scholarly journals Quantifying landslide frequency and sediment residence time in the Nepal Himalaya

2019 ◽  
Vol 5 (4) ◽  
pp. eaav3482 ◽  
Author(s):  
D. M. Whipp ◽  
T. A. Ehlers
Keyword(s):  
Residence Time ◽  
River Sediment ◽  
Drainage Basin ◽  
Drainage Basins ◽  
Nepal Himalaya ◽  
Stochastic Nature ◽  
Two Samples ◽  
Mountainous Landscapes ◽  
Landslide Frequency ◽  
The Difference

Quantifying how Earth surface processes interact with climate, tectonics, and biota has proven challenging, in part due to the stochastic nature of erosion and sedimentation. Landsliding is a common stochastic erosional process that may account for >50% of the sediment produced in steep mountainous landscapes. Here, we calculate the effects of landsliding and the residence time of sediment in a steep drainage basin in the Nepal Himalaya using a numerical model of landslide erosion combined with published cooling age distributions from two river sediment samples collected several years apart. We find that the difference in the two samples can be explained by landsliding and that the age distributions suggest that the residence time of sediment in the catchment is no greater than 50 years. This sensitivity to landsliding thus offers potential to improve our understanding of stochastic erosional processes, and further suggests that sediment is rapidly evacuated from steep mountainous drainage basins.

Stochastic Artificial Aeration Control for Regional Drainage Basins

1982 ◽  
Vol 104 (4) ◽  
pp. 337-342
Author(s):  
N. M. Olgac ◽  
R. W. Longman ◽  
C. A. Cooper
Keyword(s):  
Regional Planning ◽  
Drainage Basin ◽  
Measurement Data ◽  
Drainage Basins ◽  
Artificial Aeration ◽  
Stochastic Nature ◽  
Mathematical Mode ◽  
Discrete Nature ◽  
River Drainage Basin ◽  
Quality Measurements

Regional planning for the abatement of pollution in a river drainage basin can profitably include artificial in-stream aeration as a key component in a coordinated abatement effort. This technique compares very favorably, on a capital expense basis, with more traditional abatement methods. A general drainage basin structure containing a river, or rivers, with tributaries in a graphical tree structure is considered. The mathematical mode developed is a general formulation which deals with the arbitrary number of confluences in the basin, tributaries entering the controlled section, the spacially discrete nature of the feedback water quality measurements and of the treatment sites, and the stochastic nature of the measurements and pollution sources. An optimal aeration strategy is determined for each aerator as a function of measurement data throughout the basin, and examples are given to illustrate the results.

DRAINAGE BASIN AS A COMPLEX SOCIO-NATURAL HIERARCHICAL SYSTEM

2020 ◽  
Vol 42 (3) ◽  
pp. 293-303
Author(s):  
VALERIY BONDAREV
Keyword(s):  
Drainage Basin ◽  
Temporal Analysis ◽  
Large River ◽  
Hierarchical Level ◽  
Effective Management ◽  
Drainage Basins ◽  
Time Intervals ◽  
Natural Systems ◽  
Spatial And Temporal Analysis ◽  
Entire Complex

The theoretical and methodological basis of the systems hierarchical spatial and temporal analysis of a drainage basin, which addresses the problems of effective management in socio-natural systems of different ranks, is considered. It is proposed to distinguish 9 orders of forms that are relevant to the analysis of drainage basins, where the first level is represented by individual aggregates and particles, and the last - by basins of large and the largest rivers. As part of the allocation of geological, historical and modern time intervals, the specificity of the implementation of processes in basins of different scales from changing states, through functioning to evolution is demonstrated. The interrelation of conditions and factors that determine the processes occurring within the drainage basins is revealed. It is shown that a specific combination of conditions and factors that determine processes in the drainage basin is associated with the hierarchy of the objects under consideration, i.e. the choice of a spatial-temporal hierarchical level is crucial for the organization of study within drainage basins. At one hierarchical level, some phenomenon can be considered as a factor, and at another - as a condition. For example, tectonic processes can be considered as an active factor in the evolution of large river basins in the geological perspective, but for small drainage basin, this is already a conservative background condition. It is shown that at the historical time the anthropogenic factor often comes to the fore, with the appearance of which in the functioning of the drainage basin, there is a need to take into account the entire complex of socio-environmental problems that can affect the sustainable state of various territories, especially in the field of water and land use. Hierarchical levels of managing subjects are identified, which are primarily responsible for effective management at the appropriate hierarchical level of the organization of the socio-natural system within the catchment area, starting from an individual to humankind as a whole.

