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In Arctic landscapes, modern surface warming has significantly altered geomorphic process rates. Along the Beaufort Sea coastline bounding Alaska’s North Slope, the mean annual coastal erosion rate has doubled from ~7 m/yr for 1955-1979 to ~14 m/yr for 2002-2007. Locally the erosion rate reaches 30 m/yr. A robust understanding of the processes that govern the rate of erosion is required in order to predict the response of the coast and its adjacent landscape to a rapidly changing climate, with implications for sediment and carbon fluxes, oilfield infrastructure, and animal habitat.
On the Beaufort Sea coast, bluffs in regions of ice-rich silt-dominated permafrost are abundant. This type of coast is vulnerable to rapid erosion due to its high ice content and the small grain size of bluff sediment. The bluff material at our study site near Drew Point is 64% ice, making the bluff susceptible to thermal erosion. Liberated sediment is removed from the system in suspension and does not form sheltering beaches or barrier islands which would provide a negative feedback to erosion. During the sea ice-free season, relatively warm waters abut the bluff and ocean water melts a notch into the 4-m tall bluffs. The bluffs ultimately fail by the toppling of polygonal blocks bounded by mechanically weak ice-wedges that are spaced roughly 10-20 m apart. The blocks then temporarily armor the coast against further attack.
We document the style and the drivers of coastal erosion in this region through simultaneous measurements of the oceanic and atmospheric conditions, and time-lapse imagery. We extract proxies for erosion rate from time-lapse imagery of both a degrading block and a retreating bluff from the summer of 2010, and compare the proxy record with environmental conditions and melt rate models. These observations verify that the dominant process by which erosion occurs is thermal insertion of a notch, toppling of blocks, and subsequent melting of the ice in the block. The annual retreat rate is governed by the length of the sea ice-free season, water and air temperatures, and the water level history, including both storm surge and wave height.
Motivated by these observations, we developed a numerical model to capture the evolution of the permafrost bluffs on the North Slope. We honor the high ice content of the bluff materials and the role of the toppled block in temporarily armoring the coast. We employ a positive degree day algorithm to drive subaerial melt, and a modified iceberg melting algorithm to determine rate of notch incision. Our model is first applied to the 2010 coastal retreat history, and is then used to address field and remote sensing observations over a variety of timescales. Finally, we employ the model to explore expected changes in coastal retreat rates in a range of climate scenarios that include increases in the duration of sea-ice free conditions, warming ocean temperatures, and changes in storm frequencies.
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In China, permafrost is mainly underlain on the Qinghai-Tibet Plateau (QTP), which is the largest mid-low latitude permafrost region in the world. Owing to the unique and extremely high altitude, permafrost area on the QTP approximately amounts to 1.06 million km2. Permafrost on the QTP is one of the most sensitive indicators to global climate change, because it is the product between the earth and atmosphere system. The active layer is the interface between the earth and atmosphere. To understand the present condition of active layer and permafrost thermal state is the foundation to learn about the hydrological cycles, infrastructures built on and in permafrost, soil carbon release and uptake, and biogeochemical and ecological processes in cold regions. The observations can depict the present state of permafrost, but models are eventually essential to predict future changes of permafrost. Despite the fact that geophysical surveys and boreholes are the most reliable sources of information about permafrost, they are extremely costly and are mostly available from relatively small regions. I tried to implement the Geophysical Institute Permafrost Lab Version2 (GIPL2) model on the Qinghai-Tibet Plateau (QTP). The GIPL2 model can provide more permafrost thermal state than those of statistical empirical models. I am interested in applying the GIPL2 model to the Qinghai Tibet Plateau in order to know the thermal state of QTP permafrost and its response to recent climate changes. The results of our present work using the original version of GIPL2 indicated that for the whole permafrost area of the QTP, the simulated ALT ranges from 0 to 8 m, with an average of 2.30 m. The simulated 18 ALT sites are generally underestimated compared with the observed values with the MBE value of -0.14 m and the RMSE value of 0.22 m. +
