Dr Omer Yetemen
Conjoint Senior Lecturer
School of Engineering
- Phone:4921 5452
Omer joined the Discipline of Civil Engineering in Jan 2016. He received his PhD in Civil Engineering from the University of Washington, Seattle, USA. Then, he worked as a Postdoctoral Fellow at the Global Institute for Water Security at the University of Saskatchewan, Canada. His interests are ecohydrology, geomorphology, land-surface modelling and vegetation dynamics. The overarching goal of his research is trying to improve our current understanding about the role of climate on land-surface processes through vegetation dynamics.
- Doctor of Philosophy, University of Washington
- Bachelor of Geological Engineering, Istanbul Technical University, Turkey
- Master of Science, Istanbul Technical University, Turkey
- Master of Science, University of Nebraska, USA
- landscape evolution modeling
- vegetation dynamics
|Dates||Title||Organisation / Department|
|15/10/2009 - 15/6/2014||Graduate Research Assistant||University of Washington
Department of Civil and Environmental Engineering
|14/8/2006 - 30/9/2009||Graduate Research Assistant||University of Nebraska
Earth and Atmospheric Sciences
|25/8/2014 - 15/1/2016||Postdoctoral Fellow||University of Saskatchewan
Global Institute for Water Security
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
|Instructor||27/2/2017 - 2/6/2017|
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
|Instructor||22/2/2016 - 3/6/2016|
Environmental Engineering Project 2
Faculty of Engineering and Built Environment - The University of Newcastle (Australia)
|Instructor||25/7/2016 - 25/11/2016|
For publications that are currently unpublished or in-press, details are shown in italics.
Journal article (16 outputs)
Yetemen O, 'Simulating the evolution of the topography-climate coupled system (2021)
Srivastava A, Saco PM, Rodriguez JF, Kumari N, Chun KP, Yetemen O, 'The Role of Landscape Morphology on Soil Moisture Variability in Semi-arid Ecosystems', Hydrological Processes, (2020)
Chun KP, He Q, Fok HS, Ghosh S, Yetemen O, Chen Q, Mijic A, 'Gravimetry-based water storage shifting over the China-India border area controlled by regional climate variability', Science of the Total Environment, 714 (2020) [C1]
Kumari N, Saco PM, Rodriguez JF, Johnstone SA, Srivastava A, Chun KP, Yetemen O, 'The Grass is not Always Greener on the Other Side: Seasonal Reversal of Vegetation Greenness in Aspect-driven Semiarid Ecosystems', Geophysical Research Letters, 47 (2020) [C1]
Baltaci H, Akkoyunlu BO, Arslan H, Yetemen O, Ozdemir ET, 'The influence of meteorological conditions and atmospheric circulation types on PM10 levels in western Turkey', ENVIRONMENTAL MONITORING AND ASSESSMENT, 191 (2019) [C1]
Yeo IY, Lang MW, Lee S, McCarty GW, Sadeghi AM, Yetemen O, Huang C, 'Mapping landscape-level hydrological connectivity of headwater wetlands to downstream waters: A geospatial modeling approach - Part 1', Science of the Total Environment, 653 1546-1556 (2019) [C1]
Yeo IY, Lee S, Lang MW, Yetemen O, McCarty GW, Sadeghi AM, Evenson G, 'Mapping landscape-level hydrological connectivity of headwater wetlands to downstream waters: A catchment modeling approach - Part 2', Science of the Total Environment, 653 1557-1570 (2019) [C1]
Yetemen O, Saco PM, Istanbulluoglu E, 'Ecohydrology Controls the Geomorphic Response to Climate Change', GEOPHYSICAL RESEARCH LETTERS, 46 8852-8861 (2019) [C1]
Saco PM, Moreno-de las heras M, Keesstra S, Baartman J, Yetemen O, Rodriguez J, 'Vegetation and soil degradation in drylands: Non linear feedbacks and early warning signals', Current Opinion in Environmental Science & Health, 5 67-72 (2018) [C1]
Yetemen O, Istanbulluoglu E, Vivoni ER, 'The implications of geology, soils, and vegetation on landscape morphology: Inferences from semi-arid basins with complex vegetation patterns in Central New Mexico, USA', Geomorphology, 116 246-263 (2010)
This paper examines the relationship between land surface properties (e.g. soil, vegetation, and lithology) and landscape morphology quantified by the catchment descriptors: the s... [more]
