Erkan Istanbulluoglu

University of Washington | UW · Department of Civil and Environmental Engineering

We developed a new rule-based, cellular-automaton algorithm for predicting the hazard extent, sediment transport, and topographic change associated with the runout of a landslide. This algorithm, which we call MassWastingRunout (MWR), is coded in Python and implemented as a component for the package Landlab. MWR combines the functionality of simple...

Forest roadside ditch lines capture and redirect road runoff and typically have erosion control treatments installed therein. Existing methods used to determine the effectiveness of roadside ditch line erosion control treatments estimate fixed fractional reductions in sediment yield. However, fixed fractional reductions do not describe dependence o...

We developed a new rule-based, cellular-automaton algorithm for predicting the hazard extent, sediment transport and topographic change associated with the runout of a landslide. This algorithm, which we call MassWastingRunout (MWR), is coded in Python and implemented as a component for the package Landlab. Given the location and geometry of an ini...

Projecting how arid and semi‐arid ecosystems respond to global change requires the integration of a wide array of analytical and numerical models to address different aspects of complex ecosystems. We used the Landlab earth surface modeling toolkit (Hobley et al., 2017, https://doi.org/10.5194/esurf-5-21-2017) to couple several ecohydrologic and ve...

Landslides are commonly occurring global geological hazards, with negative and far-reaching consequences for human life, and the economic and natural environment. This study analyzes the risk, vulnerability, and resilience of several landslide-prone areas in eight countries based on community perception and attitude related to landslide events thro...

The relationship between traffic and forest road erosion has been studied for decades, and the answer to the question “what happens when traffic is present on unpaved forest roads?” is simple: erosion increases. However, the answer to the question “why does it increase?” is complex and requires us to consider forest road erosion through an integrat...

Modeled stream discharge is often used to drive sediment transport models across channel networks. Because sediment transport varies non‐linearly with flow rates, discharge modeled from daily total precipitation distributed evenly over 24‐hr may significantly underestimate actual bedload transport capacity. In this study, we assume bedload transpor...

Changes in the severity and likelihood of flooding events are typically associated with changes in the intensity and frequency of streamflows, but temporal adjustments in a river's conveyance capacity can also contribute to shifts in flood hazard. To assess the relative importance of channel conveyance to flood hazard, we compare variations in chan...

Vegetation degradation is the key cause of land desertification in arid areas. Water stress is one of the most critical factors leading to vegetation degradation. The water needed for vegetation growth is inseparable from the water cycle processes. It is a new scope to reveal the vegetation water demand mechanisms from the water cycle processes. Wa...

Plain Language Summary Currently, we cannot forecast flooding depths and extent in real‐time at a high level of detail in urban areas. This is the result of two key issues: detailed and accurate flood modeling requires a lot of computing power for large areas such as a city, and uncertainty in precipitation forecasts is high. We present an innovati...

Climate change has been concerned as a trigger of hydrologic changes around the world. Budyko framework was widely used in hydrologic sensitivity analyses on the steady‐state water balance. The unsteady‐state responses, for example the inter‐annual hydrologic sensitivity, were not well investigated, especially for catchments influenced by croplands...

Abstract A mountain watershed network model is presented for use in decadal to centurial estimation of source‐to‐sink sediment dynamics. The model requires limited input parameters and can be effectively applied over spatial scales relevant to management of reservoirs, lakes, streams, and watersheds (1–100 km2). The model operates over a connected...

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...

We developed a new approach for mapping landslide hazards by combining probabilities of landslide impacts derived from a data-driven statistical approach and a physically based model of shallow landsliding. Our statistical approach integrates the influence of seven site attributes (SAs) on observed landslides using a frequency ratio (FR) method. In...

River channel beds aggrade and incise through time in response to temporal variation in the upstream supply of water and sediment. However, we lack a thorough understanding of which of these is the dominant driver of channel bed elevation change. This lack hampers flood hazard prediction, as changes to the bed elevation can either augment or reduce...

Erosion rate data worldwide show complex and contrasting dependencies to climate. Laboratory and numerical model experiments on abiotic landscapes suggest a positive response: Wetter (drier) shift in climate leads to an increase (decrease) in erosion rates with longer relaxation times under a drier climate. We performed eco‐geomorphic landscape evo...