scholarly journals A Stepwise GIS Approach for the Delineation of River Valley Bottom within Drainage Basins Using a Cost Distance Accumulation Analysis

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 827
Author(s):  
Gasper L. Sechu ◽  
Bertel Nilsson ◽  
Bo V. Iversen ◽  
Mette B. Greve ◽  
Christen D. Børgesen ◽  
...  
Keyword(s):  
Spatial Data ◽  
Nutrient Loading ◽  
Drainage Basin ◽  
River Valley ◽  
Management Tool ◽  
Drainage Basins ◽  
Valley Bottom ◽  
Management Actions ◽  
Cost Distance ◽  
River Valleys

River valley bottoms have hydrological, geomorphological, and ecological importance and are buffers for protecting the river from upland nutrient loading coming from agriculture and other sources. They are relatively flat, low-lying areas of the terrain that are adjacent to the river and bound by increasing slopes at the transition to the uplands. These areas have under natural conditions, a groundwater table close to the soil surface. The objective of this paper is to present a stepwise GIS approach for the delineation of river valley bottom within drainage basins and use it to perform a national delineation. We developed a tool that applies a concept called cost distance accumulation with spatial data inputs consisting a river network and slope derived from a digital elevation model. We then used wetlands adjacent to rivers as a guide finding the river valley bottom boundary from the cost distance accumulation. We present results from our tool for the whole country of Denmark carrying out a validation within three selected areas. The results reveal that the tool visually performs well and delineates both confined and unconfined river valleys within the same drainage basin. We use the most common forms of wetlands (meadow and marsh) in Denmark’s river valleys known as Groundwater Dependent Ecosystems (GDE) to validate our river valley bottom delineated areas. Our delineation picks about half to two-thirds of these GDE. However, we expected this since farmers have reclaimed Denmark’s low-lying areas during the last 200 years before the first map of GDE was created. Our tool can be used as a management tool, since it can delineate an area that has been the focus of management actions to protect waterways from upland nutrient pollution.

A method for measuring the residence time distribution of particles in a fluidized bed based on digital image analysis

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jiamin Li ◽  
Xiaoping Chen ◽  
Jiliang Ma ◽  
Cai Liang
Keyword(s):  
Image Analysis ◽  
Fluidized Bed ◽  
Residence Time ◽  
Digital Image ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Digital Image Analysis ◽  
Color Space ◽  
The Difference ◽  
Accuracy And Repeatability

AbstractTraditional methods for measuring the residence time distribution (RTD) of particles in a fluidized bed are complex and time-consuming. To this regard, the present work proposes a new measurement method with remarkable efficiency based on digital image analysis. The dyed tracers are recognized in the images of the samples due to the difference of colors from bed materials. The HSV and the well-known RGB color space were employed to distinguish the tracers. By enhancing the Saturation and the Value in HSV and adjusting the gray range of images, the recognition error is effectively reduced. Then the pixels representing the tracers are distinguished, based on which the concentration of the tracers and RTD are measured. The efficiency, accuracy and repeatability of the method were validated by RTD measurements experiments. The method is also fit for distinguishing the target particles from multi-component systems consisting of particles of different colors.

scholarly journals Reconstruction of North American drainage basins and river discharge since the Last Glacial Maximum