This paper examines the relationship between land surface properties (e.g. soil, vegetation, and lithology) and landscape morphology quantified by the catchment descriptors: the slope-area (S-A) relation, curvature-area (C-A) relation, and the cumulative area distribution (CAD), in two semi-arid basins in central New Mexico. The first site is composed of several basins located in today's desert elevations with mesic north-facing and xeric south-facing hillslopes underlain by different lithological formations. The second site is a mountainous basin exhibiting vegetation gradients from shrublands in the lower elevations to grasslands and forests at higher elevations. All three land surface properties were found to have significant influences on the S-A and C- A relations, while the power-law exponents of the CADs for these properties did not show any significant deviations from the narrow range of universal scaling exponents reported in the literature. Among the three different surface properties we investigated, vegetation had the most profound impact on the catchment descriptors. In the S-A diagrams of the aspect-controlled ecosystems, we found steeper slopes in north-facing aspects than south-facing aspects for a given drainage area. In elevation-controlled ecosystems, forested landscapes exhibited the steepest slopes for the range of drainage areas examined, followed by shrublands and grasslands in all soil textures and lithologies. In the C-A diagrams, steeper slopes led to a higher degree of divergence on hillslopes and a higher degree of convergence in the valleys than shallower slopes. The influence of functional types of vegetation detected on observed topography provided some initial understanding of the potential impacts of life on the organization of topography. This finding also emphasizes the critical role of climate in catchment development. We suggest that climatic fluctuations that are capable of replacing vegetation communities could lead to highly amplified hydrological and geomorphic responses.
Yetemen O, Yalcin T, 'Climatic parameters and evaluation of energy consumption of the Afyon geothermal district heating system, Afyon, Turkey', Renewable Energy, 34 706-710 (2009)
Afyon geothermal district heating system (AFJET) provides heating to 4519 residences, covering an area of 513,683 m2. Due to limitations in reinjection capacity, geothermal waters... [more]
Afyon geothermal district heating system (AFJET) provides heating to 4519 residences, covering an area of 513,683 m2. Due to limitations in reinjection capacity, geothermal waters are released to the Akarcay Stream, detrimentally affecting the environment. Optimum heating load of the system was determined for a given ambient conditions with respect to different outdoor temperatures. Usage of AFJET was found to be higher than the optimum consumption rates. Optimizing the usage of geothermal water will decrease operational cost, increase equipment life-span, and reduce environmental pollution.
Yalcin T, Yetemen O, 'Local warming of groundwaters caused by the urban heat island effect in Istanbul, Turkey', Hydrogeology Journal, 17 1247-1255 (2009)
The urban heat island (UHI) is a result of urbanization, causing local microclimatologic changes such as increase in ambient temperature. Factors causing the UHI effect are anthro... [more]
The urban heat island (UHI) is a result of urbanization, causing local microclimatologic changes such as increase in ambient temperature. Factors causing the UHI effect are anthropogenic energy release, energy absorption by concrete, tarmac structures and traffic, although the main factor is the replacement of vegetation with man-made structures. These factors cause heating of not only local air but also subsurface and groundwater. Observations of groundwater temperatures from the urban, southern part of Istanbul (Turkey) and the rural, northern part of Istanbul revealed that the urban groundwater temperatures were 3.5°C higher than the rural. Urbanization is a direct consequence of improvements in technology and modern life. However, this comes at the cost of an ever-increasing demand for energy. Exploitation of low-enthalpy geothermal energy is an attractive alternative to fossil fuel based energies. From the environmental point of view, clean and cheap energy is the most preferable, with heat pumps being the best choice for recovery purposes. Usage of elevated groundwater temperature in the heat pumps in urban areas increases the efficiency of the heat pump system and yields more thermal energy than that of rural groundwater. This system may be applicable to Istanbul. © Springer-Verlag 2009.
