Assessment of the coupled effects of vegetation leaf and root characteristics on soil suction: an integrated numerical modeling and probabilistic approach

  • H. Zhu
  • M. Indupriya
  • V. K. Gadi
  • S. Sreedeep
  • G. X. MeiEmail author
  • A. Garg
Short Communication


Root depth and leaf area ratio are two important features of a plant and exhibit a coupled relation. Assessing their coupled effects on induced soil suction is essential for analyzing the performance of a green infrastructure, such as water storage/drainage in green roofs and stability of a vegetated slope. Previously soil moisture induced by vegetation was often presented deterministically without considering the overall effects of leaf and root characteristics in a probabilistic manner. The main objective of this study is to investigate the influence of coupled variations in root and leaf characteristics on vegetation-induced soil suction. In addition, the coupled effects were analyzed using statistical approach. Different combinations of the leaf area index and root depth of the same plant were assessed. Probabilistic analysis was then conducted by computing suction profiles in form of quantiles. It was found that the biggest variability in suction profiles occurs at around 0.6 times the root depth and the minimum occurred at near surface and at maximum root depth. This depth at 0.6 times root depth corresponds to the maximum root density. It implies that the probabilistic analysis becomes more and more important while assessing suction profiles near the maximum root density.


Leaf area ratio Probabilistic framework Root depth Soil suction Variability 

List of symbols


Soil surface level (1 mm below soil surface)


Depth corresponding to the maximum root area index


Degree of compaction of soil


Potential evaporation


Constant that governs the extinction of radiation by leaves


Leaf area index


Potential evapotranspiration


n% quantile of results from all realizations


Root area index


Root depth


Maximum root depth


Transpiration reduction function


Potential transpiration



The work described in this paper was supported by the Research Grant Council (No. C6012-15G) of the Hong Kong Special Administrative Region.


