Dense hydrological networks for high resolution soil moisture product validation

Anna Balenzano (1), Francesco Mattia (1), Giuseppe Satalino (1), Francesco Lovergine (1), Michele Rinaldi (2) and M. H. Cosh (3)

(1) Consiglio Nazionale delle Ricerche (CNR) - Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA), sede di Bari, via Amendola 122/D - 70126 Bari, Italy.

(2) Consiglio per la ricerca in Agricoltura e l’analisi dell’Economia Agraria (CREA) , (3) USDA, Agricultural Research Service, Hydrology and Remote Sensing Laboratory, Beltsville, MD, USA

Email: anna.balenzano@cnr.it

Abstract The increasing availability of soil moisture (SM) products provided by present satellite missions, e.g. the ESA SMOS, EUMETSAT ASCAT and the NASA SMAP missions, has stimulatedthe creation of long-term and accurate in situ SM networks at a global scale, to support calibration and validation activities. As SM products are currently operationally derived by microwaveradiometers and scatterometers, many efforts have been made to identify strategies to deal with the scale-mismatch between the satellite coarse spatial resolutions (e.g. 25-36km) and thepoint measurements on the ground, e.g. upscaling observations from sparse networks. Recently, the use of ESA Sentinel -1 observations to support systematic SM product generation atregional/continental scale has risen the needs to tailor the validation strategy to high spatial resolution SM product (e.g 1km). This includes setting up ground networks purposely designedfor validating SSM products at such a higher spatial resolution This poster presents two dense hydrological networks of 3-4km2 extent, located in the Capitanata plain (Southern Italy). TheCapitanata plain, stretching on 4000 km2 (i.e. the second largest plain in Italy), is a crucial area for the durum wheat production in Italy and presents important challenges for the watermanagement, as the area is prone to flash-flood/drought events and needs accurate yield forecast.

ACKNOWLEDGEMENTS. This research is supported by the Scientific Exploitation of OperationalMissions (SEOM) program of the European Space Agency, through the project “Exploitation of S-1 forSurface Soil Moisture Retrieval at High Resolution (Exploit-S-1)” contract n. 4000118762/16-NB(https://exploit-s-1.ba.issia.cnr.it

APULIAN TAVOLIERE SITE (JECAM SITE)

4000 km2 (i.e., the second largest plain in Italy) semi-arid Mediterranean climate (annual

rainfall about 550 mm) almost flat topography main crops: durum wheat, barley, oat, tomato,

chickpea, broad bean, sunflower

Agricultural areas (CORINE)

Datalogger

2.5cm Soil moisture and

Soil Temperature sensors10cm

40cm

20cm

Soil moisture sensors

GROUND NETWORKS

Segezia

Example of SSM sampling grid of 5x5 point measurements

00.

50

SSM

[m

3 /m3 ]

REPRESENTATIVENESS OF POINT SCALE MEASUREMENTS AT 100m RESOLUTION

Foggia

Foggia site

Segezia site

Segezia experimental farm of approx. 4km2 located in the Cervaro basin

main crops: cereals (durum wheat, barley, oat) and pasture

Foggia experimental fields in an area of approx. 3km2 located in the Candelarobasin

main crops: durum wheat and tomato network of 10 ground soil moisture

stations + pluviometer, installed in June 2017

Calibration in progress

The stations are distributed with anaverage spacing of approximately0.5km considering the hydrographicnetwork and the topography

11 soil moisture stations installed in Feb. 2014Each station: EM50 datalogger &

Decagon 5TM & 10HS capacitance devices installed horizontally at 2.5cm, 10cm, 20cm and 40cm depths, respectively

1 meteo station soil specific calibration

SOIL SPECIFIC CALIBRATION

SSM

[m3 /m

3 ]

17 Kopechy ring SSM measurementsco-located with the stations vs sensor DN

Calibration error (0.03m3/m3 in average) and correlation (0.86 in average)

Sg rmse R1 0.030 0.812 0.026 0.933 0.056 0.764 0.023 0.945 0.027 0.866 0.033 0.857 0.043 0.818 0.033 0.849 0.044 0.89

10 0.028 0.9311 0.035 0.82

0

50

100

150

200

250

300

350

400

Histogram of the surface soil moisture (SSM) measurements collected by the ground stations on the S-1 (A146) acquisition dates from 2015 to 2017. (1190 points

Dry- medium wet soil conditions

SSM in m3/m3

0

0.1

0.2

0.3

0.4

0.5

0 200 400 600 800DN

Sg07 Sg10

SOIL MOISTURE CONDITION AND SOIL TEXTURE

highly anthropogenic environment & increasing evaporative demand → significant reduction in water availability & increased water demand (e.g. irrigation, energy, industry, etc.) → risk of future yield loss

LOAM ; 6

SANDY LOAM; 4

SILT LOAM; 1

0.00

0.20

0.40

0.60

0.80

1.00

0.00 0.10 0.20 0.30

CV

Mean SSM [m3/m3]

𝐶𝐶𝐶𝐶 = 𝜎𝜎𝜇𝜇

= 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴[𝐵𝐵𝜇𝜇]

R2=0.67

0

0.01

0.02

0.03

0.04

0.05

0.06

0 0.1 0.2 0.3 0.4 0.5 0.6

MSE

SSM

(m3/

m3)

SSM (m3/m3)

N=1, 100m, CL =90%Cofficient of Variation vs mean SSM

Measuring sampling error