment

2020 ◽  
Author(s):  
Alfonso Senatore ◽  
Alessio Liotti ◽  
Massimo Micieli ◽  
Nicola Durighetto ◽  
Gianluca Botter ◽  
...  
Keyword(s):  
Climatic Variability ◽  
Network Dynamics ◽  
River Network ◽  
River Networks ◽  
Good Representation ◽  
Drainage Network ◽  
Topographic Wetness Index ◽  
Research Activity ◽  
Wide Range ◽  
Contraction Dynamics

<p>Empirical evidence indicates that the active part of the drainage networks, i.e. that characterized by flowing water, is not static but, conversely, it experiences significant expansion/contraction dynamics produced by the interactions between hydrological and climatic variability, morphological features and soil properties in the contributing catchment. The expansion and contraction dynamics of the "wet" component of the river network can be identified in a wide range of climatic conditions, particularly in the headwaters. In these areas, the observed river network dynamics largely depend on the capacity of the upstream drainage area to concentrate surface runoff in channelized sites.</p><p>The study presents a research activity carried out in the framework of the European project "DyNET: Dynamical River Networks" (http://www.erc-dynet.it/), specifically aimed at analysing in detail the processes and agents overseeing changes in form and in the length of river networks in a Mediterranean environment. The contribution describes the first results achieved in the southernmost of the basins under investigation in the DyNET project, namely the Turbolo creek catchment (Calabria, Southern Italy). Bi-weekly surveys were conducted in two sub-catchments having a total area of more than 1 km<sup>2</sup>, both during the recession (contraction) and reactivation (expansion) phases of the drainage network. The empirical data were used for the validation of a statistical model of the wet network dynamics, designed to estimate the total length of the active network over time. This length was distributed spatially on the river network in an objective way by defining a two-way relationship between active stream length and the Topographic Wetness Index (TWI). The modelling of the network contraction and expansion dynamics was possible using a few meteorological and hydrological variables. The combined use of information on the overall length of the network and the TWI led to a reasonably good representation of the drainage network dynamics over space and time.</p>

UAV thermal images to support the study of the expansion and contraction dynamics of river networks: a preliminary methodological approach

2020 ◽  
Author(s):  
Massimo Micieli ◽  
Gianluca Botter ◽  
Giuseppe Mendicino ◽  
Alfonso Senatore
Keyword(s):  
Quantitative Description ◽  
Weather Conditions ◽  
Control Area ◽  
River Network ◽  
River Networks ◽  
Flowing Water ◽  
Climatic Fluctuations ◽  
Thermal Images ◽  
Basin Scale ◽  
Contraction Dynamics

<p>River networks are dynamic entities, periodically subject to expansion and contraction processes due to natural hydrological and climatic fluctuations. The ERC project "DyNET: Dynamical River Networks" aims at providing a systematic and quantitative description of such processes. The experimental activities are focused on the mapping at the basin scale of the active (i.e., characterized by flowing water) portion of the river network with the aid of drones, satellite images and field surveys, for the collection of data useful to the modelling of evolutionary processes and the development of theories to be extended on a regional scale. The use of UAVs (Unmanned Air Vehicles) specifically concerns the observation of the space-time evolution of processes, allowing to monitor wide areas and identify the presence/absence of flowing water in the river network with the help of infrared (IR) thermal imaging cameras.</p><p>The contribution discusses the effectiveness of UAVs for river networks dynamics monitoring in the Turbolo creek network (Calabria, southern Italy). Specifically, an experimental method is described that identifies and extrapolates from thermal images the pixels representing the active river network. The method is defined based on multiple acquisitions of thermal IR images on some channelized sites in different periods of the year, weather conditions, daytimes and flight altitudes. Several surveys were carried out in autumn, winter and spring seasons, with variable cloud conditions, always repeating the same flight plan, at three different altitudes and at three different times for each day of analysis. During the experiments, air temperature data were recorded by a weather station near the test area, as well as the water temperature values ​​in a small control area in the river bed, with the ascertained presence of water, monitored by the UAV. The thermal images were analyzed on GIS software, extrapolating the pixels falling within a range of values defined from the control area. The "water pixels" thus obtained allowed, through appropriate post-processing, to reconstruct the active river network even in areas not accessible by land. The methodology developed allows defining, for different periods of the year and weather conditions, optimal altitudes and flight times to accurately identify the expansion/contraction dynamics of river networks.</p>

Danube River Basin: Progress with the Environmental Programme

1999 ◽  
Vol 40 (10) ◽  
pp. 1-8 ◽  
Author(s):  
T. Botterweg ◽  
D. W. Rodda
Keyword(s):  
River Basin ◽  
Action Plan ◽  
Waste Water Treatment ◽  
Warning System ◽  
Danube River ◽  
The Black Sea ◽  
Research Activity ◽  
Global Environment Facility ◽  
Major Activity ◽  
Wide Range

