Daniel Edward James Hobley

Cardiff University | CU · School of Earth and Ocean Sciences

Large earthquakes rapidly denude hillslopes by triggering thousands of coseismic landslides. The sediment produced by these landslides is initially quickly mobilised from the landscape by an interconnected cascade of processes. This cascade can dramatically but briefly enhance local erosion rates. Hillslope and channel processes, such as landslidin...

Mass movement deposit grain‐size distributions (GSDs) record initiation, transport, and deposition mechanisms, and contribute to the rate at which sediment is exported from hillslopes to channels. Defining the GSD of a mass movement deposit is a significant challenge because they are often difficult to access, are heterogeneous in planform and with...

Dryland regions are characterised by water scarcity and are facing major challenges under climate change. One difficulty is anticipating how rainfall will be partitioned into evaporative losses, groundwater, soil moisture, and runoff (the water balance) in the future, which has important implications for water resources and dryland ecosystems. Howe...

Study region Little Kinyasungwe River Catchment, central semi-arid Tanzania. Study focus The structure and hydraulic properties of superficial geology can play a crucial role in controlling groundwater recharge in drylands. However, the pathways by which groundwater recharge occurs and their sensitivity to environmental change remain poorly resolv...

Large earthquakes cause rapid denudation of hillslopes by triggering thousands of coseismic landslides. The sediment produced by these landslides is initially mobilised out of the landscape as a cascade of unknown magnitude. This cascade dramatically enhances local erosion rates before rapidly returning to pre-earthquake levels. Identifying the ind...

Dryland regions are characterized by water scarcity and are facing major challenges under climate change. One difficulty is anticipating how rainfall will be partitioned into evaporative losses, groundwater, soil moisture and runoff (the water balance) in the future, which has important implications for water resources and dryland ecosystems. Howev...

Individual, large thrusting earthquakes can cause hundreds to thousands of years of exhumation in a geologically instantaneous moment through landslide generation. The bedrock landslides generated are important weathering agents through the conversion of bedrock into mobile regolith. Despite this, orogen-scale records of surface uplift and exhumati...

Numerical simulation of the form and characteristics of Earth's surface provides insight into its evolution. Landlab is an open-source Python package that contains modularized elements of numerical models for Earth's surface, thus reducing time required for researchers to create new or reimplement existing models. Landlab contains a gridding engine...

Abstract. Numerical simulation of the form and characteristics of Earth's surface provides insight into its evolution. Landlab is an Open Source Python package that contains modularized elements of numerical models for Earth's surface, thus reducing time required for researchers to create new or reimplement existing models. Landlab contains a gridd...

Facets formed along the footwalls of active normal‐fault blocks display a variety of longitudinal profile forms, with variations in gradient, shape, degree of soil cover, and presence or absence of a slope break at the fault trace. We show that a two‐dimensional, process‐oriented cellular automaton model of facet profile evolution can account for t...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Abstract. Individual, large thrusting earthquakes can cause hundreds to thousands of years of exhumation in a geologically instantaneous moment through landslide generation. The bedrock landslides generated are important weathering agents through the conversion of bedrock into mobile sediment. Despite this, records of surface uplift and exhumation...

Quantifying the sediment cascade of the Wenchuan earthquake. Large infrequent earthquakes can produce tens of thousands of landslides, equalling half a century of erosion, in an instant. All this loose sediment eventually ends up in the channel network and eroded out of the mountain range, but the processes of the remobilisation and their timescale...

Earthquakes alter the topography of mountain ranges by shortening and thickening the crust, while also causing erosion via co-seismic landsliding. For single large (>Mw7) earthquakes, co-seismic landslide volumes can exceed the volume of rock uplifted by the earthquake. Hence, large earthquakes are hypothesised to generate rock uplift, but minimal...

Knowledge infrastructure is an intellectual framework for creating, sharing, and distributing knowledge. In this paper, we use knowledge infrastructure to address common barriers to entry into numerical modeling in Earth sciences as demonstrated in three computational narratives: physical process modeling education, replicating published model resu...

On Earth, the sublimation of massive ice deposits at equatorial latitudes under cold and dry conditions in the absence of any liquid melt leads to the formation of spiked and bladed textures eroded into the surface of the ice. These sublimation-sculpted blades are known as penitentes. For this process to take place on another planet, the ice must b...

Assessments of water balance changes, watershed response, and landscape evolution to climate change require representation of spatially and temporally varying rainfall fields over a drainage basin, as well as the flexibility to simply modify key driving climate variables (evaporative demand , overall wetness, storminess). An empirical-stochastic ap...

This paper describes and explores a new continuous-time stochastic cellular automaton model of hillslope evolution. The Grain Hill model provides a computational framework with which to study slope forms that arise from stochastic disturbance and rock weathering events. The model operates on a hexagonal lattice, with cell states representing fluid,...

Assessments of water balance, watershed response, and landscape evolution to climate change require representation of spatially and temporally varying rainfall fields over a drainage basin, as well as the flexibility to simply modify key driving climate variables (evaporative demand, overall wetness, storminess). An empirical-stochastic approach to...

