COUPLING CESIUM-137 RECORDS TO CALIBRATE THE … · coupling cesium-137 measurements and sediment...

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COUPLING CESIUM-137 MEASUREMENTS AND SEDIMENT LOAD RECORDS TO CALIBRATE THE SEDIMENT DELIVERY DISTRIBUTED MODEL (SEDD). A REGIONAL STUDY IN CALABRIA,SOUTHERN ITALY by Paolo Porto Erosion Modelling Workshop Joint Research Centre Ispra (VA), Italy 20 - 21 - 22 March 2017 137 Cs SEDD = = p N j j i j i i s SDR 1 , , exp λ β

Transcript of COUPLING CESIUM-137 RECORDS TO CALIBRATE THE … · coupling cesium-137 measurements and sediment...

COUPLING CESIUM-137 MEASUREMENTS AND SEDIMENT LOADRECORDS TO CALIBRATE THE SEDIMENT DELIVERY DISTRIBUTEDMODEL (SEDD). A REGIONAL STUDY IN CALABRIA, SOUTHERNITALY by Paolo Porto

Erosion Modelling WorkshopJoint Research Centre Ispra (VA), Italy20-21-22 March 2017

137CsSEDD

−= ∑

=

pN

j ji

jii s

SDR1 ,

,expλ

β

RUSLE SDR

Ri Ki LSi Ci PiY = √ sp,i

(- βexp _______Lp,i)x

R = Rainfall and erosivity factorK = Erodibility factor

LS = Topographic factorsC = Cover and management factorP = Support practice factor

The SEDD Model (Ferro e Minacapilli, 1995)

Y = Sediment yield

SEDD Calibration and Validation(Ferro and Porto, 2000)

∑∑==

−==

uu N

ii

ip

ipiiiii

N

iib SU

sl

SLKCRYY1 ,

,

1exp β

Sediment yield values Yb atthe catchment outlet

Recursive approach for the calculationof the coefficient β

Disadvantages

Need to derive information on sediment deliveryby using tracers (137Cs, 210Pb, 7Be)

Measurements are made at the catchment outletMeasurements are necessary

EARTH ON THE EDGE: SCIENCE FOR A SUSTAINABLE PLANETMELBOURNE Australia 2011 – IUGG - 28 June — 7 July 2011

Soil eroded

137Cs activity

SOIL

SA

MP

LE

Undisturbed site Eroded site

SOIL

SA

MP

LE

UNIVERSITY MEDITERRANEA of REGGIO CALABRIA Department of AGRARIA - Prof. Paolo PortoSo

il de

pth

41 km2

14.8 km2

31.2 km21.4 km2

0.014 km2

The sampling strategy

Reference profiles

W1 BONIS TRIONTO

0

50

100

150

200

250

0 40 80 120 160

Mas

sde

pth

(kg

m-2

)

( q g )

5795 Bq m-2

MELITOALACO

Erosion and deposition sites

W1 BONIS TRIONTO

MELITO

The sediment delivery ratio for each unit orsubcatchment can be derived from the 137Csmeasurements using the following equation:

∑∑ ∑−

=

ee

e dde

j SX

SXSXSDR

UNIVERSITÀ DEGLI STUDI MEDITERRANEA DI REGGIO CALABRIA Dipartimento di AGRARIA

SPEAKER: Paolo Porto

SEDD Calibration using 137Cs (Porto and Walling, 2015)

RUSLE SDR

Ri Ki LSi Ci PiY = √ sp,i

(- βexp _______Lp,i)x

R = Rainfall and erosivity factorK = Erodibility factor

LS = Topographic factorsC = Cover and management factorP = Support practice factor

The SEDD Model (Ferro e Minacapilli, 1995)

Y = Sediment yield

SDR by137Cs

The long-term suspended sediment records

Equipped in 1960Mean = 0.72 t ha-1 yr-1

Alaco

Equipped in 1961Mean = 0.4 t ha-1 yr-1

Melito

Equipped in 1963Mean = 0.21 t ha-1 yr-1

Equipped in 1978Mean = 8.2 t ha-1 yr-1

W1 Trionto

UNIVERSITÀ DEGLI STUDI MEDITERRANEA DI REGGIO CALABRIA Dipartimento di AGRARIA

SPEAKER: Paolo Porto

SEDD Validation (annual data)

0.01

0.1

1

10

100

0.01 0.1 1 10 100

Pred

icte

d se

dim

ent y

ield

(t h

a-1)

Measured sediment yield (t ha-1)

AlacoBonisMelitoTriontoW1PA

CONCLUSIONS

A distributed approach that integrates a sedimentdelivery model within a GIS offers considerablepotential for representing soil erosion and depositionprocesses within a catchment

In this context, calibration and validation of such modelsshould, however, not be restricted to comparison ofpredicted and measured outputs at the catchmentoutlet, but should take account of the internalfunctioning of the catchment

UNIVERSITÀ DEGLI STUDI MEDITERRANEA DI REGGIO CALABRIA Dipartimento di AGRARIA

SPEAKER: Paolo Porto

CONCLUSIONS

The use of 137Cs measurements to derive estimates ofsoil redistribution rates within a catchment provides aneffective means for testing the performance of suchmodels.

The results related to 5 catchments located in Calabriademonstrated that estimates of the sediment deliveryratio derived from the 137Cs measurements provides aneffective means of calibrating the model specificparameter β in SEDD

UNIVERSITÀ DEGLI STUDI MEDITERRANEA DI REGGIO CALABRIA Dipartimento di AGRARIA

SPEAKER: Paolo Porto