2016 ◽  
Vol 4 (4) ◽  
pp. 831-869 ◽  
Author(s):  
Andrew D. Wickert
Keyword(s):  
North American ◽  
Drainage Basin ◽  
Ice Sheets ◽  
Glacial Isostatic Adjustment ◽  
Drainage Basins ◽  
Last Glacial ◽  
Isostatic Adjustment ◽  
The North ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Over the last glacial cycle, ice sheets and the resultant glacial isostatic adjustment (GIA) rearranged river systems. As these riverine threads that tied the ice sheets to the sea were stretched, severed, and restructured, they also shrank and swelled with the pulse of meltwater inputs and time-varying drainage basin areas, and sometimes delivered enough meltwater to the oceans in the right places to influence global climate. Here I present a general method to compute past river flow paths, drainage basin geometries, and river discharges, by combining models of past ice sheets, glacial isostatic adjustment, and climate. The result is a time series of synthetic paleohydrographs and drainage basin maps from the Last Glacial Maximum to present for nine major drainage basins – the Mississippi, Rio Grande, Colorado, Columbia, Mackenzie, Hudson Bay, Saint Lawrence, Hudson, and Susquehanna/Chesapeake Bay. These are based on five published reconstructions of the North American ice sheets. I compare these maps with drainage reconstructions and discharge histories based on a review of observational evidence, including river deposits and terraces, isotopic records, mineral provenance markers, glacial moraine histories, and evidence of ice stream and tunnel valley flow directions. The sharp boundaries of the reconstructed past drainage basins complement the flexurally smoothed GIA signal that is more often used to validate ice-sheet reconstructions, and provide a complementary framework to reduce nonuniqueness in model reconstructions of the North American ice-sheet complex.

scholarly journals The Use of Heap Bioleaching as a Pre-Treatment for Platinum Group Metal Leaching

2017 ◽  
Vol 262 ◽  
pp. 151-154
Author(s):  
James M. Mwase ◽  
Jochen Petersen
Keyword(s):  
Platinum Group Metal ◽  
Metal Leaching ◽  
Flotation Concentrate ◽  
Group Metal ◽  
Two Samples ◽  
Heap Bioleaching ◽  
Mineral Recovery ◽  
The Difference ◽  
Pre Treatment

Two samples, a Platreef flotation concentrate and coarse ore (<6 mm), were column bioleached at 65°C using a culture dominated by Metallosphaera hakonensis. Based on solution assays, extractions in excess of 90% Cu and Ni were achieved from the flotation concentrate, while from the coarse ore 96% Cu and 67% Ni extractions were achieved. The difference in extraction levels and leaching patterns despite identical conditions used for both samples is discussed, as is the performance of the samples during a follow-up leach step using cyanide to extract the PGMs in a separate column leach experiment. While the recovery of Pd and Au was excellent during these steps, recovery of Pt was limited to 35% after 45 days for the concentrate and 56% after 60 days for the whole ore material, primarily due to the presence of a refractory Pt mineral. Recovery from a concentrate without pre-treatment was substantially lower.

Peak runoff simulation in a subarctic region

1976 ◽  
Vol 3 (4) ◽  
pp. 555-562
Author(s):  
J. Penel ◽  
T. Kung
Keyword(s):  
Meteorological Parameters ◽  
Drainage Basin ◽  
Flow Simulation ◽  
Drainage Basins ◽  
Runoff Simulation ◽  
Subarctic Region ◽  
Physical Conditions ◽  
Spring Peak ◽  
Peak Runoff ◽  
Peak Discharges

Due to the lack of stream guaging stations, a peak flow simulation based on physical and meteorological parameters was established for the area along the proposed Mackenzie Valley Highway between Fort Good Hope and the Dempster Highway.Calculations based on snowmelt and rain-on-snow runoff were developed, as it was found that the snowmelt of May or early June gave the yearly spring peak discharge.Due to the gap in existing flow data, a unit hydrograph method was developed to generate additional yearly spring peak discharges. Altogether, hydrographs from four gauged watersheds of similar physical conditions with size ranging from 250 to 8 200 mi2 (648 to 21 240 km2) were used. In total, 46 yearly peak flows were generated.A regression equation of peak discharge computation was derived, using different hydrological and meteorological parameters. It was found that the most significant factors were the drainage basin area, the lake areas in the drainage basin, the water equivalent of the snow on the ground prior to melt, the rainfall in the period close to peak discharges, and the duration of snowmelt.The simulation was calibrated for drainage basins between 100 and 10 000 mi2 (250 to 25 000 km2).