The volume associated with the extensive landsliding associated with the Mw 7.9 Wenchuan earthquake is thought to match the volume of crust added to the Longmen Shan region by the earthquake. This observation, along with similar observations from the Mw 7.6 Chi Chi and other large continental earthquakes have led to the suggestion that large earthq...

This paper describes and explores a new continuous-time stochastic cellular automaton model of hillslope evolution. The Grain Hill model provides a computational framework with which to study slope forms that arise from stochastic disturbance and rock weathering events. The model operates on a hexagonal lattice, with cell states representing fluid,...

Quantifying off-fault deformation (OFD) rates on geomorphic time scales (10²-10⁵ yr) along strike-slip faults is critical for resolving discrepancies between geologic and geodetic slip-rate estimates, improving knowledge of seismic hazard, and understanding the influence of tectonic motion on landscapes. Quantifying OFD over these time scales is ch...

Stepped fan deposits and phyllosilicate mineralogies are relatively common features on Mars but have not previously been found in association with each other. Both of these features are widely accepted to be the result of aqueous processes, but the assumed role and nature of any water varies. In this study we have investigated two stepped fan depos...

Representation of flowing water in landscape evolution models (LEMs) is often simplified compared to hydrodynamic models, as LEMs make assumptions reducing physical complexity in favor of computational efficiency. The Landlab modeling framework can be used to bridge the divide between complex runoff models and more traditional LEMs, creating a new...

The ability to model surface processes and to couple them to both subsurface and atmospheric regimes has proven invaluable to research in the Earth and planetary sciences. However, creating a new model typically demands a very large investment of time, and modifying an existing model to address a new problem typically means the new work is constrai...

Tectonic displacement of drainage divides and the consequent deformation of river networks during crustal shortening have been proposed for a number of mountain ranges, but never tested. In order to preserve crustal strain in surface topography, surface displacements across thrust faults must be retained without being recovered by consequent erosio...

Hydrologic models and modeling components are used in a wide range of applications. Rainfall-runoff models are used to investigate the evolution of hydrologic variables, such as soil moisture and surface water discharge, throughout one or more rainfall events. Longer-term landscape evolution models also include aspects of hydrology, albeit in a hig...

The ability to model surface processes and to couple them to both subsurface and atmospheric regimes has proven invaluable to research in the Earth and planetary sciences. However, creating a new model typically demands a very large investment of time, and modifying an existing model to address a new problem typically means the new work is constrai...

Debris flows are a typical hazard on steep slopes after wildfire, but unlike debris flows that mobilize from landslides, most post-wildfire debris flows are generated from water runoff. The majority of existing debris-flow modeling has focused on landslide-triggered debris flows. In this study we explore the potential for using process-based rainfa...

Arid and semi-arid grasslands of southwestern United States have changed dramatically over the last 150 years due to woody plant encroachment. Driven by overgrazing, reduced fire frequency, and climate change, shrub encroachment is considered as a major form of desertification. In Landlab we represent ecohydrologic plant dynamics, fires, grazing, a...

Along a 200 km transect of the Atacama Desert in northern Chile a series of mudflow-dominated alluvial fans derive from the volcanic Andean foothills, flowing onto the hyperarid interior basin at about 1100 m elevation. The fan systems, centered at about 20.5°S, 69.4ºW are active at about decadal frequency. Individual flows extend 20-30 km across t...

CellLab-CTS 2015 is a Python-language software library for creating two-dimensional, continuous-time stochastic (CTS) cellular automaton models. The model domain consists of a set of grid nodes, with each node assigned an integer state code that represents its condition or composition. Adjacent pairs of nodes may undergo transitions to different st...

Many semiarid and desert ecosystems are characterized by patchy and dynamic vegetation. Topography plays a commanding role on vegetation patterns. It is observed that plant biomes and biodiversity vary systematically with slope and aspect, from shrublands in low desert elevations, to mixed grass/shrublands in mid elevations, and forests at high ele...

CellLab-CTS 2015 is a Python-language software library for creating two-dimensional, continuous-time stochastic (CTS) cellular automaton models. The model domain consists of a set of grid nodes, with each node assigned an integer state-code that represents its condition or composition. Adjacent pairs of nodes may undergo transitions to different st...

Understanding the incomplete nature of the stratigraphic record is fundamental for interpreting stratigraphic sequences. Methods for quantifying stratigraphic completeness for one-dimensional stratigraphic columns, defined as the proportion of time intervals of some length that contain stratigraphy, are commonplace; however, quantitative assessment...

In arid and semi-arid regions, geomorphic response of a catchment is tightly coupled with Eco-hydrologic dynamics. Climate-driven biotic and abiotic processes strongly influence land-surface-atmosphere interactions and thus play an important role in landscape evolution. Landscape Evolution Models (LEMs) provide a platform for scientists to quantita...

