Basin-scale availability of salmonid spawning gravel as influenced by channel type and hydraulic roughness in mountain catchments

2004 ◽  
Vol 61 (11) ◽  
pp. 2085-2096 ◽  
Author(s):  
John M Buffington ◽  
David R Montgomery ◽  
Harvey M Greenberg
Keyword(s):  
Grain Size ◽  
Spatial Pattern ◽  
Pacific Northwest ◽  
General Framework ◽  
Spawning Habitat ◽  
Hydraulic Roughness ◽  
Digital Elevation ◽  
Basin Scale ◽  
Study Sites ◽  
Channel Type

A general framework is presented for examining the effects of channel type and associated hydraulic roughness on salmonid spawning-gravel availability in mountain catchments. Digital elevation models are coupled with grain-size predictions to provide basin-scale assessments of the potential extent and spatial pattern of spawning gravels. To demonstrate both the model and the significance of hydraulic roughness, we present a scenario for optimizing the spatial extent of spawning gravels as a function of channel type in Pacific Northwest catchments. Predictions indicate that hydraulic roughness could control more than 65% of the potential available spawning habitat at our study sites. Results further indicate that bar roughness can be important for maintaining spawning gravels in lower mainstem reaches, while wood roughness may be required for spawning-gravel maintenance in steeper, upper mainstem channels. Our analysis indicates that wood loss and consequent textural coarsening could deplete up to one third of the potentially usable spawning area at our study sites.

scholarly journals Heterogeneous spatial and temporal pattern of surface elevation change and mass balance of the Patagonian ice fields between 2000 and 2016

2019 ◽  
Vol 13 (9) ◽  
pp. 2511-2535 ◽  
Author(s):  
Wael Abdel Jaber ◽  
Helmut Rott ◽  
Dana Floricioiu ◽  
Jan Wuite ◽  
Nuno Miranda
Keyword(s):  
Spatial Pattern ◽  
Mass Balance ◽  
Temporal Trend ◽  
Sar Interferometry ◽  
Surface Elevation ◽  
Radar Signal ◽  
Elevation Change ◽  
Mass Losses ◽  
Digital Elevation ◽  
Surface Elevation Change

Abstract. The northern and southern Patagonian ice fields (NPI and SPI) have been subject to accelerated retreat during the last decades, with considerable variability in magnitude and timing among individual glaciers. We derive spatially detailed maps of surface elevation change (SEC) of NPI and SPI from bistatic synthetic aperture radar (SAR) interferometry data of the Shuttle Radar Topography Mission (SRTM) and TerraSAR-X add-on for Digital Elevation Measurements (TanDEM-X) for two epochs, 2000–2012 and 2012–2016, and provide data on changes in surface elevation and ice volume for the individual glaciers and the ice fields at large. We apply advanced TanDEM-X processing techniques allowing us to cover 90 % and 95 % of the area of NPI and 97 % and 98 % of SPI for the two epochs, respectively. Particular attention is paid to precisely co-registering the digital elevation models (DEMs), accounting for possible effects of radar signal penetration through backscatter analysis and correcting for seasonality biases in case of deviations in repeat DEM coverage from full annual time spans. The results show a different temporal trend between the two ice fields and reveal a heterogeneous spatial pattern of SEC and mass balance caused by different sensitivities with respect to direct climatic forcing and ice flow dynamics of individual glaciers. The estimated volume change rates for NPI are -4.26±0.20 km3 a−1 for epoch 1 and -5.60±0.74 km3 a−1 for epoch 2, while for SPI these are -14.87±0.52 km3 a−1 for epoch 1 and -11.86±1.99 km3 a−1 for epoch 2. This corresponds for both ice fields to an eustatic sea level rise of 0.048±0.002 mm a−1 for epoch 1 and 0.043±0.005 mm a−1 for epoch 2. On SPI the spatial pattern of surface elevation change is more complex than on NPI and the temporal trend is less uniform. On terminus sections of the main calving glaciers of SPI, temporal variations in flow velocities are a main factor for differences in SEC between the two epochs. Striking differences are observed even on adjoining glaciers, such as Upsala Glacier, with decreasing mass losses associated with slowdown of flow velocity, contrasting with acceleration and increase in mass losses on Viedma Glacier.

