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: [email protected] 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 stimulated the 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 microwave radiometers 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 the point 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 at regional/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 designed for validating SSM products at such a higher spatial resolution This poster presents two dense hydrological networks of 3-4km 2 extent, located in the Capitanata plain (Southern Italy). The Capitanata plain, stretching on 4000 km 2 (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 water management, 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 Operational Missions (SEOM) program of the European Space Agency, through the project “Exploitation of S-1 for Surface 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 km 2 (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) Data logger 2.5cm Soil moisture and Soil Temperature sensors 10cm 40cm 20cm Soil moisture sensors GROUND NETWORKS Segezia Example of SSM sampling grid of 5x5 point measurements 0 0. 50 SSM [m 3 /m 3 ] 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 Candelaro basin 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 an average spacing of approximately 0 .5km considering the hydrographic network and the topography 11 soil moisture stations installed in Feb. 2014 Each 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 [m 3 /m 3 ] 17 Kopechy ring SSM measurements co-located with the stations vs sensor DN Calibration error (0.03m 3 /m 3 in average) and correlation (0.86 in average) Sg rmse R 1 0.030 0.81 2 0.026 0.93 3 0.056 0.76 4 0.023 0.94 5 0.027 0.86 6 0.033 0.85 7 0.043 0.81 8 0.033 0.84 9 0.044 0.89 10 0.028 0.93 11 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 0 200 400 600 800 DN 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 [m 3 /m 3 ] = = [ ] R 2 =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 (m 3 /m 3 ) N=1, 100m, CL =90% Cofficient of Variation vs mean SSM Measuring sampling error