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MASOMED: MApping SOil variability within rainfed MEDiterranean agroecosystems using hyperspectral data

Start date: 03-05-2017 - End date: 19-05-2017

Status: Confirmed

Open to sharing: Yes

Confidential: No

Transnational Access: Yes

Open to training: No

Grounded / Maintenance: No


Aircraft name: CASA 212 RS - INTA

Airport: The study area is located in the centre of Spain, in the north-west sector of the Autonomous Community of Castilla-La Mancha, Province of Toledo, approximately 50 km SW from Madrid (please refer to the attached document “MASOMEDstudysite.pdf” for a map and coordinates of the proposed study site). This area joins characteristics of special interest in terms of this proposal, such as Mediterranean climate, extended agricultural rainfed uses, mostly evolved soils, and erosion features associated to contrasting soil horizons. Furthermore and most important for the aim of this proposal related to detect changes in the area, data exist from the 2011 dry season in this study area linked with the 1st Camarana EUFAR TA proposal (SEDMEDHY) and related works where erosion stages were determined in fields that were free of vegetation in summer 2011 (Schmid et al., 2016). The study area is situated in the Tagus Basin (South Iberian Meseta), and corresponds to the Guadarrama river catchment. The climate is Mediterranean, with a continental variant that shows cool winter temperatures, and low precipitations with maximum in late autumn, winter and late spring and an outstanding minimum in summer. The meteorological station of Las Ventas de Retamosa (station 3282 of the National Network of the Spanish Ministry of Environment), situated in the northern limit of the area, provides temperature and precipitation data. The average monthly temperature is in the range of 6.1 to 24.7ºC with an average annual temperature of 14.6ºC and an average monthly rainfall of 7 to 56 mm with an average yearly rainfall of 429 mm, respectively. The substrate is formed by Miocene arkoses (feldpars, quartz, phyllosilicates as main constituents), and Quaternary associated sediments constituting forms as glacis, terraces and alluvial fans. Such materials and forms are associated to a gently undulating relief, at altitudes between 500 and 640 m a.s.l. Dominant soils are highly developed: Alfisols (Calcic Haploxeralfs, according to the Soil Taxonomy (Soil Survey Staff, 2010)), or Luvisols, (Calcic Luvisols according to the IUSS Working Group WRB, 2006). The typical profile is characterized by an A horizon, a Bt horizon and a Ck horizon that overlies the arkosic material. Erosion intensity and plowing practices determine the presence of different soil horizons in surface, with contrasting soil properties. An over flight in the spring period (preferably at the end of April or beginning of May) would be considered an ideal option due to the following reasons: 1) cereal crop cultivation will have a maximum active photosynthetic activity; 2) further cultivations such as grapevines and olive groves with active photosynthesis and soil exposed around the individual plants will be present; and 3) abandoned areas will be either in fallow or have an annual vegetation with a green coverage that should be clearly visible.

Project description

Project theme: TA-020. Airborne imaging for environmental science applications.

Project abstract: Cultivation and land use practices have a long history within the Mediterranean region exploiting soils as a natural resource. The soils are an essential factor contributing to agricultural production of rainfed crops such as cereals, olive groves and vineyards. Inadequate management is endangering their quality and productivity. The main objective of this proposal is to map soil variability and quality related to crop stress and land management within a Mediterranean environment based on hyperspectral data within the visible, near-infrared, short-wave infrared as well as thermal infrared including medium and long wave infrared range. The following scientific issues are considered: 1) determining soil variability throughout the study area using high resolution hyperspectral data; 2) assessing the spatial distribution of rainfed agroecosystems according to abiotic and biotic properties; 3) relating vegetation stress to soil degradation processes and conditions; 4) classify soil and crop cover related to soil erosion processes; 5) addressing the potential of future space-borne hyperspectral sensors; and 6) integrating existing space-borne sensors to enhance soil and vegetation cover information using time series. Airborne acquisition will be accompanied by a field campaign including field spectroscopy soil sampling and analyses and characterising vegetation parameters. The aim will be to acquire data from space-borne sensors at the time of the hyperspectral acquisition as well as obtaining data sets from other selected dates during the period of the crop cultivations. An integrated methodology will be implemented to incorporate the multi-source data obtained and compile a database based on GIS technologies.