In an ongoing NASA project, our team is producing enhanced global flood hazard maps from advanced modeling, remote sensing and big data analytics. The innovation is that we couple long-term Water Balance Model (WBM) global scale hydrologic flow simulations with the 2-D LISFLOOD-FP model to generate continental scale flood inundation maps that are then integrated with the flood map information from the DFO, including their radiometry-based satellite discharge estimations, i.e. “River Watch”. These remotely sensed discharge stations will be employed to associate flow return periods to the DFO satellite flood maps (up to the 25-year floodplain) that can then be cross-validated with frequencies of inundation from the flood model historic simulations. Furthermore, we collaborate with Google Inc and use their EE platform for big data analytics, such as downscaling our model simulations of flood hazard to adequate resolutions for decision-makers. This poster will present first achievements for Australia, Africa and CONUS, and discuss challenges and perspectives. +
In complex systems, emergence occurs when a ‘new’ property arises at higher levels of organization that cannot be directly deduced from the behavior of constituent elements. While many geomorphic systems exhibit emergence, numerical models of surface processes typically address emergence by carefully selecting the appropriate spatio-temporal scale to parameterize the relevant physics, chemistry, and biology that is occurring at lower levels of organization. This is an effective strategy where finer-scale processes are either poorly constrained or intractable to model numerically. The concept of the geomorphic transport law reifies this strategy by adopting a ‘top down’ approach where surface processes are encoded into the set of partial differential equations chosen. However, as data resolution and computational power increase, there are new opportunities to build models that simulate processes from the ‘bottom up’.
One such opportunity is in the simulation of biologically driven soil production and sediment transport. Biological systems exhibit some of the most compelling examples of emergence (e.g., insect societies, flocking behavior, fairy circles) that are readily simulated using Agent-Based Models (ABMs). Given that biota drive many of the most widely used geomorphic transport laws, it is worth taking stock of whether ABMs can provide new insights into surface process modeling. We present two promising examples where we think ABMs might provide new, testable predictions of soil production and sediment transport. The first example focuses on tree seeding, recruitment, growth, and death. Rules for soil production via tree root growth monotonically decrease with soil depth. However, because soil production in the model depends not only on individual tree root growth but also the probability of an unstressed tree growing at any given location, humped soil production functions emerge over the long-term. The second example focuses on one hypothesized mechanism for mima mound formation. Rules for burrowing organisms allow for preferential upslope transport of sediment into mounds while gravitational processes (i.e., creep) degrade mounds. Both examples highlight how ABMs help make rules for ecological dynamics explicit. Bulk coefficients common to conventional treatments of soil production and sediment transport laws are thus allowed to emerge from the empirically constrained rulesets that are used.
In gravel-bedded rivers, bed material abrasion is a well-recognized control on the balance between fine and coarse sediment fluxes. We suggest that in some landscapes, abrasion may also be an important control on the morphodynamics of sediment pulses. Here, we employ a simple morphodynamic model to explore the extent to which bed material abrasion controls the downstream fate of sediment pulses in terms of transit time and the magnitude of response in channel bed elevation and grain size change. The Network Sediment Transporter (NST) is a Lagrangian 1-D morphodynamic model component that tracks bed sediment moving and interacting on a river network. The NST is implemented in Landlab, a Python-based package for modeling the Earth’s surface. The NST tracks ‘parcels’ of sediment (collections of grains of homogeneous size, density, etc.) as they transport through the network, allowing us to explicitly tag and follow sediment as originating in the mass wasting deposit and give that sediment unique abrasion characteristics. The model requires inputs about channel morphology, flow, and bed sediment attributes. Here, we compare the results of a simple sediment pulse simulation without abrasion of the bed material to an identical pulse with abrasion rates equal to measurements made on a volcanic mass wasting deposit in the Cascade Range of Washington. The differences between pulse behavior with and without abrasion have implications for hazards in volcanic terrains where channels are commonly subject to large mass wasting deposits of heterogeneous sedimentary characteristics. Understanding the fate of these large sediment pulses will increase our understanding of downstream channel aggradation and increases in flood frequency. +