Reconstructing provenance changes in sediments supplying the South East African margin

2021 ◽  
Author(s):  
Ellie Pryor ◽  
Ian Hall ◽  
Morten Andersen ◽  
Daniel Babin ◽  
Yue (Merry) Cai ◽  
...  
Keyword(s):  
South African ◽  
Marine Sediment ◽  
River Sediment ◽  
Middle Stone Age ◽  
Source Rocks ◽  
Drainage Basins ◽  
Sediment Samples ◽  
Terrigenous Sediment ◽  
Geological Unit ◽  
Spatial Coverage

&lt;div&gt; &lt;p&gt;Sediment provenance is of key importance for understanding transport history and characterising sediment source regions in the marine and terrestrial environment. Radiogenic isotopes are widely used to identify inland and coastal sediment origins. They document changes in detrital terrigenous sediment fluxes which can be related to continental hydrological variability. Understanding sediment sources to the ocean is a pre-requisite before interpreting past climate archives in marine sediment cores.&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;South African coastal drainage basins are composed of various geological units, each reflected by different radiogenic isotope signals in the sediment. In addition to the age and nature of their source rocks, the sediment type influences this radiogenic signature.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;Here, we present a review of the present-day radiogenic isotopic fingerprints of South African river catchments signals from new river sediment samples with the aim to gain a broad spatial coverage of the source rocks in the region and their relative contributions of terrigenous sediment delivered to the ocean. This information will be applied to marine sediment core MD20-3591 (36&amp;#176; 43.707 S; 22&amp;#176; 9.151 E, water depth 2464m), located offshore South Africa which has the potential to record both Agulhas Current and terrestrial variability. The core site receives a significant amount of terrigenous material from the African continents via riverine input. During the last glacial period, these rivers flowed across the continental shelf within a subdued incised valley. The Gourritz River catchment drains the Cape Supergroup and Karoo Supergroup, typical of these southern drainage basins, whereas the eastern Cape rivers drain the Karoo Supergroup geological unit which is capped by the Drakensberg basalts.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;&lt;div&gt; &lt;p&gt;&lt;span&gt;We are using the knowledge gained from these new South African terrestrial river sediment samples to identify the sources and transport pathways of the terrigenous sediments in MD20-3591. Of particular interest is the sensitivity of the radiogenic isotopic signatures to grain size variabilities and how this relationship can help to define local or distal sediments. These records will allow us to explore variability in regional hydroclimate in relation to the abundant archaeological evidence of cultural and technological innovations of Middle Stone Age humans in southern Africa.&lt;/span&gt;&lt;/p&gt; &lt;/div&gt;

Cyprinid Fishes: An Overview on the Present Status in Meghalaya, India

2020 ◽  
Vol 7 (1) ◽  
pp. 13-22
Author(s):  
Rupak Nath ◽  
◽  
S M Kharbuli
Keyword(s):  
Drainage Basin ◽  
Diversity Indices ◽  
Drainage Basins ◽  
Lower Elevation ◽  
Occasional Occurrence ◽  
Elevation Zone ◽  
Commercially Important ◽  
Cyprinid Fishes ◽  
Catch Composition ◽  
Rivers And Reservoirs

Cyprinid fishes of Meghalaya were investigated from twin drainage basins Brahmaputra and Barak-Surma-Meghna. 27 cyprinid fishes under 14 genus and 7 sub families were recorded from rivers and reservoirs of four different gradient zones. The diversity of Cyprinid fishes was highest with 49% representation of Cyprinids at lower elevation Zone IV below 500 m above MSL and bio diversity indices estimated as H: 3.05, 1-D: 0.10. In contrary lowest diversity with 7% representation of fishes was observed at elevation 1501 to 2000 m above MSL in Zone I with bio diversity indices H: 0.25, 1-D: 0.57. Distribution of commercially important cyprinids under genus Labeo, Systomus and Cirrhinus were found to be restricted to rivers of Barak-Surma-Meghna drainage basin. Catch percentage of cyprinids indicates that 70% of fishes exhibit occasional occurrence and 30% as common occurrence. High percentage of occasional occurrence, low catch composition percentage and with restricted distribution of commercially important fishes to only certain rivers of Barak-Surma-Meghna drainage is an indication of depletion of cyprinid resources in the state and requires taking multi prong conservation measures to protect cyprinid fishes in Meghalaya.

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