Erosion, sedimentation and bioturbation modelling: field data and analytical model

Andrea Román-Sánchez, Ana Laguna, Tony Reimann, J.V.Giraldez,, Adolfo Peña, Jakob Wallinga, Tom Vanwalleghem

Department of Agronomy, University of Cordoba, Spain

Soil Geography and Landscape group & Netherland Centre for Luminescence Dating (NCL). Wageningen University

Soil Erosion Modelling, JRC Ispra, March 2017

IntroductionSoil erosion rates increasewith anthropogenic activities

-Stripping of natural vegetation (forest cultivation)-Changes in land cover (cultivation or urbanisation)-Cultivation of steep slopes-Over-grazing-Wildfires

Mediterranean ecosystem important wind and water erosion in forest sites

Gully: 1.1- 455 t ha-1 yr-1

(Poesen et al., 2006)

Rusle Model sheet+rill4.61 t ha−1 yr−1

(Panagos et al., 2015)

Measurement sheet+rill: 8.8 t ha-1 yr−1

(Cerdan et al., 2006 )

Probability plots of rates of soil erosion from agricultural fields under conventional (e.g., tillage) and conservation agriculture (e.g., terracing and no-till methods), with erosion rates from areas

and plots under native vegetation, rates of soil production, and geologic rates of erosion

David R. Montgomery PNAS 2007;104:13268-13272

Introduction: tolerable soil erosion?

Definitions tolerable soil erosion:- Roose (1996)-Soil loss balanced by soil formation through weathering of rocks

- International Society of Soil Science (ISSS) (1996)- The maximum rate of soil erosion that permits an optimum level of crop productivity to be sustained economically and indefinitely

- Boardman and Poesen (2006)- Rate of soil erosion is not larger than the rate of soil production

Tolerable soil erosion rates = soil formation rates

(Bennett 1939, Alexander 1988, Wakatsuki and Rasyidin, 1992, Heimsath et al. 1997, Schaller et al. 2001, Wilkinson and McElroy, 2007)

-Dust deposition0-0.2 t ha-1 yr-1

-Weathering0.02 -1.4 t ha-1 yr-1

No deterioration of soil functions

Alewell et al., (2015), J Soils Sediments 15:1383–1399

Introduction𝑑𝑑𝑑𝑑𝑑𝑑𝑑

= 𝑃𝑃 − 𝐷𝐷

Steady-state P=D

Despite the efforts, little is known about soil formation processes in order to model soil formation and establish tolerable rates of soil erosion

The role of bioturbation in soil formation is poorly understood

Luminescence techniques using feldspar single-grain Infrared stimulated measurements (IRSL and post-IR IRSL) can give us direct information of bioturbation and erosion-deposition processes.

Background

IRSL/OSL

DOSE RATE

6

Background

Objectives

1- Reconstruct soil processes (lateral and vertical movement) by luminescence methods

2- Test feldspar single grain IRSL techniques as an alternative (labour efficient)

Introduction

Pioneering studies using quartz OSL to quantifying pedogenesisprocesses

(Heimsath et al., 2002 Stockmann et al., 2013, Johnson et al., 2014)

Sydney

Study area (Sierra de Cordoba)

Study area

Martin Gonzalo

SC-10SC-9

SC-8

SC-7

North facingSouth facing

SC-8

SC-9

SC-10

SC-7

Study areaSAMPLING4 profiles along a catena

Mobile regolith - 51 cm 57 cm

47 cm

97 cm

Materials and Methods

Depth samples:- 15 samples

5 cm

20 cm

35 cm

50 cm

Theoretical model with exponential decrease age profiles

Results: fit to Advection-diffusion equation

Johnson et al. 2014

erosiondeposition

Conclusions- Luminescence can be used for reconstructing vertical and lateral relocation

- Feldspar luminescence performance as good as quartz and the labour is more efficient

- Observed age-depth trends along the hillslope corroborate physical processes

Acknowledgements

Spanish Ministry of Economy and Competitiveness AGL2012-40128-C03-02

Predoctoral grants of Spanish Ministry of Economy and Competitiveness (FPI)

Questions?

Andrea Román Sánchezo92rosaa@uco.es

Thanks !