Measurements to be made by aircraft: Soils within Mediterranean areas form part of a fragile ecosystem, and are greatly influenced by extensive human activities for food production that imply an agricultural land use affecting soil conditions and causing soil degradation (García-Ruiz, 2010). The traditional agricultural activities in southern Europe include the cultivation of rainfed crops, vineyards and olive groves. In this case, the potential impact of agricultural practices is highly dependent on management strategies such as bare soil exposure and tillage practices. Factors such as climate, crop rotation, agricultural practices and policy regulations have a profound impact on the management of cultivated lands (Previtali, 2014). In the past, the European Common Agricultural Policy has introduced changes such as a set-aside program requiring farmers to take certain percentages of their arable land out of production (Boellstorff and Benito, 2005). It has been observed that in recent years, arable land is being cultivated on a yearly basis and that there is a diminishing tendency to leave land in fallow. This means that there is a change occurring in the land management. This proposal is part of an overall research aiming at developing an integrated methodology using hyperspectral optical, thermal and lidar data combined with SAR single and full polarimetric data to map soil resources and land management activities. As a follow-on to the SEDMEDHY-TA proposal that successfully acquired hyperspectral and lidar data in the dry season (summer 2011) and allowed to develop a methodology to map erosion stages (Schmid et al, 2016), the present study aims at mapping the soil variability during the growing season and associated vegetation stress indicators within the rainfed Mediterranean agroecosystems based on hyperspectral optical and thermal data. For this, the following scientific issues are pursued: 1) determining soil variability throughout the study area using the full potential of visible, near infrared, and thermal infrared hyperspectral CASI 1500i and AHS data; 2) assessing the spatial distribution of the different rainfed agroecosystems according to abiotic and biotic properties; 3) relating vegetation stress to soil degradation processes and conditions; 4) detect changes related to soil erosion of soil surface covers by comparing current conditions with those identified in previous work (Schmid et al., 2016), and developing a decision tree methodology to classify the soil and crop cover related to soil erosion processes at the pixel level; 5) assessing the variability of soil properties at different spatial scales with the aim of testing the transferability of the methods used to future hyperspectral space-borne sensors such as EnMAP, HISUI, PRISMA, SHALOM; and 6) integrating existing space-borne optical, thermal infrared and radar sensors such as Landsat 8, ASTER, Copernicus Sentinel 1 and 2 and linking to Radarsat2 data to enhance soil and vegetation cover information using time series. The latter issue aims to study the potential of combining multi-source data (optical, radar, thermal) to asses and spatially map soil quality and crop stress, and to test and develop a simplified methodology that can determine soil and vegetation cover properties associated to soil degradation processes based on current satellite sensors. Data obtained from space-borne sensors will be acquired at the time of the hyperspectral acquisition as well as obtaining data sets from other selected dates during the period of the crop cultivations. Field work will include obtaining spectral data with field spectroradiometers and a thermal radiometer (multispectral CIMEL 312-2) as well as field measurements of soil and vegetation parameters and agricultural activities. An integrated methodology will be further implemented to incorporate the data obtained with the different sensors at the different spatial and spectral resolutions and compiling a database based on GIS technologies. Hyperspectral data obtained with the CASI 1500i and AHS sensors will be used to determine land cover and soil and vegetation characteristics associated to soil degradation processes. The spatial distribution and fraction cover of soil and vegetation surfaces will be assessed and related to the agricultural management practises. For this, spectral unmixing and hard classifier methods will be used. Then visible-near infrared (VNIR: 0.4-1.0 µm) soil and vegetation spectroscopy data will be used to map soil properties (iron content, organic carbon), crop productivity through different vegetation indices (NDVI, red-edge derived indices), water crop stress (water band ~0.94 µm), crop conditions (stressed/healthy through location and slope of the red-edge). Short-wave infrared (SWIR: 1-2.45 µm) spectroscopy data will allow to determine the fraction of vegetation or plant residues, additional soil properties (clay, organic matter, carbonate content). The thermal infrared (TIR: 3-5, 8-12 µm) data will allow to further determine water crop stress, dry vegetation residues, additional soil properties (sand content, better clay and carbon determination). The main output of our proposed activity will be a set of thematic maps of soil and crop variability and related parameters such as land cover, land use and soil properties. The methodology developed and results will be published in international peer-reviewed journals such as Catena, Agriculture Ecosystems and Environment and Remote Sensing of the Environment.

Season: Preferred date would be April 2017, extendable depending on winter weather conditions until early May 2017. Agreement to shate aircraft time: Yes

Weather constraints: The proposed activities require clear sky conditions. Some (cumulus) clouds (less than 10%) can be accepted if not positioned on the target area as shadows.

Time constraints: Time of acquisition would be ideal within +/- 2 hours local solar noon in order to reduce shadow effects. The acquisition window would be preferably in the last week of April 2017 to the first week of May 2017, before the end of the growing season for cereal crops.

Flights (number and patterns): In order to cover the study site of 5 km by 19 km, four parallel flight lines with a N-S direction at 2625 m above ground with the Compact Airborne Spectrographic Imager CASI 1500i and three parallel flight lines at 1825 m above ground with the Airborne Hyperspectral Scanner AHS would be needed to obtain 1 m (CASI) and 3 m (AHS) spatial resolution images. It would be important that the flight lines are taken always in the North to South direction meaning that the flight direction is against the sun. The total flight time is estimated to be about 5 hours.

Instruments: INTA Airborne Hyperspectral Scanner

Other constraints: None

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