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through on-line media, followed by two workshops through which a large number of potential science questions were collated, p...

We developed a new approach for mapping landslide hazard by combining probabilities of landslide impact derived from a data-driven statistical approach and process-based model of shallow landsliding. Our statistical approach integrates the influence of seven site attributes on observed landslides using a frequency ratio method. Influential attribut...

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...

Spatially-distributed time-series data support a range of environmental modeling and data research efforts. A critical first step to any such effort is acquiring interpolated hydrometeorological data. Standardized tools to facilitate this process into analyses have not been readily available for watershed scale research. Here, we introduce the Obse...

The Pacific Northwest is the most highly glacierized region in the conterminous United States (858 glaciers; 466 km²). These glaciers have displayed ubiquitous patterns of retreat since the 1980s mostly in response to warming air temperatures. Glacier melt provides water for downstream uses including agricultural water supply, hydroelectric power g...

We develop a hydroclimatological approach to the modeling of regional shallow landslide initiation that integrates spatial and temporal dimensions of parameter uncertainty to estimate an annual probability of landslide initiation based on Monte Carlo simulations. The physically based model couples the infinite-slope stability model with a steady-st...

Different formulas have been developed to estimate the mean annual evapotranspiration ratio (E/P) from the mean annual aridity index (Ep/P) based on the Budyko framework. A major challenge in using the Budyko framework for the interannual behaviors of a catchment is the missed storage. Here we develop a null-parameter formula of the storage-evapotr...

Different formulas have been developed to estimate the mean annual evapotranspiration ratio (E/P) at catchment scale from the mean annual aridity index (Ep/P) based on the Budyko framework. A major challenge in using the Budyko framework for the inter-annual behaviors of a catchment is the missed storage in these formulas. Efforts have been contrib...

Soil-mantled pole-facing hillslopes on Earth tend to be steeper, wetter, and have more vegetation cover compared to adjacent equator-facing hillslopes. These and other slope aspect controls are often the consequence of feedbacks among hydrologic, ecologic, pedogenic, and geomorphic processes triggered by spatial variations in mean annual insolation...

Gully erosion was evidence of land degradation in the southern Piedmont, site of the Calhoun Critical Zone Observatory (CCZO), during the cotton farming era. Understanding of the underlying gully erosion processes is essential to develop gully erosion models that could be useful in assessing the effectiveness of remedial and soil erosion control me...

Woody plant encroachment over the past 140 years has substantially changed grasslands in western North American. We studied encroachment of western juniper (Juniperus occidentalis var. occidentalis) into a previously mixed shrub-grassland site in central Oregon (USA) using a modified version of CATGraSS (Cellular Automata Tree-Grass-Shrub Simulator...

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...

In this study, we developed the Urban Ecohydrology Model (UEM) to investigate the role of bioretention on watershed water balance, runoff production, and streamflow variability. UEM partitions the land surface into pervious, impervious, and bioretention cell fractions. Soil moisture and vegetation dynamics are simulated in pervious areas and bioret...

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...

Gully erosion was the primary driver of land degradation in Southern Piedmont, site of the Calhoun Critical Zone Observatory (CCZO), during the cotton farming era. Understanding of underlying erosion processes is essential to develop a model useful in assessing the effectiveness of gully stabilization and soil erosion control. Development of proces...

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...

Biogeoscience is a rapidly growing interdisciplinary field that aims to bring together biological and geophysical processes. This book builds an enhanced understanding of ecosystems by focusing on the integrative connections between ecological processes and the geosphere, hydrosphere and atmosphere. Each chapter provides studies by researchers who...

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...

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...

The energy and water balance of a Phragmites australis dominated wetland in south central Nebraska was analyzed to assess consumptive water use and the potential for “water savings” as a result of vegetation eradication via herbicide treatment. Energy balance measurements were made at the field site for two growing seasons (treated and untreated),...

In glacier-fed rivers, melting of glacier ice sustains streamflow during the driest times of the year, especially during drought years. Anthropogenic and ecologic systems that rely on this glacial buffering of low flows are vulnerable to glacier recession as temperatures rise. We demonstrate the evolution of glacier melt contribution in watershed h...