In many areas of the world, the environment has been engineered to reduce variability (increase robustness) for human development. As much of the agricultural land in the middle US is located in arid and semi-arid regions, agricultural practices depend on irrigation. Since the 1960’s thousands of fields are watered using center pivot irrigation, each of which requires about 800 gpm (4,361 m3/day) (New and Fipps, 2017). Groundwater supported irrigation was dependable for decades, but now many areas of the High Plains aquifer, which is partly composed of the Ogallala aquifer, is at risk of depletion, and farming is facing difficult circumstances. On the positive side, western Kansas has very high potential capacity for wind power production, but opportunities to use this locally produced energy to improve prospects for the farming community face scientific and engineering challenges and, communities are not aware of many potentially promising alternatives. The Food-Energy-Water calculator (FEW) is a tool designed to introduce new alternatives to these communities and the scientists, engineers, and governmental entities who support them. In this study, Agent-Based Modeling (ABM) is used to coordinate the many types of actors, information and alternatives relevant to this problem. For more creative agricultural scenarios, a crop model called Decision Support System for Agrotechnology Transfer (DSSAT) can be used to calculate crop yields and income. The resulting ABM based FEW calculator provides a more realistic and effective framework for managing the complexity between the human and natural system dynamics. +
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In most mountainous regions reconstructed glacial histories are the primary record of past climate and are typically based on unsorted accumulations of debris (moraines) deposited at the terminus of glaciers. Former glacier geometries— preserved as moraines and trim lines— are the primary constraint for extracting paleoclimate estimates using either equilibrium-line altitudes or numerical glacier models.
It is an implicit assumption in the glacial geology community that terminal moraines were formed by glaciers responding to the mean value of summer temperature and winter precipitation at the time of formation. In reality glacier termini oscillate around a mean glacial length even in a steady climate, defined by a constant mean and constant standard deviation. These length oscillations are driven by the alignment of more negative (positive) periods of mass balance that arise out of random year-to-year climate variability. Because glaciers that override moraines almost always destroy them, the furthest terminal moraines from the headwall during the time period of interest represent the maximum excursion of the glacier from its mean length. This implies that paleoclimate estimates based upon the furthest terminal moraine are actually maximum estimates of climate change.
We use a linearized glacier model developed by Roe and O’Neal (2009) to determine the mean length of eleven Last Glacial Maximum (LGM) glaciers in the northern Front Range, Colorado. Mean glacier lengths during the LGM were ~15% upvalley from the LGM terminal moraines. In the Colorado Front Range estimating LGM paleoclimate from the furthest terminal moraine rather than the mean length adds an extra ~1°C temperature change or an additional 25% increase in precipitation to estimate of differences from the modern climate. Furthermore, it is possible that ‘recessional’ moraines were formed by length oscillations driven by interannual variability. +
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In recent years a large number of numerical models have been developed and implemented to study basic and applied problems of research moprhodyanmics. Some of these models treat the bed material as uniform; others consider the bed material as a mixture of sand and gravel. The vast majority of the morphodynamic models that account for the non-uniformity of the bed material size are based on the active layer approximation, i.e. the channel bed deposit in two different regions. The active layer, which is the topmost part of the bed deposit, is modeled as mixed layer whose particles can interact with the bed material transport. Particles in the rest of the channel deposit, the substrate, can be exchanged with the bed material transport only when the channel bed aggrades or degrades. Morphdynamic formulations based on the active layer approximation, however, have well known limitations:1) they neglect the vertical fluxes within the deposit associated with e.g. bedform migration, 2) they cannot capture the infiltration of fine sediment and tracer stone dispersal and 3) the statistical nature of sediment entrainment is neglected. To overcome these limitations, Parker and coauthors in 2000 introduced a continuous, i.e. not layer-based, morphodynamic framework based on a stochastic description of the bed surface elevation, of the entrainment and deposition. In this framework particle entrainment rates are computed as a function of the flow and sediment characteristics, while particle deposition is estimated with a step length formulation. However, due to the lack of mathematical functions describing the variability of bed elevation, entrainment and deposition, the continuum framework has never been implemented. Here we present one of the first implementation of the continuum framework at laboratory scale and its validation against laboratory experiments on tracer stones dispersal. The validated model is then used to investigate the dependence of the model results on different particle step lengths.