The deflated surfaces of the alluvial fans in Saheki crater reveal the most detailed record of fan stratigraphy and evolution found, to date, on Mars. During deposition of at least the uppermost 100 m of fan deposits, discharges from the source basin consisted of channelized flows transporting sediment (which we infer to be primarily sand- and grav...

[1] Significant numbers of valleys have been identified in the Martian midlatitudes (30-60 °N/S), spatially associated with extant or recent ice accumulations. Many of these valleys date to the Amazonian, but their formation during these cold, dry epochs is problematic. In this study we look in detail at the form, distribution and quantitative geom...

Ecohydrologic dynamics is tightly coupled with biogeochemical cycles, land surface atmosphere interactions, the geomorphic phenomena, and landscape evolution. Therefore, ecohydrology plays a central role in understanding and predicting the consequences of global change on the landscape system. Models encapsulate the scientific community’s quantitat...

This presentation discusses the implementation of component-based software design in Eco-hydrologic modeling. As a first step, we present development and integration of a radiation component that uses the local topographic variables to compute shortwave and longwave radiation data over a complex terrain for modeling Eco-hydrologic dynamics. This co...

Europa girdled / By jagged blades of ice. Are / Returns polarized?

Alluvial fans in the Atacama may constitute a strong analog to those on Mars, with fans in both environments forming from hundreds of individual runoff events.

Recently the inventory of fluvial features that have been dated to the late Hesperian to early Amazonian epoch has increased dramatically, including a reassessment of the ages of the large alluvial fans and deltas (e.g., Eberswalde) to this time period. Mid-latitude Valleys (MLVs) are distinct from the older, more integrated Noachian-Hesperian Vall...

Noachian mars was dry but eroded. Mars at the Noachian-Hesperian was wetter. Mars during the Hesperian to Amazonian supported limited fluvial incision.

Extreme precipitation events in arid mountain regions determine flood, debris flow, and landslide hazards, and are principal drivers of geomorphic change. Increased frequency of intense precipitation in many regions of the world over the past few decades increases the importance of documenting and understanding such events when they occur. We use t...

The hydro-climatic evolution of Mars can be subdivided into four epochs with distinct environments: Earliest Mars, the Noachian, the Noachian-Hesperian boundary, and later events. Many uncertainties remain about their enviroments and history.

Fluvial landforms of the Hesperian-Amazonian transition are of particular interest because they may represent the last widespread episode of aqueous activity. This activity took place during a time probably characterized by a thin cold atmosphere.

We map and analyze a suite of 761 small-scale, post-Noachian channel segments in the martian southern midlatitudes, over an area 320 × 560 km. Scaling and distribution of the channels is most consistent with formation under a thick ice cover.

Martian alluvial fans have now been recognized in many craters around the equatorial latitudes of Mars. HiRISE imagery reveals that their surfaces often show a radial pattern of narrow (10s to 100s of meters), long (km), low relief (<10 m), flat topped ridges. These may crosscut and superpose on each other, branch (especially at their downslope end...

Bed erosion and sediment transport are ubiquitous and linked processes in rivers. Erosion can either be modeled as a "detachment limited" function of the shear stress exerted by the flow on the bed, or as a "transport limited" function of the sediment flux capacity of the flow. These two models predict similar channel profiles when erosion rates ar...

The transient response of bedrock rivers to a drop in base level can be used to discriminate between competing fluvial erosion models. However, some recent studies of bedrock erosion conclude that transient river long profiles can be approximately characterized by a transport-limited erosion model, while other authors suggest that a detachment-limi...

Both glacial and fluvial processes are key elements in molding landscapes in high mountain environments-glaciers are highly efficient erosional agents and producers of sediment but are restricted spatially, while rivers can transmit such signals through landscapes and flush this sediment out of mountain belts and into sedimentary basins. However, l...

Upland rivers control the large-scale topographic form of mountain belts, allow coupling of climate and tectonics at the earth’s surface and are responsible for large scale redistribution of sediment from source areas to sinks. However, the details of how these rivers behave when perturbed by changes to their boundary conditions are not well unders...

Both glacial and fluvial processes are well recognised as key elements in moulding landscapes in high mountain environments - rivers transmit baselevel change signals through such landscapes and flush sediment out of mountain belts and into basins, while glaciers are highly efficient erosional agents and producers of sediment, capping relief produc...

Hillslope processes in steep mountainous catchments load river channels with coarse, poorly sorted, loose material which the rivers must mobilize before incising bedrock. Similar situations may arise where bedrock channels erode by plucking, or where channels process landscapes draped with glacial or other non-fluvial sediment. However, despite the...

Prominent convexities in channel long profiles, or knickzones, are an expected feature of bedrock rivers responding to a change in the rate of base level fall driven by tectonic processes. In response to a change in relative uplift rate, the simple stream power model which is characterized by a slope exponent equal to unity predicts that knickzone...

Traditionally, river channels have been modelled as either detachment- or transport-limited; in the former case, incision rates are controlled by the stream's ability to erode the bed, in the latter rates are controlled by downstream divergence in sediment carrying capacity. Previous studies have highlighted the expected differences in channel dyna...