An Internationally funded Programme, involving the European Commission, the Global Environment Facility managed by UN Development Programme, the World Bank and the European Bank for Reconstruction and Development, is addressing river basin problems in a unique situation. The solution of these should lead to the prevention of pollution and better water quality, protected ecosystems, sustainable water resources and more efficient sewerage and waste water treatment facilities for the 90 million population living in the region and the reduction of pollution impact on the Black Sea into which the Danube River flows. The paper introduces current Programme activities, the challenges being met and progress. Work is described for implementing a monitoring strategy, an accident emergency warning system and implementation of the 1994 Strategic Action Plan. The applied research activity is explained. The Programme is a major activity with many elements addressing a wide range of environmental problems in the catchment of a major international waterway.

scholarly journals Setting the Flow Accumulation Threshold Based on Environmental and Morphologic Features to Extract River Networks from Digital Elevation Models

2021 ◽  
Vol 10 (3) ◽  
pp. 186
Author(s):  
HuiHui Zhang ◽  
Hugo A. Loáiciga ◽  
LuWei Feng ◽  
Jing He ◽  
QingYun Du
Keyword(s):  
Spatial Scales ◽  
Digital Elevation Models ◽  
Regional Scale ◽  
Drainage Density ◽  
River Network ◽  
Landscape Patterns ◽  
Estimation Methods ◽  
River Networks ◽  
Flow Accumulation ◽  
Digital Elevation

Determining the flow accumulation threshold (FAT) is a key task in the extraction of river networks from digital elevation models (DEMs). Several methods have been developed to extract river networks from Digital Elevation Models. However, few studies have considered the geomorphologic complexity in the FAT estimation and river network extraction. Recent studies estimated influencing factors’ impacts on the river length or drainage density without considering anthropogenic impacts and landscape patterns. This study contributes two FAT estimation methods. The first method explores the statistical association between FAT and 47 tentative explanatory factors. Specifically, multi-source data, including meteorologic, vegetation, anthropogenic, landscape, lithology, and topologic characteristics are incorporated into a drainage density-FAT model in basins with complex topographic and environmental characteristics. Non-negative matrix factorization (NMF) was employed to evaluate the factors’ predictive performance. The second method exploits fractal geometry theory to estimate the FAT at the regional scale, that is, in basins whose large areal extent precludes the use of basin-wide representative regression predictors. This paper’s methodology is applied to data acquired for Hubei and Qinghai Provinces, China, from 2001 through 2018 and systematically tested with visual and statistical criteria. Our results reveal key local features useful for river network extraction within the context of complex geomorphologic characteristics at relatively small spatial scales and establish the importance of properly choosing explanatory geomorphologic characteristics in river network extraction. The multifractal method exhibits more accurate extracting results than the box-counting method at the regional scale.

scholarly journals A new vector-based global river network dataset accounting for variable drainage density

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Peirong Lin ◽  
Ming Pan ◽  
Eric F. Wood ◽  
Dai Yamazaki ◽  
George H. Allen
Keyword(s):  
Spatial Variability ◽  
Flow Direction ◽  
River System ◽  
Drainage Density ◽  
River Network ◽  
River Networks ◽  
Digital Elevation ◽  
Machine Learning Approach ◽  
Elevation Model ◽  
National Hydrography Dataset

AbstractSpatial variability of river network drainage density (Dd) is a key feature of river systems, yet few existing global hydrography datasets have properly accounted for it. Here, we present a new vector-based global hydrography that reasonably estimates the spatial variability of Dd worldwide. It is built by delineating channels from the latest 90-m Multi-Error-Removed Improved Terrain (MERIT) digital elevation model and flow direction/accumulation. A machine learning approach is developed to estimate Dd based on the global watershed-level climatic, topographic, hydrologic, and geologic conditions, where relationships between hydroclimate factors and Dd are trained using the high-quality National Hydrography Dataset Plus (NHDPlusV2) data. By benchmarking our dataset against HydroSHEDS and several regional hydrography datasets, we show the new river flowlines are in much better agreement with Landsat-derived centerlines, and improved Dd patterns of river networks (totaling ~75 million kilometers in length) are obtained. Basins and estimates of intermittent stream fraction are also delineated to support water resources management. This new dataset (MERIT Hydro–Vector) should enable full global modeling of river system processes at fine spatial resolutions.

scholarly journals An Innovative Framework for Real Time Monitoring of Pollutant Point Sources in River Networks

