3 4Accurate, precise and rapid acquisition of topographic data is fundamental to many 5 sub-disciplines of physical geography. Technological developments over the past few 6 decades have made fully distributed data sets of centimetric resolution and accuracy 7commonplace; yet the emergence of Structure from Motion (SfM) with Multi-View 8 Stereo (MVS) in recent years has revolutionised three-dimensional topographic surveys 9in physical geography by democratising data collection and processing. SfM-MVS 10 originates from the fields of computer vision and photogrammetry, requires minimal 11 expensive equipment or specialist expertise, and under certain conditions can produce 12 point clouds of comparable quality to existing survey methods (e.g. Terrestrial Laser 13 Scanning). Consequently, applications of SfM-MVS in physical geography have 14 multiplied rapidly. There are many practical options available to physical geographers 15 when planning a SfM-MVS survey (e.g. platforms, cameras, software); yet, many 16 focused SfM-MVS end-users are uncertain as to the errors associated with each choice 17 and, perhaps most fundamentally, the processes actually taking place as part of the 18 SfM-MVS workflow. This paper details the typical workflow applied by SfM-MVS 19 software packages, reviews practical details of implementing SfM-MVS, combines 20 existing validation studies to assess practically achievable data quality and reviews the 21 Real-time kinetic (RTK) surveys are commonplace in physical geography where a direct 113

. (2013) 'Concepts of hydrological connectivity : research approaches, pathways and future agendas.', Earth-science reviews., 119 . pp. 17-34. Further information on publisher's website:http://dx.doi.org/10.1016/j.earscirev.2013.02.001Publisher's copyright statement: NOTICÅ: this is the author's version of a work that was accepted for publication in Earth-Science Reviews. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Earth-Science Reviews, 119, 2013Reviews, 119, , 10.1016Reviews, 119, /j.earscirev.2013.001. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. to direct future research into process-based hydrological connectivity this paper: i) evaluates the 20 extent to which different concepts of hydrological connectivity have emerged from different 21 approaches to measure and predict flow in different environments; ii) discusses the extent to which 22 these different concepts are mutually compatible; and iii) assesses further research to contribute to 23 a unified understanding of hydrological processes. Existing research is categorised into five different 24 approaches to investigating hydrological connectivity: i) evaluating soil -moisture patterns (soil-25 moisture connectivity); ii) understanding runoff patterns and processes on hillslopes (flow -process 26 connectivity); iii) investigating topographic controls (terrain-connectivity) including the impact of 27 road networks on hydrological connectivity and catchment runoff; iv) developing models to explore 28 and predict hydrological connectivity; and v) developing indices of hydrological connectivity . Analysis 29 of published research suggests a relationship between research group, approach, geographic setting 30 and the interpretation of hydrological connectivity. To further understanding of hydrological 31 connectivity our knowledge needs to be developed using a range of techniques and approaches, 32 there should be common understandings between researchers approaching the concept from 33 different perspectives, and these meanings need to be communicated effectively with those 34 responsible for land management. 35 36

Article:James, MR, Robson, S and Smith, MW orcid.org/0000-0003-4361-9527 (2017) 3-D uncertainty-based topographic change detection with structure-from-motion photogrammetry: precision maps for ground control and directly georeferenced surveys. Earth Surface Processes and Landforms, 42 (12). pp. 1769 -1788 https://doi.org/10.1002/esp.4125 © 2017, Wiley. This is the peer reviewed version of the following article: "James, M. R., Robson, S., and Smith, M. W. (2017) 3-D uncertainty-based topographic change detection with structure-from-motion photogrammetry: precision maps for ground control and directly georeferenced surveys. Earth Surf. Process. Landforms" which has been published in final form at http://doi.org/10.1002/esp.4125. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. , et al., 2013), which is particularly valuable for complex 24 topography. We introduce this method by: (1) using simulated UAV surveys, 25 2 processed in photogrammetric software, to illustrate the spatial variability of precision 26 and the relative influences of photogrammetric (e.g. image network geometry, tie 27 point quality) and georeferencing (e.g. control measurement) considerations; (2) we 28 then present a new Monte Carlo procedure for deriving this information using 29 standard SfM software and integrate it into confidence-bounded change detection; 30 before (3) demonstrating geomorphological application in which we use benchmark 31 TLS data for validation and then estimate sediment budgets through differencing 32 annual SfM surveys of an eroding badland. We show how 3-D precision maps 33 enable more probable erosion patterns to be identified than existing analyses, and 34 how a similar overall survey precision could have been achieved with direct survey 35 georeferencing for camera position data with precision half as good as the GCPs'. 36Where precision is limited by weak georeferencing (e.g. camera positions with multi-37 metre precision, such as from a consumer UAV), then overall survey precision can 38 scale as n -½ of the control precision (n = number of images). Our method also 39 D...

