Critical Tokunaga model for river networks

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.

Download Full-text

Landslide-Induced Mass Transport of Radionuclides along Transboundary Mailuu-Suu River Networks in Central Asia

Remote Sensing ◽

10.3390/rs13040698 ◽

2021 ◽

Vol 13 (4) ◽

pp. 698 ◽

Cited By ~ 1

Author(s):

Fengqing Li ◽

Isakbek Torgoev ◽

Damir Zaredinov ◽

Marina Li ◽

Bekhzod Talipov ◽

...

Keyword(s):

Mass Transport ◽

Surface Waters ◽

Natural Radionuclides ◽

River Basin Management ◽

River Networks ◽

Pollution Dispersion ◽

Continuous Release ◽

Political Conflicts ◽

Exposure Pathway ◽

Analysis System

Seismically triggered landslides are a major hazard and have caused severe secondary losses. This problem is especially important in the seismic prone Mailuu-Suu catchment in Kyrgyzstan, as it hosts disproportionately sensitive active or legacy uranium sites with deposited radioactive extractive wastes. These sites show a quasi-continuous release of radioactive contamination into surface waters, and especially after natural hazards, a sudden and massive input of pollutants into the surface waters is expected. However, landslides of contaminated sediments into surface waters represent a substantial exposure pathway that has not been properly addressed in the existing river basin management to date. To fill this gap, satellite imagery was massively employed to extract topography and geometric information, and the seismic Scoops3D and the one-dimensional numerical model, Hydrologic Engineering Centre, River Analysis System (HEC-RAS), were chosen to simulate the landslide-induced mass transport of total suspended solids (TSS) and natural radionuclides (Pb-210 as a proxy for modeling purposes) within the Mailuu-Suu river networks under two earthquake and two hydrological scenarios. The results show that the seismically vulnerable areas dominated in the upstream areas, and the mass of landslides increased dramatically with the increase of earthquake levels. After the landslides, the concentrations of radionuclides increased suddenly and dramatically. The peak values decreased along the longitudinal gradient of river networks, with the concentration curves becoming flat and wide in the downstream sections, and the transport speed of radionuclides decreased along the river networks. The conclusions of this study are that landslides commonly release a significant amount of pollutants with a relatively fast transport along river networks. Improved quantitative understanding of waterborne pollution dispersion across national borders will contribute to better co-ordination between governments and regulatory authorities of riparian states and, consequently, to future prevention of transnational political conflicts that have flared up in the last two decades over alleged pollution of transboundary water bodies.

Download Full-text

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

Scientific Data ◽

10.1038/s41597-021-00819-9 ◽

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.

Download Full-text

Inverse Problem for Looped River Networks – Lower oder River Case Study

Archives of Environmental Protection ◽

10.2478/aep-2013-0010 ◽

2013 ◽

Vol 39 (1) ◽

pp. 105-118

Author(s):

Jacek Kurnatowski

Keyword(s):

Mathematical Modeling ◽

Flow Resistance ◽

Flow Distribution ◽

River Networks ◽

Sensitivity Equation ◽

Flow Measurements ◽

Sensitivity Equation Method ◽

Coefficients Identification ◽

Oder River

Abstract Identification of coefficients determining flow resistance, in particular Manning’s roughness coefficients, is one of the possible inverse problems of mathematical modeling of flow distribution in looped river networks. The paper presents the solution of this problem for the lower Oder River network consisting of 78 branches connected by 62 nodes. Using results of six sets of flow measurements at particular network branches it was demonstrated that the application of iterative algorithm for roughness coefficients identification on the basis of the sensitivity-equation method leads to the explicit solution for all network branches, independent from initial values of identified coefficients.

Download Full-text

River networks and groundwater flow: a simultaneous solution of a coupled system

Journal of Hydrology ◽

10.1016/j.jhydrol.2004.06.034 ◽

2005 ◽

Vol 301 (1-4) ◽

pp. 216-234 ◽

Cited By ~ 71

Author(s):

Orhan Gunduz ◽

Mustafa M. Aral

Keyword(s):

Groundwater Flow ◽

Coupled System ◽

River Networks ◽

Simultaneous Solution

Download Full-text

Effects of the combination of aeration and biofilm technology on transformation of nitrogen in black-odor river

Water Science & Technology ◽

10.2166/wst.2016.212 ◽

2016 ◽

Vol 74 (3) ◽

pp. 655-662 ◽

Cited By ~ 16

Author(s):

Mei Pan ◽

Jun Zhao ◽

Shucong Zhen ◽

Sheng Heng ◽

Jie Wu

Keyword(s):

Enzyme Activity ◽

Nitrogen Removal ◽

Removal Rate ◽

River Networks ◽

Water Tank ◽

Simulation Experiments ◽

Overlying Water ◽

Combined Process ◽

Polluted Rivers ◽

Laboratory Water

Excess nitrogen in urban river networks leading to eutrophication has become one of the most urgent environmental problems. Combinations of different aeration and biofilm techniques was designed to remove nitrogen from rivers. In laboratory water tank simulation experiments, we assessed the removal efficiency of nitrogen in both the overlying water and sediments by using the combination of the aeration and biofilm techniques, and then analyzed the transformation of nitrogen during the experiments. Aeration (especially sediment aeration) combined with the biofilms techniques was proved efficient in removing nitrogen from polluted rivers. Results indicated that the combination of sediment aeration and biofilms, with the highest nitrogen removal rate from the overlying water and sediments, was the most effective combined process, which especially inhibited the potential release of nitrogen from sediments by reducing the enzyme activity. It was found that the content of dissolved oxygen in water could be restored on the basis of the application of aeration techniques ahead, and the biofilm technique would be effective in purifying water in black-odor rivers.

Download Full-text