2021 ◽  
Author(s):  
Mehdi Mazaheri ◽  
J. M. V. Samani ◽  
Fulvio Boano
Keyword(s):  
Real Time ◽  
Transport Model ◽  
River Network ◽  
Point Sources ◽  
Release Time ◽  
River Networks ◽  
Observation Data ◽  
Geostatistical Approach ◽  
Pollutant Sources ◽  
Simultaneous Identification

Abstract The simultaneous identification of location and source release history in complex river networks is a very complicated ill-posed problem, particularly in a case of multiple unknown pollutant sources with time-varying release pattern. This study presents an innovative method for simultaneous identification of the number, locations and release histories of multiple pollutant point sources in a river network using minimum observation data. Considering two different type of monitoring stations with an adaptive arrangement as well as real-time data collection at those stations and using a reliable numerical flow and transport model, at first the number and suspected reach of presence of pollutant sources are determined. Then the source location and its intensity function is calculated by solving inverse source problem using a geostatistical approach. A case study with three different scenarios in terms of the number, release time and location of pollutant sources are discussed, concerning a river network with unsteady and non-uniform flow. Results showed the capability of the proposed method in identifying of sought source characteristics even in complicated cases with simultaneous activity of multiple pollutant sources.

scholarly journals On the propagation of diel signals in river networks using analytic solutions of flow equations

2015 ◽  
Vol 12 (8) ◽  
pp. 8175-8220 ◽  
Author(s):  
M. Fonley ◽  
R. Mantilla ◽  
S. J. Small ◽  
R. Curtu
Keyword(s):  
Analytic Solutions ◽  
River Network ◽  
Low Flow ◽  
River Networks ◽  
Signal Delay ◽  
Flow Conditions ◽  
Flow Equations ◽  
Linear Transport Equation ◽  
Daily Evapotranspiration ◽  
Self Similar

Abstract. Two hypotheses have been put forth to explain the magnitude and timing of diel streamflow oscillations during low flow conditions. The first suggests that delays between the peaks and troughs of streamflow and daily evapotranspiration are due to processes occurring in the soil as water moves toward the channels in the river network. The second posits that they are due to the propagation of the signal through the channels as water makes its way to the outlet of the basin. In this paper, we design and implement a theoretical experiment to test these hypotheses. We impose a baseflow signal entering the river network and use a linear transport equation to represent flow along the network. We develop analytic streamflow solutions for two cases: uniform and nonuniform velocities in space over all river links. We then use our analytic solutions to simulate streamflows along a self-similar river network for different flow velocities. Our results show that the amplitude and time delay of the streamflow solution are heavily influenced by transport in the river network. Moreover, our equations show that the geomorphology and topology of the river network play important roles in determining how amplitude and signal delay are reflected in streamflow signals. Finally, our results are consistent with empirical observations that delays are more significant as low flow decreases.

scholarly journals Modeling Network Dynamics

2020 ◽  
pp. 145-171
Keyword(s):  
Communication Networks ◽  
Random Network ◽  
Network Dynamics ◽  
Network Models ◽  
Random Networks ◽  
Social Phenomena ◽  
Disease Propagation ◽  
The Social ◽  
Wide Range ◽  
Model Dynamics

Social relationships and the social networks over these relationships do not occur arbitrarily. However, the random networks dealt with in this chapter are important tools for modeling the networks of these systems. The authors use random networks to understand and to model dynamics regarding the whole social structure. Random network models became the topic of several studies independently from social network analysis in the 1950s. These models were used in the analysis of a wide range of social and non-social phenomena, from electrical and communication networks to the speed and manner of disease propagation. This chapter explores the modeling network dynamics of random networks.

scholarly journals High Froude Number Experimental Investigation of the 2 DOF Behavior of a Multihull Float in Head Waves

2021 ◽  
Vol 6 (01) ◽  
pp. 1-20
Author(s):  
Paul Kerdraon ◽  
Boris Horel ◽  
Patrick Bot ◽  
Adrien Letourneur ◽  
David David Le Touzé
Keyword(s):  
High Performance ◽  
Good Representation ◽  
Prediction Program ◽  
Modeling Approach ◽  
Head Waves ◽  
Wide Range ◽  
Dynamic Velocity ◽  
Velocity Prediction ◽  
High Froude Number ◽  
Stability Issues