  1. 1.
    Allam MM, Sridharan A (1981) Effect of wetting and drying on shear strength. J Soil Mech Found Div 107(4):421–438Google Scholar
  2. 2.
    Bordoloi S, Hussain R, Gadi VK, Bora H, Sahoo L, Karangat R, Garg A, Sreedeep S (2017) Monitoring soil cracking and plant parameters for mixed grass species. Geotech Lett 1:1–7Google Scholar
  3. 3.
    Cattanio JH (2017) Leaf area index and root biomass variation at different secondary forest ages in the eastern Amazon. For Ecol Manag 400:1–11CrossRefGoogle Scholar
  4. 4.
    Chen X, Zhang L, Chen L, Li X, Liu D (2018) Slope stability analysis based on the Coupled Eulerian-Lagrangian finite element method. Bull Eng Geol Environ. Google Scholar
  5. 5.
    Deb SK, Shukla MK, Šimůnek J, Mexal JG (2013) Evaluation of spatial and temporal root water uptake patterns of a flood-irrigated pecan tree using the HYDRUS (2D/3D) model. J Irrig Drain Eng 139(8):599–611CrossRefGoogle Scholar
  6. 6.
    Feddes R, Kowalik P, Zaradny H (1978) Simulation of field water use and crop yield. Centre for Agricultural Publishing and Documentation, WageningenGoogle Scholar
  7. 7.
    Fredlund DG, Morgenstern NR, Widger RA (1978) The shear strength of unsaturated soils. Can Geotech J 15(3):313–321CrossRefGoogle Scholar
  8. 8.
    Gadi VK, Tang YR, Das A, Monga C, Garg A, Berretta C, Sahoo L (2017) Spatial and temporal variation of hydraulic conductivity and vegetation growth in green infrastructures using infiltrometer and visual technique. CATENA 155:20–29CrossRefGoogle Scholar
  9. 9.
    Gadi VK, Bordoloi S, Garg A, Kobayashi Y, Sahoo L (2016) Improving and correcting unsaturated soil hydraulic properties with plant parameters for agriculture and bioengineered slopes. Rhizosphere 1:58–78CrossRefGoogle Scholar
  10. 10.
    Garg A, Ng CWW (2015) Investigation of soil density effect on suction induced due to root water uptake by Schefflera heptaphylla. J Plant Nutr Soil Sci 178(4):586–591CrossRefGoogle Scholar
  11. 11.
    Garg A, Leung AK, Ng CWW (2015) Transpiration reduction and root distribution functions for a non-crop species Schefflera heptaphylla. CATENA 135:78–82CrossRefGoogle Scholar
  12. 12.
    Garg A, Leung AK, Ng CWW (2015) Comparisons of soil suction induced by evapotranspiration and transpiration of Schefflera heptaphylla. Can Geotech J 52(12):2149–2155CrossRefGoogle Scholar
  13. 13.
    Garg A, Hazra B, Zhu H, Wen Y (2019) A simplified probabilistic analysis of water content and wilting in soil vegetated with non-crop species. Catena 175:123–131CrossRefGoogle Scholar
  14. 14.
    Hau BC, Corlett RT (2003) Factors affecting the early survival and growth of native tree seedlings planted on a degraded hillside grassland in Hong Kong, China. Restor Ecol 11:483–488CrossRefGoogle Scholar
  15. 15.
    Hazra B, Gadi V, Garg A, Ng CWW, Das GK (2017) Probabilistic analysis of suction in homogeneously vegetated soils. CATENA 149:394–401CrossRefGoogle Scholar
  16. 16.
    Huang X, Luo G, Lv N (2017) Spatial-temporal patterns of grassland evapotranspiration and water use efficiency in arid areas. Ecol Res 32(4):523–535CrossRefGoogle Scholar
  17. 17.
    Jackson RB, Canadell J, Ehleringer JR, Mooney HA, Sala OE, Schulze ED (1996) A global analysis of root distributions for terrestrial biomes. Oecologia 108(3):389–411CrossRefGoogle Scholar
  18. 18.
    Kashiwagi J, Krishnamurthy L, Crouch JH, Serraj R (2006) Variability of root length density and its contributions to seed yield in chickpea (Cicer arietinum L.) under terminal drought stress. Field Crops Res 95(2-3):171–181CrossRefGoogle Scholar
  19. 19.
    Kim J, Jeong S, Park S, Sharma J (2004) Influence of rainfall-induced wetting on the stability of slopes in weathered soils. Eng Geol 75(3–4):251–262CrossRefGoogle Scholar
  20. 20.
    Lei G, Usai S, Wu W (2019) Centrifuge study of soil arching in slope reinforced by piles. Recent advances in geotechnical research. Springer, Cham, pp 105–115CrossRefGoogle Scholar
  21. 21.
    Leung AK, Garg A, Ng CWW (2015) Effects of plant roots on soil-water retention and induced suction in vegetated soil. Eng Geol 193:183–197CrossRefGoogle Scholar
  22. 22.
    Li DQ, Chen YF, Lu WB, Zhou CB (2011) Stochastic response surface method for reliability analysis of rock slopes involving correlated non-normal variables. Comput Geotech 38(1):58–68CrossRefGoogle Scholar
  23. 23.
    Mickovski SB, Gonzalez-Ollauri A, Tardio G (2017) Novel approaches to quantification of the vegetation effects on soil strength. In: Proceedings of 19th international conference on soil mechanics and geotechnical engineering, Seoul, Korea, pp 3167–3170Google Scholar
  24. 24.
    Monteith JL (1965) Evaporation and environment. Symp Soc Exp Biol 19(205–23):4Google Scholar
  25. 25.
    Ni JJ, Leung AK, Ng CWW (2018) Unsaturated hydraulic properties of vegetated soil under single and mixed planting conditions. Géotechnique. Google Scholar
  26. 26.
    Ng CWW, Garg A, Leung AK, Hau BCH (2016) Relationships between leaf and root area indices and soil suction induced during drying–wetting cycles. Ecol Eng 91:113–118CrossRefGoogle Scholar
  27. 27.
    Qi XH, Li DQ (2018) Effect of spatial variability of shear strength parameters on critical slip surfaces of slope. Eng Geol 239:41–49CrossRefGoogle Scholar
  28. 28.
    Richards BG (1965) Measurement of free energy of soil moisture by the psychrometric technique using thermistors. Buttersworth & Company, BrisbaneGoogle Scholar
  29. 29.
    Switala B, Askarinejad A, Wu W, Springman SM (2018) Experimental validation of a coupled hydro-mechanical model for vegetated soil. Geotechnique 68(5):375–385CrossRefGoogle Scholar
  30. 30.
    Świtala BM, Wu W (2019) Simulation of rainfall-induced landslide of the vegetated slope. Recent advances in geotechnical research. Springer, Cham, pp 187–196Google Scholar
  31. 31.
    Take WA, Beddoe RA, Davoodi-Bilesavar R, Phillips R (2015) Effect of antecedent groundwater conditions on the triggering of static liquefaction landslides. Landslides 12(3):469–479CrossRefGoogle Scholar
  32. 32.
    Tratch D (1996) Moisture uptake within the root zone. In: M.Sc. thesis, Department of Civil Engineering, University of Saskatchewan, CanadaGoogle Scholar
  33. 33.
    Van Genuchten MT (1980) A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci Soc Am J 44(5):892–898CrossRefGoogle Scholar
  34. 34.
    Vanapalli SK, Fredlund DG, Pufahl DE, Clifton AW (1996) Model for the prediction of shear strength with respect to soil suction. Can Geotech J 33(3):379–392CrossRefGoogle Scholar
  35. 35.
    Varado N, Braud I, Ross PJ (2006) Development and assessment of an efficient vadose zone module solving the 1D Richards’ equation and including root extraction by plants. J Hydrol 323(1):258–275CrossRefGoogle Scholar
  36. 36.
    Wu W, Switala BM, Acharya MS, Tamagnini R, Auer M, Graf F, Xiang W (2015) Effect of vegetation on stability of soil slopes: numerical aspect. Recent advances in modeling landslides and debris flows. Springer, Cham, pp 163–177Google Scholar
  37. 37.
    Zhou C, Ng CWW (2014) A new and simple stress-dependent water retention model for unsaturated soil. Comput Geotech 62:216–222CrossRefGoogle Scholar
  38. 38.
    Zhu H, Zhang LM (2015) Evaluating suction profile in a vegetated slope considering uncertainty in transpiration. Comput Geotech 63:112–120CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  • H. Zhu
    • 1
  • M. Indupriya
    • 2
  • V. K. Gadi
    • 3
  • S. Sreedeep
    • 3
  • G. X. Mei
    • 4
    Email author
  • A. Garg
    • 3
  1. 1.Department of Civil and Environmental EngineeringThe Hong Kong University of Science and TechnologyKowloonHong Kong
  2. 2.Department of Civil and Environmental EngineeringStanford UniversityStanfordUSA
  3. 3.Department of Civil EngineeringIndian Institute of Technology GuwahatiGuwahatiIndia
  4. 4.Department of Civil Engineering and ArchitectureGuangxi UniversityNanningChina

Personalised recommendations