In recent years, seismic signals previously thought of as “noise” have become a subject of study for environmental seismologists. These signals can reveal Critical Zone and geomorphic processes which traditionally are not well-constrained, such as the roles biota play in weathering, movement of mass, and landscape evolution. Wind-driven tree sway is central to conceptual models of physical bedrock weathering and subsequent soil production. However, despite documentation, seismic signals of wind-tree interactions have been largely ignored by surface process researchers. Our work focuses on identifying the seismic signature of tree-captured wind by comparing seismic data in areas with little to no vegetation against heavily vegetated areas. Using meteorological and seismic data from the Transportable Array deployed in Alaska, we isolate this vegetation effect on seismicity by selecting for periods with high-wind events in the absence of rain. We hypothesize that there is a difference in strength of seismicity which scales with percent tree cover. We use a combination of wind speed and seismic data to explore the impact of vegetation on seismic amplitude and examine the spectral signature of wind moving trees in order to better understand its contribution toward soil production and nutrient/carbon cycling in the Critical Zone. +
In terrestrial ecosystems, rock fractures as unsaturated reservoirs for vegetation have been recently recognized as a key ecohydrological process. However, it remains unclear how the coupling between plant water use strategies and rock water storage interplay. We selected Douglas fir and Engelmann spruce trees growing on both soils and exposed limestone cliffs in the Canadian Rockies. We measured sap flow, stem water potential, and superficial fracture substrate moisture for trees growing in rock fractures and glacial till. Isotopic analysis of precipitation, plants, and soil samples revealed that the trees do not have access to any long-term water sources but rather use recent precipitation values. To explore the relationship within the system, we built a stock-flow model with three stocks: the surface fracture, the deep fracture, and the tree itself, and observed that cliff trees respond slightly differently to water replenishment due to the cliff architecture. Plant regulation coupled with rock water storage is crucial to model water movement through plants in highly water-limited environments correctly. Our study highlights the importance of understanding how trees access rock moisture storage in water-limited environments. +
In the nearshore environment, bedforms are prominent small-scale morphological features controlling hydrodynamic dissipation and sediment transport. Vortices are typically regarded as the primary mechanism driving sediment transport over vortex ripples with a steepness larger than 0.1 due to boundary layer separation. As these bedforms induced vortices must cascade into small turbulent coherent structures and eventually get dissipated, a research gap exists concerning the role of coherent structures on bedform evolutions. Here, we investigate the mechanism driving bedform evolution from an initially flat bed, for medium and fine sand ripples in oscillatory flows. Due to much lower steepness, the ripple-induced vortices are much weaker, and we hypothesize that turbulent coherent structures play a crucial role in sediment transport to initiate small bed features. In this numerical study, the Eulerian two-phase flow model, SedFoam, is utilized. The laboratory experimental scenarios from Perillo et al. (2014, Sedimentology) are modeled for medium sand ripple (d_50=0.25 mm) at mobility numbers varied from 10 to 60. By conducting a three-dimensional (3D) large-eddy simulation (LES), the generation and evolution of energy-containing turbulent coherent structures are resolved, as well as their effect on sediment transport. The simulation results demonstrate that the turbulent coherent structures, generated by shear flow in the turbulent boundary layer, are the dominant mechanism driving the initial formation of 3D small bed features, which eventually evolve into more organized symmetrical small ripples (SSR). The simulated time-dependent bedform characteristics, including ripple length and height, are further validated against measurements. +
