de Jong, Steven
The optical and infrared parts of these
images give information on
vegetation, land use and soil type. The
thermal images provide information on
the spatial variation of surface Y
temperature and hence, on the heat-
Fieldwork Data DAIS Image
and water balance in the catchment. ; Statistical Interpretation
With the information of the thermal Survey [> Soil Samples > Exploration l
images, insight on the thermal i
behaviour of surfaces (soils and :
vegetation) can be obtained. With the y Bi Processing
aid of a thermal model, the thermal ; l
behaviour of soils and vegetation can »/ Interpolation
be predicted, and our knowledge on Le Classification
thermal images and the information in
these images can be enlarged (Strobl, J
et al, 1996a, 1997; Muller, 1997; ,
Hausold, 2000). The Peyne catchment Modelling ke Temperature
is chosen as the research area for this Map
study, for its large variance on a small |
scale. This variance presents itself in
the vegetation and land use, the rocks
and soils, and the morphology of Figure 1: Flow diagram of the research approach
the landscape.
The objectives of this study are to 1) investigate the integrated use of optical and thermal remote sensing information
acquired simultaneously, 2) to map differences in surface temperature in the Peyne catchment and to explain these
variations and 3) to develop a regional model simulating the spatial and temporal variation of surface temperature using
information extracted from DAIS and collected in the field. This paper describes the approach and methods used and
the preliminary results. A flow diagram of the research approach is given in figure 1.
2 STUDY AREA AND DATA COLLECTION
The study area is situated in the south of France and forms a part of the catchment of the river *Peyne'. This sub-
catchment of the Hérault is located about 60 km west of Montpellier (N: 43°35’ and E: 3°15°). The size of the study
area is about 12 km”, and is chosen in such a way that it is completely covered by the DAIS imagery. It is situated in
the central part of the Peyne catchment. This part of the catchment covers most of the natural variation present in the
area. Three parts can be distinguished in the area. A northern part that is moderately undulating and that is vegetated
with maquis. The present soils are shallow, and the underlying rock is predominantly calcareous and flysch. The central
part is a transition zone, which is covered by garrigue vegetation. In the southern part, the plains are mostly used for
vine culture. In the south-east, the area is bordered by a basalt-ridge. The climate in the study area is characterised by
short, high intensity rainfall events in spring and autumn and by persistent dry periods in summer. Most precipitation
falls in the early spring and the autumn. The average winter- and summer temperatures are 3 °C and 25 °C respectively.
The altitude of the area varies from 90 to 350 m. above see level (Andrieux, 1993).
A two-month field-campaign was carried out, during which the DAIS-flight took place. During this field-campaign, a
survey was carried out, and several field measurements were taken. During the survey, information on landcover type
and the percentage of vegetation cover was collected. Vineyards show significant variation in management and
coverage. Therefore, additional information was collected on vineyards such as the orientation of the rows, whether the
soils were ploughed or not, the percentage of litter and whether the plants were tied up or not. As input for the surface
temperature model, measurements were taken on soil moisture, soil density and soil porosity. The soil moisture
measurements are corrected for their variability in time. Temperature measurements were taken with a handheld radiant
thermometer. Two sets of temperature data are distinguished; the first set is a temperature timeseries of 12 hours.
Temperature measurements for this timeseries were taken every 30 minutes of bare soil surfaces and vegetation
surfaces. The other temperature data set, comprise the temperature values and variations of the different landcover
types. These temperature measurements are used for the surface temperature model. Furthermore, optical reflectance
spectra of the landcover types were measured with a portable field spectrometer (ASD FieldSpec), and of a number of
characteristic points. The exact geographical location for each of the points was determined by a Differential Global
Positioning System. Both the spectral- and DGPS data are used to correct the DAIS images.
348 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.