In the last decade advances in surveying technology have opened up the possibility of representing topography and monitoring surface changes over experimental plots (<10 m2) in high resolution (~103 points m‐1). Yet the representativeness of these small plots is limited. With ‘Structure‐from‐Motion’ (SfM) and ‘Multi‐View Stereo’ (MVS) techniques now becoming part of the geomorphologist's toolkit, there is potential to expand further the scale at which we characterise topography and monitor geomorphic change morphometrically. Moving beyond previous plot‐scale work using Terrestrial Laser Scanning (TLS) surveys, this paper validates robustly a number of SfM‐MVS surveys against total station and extensive TLS data at three nested scales: plots (<30 m2) within a small catchment (4710 m2) within an eroding marl badland landscape (~1 km2). SfM surveys from a number of platforms are evaluated based on: (i) topography; (ii) sub‐grid roughness; and (iii) change‐detection capabilities at an annual scale. Oblique ground‐based images can provide a high‐quality surface equivalent to TLS at the plot scale, but become unreliable over larger areas of complex terrain. Degradation of surface quality with range is observed clearly for SfM models derived from aerial imagery. Recently modelled ‘doming’ effects from the use of vertical imagery are proven empirically as a piloted gyrocopter survey at 50m altitude with convergent off‐nadir imagery provided higher quality data than an Unmanned Aerial Vehicle (UAV) flying at the same height and collecting vertical imagery. For soil erosion monitoring, SfM can provide data comparable with TLS only from small survey ranges (~5 m) and is best limited to survey ranges ~10–20 m. Synthesis of these results with existing validation studies shows a clear degradation of root‐mean squared error (RMSE) with survey range, with a median ratio between RMSE and survey range of 1:639, and highlights the effect of the validation method (e.g. point‐cloud or raster‐based) on the estimated quality. Copyright © 2015 John Wiley & Sons, Ltd.

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6The dynamics of supraglacial pond development in the Everest region are not well 7 constrained at a glacier scale, despite their known importance for meltwater storage, 8 promoting ablation, and transmitting thermal energy englacially during drainage events. 9Here, we use fine-resolution (~ 0.5 -2 m) satellite imagery to reveal the spatiotemporal 10 dynamics of 9,340 supraglacial ponds across nine glaciers in the Everest region, ~2000 -11 2015. Six of our nine study glaciers displayed a net increase in ponded area over their 12 observation periods. However, large inter-and intra-annual changes in ponded area were 13 observed of up to 17 % (Khumbu Glacier), and 52 % (Ama Dablam) respectively. 14 Additionally, two of the fastest expanding lakes (Spillway and Rongbuk) partially drained 15 over our study period. The Khumbu Glacier is developing a chain of connected ponds in the 16 lower ablation area, which is indicative of a trajectory towards large lake development. We 17show that use of medium-resolution imagery (e.g. 30 m Landsat) is likely to lead to large 18 classification omissions of supraglacial ponds, on the order of 15 -88 % of ponded area, and 19 77 -99 % of the total number of ponds. Fine-resolution imagery is therefore required if the 20 full spectrum of ponds that exist on the surface of debris-covered glaciers are to be analysed. 21

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This paper presents new methods of estimating the aerodynamic roughness (z 0 ) of glacier ice directly from three-dimensional point clouds and digital elevation models (DEMs), examines temporal variability of z 0 , and presents the first fully distributed map of z 0 estimates across the ablation zone of an Arctic glacier. The aerodynamic roughness of glacier ice surfaces is an important component of energy balance models and meltwater runoff estimates through its influence on turbulent fluxes of latent and sensible heat. In a warming climate these fluxes are predicted to become more significant in contributing to overall melt volumes. Ice z 0 is commonly estimated from measurements of ice surface microtopography, typically from topographic profiles taken perpendicular to the prevailing wind direction. Recent advances in surveying permit rapid acquisition of high-resolution topographic data allowing revision of assumptions underlying conventional z 0 measurement. Using Structure from Motion (SfM) photogrammetry with Multi-View Stereo (MVS) to survey ice surfaces with millimeter-scale accuracy, z 0 variation over 3 orders of magnitude was observed. Different surface types demonstrated different temporal trajectories in z 0 through 3 days of intense melt. A glacier-scale 2 m resolution DEM was obtained through terrestrial laser scanning (TLS), and subgrid roughness was significantly related to plot-scale z 0 . Thus, we show for the first time that glacier-scale TLS or SfM-MVS surveys can characterize z 0 variability over a glacier surface potentially leading to distributed representations of z 0 in surface energy balance models.