In the same way that watersheds filter precipitation signals into a time series of flow response, watersheds also filter sediment production signals into a time series of bedload transport. Here, we describe the Mass Wasting Router, a new watershed-scale sediment production and transport model written for Landlab that couples an existing shallow landslide hazard model (LandslideProbability) with an existing network-scale bedload transport model (NetworkSedimentTransporter) by (1) delineating hillslope scale landslides from maps of landslide probability, (2) routing the landslides through the watershed using a “precipiton” or “agent” style model and (3) fluvially eroding the mass wasting deposits and creating parcels for the NetworkSedimentTransporter. Preliminary model runs indicate that variation in soil cohesion and precipitation intensity drive landslide-derived hillslope sediment production rates but valley storage processes, driven by debris flow deposition patterns, modulate bedload transport rates at the basin outlet. +
In the southern San Andreas Fault zone, the San Gorgonio Pass (SGP) stands as a region of intricate structural complexity, pivotal for the assessment of seismic hazards due to its potential role in modulating earthquake rupture propagation. This investigation delves into the SGP's crucial function in earthquake dynamics amid ongoing discussions on slip partitioning among its fault strands, aiming to fill a substantial knowledge gap concerning fault activity spanning the last 1 to 100 thousand years. The challenge of estimating slip rates, exacerbated by a dearth of datable materials within the SGP's challenging terrain, calls for innovative methodologies to assess uplift rates along previously overlooked fault segments. In our study, we use thermoluminescence (TL) thermochronology to evaluate differential uplift by analysing bedrock erosion rates. Although AHe dating sheds light on thermal histories and erosion rates across millions of years, it falls short in detailing the recent uplift history vital for grasping Quaternary fault dynamics. In contrast, cosmogenic 10Be dating proves effective in measuring surface erosion rates over millennial timescales, providing insights into contemporary geological activities. TL dating, with its capacity to discern bedrock exhumation over 10-100 ka, acts as a bridge between the temporal scales of AHe thermochronology (Ma) and cosmogenic 10Be denudation rates (ka). By juxtaposing erosion rates across different faults within the SGP, our research aims to pinpoint active fault segments, thereby enriching our understanding of fault dynamics and seismic risk in the southern San Bernardino Mountains. +
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In this study, a methodology based on a multi-resolution wavelet analysis is introduced to extract a regularized topographic index (TI) distribution from a high-resolution DEM (digital elevation model). The methodology is a promising method to deal with common problems in hydrological applications of high-resolution DEMs, which usually contain noise, pits and redundant information. Formation of several unconnected saturated zones is a particular case of such problems when TOPMODEL is employed for simulation of hydrological processes within a basin. The proposed method includes four steps. The first two steps are used for smoothing and de-noising purposes and include decomposition of the original DEM into multi-level sub-signals by 2-dimentional discrete wavelet transform (DWT) and thresholding of the wavelet coefficients. In the next step, the original smoothed and filtered DEM is reconstructed using inverse DWT. Finally, the TI distribution and its information content are computed. The computed information content is used as a metric to identify an optimal TI distribution which contains reasonable topography information in the absence of noise and redundancy. Application of the procedure to 1-m resolution LiDAR (light detection and ranging) DEM of the Elder Creek River watershed via the TOPMODEL framework indicates its filtering ability to smooth and connect the saturated areas during the hydrological process. In addition to the rainfall-runoff modeling, the proposed pre-processing technique may be applied wherever a high-resolution DEM is employed for distributed simulation of hydro-environmental processes. +
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In this study, implicit and explicit spectral solutions are considered for solving the linear diffusion term of a simple 2D loosely coupled landscape evolution model. Spectral methods are powerful tools for solving elliptical partial differential equations and are widely used in other fields, though they have received comparatively little attention in landscape evolution modelling. In the LEM considered, the land surface elevation is altered by three processes: regional uplift, fluvial incision, and linear hillslope diffusion. In the simplest case, these processes act in an undifferentiated way across the entire landscape. While a recent algorithm has provided