Istanbulluoglu E, Yetemen O, Vivoni ER, Gutiérrez-Jurado HA, Bras RL, 'Eco-geomorphic implications of hillslope aspect: Inferences from analysis of landscape morphology in central New Mexico', Geophysical Research Letters, 35 (2008)
We investigate the influence of hillslope aspect on landscape morphology in central New Mexico, where differences in soils, vegetation, and landforms are observed between mesic no... [more]
We investigate the influence of hillslope aspect on landscape morphology in central New Mexico, where differences in soils, vegetation, and landforms are observed between mesic north-facing and xeric south-facing slopes. Slope-area and curvature-area relations, derived from a Digital Elevation Model (DEM), are used to characterize the opposing hillslope morphologies. In all geologies and elevation ranges studied, topographic data reveal significantly steeper slopes in north-facing aspects, and shallower slopes in south-facing aspects. North-facing slope curvatures are also greater than south-facing curvatures. Using a conceptual slope-area model, we suggest that for a given drainage area, steeper north-facing slopes imply lower soil erodibility. We argue that this interpretation, consistent with recent views of ecosystem control on semiarid erosion rates, shows the influence hillslope aspect on topography and its associated vegetation communities. Observed valley asymmetry in the region reinforces this concept and suggests a long-term legacy of aspect-modulated ecogeomorphic proceses. Copyright 2008 by the American Geophysical Union.
|Show 13 more journal articles|
Conference (5 outputs)
Yetemen Ö, Avcioglu A, Çaglar F, Ekberzade B, Çetiner U, Sen ÖL, et al., 'A co-evolutionary modelling framework for water-soil-vegetation interactions in Turkish semiarid landscapes for sustainable natural resources under climate change', Vienna (2020)
Kumari N, Yetemen O, Srivastava A, Rodriguez JF, Saco PM, 'The spatio-temporal ndvi analysis for two different Australian catchments', 23rd International Congress on Modelling and Simulation - Supporting Evidence-Based Decision Making: The Role of Modelling and Simulation, MODSIM 2019 (2019)
Copyright © 2019 The Modelling and Simulation Society of Australia and New Zealand Inc. All rights reserved. Contrasts in insolation lead to the development of aspect-controlled e... [more]
Copyright © 2019 The Modelling and Simulation Society of Australia and New Zealand Inc. All rights reserved. Contrasts in insolation lead to the development of aspect-controlled ecosystems characterized by heterogeneity in vegetation type and density in semi-arid ecosystems. The aspect-controlled solar radiation creates variation in the type and amount of vegetation across the two opposite facings of the hillslopes. In the Southern Hemisphere (SH), the north-facing slopes (NFS) have an abundance of paleotropical xeric biota, whereas the south-facing slopes (SFS) have higher densities of mesic temperate species. The reverse patterns are mostly observed in the Northern Hemisphere (NH). In the SH, SFS are dominated by the evergreen sclerophyllous woodland, while open scrub vegetation with spiny shrubs, sub-shrubs, and small trees exist on the NFS. This general vegetation pattern creates differences in erosion control and resistance on different slopes, and thus the underlying landscapes evolve differently. Although many previous studies have focused on aspect-controlled vegetation growth in the NH, there have been limited studies in the SH, especially in Australia. Remote sensing provides one of the best options to capture the long-term biomass changes over the large spatial and temporal coverage. The normalized difference vegetation index (NDVI) is based on the relationship between the reflectance of the red and near-infrared bands of multispectral sensors, and it can be used due to its computational simplicity and easy accessibility. In this study, we considered two catchments, Mount Wilson, South Australia and Risdon Hills in Tasmania to study the long-term spatial and temporal variation in NDVI at these catchments. Both sites are unaffected or minimally affected from anthropogenic activities upon visual inspection through Google EarthTM, in addition to reviewing both sites from the literature. We also explored how the precipitation and potential evapotranspiration patterns at these sites affect the vegetation growth during the year. In this study, we extracted NDVI values derived from Landsat 5, 7, and 8 (obtained from Google Earth Engine) for a 18-year period (2000-2017) for both catchments. Thereafter, we used 30-m SRTM DEM to calculate the aspect and slope datasets for two locations. With the aspect data classified, the vegetation index NDVI is computed for each slope, NSF and SFS. We compared and contrasted the inter-annual variability in NDVI at the two sites to capture the temporal variation in NDVI. We have also introduced NDVIdiff as the difference between NDVI at NFS to SFS, where NDVIdiff > 0 states that NDVI is higher on NFS than SFS and vice-versa. The spatial NDVI is extracted for the summer and winter months, November and June, respectively, to see the seasonal NDVI at each catchment. The results show that the Mount Wilson site (~35°S) has higher NDVI values than the Risdon Hill site throughout the year though receiving similar annual precipitation. It is observed that the Mount Wilson site shows approximately similar NDVI on NFS and SFS in the austral summer period. However, in the winter season when seasonal total precipitation exceeds total PET demand, the NDVI on NFS is comparatively higher than on SFS, which is attributed to differences in vegetation phenology on opposing hillslopes and relatively more incoming solar radiation on NFS than SFS. On the other hand, the site at Risdon Hills (~42°S) has relatively lower range of NDVI at both NFS and SFS, and NDVI at NFS and SFS does not vary noticeably. Further, the spatial NDVI patterns at both locations also illustrate similar behaviour, following the temporal patterns at both locations.