Arid and semiarid grasslands of southwestern North America have changed dramatically over the last 150 years as a result of woody plant encroachment. Overgrazing, reduced fire frequency, and climate change are known drivers of woody plant encroachment into grasslands. In this study, relatively simple algorithms for encroachment factors (i.e., grazi...

In this Commentary, we argue that it is possible to improve the physical realism of hydrologic models by making better use of existing hydrologic theory. We address the following questions: (1) what are some key elements of current hydrologic theory; (2) how can those elements best be incorporated where they may be missing in current models; and (3...

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...

In many partially glacierized watersheds glacier recession driven by a warming climate could lead to complex patterns of streamflow response over time, often marked with rapid increases followed by sharp declines, depending on initial glacier ice cover and rate of climate change. Capturing such ‘‘phases’’ of hydrologic response is critical in regio...

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...

In many partially glacierized watersheds glacier recession driven by a warming climate could lead to complex patterns of streamflow response over time, often marked with rapid increases followed by sharp declines, depending on initial glacier ice cover and rate of climate change. Capturing such “phases” of hydrologic response is critical in regions...

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...

Observations at the field, catchment, and continental scales across a range of arid and semiarid climates and latitudes reveal aspect-controlled patterns in soil properties, vegetation types, ecohydrologic fluxes, and hillslope morphology. Although the global distribution of solar radiation on earth's surface and its implications on vegetation dyna...

Topography plays a commanding role on organization of vegetation in semiarid ecosystems. A good example is aspect control on plant organization in parts of central New Mexico, where north-facing slopes are dominated with mesic plants whereas south-facing slopes are dominated with xeric vegetation types. Another example is elevation control on biodi...

Solar radiation has a clear signature on the spatial organization of ecohydrologic fluxes, vegetation patterns and dynamics, and landscape morphology in semiarid ecosystems. Existing landscape evolution models (LEMs) do not explicitly consider spatially-explicit solar radiation as model forcing. Here, we improve an existing LEM to represent coupled...

Soil saturated hydraulic conductivity (KS) is partly affected by vegetation activities, which can either increase KS by enhancing macropore flow or reduce KS by clogging pore space. Despite the complex interactions of KS with vegetation, the impact of devegetation on KS has not been adequately addressed, particularly in regions that are prone to dr...

Arid and semi-arid grasslands of southwestern North America have changed dramatically over the jast 150 years as a result of shrub encroachment, i.e. the increase in density, cover and biomass of indigenous shrubby plants in grasslands. Numerous studies have documented the expansion of shrublands in the southwestern American grasslands; in particul...

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...

Runoff has been in decline in most river basins in China during the last 50 years. The Weihe River, the largest tributary of the Yellow River, has experienced runoff declines as large as 35% in the last century. Little is known regarding the relative contributions of climate and human impact to the observed hydrological trends in the Weihe River Ba...

Spatial patterns of ecosystem productivity arise from the terrain-modulated wetting and drying of the landscape. Using a daily relative greenness (rG) index, we explore the relations between spatial variability of plant productivity and landscape morphology, and how these relations change over time. The rG index is defined as a measure of local veg...

In semiarid complex terrain, the combination of elevation and aspect promotes variations in the water and energy balance, resulting in slopes with distinct ecologic and hydrologic properties. Quantifying the differential energy and water dynamics of opposing slopes can provide essential information on the potential effects of climate variability on...

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...

Key Points Explicitly treated of topographic influence on incoming shortwave radiation. Plant specific biological processes affect vegetation composition.

For many of the world's lakes, particularly those in remote regions, an assessment of the basin's sensitivity to climate change is limited by the availability of appropriate hydrologic data. A regional steady-state lake water balance model was developed that uses simple, yet easily estimated or obtained, data to generate an aridity index (potential...

Predicting vegetation response in regions of ecotone transition under a changing climate is a among grand challenges in ecohydrology. In a small basin (1.3 sq km) in Sicily, Italy, where north-facing slopes are characterized by Quercus (tree), and south-facing slopes by Opuntia ficus-indaca (evergreen perennial species drought tolerant) and grasses...