Accuracy Analysis of DEM Based on Coons Surface

2011 ◽  
Vol 65 ◽  
pp. 214-217
Author(s):  
Yao Ge Wang ◽  
Peng Yuan Wang
Keyword(s):  
Spatial Pattern ◽  
Spatial Autocorrelation ◽  
Boundary Curve ◽  
Digital Elevation ◽  
Grid Points ◽  
Elevation Model ◽  
Global Spatial Autocorrelation ◽  
Core Problem ◽  
Dem Model ◽  
Better Than

Interpolation is the core problem of Digital Elevation Model (DEM). The Coons DEM model is better than bilinear interpolation and moving surface fitting. It is constructed by grid boundary curve, the curve interpolates by some adjoining grid points. Its spatial pattern of error is random in global area, there is no significant global spatial autocorrelation, but it is an increasing trend along with the terrain average gradient increases.There is significant local spatial autocorrelation, the spatial pattern of error converges strongly in local areas.

RUSLE Model based Assessment of Soil Erosion in Parbati River Basin, Central India using Google Earth Engine and GIS

2021 ◽  
Author(s):  
Rohit Kumar ◽  
Benidhar Deshmukh ◽  
Kiran Sathunuri
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
Spatial Pattern ◽  
River Basin ◽  
Soil Loss ◽  
Google Earth ◽  
Rusle Model ◽  
High Soil ◽  
Basin Scale ◽  
Google Earth Engine

<p>Land degradation is a global concern posing significant threat to sustainable development. One of its major aspects is soil erosion, which is recognised as one of the critical geomorphic processes controlling sediment budget and landscape evolution. Natural rate of soil erosion is exacerbated due to anthropogenic activities that may lead to soil infertility. Therefore, assessment of soil erosion at basin scale is needed to understand its spatial pattern so as to effectively plan for soil conservation. This study focuses on Parbati river basin, a major north flowing cratonic river and a tributary of river Chambal to identify erosion prone areas using RUSLE model. Soil erodibility (K), Rainfall erosivity (R), and Topographic (LS) factors were derived from National Bureau of Soil Survey and Land Use Planning, Nagpur (NBSS-LUP) soil maps, India Meteorological Department (IMD) datasets, and SRTM30m DEM, respectively in GIS environment. The crop management (C) and support practice (P) factors were calculated by assigning appropriate values to Land use /land cover (LULC) classes derived by random forest based supervised classification of Sentinel-2 level-1C satellite remote sensing data in Google Earth Engine platform. High and very high soil erosion were observed in NE and NW parts of the basin, respectively, which may be attributed to the presence of barren land, fallow areas and rugged topography. The result reveals that annual rate of soil loss for the Parbati river basin is ~319 tons/ha/yr (with the mean of 1.2 tons/ha/yr). Lowest rate of soil loss (i.e. ~36 tons/ha/yr with mean of 0.22 tons/ha/yr) has been observed in the open forest class whereas highest rate of soil loss (i.e. ~316 tons/ha/yr with mean of 32.08 tons/ha/yr) have been observed in gullied area class. The study indicates that gullied areas are contributing most to the high soil erosion rate in the basin. Further, the rate of soil loss in the gullied areas is much higher than the permissible value of 4.5–11 tons/ha/yr recognized for India. The study helps in understanding spatial pattern of soil loss in the study area and is therefore useful in identifying and prioritising erosion prone areas so as to plan for their conservation.</p>

scholarly journals Predicted ripple dimensions in relation to the precision of in situ measurements

2016 ◽  
Author(s):  
Knut Krämer ◽  
Christian Winter
Keyword(s):  
Dynamic Evolution ◽  
Sediment Properties ◽  
Hydraulic Roughness ◽  
Empirical Relations ◽  
Digital Elevation ◽  
Shelf Sea ◽  
Waves And Currents ◽  
Order Of Magnitude ◽  
Accuracy Of Measurement

Abstract. Ripples are common morphological features in sandy marine environments. Their shapes and dimensions are closely related to local sediment properties and the forcing by waves and currents. Numerous predictors for the geometry and hydraulic roughness of ripples exist but due to their empirical nature, they may fail to properly reflect conditions in the field. Here, situ measurements of ripple dimensions and their dynamics in a shallow shelf sea are reported. Technical and methodological limits of the detection of ripple dimensions and their dynamic evolution due to changing forcing are assessed. Methods of bed detection from sonar data and analysis of ripple dimensions in digital elevation models (DEM) are compared and evaluated. The range of measured ripple dimensions is quantified and compared to results of traditional and recent empirical predictors. The precision of measurements of bedform dimensions is taken as the repeatability of a measurement for inactive conditions and the accuracy of measurement is assessed via comparison to predicted dimensions. The precision of detection is limited to 10 % of the absolute ripple dimensions. The order of magnitude of the ripple dimension can be predicted by the empirical relations. However, these tend to return the height of the largest ripples rather than average heights. The application of different methods for detection of heights may result in derived form roughness heights by up to a factor of two.