Srivastava A, Yetemen O, Kumari N, Saco PM, 'Aspect-controlled spatial and temporal soil moisture patterns across three different latitudes', 23rd International Congress on Modelling and Simulation - Supporting Evidence-Based Decision Making: The Role of Modelling and Simulation, MODSIM 2019 (2019)
Copyright © 2019 The Modelling and Simulation Society of Australia and New Zealand Inc. All rights reserved. Soil moisture in semi-arid areas plays a critical role as it regulates... [more]
Copyright © 2019 The Modelling and Simulation Society of Australia and New Zealand Inc. All rights reserved. Soil moisture in semi-arid areas plays a critical role as it regulates numerous ecohydrologic processes in land surface hydrology, subsurface hydrology, and vegetation dynamics. Studies on soil moisture distribution and dynamics currently rely on data obtained using three types of approaches: In situ (generally point-scale) measurements, remotely sensed observations, and modelling approaches. The spatial variability of soil moisture plays a vital role in the estimation of land surface fluxes (evapotranspiration (ET) and runoff) due to the non-linear relationship between soil moisture and the associated physical processes. Understanding this variability is essential for the optimal management of water resources and ecosystem sustainability. Although a considerable amount of work has been done on the subject, the ability to understand and characterize the mechanisms that determine the distribution patterns of soil water content still remains a challenge at the centre of hydrological research, especially for ungauged catchments. It is necessary to understand the spatial variability of soil moisture and its influencing factors, which will provide a basis to improve our understanding of hydrological, biogeochemical processes, and lateral and subsurface flow processes. The effects of several factors that control soil moisture variability (SMV) in semi-arid landscapes (microclimate, vegetation, topography, soil depth, soil texture, etc.) have been documented in previous work. However, the control of latitude on SMV under different environmental conditions still remains poorly understood. Latitude significantly affects the availability of water and energy as the global distribution of solar radiation varies from the equator to higher latitudes. Latitude has a dominant control on the availability of water because of the varying amount of solar radiation on north-facing slopes (NFS) and south-facing slopes (SFS), which influences soil moisture variations. This study focusses on evaluating and comparing the effect of latitude on SMV, and its control on soil moisture patterns. To this end, we use a modelling framework to capture the joint effects of aspect and latitude on SMV. We used the Bucket Grassland Model (BGM), equipped with a vegetation dynamics component, to analyse soil moisture patterns and variability at various latitudes (45°N, 34°N, and 15°N). The main objective of this study is to investigate changes in soil moisture patterns at various latitudes and differences in SMV on the different aspects for a synthetic domain. We conducted different simulations as a sensitivity analysis (at various latitudes) using BGM to study the effect of aspect-related soil moisture variations in a semi-arid landscape. The latitudinal patterns of modeled soil moisture are analysed, and distinct variations are identified in the SMV. The results show that water stress varies with aspect and are affected by latitude, which in turn affect the SMV. Further, they show that SMV increases moving towards higher latitudes. Also, aspect-related soil moisture differences are enhanced at higher latitudes. Therefore, it is not possible to characterize soil moisture variations or model surface hydrological processes at the catchment scale, without explicitly accounting for aspect, particularly in ecosystems where the aspect has a dominant effect.
