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