HPCCprojects:Spatial distribution of solar radiation as a driver of hillslope asymmetry across latitudes


Spatial distribution of solar radiation as a driver of hillslope asymmetry across latitudes

Project description

Ecohydrologic roles of incoming solar radiation on landscape evolution in a semi-arid ecosystem are demonstrated by Yetemen et al. [2015] with CHILD (Channel-Hillslope Integrated Landscape Development) landscape evolution model. In this framework, the CHILD model which is equipped with a solar radiation-driven ecohydrologic vegetation dynamics model and a vegetation-modulated fluvial incision model, is sufficient to reproduce first-order characteristic of aspect-related observed vegetation distribution and hillslope and catchment-scale geomorphic patterns in New Mexico [Istanbulluoglu et al., 2008].
Poulos et al. [2012] investigated hillslope asymmetry across the American Cordillera from 60°N to 60°S latitude. They described hillslope asymmetry with an index, HAI (Hillslope Asymmetry Index) which is a comparison of median slope of different aspects (N versus S, or E versus W). They calculated HAI of N-to-S, HAIN-S through the American Cordillera based on 90-m DEM by using a 5 km by 5 km sliding window, the HAIN-S is nearly 0 at the equator, and systematically increases toward the North Pole which means steeper north-facing slopes than south-facing slopes, and systematically decreases toward the South Pole which means steeper south-facing slopes than north-facing ones. The absolute value of HAIN-S maximizes at mid-latitudes, and then begin to decreases toward the poles, finally sign changes further than 49°N and 40°N latitudes on the Northern and Southern Hemisphere, respectively.


In this project, we want to further explore the ecohydrologic role of solar radiation on landscape development at different latitudes, from 45°N to 45°S, for a range of semi-arid climatology, mean annual precipitation from 200 mm to 500 mm. To achieve this goal, the model will be adjusted based on required changes including the amount of incoming solar radiation, timing of wet season, and storm characteristics etc. At the end of this project, we will answer following questions:

  • What is the role of solar radiation on landscape evolution at different latitudes?
  • What is the role of mean annual precipitation on this role?


2014 - 2015

Models in use

We will use the CHILD landscape evolution model [Tucker et al., 2001] equipped with vegetation dynamics and solar radiation components [Collins et al., 2004; Istanbulluoglu and Bras, 2005; Collins and Bras, 2010; Flores-Cervantes, 2010; Yetemen et al., 2015].


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Omer Yetemen


This research is supported by NSF through grants: NSF-EAR 0963858, NSF-ACI 1148305.

Publications and presentations

  • Collins, D. B. G., and R. L. Bras (2010), Climatic and ecological controls of equilibrium drainage density, relief, and channel concavity in dry lands, Water Resour Res, 46, W04508, doi:10.1029/2009WR008615.
  • Collins, D. B. G., R. L. Bras, and G. E. Tucker (2004), Modeling the effects of vegetation-erosion coupling on landscape evolution, J Geophys Res-Earth, 109, F03004, doi:10.1029/2003JF000028.
  • Flores-Cervantes, J. H. (2010), The coupled development of terrain and vegetation: the case of semiarid grasslands, PhD thesis, MIT, Boston, MA.
  • Istanbulluoglu, E., and R. L. Bras (2005), Vegetation-modulated landscape evolution: Effects of vegetation on landscape processes, drainage density, and topography, J Geophys Res-Earth, 110, F02012, doi:10.1029/2004JF000249.
  • Istanbulluoglu, E., O. Yetemen, E. R. Vivoni, H. A. Gutierrez-Jurado, and R. L. Bras (2008), Eco-geomorphic implications of hillslope aspect: Inferences from analysis of landscape morphology in central New Mexico, Geophys Res Lett, 35, L14403, doi:10.1029/2008GL034477.
  • Poulos, M. J., J. L. Pierce, A. N. Flores, and S. G. Benner (2012), Hillslope asymmetry maps reveal widespread, multi-scale organization, Geophys Res Lett, 39, L06406, doi:10.1029/2012GL051283.
  • Tucker, G. E., S. T. Lancaster, N. M. Gasparini, and R. L. Bras (2001), The Channel-Hillslope Integrated Landscape Development model (CHILD), in Landscape Erosion and Evolution Modeling, edited by R. S. Harmon and W. W. Doe III, pp. 349-388, Kluwer Academic, New York.
  • Yetemen, O., E. Istanbulluoglu, J.H. Flores-Cervantes, E.R. Vivoni, and R.L. Bras (2015), Ecohydrologic role of solar radiation on landscape evolution, Water Resour Res., 51, doi:10.1002/2014WR016169.


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