Kumari N, Achary SC, Renzullo LJ, Yetemen O, 'Applying rainfall ensembles to explore hydrological uncertainty', 23rd International Congress on Modelling and Simulation - Supporting Evidence-Based Decision Making: The Role of Modelling and Simulation, MODSIM 2019 (2019)
Copyright © 2019 The Modelling and Simulation Society of Australia and New Zealand Inc. All rights reserved. The widespread presence of spatial and temporal variability in rainfal... [more]
Copyright © 2019 The Modelling and Simulation Society of Australia and New Zealand Inc. All rights reserved. The widespread presence of spatial and temporal variability in rainfall is well known. However, this variability can not be captured by point gauge measurements alone. An accurate representation of this variability is crucial for hydrological and meteorological applications. Precipitation information is an essential input for all hydrological models, but can be especially challenging in regions where no or very few rain gauge stations are established. Moreover, the uncertainties involved in these rainfall inputs are usually not considered or ignored in the hydrological simulations. Uncertainty in precipitation input arising from errors in spatial representation, measurement or estimation accuracy, can create uncertainty in the streamflow estimation. In such cases, the use of high resolution rainfall ensembles can play crucial role in modelling the rainfall-runoff relationships, particularly for high flows or flash floods. This study aims to characterise the hydrological uncertainty involved in the high flow simulations using rainfall-runoff models. This study focuses on characterising uncertainty in rainfall-runoff model outputs through the application of ensemble precipitation estimates. We demonstrate the results for selected events in the Macleay River Basin using a simple rainfall-runoff model. The basin is situated in the New South Wales (NSW), mid-north coast of Australia and is prone to flash floods. Historically, flooding in the lower Macleay Valley occurs at every 2 or 3 years, and the largest floods have occurrence interval of 100 years. We also explored the response of basin area on this uncertainty and the cascading of this uncertainty from upstream to downstream of the basin. The GR4H model, which is an hourly implementation of GR4J, is merged with Muskingum Routing in this study. We used GPM (Global Precipitation Mission) precipitation data at 10km x 10km spatial resolution further downscaled to 2km x 2km spatial resolution for three years (2015-2017). Further, radar data along with the GPM precipitation is used to create 50 member ensemble rainfall estimates at 2km x 2km spatial and hourly temporal resolution. In order to analyse the impact of rainfall uncertainty on streamflow we selected some of the high flows events. The three sub-basins having an area between 377-860 km2 along with the Macleay Basin (~8,000 km2) is used to run the simulations. Further, we compared and contrasted the runoff generated at the outlet by grid-wise simulations, basin averaged simulation, and simulations from ensemble rainfall as input with the observed streamflow. The results show that the grid-wise streamflow generation are comparatively better in capturing the peak flow events in the Macleay Basin and sub-basins than the basin-wise streamflow output probably due to the use of the same parameter throughout the simulations, lower averaged streamflow at each sub-basins, and more amount of overall losses at the basin scale. The observed peak flow is within the range of streamflow simulated using ensemble rainfall for all the basins. The application of interest to this study is the use of ensemble precipitation forecasts to generate ensemble streamflow forecasts. This study shows that the rainfall-runoff modelling with ensemble precipitation inputs can considerably reduce the amount of uncertainty in simulation results, particularly in data-sparce regions.
Yeo I, Lang M, Huang C, Yetemen O, 'Evolution of wetland monitoring from inventory to functional assessment and modelling: a case study from a US catchment', The 22nd International Congress on Modelling and Simulation (MODSIM2017), Hobart, Tasmania, Australia (2017) [E1]
|Show 2 more conferences|
Number of supervisions
|Commenced||Level of Study||Research Title||Program||Supervisor Type|
|2017||PhD||A Global Eco-Hydro-Geomorphic Analysis||PhD (Civil Eng), College of Engineering, Science and Environment, The University of Newcastle||Principal Supervisor|
|2016||PhD||Climate - Soil - Vegetation Interactions: Eco-hydro-geomorphic Inferences from Landscape Evolution Models||PhD (Civil Eng), College of Engineering, Science and Environment, The University of Newcastle||Co-Supervisor|
|Year||Level of Study||Research Title||Program||Supervisor Type|
|2020||PhD||Coupling a Biochemical Vegetation Dynamic Model with Landscape Evolution for Climate Change Impacts Assessment||PhD (Civil Eng), College of Engineering, Science and Environment, The University of Newcastle||Co-Supervisor|
The map is a representation of a researchers co-authorship with collaborators across the globe. The map displays the number of publications against a country, where there is at least one co-author based in that country. Data is sourced from the University of Newcastle research publication management system (NURO) and may not fully represent the authors complete body of work.
|Country||Count of Publications|
Dr Omer Yetemen
Conjoint Senior Lecturer
School of Engineering
College of Engineering, Science and Environment
Callaghan, NSW 2308