a powerful implicit solution to for the fluvial incision term, explicit formulations of diffusion remain standard. However, when the desired grid is large, an explicit method may be restricted by stability to a time step too small for the timescales of interest. To solve this problem implicitly, I transform the problem into the spectral domain, solve the 2D diffusion equation with a Crank-Nicholson method, and compare the results to explicit finite difference and explicit spectral methods. In its most simple formulation, the spectral methods require periodic boundary conditions in both dimensions. Resulting from these conditions, I show a tessellating solution where the landscape takes the form of a flat torus. +
Information on flood inundation extent is important for understanding societal exposure, water storage volumes, flood wave attenuation, future flood hazard, and other variables. A number of organizations now provide flood inundation maps based on satellite remote sensing. These data products can efficiently and accurately provide the areal extent of a flood event, but do not provide floodwater depth, an important attribute for first responders and damage assessment. Here we present a new methodology and a GIS-based tool, the Floodwater Depth Estimation Tool (FwDET), for estimating floodwater depth based solely on an inundation map and a digital elevation model (DEM). We compare the FwDET results against water depth maps derived from hydraulic simulation of two flood events, a large-scale event for which we use medium resolution input layer (10 m) and a small-scale event for which we use a high-resolution (LiDAR; 1 m) input. Further testing is per- formed for two inundation maps with a number of challenging features that include a narrow valley, a large reservoir, and an urban setting. The results show FwDET can accurately calculate floodwater depth for diverse flooding scenarios but also leads to considerable bias in locations where the inundation extent does not align well with the DEM. In these locations, manual adjustment or higher spatial resolution input is required. +
Infrequent, large-magnitude discharge (>10^6 m^3/s) outburst floods—megafloods—can play a major role in landscape evolution. Prehistoric glacial lake outburst megafloods transported and deposited large boulders (≥4 m), yet few studies consider their potential lasting impact on river processes and form. We use a numerical model, constrained by observed boulder size distributions, to investigate the fluvial response to boulder deposition by megaflooding in the Yarlung-Siang River, eastern Himalaya. Results show that boulder deposition changes local channel steepness (ksn) up to ∼180% compared to simulations without boulder bars, introducing >100 meter-scale knickpoints to the channel that can be sustained for >20 kyr. Simulations demonstrate that deposition of boulders in a single megaflood can have a greater influence on ksn than another common source of fluvial boulders: incision-rate-dependent delivery of boulders from hillslopes. Through widespread boulder deposition, megafloods leave a lasting legacy of channel disequilibrium that compounds over multiple floods and persists for millennia. +
Inhabitants of Bangladesh and West Bengal rely significantly on groundwater for drinking water. Estimates suggest that 7 to 11 million drinking water wells are contaminated by high concentrations of naturally occurring arsenic. The arsenic likely derives from the pyrite-rich sediment of the Ganges basin, however, the cause and timing of mobilization of the arsenic have been difficult to determine. Generally, shallow and deep aquifers contain low concentrations of arsenic, while mid-depth aquifers (20 to 100 m) are often contaminated. The Ganges river is extremely active and has dissected large portions of previously deposited sediments, introducing significant subsurface heterogeneity and complicating the search for safe drinking water. Here, we have aggregated a variety of datasets into a PostgreSQL database, which we use to build predictive models of arsenic concentration in groundwater. We use the Bangladesh Arsenic Mitigation Water Supply Project (BAMWSP) dataset of ~4.5 million wells to train our models. The predictors for our models are largely based on ~15,000 stratigraphic sediment samples from ~10 transect and ~400 total cores. Approximately 5,000 of these samples have been analyzed for grain size, magnetic susceptibility, chemical composition, and organic matter content. We use elevation and population density as additional predictors. With this database, we will create a regional statistical model that may lead to better prediction of arsenic contaminated wells. By compiling and analyzing these data, we hope to improve water security in this rapidly developing region. +