scholarly journals A Framework for Correcting Ionospheric Artifacts and Atmospheric Effects to Generate High Accuracy InSAR DEM

2020 ◽  
Vol 12 (2) ◽  
pp. 318 ◽  
Author(s):  
Zhiwei Liu ◽  
Cui Zhou ◽  
Haiqiang Fu ◽  
Jianjun Zhu ◽  
Tingying Zuo
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Atmospheric Effects ◽  
Interferometric Synthetic Aperture Radar ◽  
Dual Polarization ◽  
Digital Elevation ◽  
Split Spectrum ◽  
Dem Accuracy ◽  
Study Sites ◽  
Aperture Radar

Repeat-pass interferometric synthetic aperture radar is a well-established technology for generating digital elevation models (DEMs). However, the interferogram usually has ionospheric and atmospheric effects, which reduces the DEM accuracy. In this paper, by introducing dual-polarization interferograms, a new approach is proposed to mitigate the ionospheric and atmospheric errors of the interferometric synthetic aperture radar (InSAR) data. The proposed method consists of two parts. First, the range split-spectrum method is applied to compensate for the ionospheric artifacts. Then, a multiresolution correlation analysis between dual-polarization InSAR interferograms is employed to remove the identical atmospheric phases, since the atmospheric delay is independent of SAR polarizations. The corrected interferogram can be used for DEM extraction. Validation experiments, using the ALOS-1 PALSAR interferometric pairs covering the study areas in Hawaii and Lebanon of the U.S.A., show that the proposed method can effectively reduce the ionospheric artifacts and atmospheric effects, and improve the accuracy of the InSAR-derived DEMs by 64.9% and 31.7% for the study sites in Hawaii and Lebanon of the U.S.A., respectively, compared with traditional correction methods. In addition, the assessment of the resulting DEMs also includes comparisons with the high-precision Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) altimetry data. The results show that the selection of reference data will not affect the validation results.

scholarly journals The Hydro-Isostatic Rebound Related to Megalake Chad (Holocene, Africa): First Numerical Modelling and Significance for Paleo-Shorelines Elevation

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3180
Author(s):  
Anthony Mémin ◽  
Jean-François Ghienne ◽  
Jacques Hinderer ◽  
Claude Roquin ◽  
Mathieu Schuster
Keyword(s):  
Central Africa ◽  
Earth Model ◽  
Lake Chad ◽  
Digital Elevation ◽  
Basin Scale ◽  
Drying Up ◽  
Successful Approach ◽  
Differential Uplift ◽  
Sahel Region ◽  
The Impact

Lake Chad, the largest freshwater lake of north-central Africa and one of the largest lakes of Africa, is the relict of a giant Quaternary lake (i.e., Megalake Chad) that developed during the early- to mid-Holocene African Humid Period. Over the drylands of the Sahara Desert and the semi-arid Sahel region, remote sensing (optical satellite imagery and digital elevation models) proved a successful approach to identify the paleo-shorelines of this giant paleo-lake. Here we present the first attempt to estimate the isostatic response of the lithosphere due to Megalake Chad and its impact on the elevation of these paleo-shorelines. For this purpose, we use the open source TABOO software (University of Urbino, Italy) and test four different Earth models, considering different parameters for the lithosphere and the upper mantle, and the spatial distribution of the water mass. We make the simplification of an instantaneous drying-up of Megalake Chad, and compute the readjustment related to this instant unload. Results (i.e., duration, amplitude, and location of the deformation) are then discussed in the light of four key areas of the basin displaying prominent paleo-shoreline morpho-sedimentary features. Whatever the Earth model and simplification involved in the simulations, this work provides a strong first-order evaluation of the impact on hydro-isostasy of Megalake Chad. It demonstrates that a water body similar to this megalake would induce a significant deformation of the lithosphere in the form of a vertical differential uplift at basin-scale reaching up to 16 m in the deepest part of the paleo-lake, and its shorelines would then be deflected from 2 m (southern shorelines) to 12 m (northern shorelines), with a maximum rate of more than 1 cm y−1. As such, any future study related to the paleo-shorelines of Megalake Chad, should integrate such temporal and spatial variation of their elevations.

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