Dynamic Velocity Prediction Programs are taking an increasingly prominent role in high performance yacht design, as they allow to deal with seakeeping abilities and stability issues. Their validation is however often neglected for lack of time and data. This paper presents an experimental campaign carried out in the towing tank of the Ecole Centrale de Nantes, France, to validate the hull modeling in use in a previously presented Dynamic Velocity Prediction Program. Even though with foils, hulls are less frequently immersed, a reliable hull modeling is necessary to properly simulate the critical transient phases such as touchdowns and takeoffs. The model is a multihull float with a waterline length of 2.5 m. Measurements were made in head waves in both captive and semi-captive conditions (free to heave and pitch), with the model towed at constant yaw and speed. To get as close as possible to real sailing conditions, experiments were made at both zero and non-zero leeway angles, sweeping a wide range of speed values, with Froude numbers up to 1.2. Both linear and nonlinear wave conditions were studied in order to test the limits of the modeling approach, with wave steepness reaching up to 7% in captive conditions and 3.5% in semi-captive ones. The paper presents the design and methodology of the experiments, as well as comparisons of measured loads and motions with simulations. Loads are shown to be consistent, with a good representation of the sustained non-linearities. Pitch and heave motions depict an encouraging correlation which confirms that the modeling approach is valid.

Identifying global hotspots of plastic waste accumulation along river networks

2021 ◽  
Author(s):  
Jesus Gomez-Velez ◽  
Stefan Krause
Keyword(s):  
Multiple Scales ◽  
Transport Model ◽  
Freshwater Ecosystems ◽  
River Network ◽  
Plastic Waste ◽  
Trapping Efficiency ◽  
River Networks ◽  
Clear Understanding ◽  
Relative Location ◽  
Plastic Pollution

<p>Global plastic pollution is affecting ecosystems and human health globally. Proposing solutions and coping strategies for this threat requires a clear understanding of the processes controlling the fate and transport of mismanaged plastics at multiple scales, going from watersheds to regions and even continents. River corridors are the primary conveyor and trap for mismanaged plastic produced within the landscape and eventually released to the ocean. New approaches that apply technological sensing innovations for monitoring plastic waste in aquatic environments can improve observations and plastic waste datasets globally. However, our understanding of when, where, and how to target monitoring is limited, reducing the benefit gained. There is therefore a critical demand for predictions of hotspots (as well as hot moments) of plastic accumulation along river networks globally, in order to optimize observational capacity.     </p><p>Here, we present a new global flow and transport model for plastic waste in riverine environments. Our model predicts that only a small fraction (roughly 2.5%) of the global mismanaged plastic that entered rivers since the 1950s has been delivered to the ocean by 2020, with an overwhelming majority sequestered in freshwater ecosystems. Furthermore, we predict the patterns of mismanaged plastic accumulation and its residence time depend on (i) the topology and geometry of the river network, (ii) the relative location of plastic sources, and (ii) the relative location and trapping efficiency of flow regulation structures, primarily large dams. Our results highlight the role of rivers as major sinks for plastic waste and the need for targeted remedial strategies that consider the structure of the river network and anthropogenic regulation when proposing intervention measures and sampling efforts.</p>

Investigating the Response of Tectonic Loading in the Himalayas on the Peripheral Forebulge through Drainage Network Analysis

2021 ◽  
Author(s):  
Parv Kasana ◽  
Vimal Singh ◽  
Rahul Devrani
Keyword(s):  
Dynamic Equilibrium ◽  
Ganga River ◽  
Indian Plate ◽  
River Networks ◽  
Drainage Network ◽  
River Systems ◽  
Himalayan Orogeny ◽  
Narmada River ◽  
Indian Lithosphere ◽  
Tectonic Loading

<p>Drainage divide migration is a conspicuous natural process through which a landscape evolves. In response to a forced climatic and tectonic disturbance, susceptible river networks transfer the transient signals to the entire river basin, which results in an incision or aggradation. The Himalayan orogeny and subduction of the Indian plate have resulted in an upward flexure in the Indian lithosphere known as a peripheral forebulge. A forebulge can flexurally uplift and migrate following the variation in tectonic load. The emergence of the central Indian plateau is a consequence of the upwarping of the Indian lithosphere (Bilham et al. 2003).  In this work, we are trying to assess the drainage network dynamics between the Narmada and Ganga river systems, which drain the uplifted central Indian plateau. We have calculated the Chi(χ) metrics, steepness index (Ksn), knickpoints for the channels in the study area. We have generated Topographic swath profiles to analyze the topographic variations on the plateau. It has been observed from the results that the rivers in the study area lack dynamic equilibrium, and river capturing is an evident response to the perturbations. Our analysis shows that the Narmada River tributaries are gaining drainage area and aggressing Northwards by capturing adjacent Ganga river tributaries. The field observations show a variation in the surface slope and presence of knickpoints (waterfalls) along the "aggressor" drainages. We propose a model to show a correlation between the tectonic loading of Himalayas, movement of forebulge, and its feedback to the river systems present on the forebulge.</p>

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