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Integrated hydrologic models are growing in application and show significant promise in unraveling connections between the surface, subsurface, land-surface and lower atmospheric systems. Recent advances in numerical methods, coupled formulation and computing power have all enabled these simulation advances. Here, I will discuss the modeling platform ParFlow, an integrated hydrologic model that has been coupled to land surface and atmospheric models. I will then discuss a recent application of this model to a large, Continental-Scale domain in North America at high resolution that encompasses both the Mississippi and Colorado watersheds. Details will include techniques for model setup and initialization, in addition to results that focus on understanding fluxes, feedbacks and systems dynamics. Additional anthropogenic complications such as the effects of pumping, irrigation and urbanization will be discussed and a path forward for integrated simulations of the hydrologic cycle will be presented. +
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Integration of humans within landscape evolution models (LEM) as responsive actors in complex human-environmental systems, is still in its infancy. LEMs that included human decision-making have done so either entirely within an agent-based model (ABM) (e.g., CYBEROSION (Wainwright 2008)) or by coupling an ABM with a LEM (e.g., MedLanD (Barton et al. 2012)). These LEM-ABM examples have analyzed the effects of land use and tillage decisions on landscape evolution, but other ways in which humans interact with geomorphic systems have yet to be explored. Our research expands human-environment interaction modeling to landscapes modified by agricultural terraces to explore the long-term geomorphic evolution in these regions.
Agricultural terraces are anthropogenic landforms that have been constructed for centuries in many parts of the world. Despite their widespread distribution and well-known reduction of sediment transport, terraces have rarely been included within LEMs (cf. Lesschen, Schoorl, and Cammeraat 2009). Recent research on agricultural terraces has revealed that terrace abandonment often increases soil erosion and landscape degradation, reversing landscape evolution patterns modified by terrace construction (Tarolli, Preti, and Romano 2014/6; Arnáez et al. 2015/5). We present the Agricultural Terraces Model (AgrTerrModel), which is a coupled LEM-ABM system for analyzing long-term human-environment interactions in terraced landscapes. The LEM component is implemented using the Landlab library and features adjustments to governing landscape evolution equations to reflect changes to geomorphic processes after terrace construction, such as the impact of stone terrace walls that block sediment movement downslope. The ABM component is implemented using the Mesa ABM framework and includes mechanisms for terrace wall collapse and maintenance, as well as agents who determine cultivation and maintenance practices for terraced land. Using the AgrTerrModel, we simulate landscape evolution in Vernazza, Liguria, Italy near Cinque Terre to analyze how the timing and amount of terrace wall maintenance affects sediment transport. The interaction between seasonal precipitation and the timing of terrace wall maintenance is of special interest due to the Mediterranean climate of the study area. This project provides new insights into the evolution of terraced landscapes and an avenue for further research into the complexity of human-environment systems.
References Cited:
Arnáez, J., N. Lana-Renault, T. Lasanta, P. Ruiz-Flaño, and J. Castroviejo. 2015/5. “Effects of Farming Terraces on Hydrological and Geomorphological Processes. A Review.” Catena 128: 122–34.
Barton, C. Michael, Isaac I. T. Ullah, Sean M. Bergin, Helena Mitasova, and Hessam Sarjoughian. 2012. “Looking for the Future in the Past: Long-Term Change in Socioecological Systems.” Ecological Modelling 241 (August): 42–53.
Lesschen, J. P., J. M. Schoorl, and L. H. Cammeraat. 2009. “Modelling Runoff and Erosion for a Semi-Arid Catchment Using a Multi-Scale Approach Based on Hydrological Connectivity.” Geomorphology 109 (3–4): 174–83.
Tarolli, Paolo, Federico Preti, and Nunzio Romano. 2014/6. “Terraced Landscapes: From an Old Best Practice to a Potential Hazard for Soil Degradation due to Land Abandonment.” Anthropocene 6: 10–25.
Wainwright, John. 2008. “Can Modelling Enable Us to Understand the Rôle of Humans in Landscape Evolution?” Geoforum; Journal of Physical, Human, and Regional Geosciences 39 (2): 659–74.
