In the field of hydrological modelling, there is mostly a lack of spatially distributed data that may allow a detailed
analysis of simulation results. This study was to demonstrate that remote sensing can partly fill this gap, as combining
reflective and thermal data allows the retrieval of estimates for evapotranspiration (ET). Two Landsat-5 TM scenes were
analysed, and the results were afterwards compared to the daily output of the Precipitation Runoff Modeling System, a
conceptual model based on Hydrologic Response Units and designed for meso- to macroscale applications. For the study
site, the mesoscale Ruwer basin located in the low mountain range of Rhineland-Palatinate (Germany), an overall good
agreement of ET estimates retrieved by both approaches was found. At one date, some mismatches indicated clear
inconsistencies in the model structure and parameterisation scheme. Based on these findings, a modified soil module was
implemented to allow for a more realistic specification of land use dependant parameters. After this, PRMS provided ET
estimates now very similar to those from Landsat TM, and the RMSE was reduced from 1.30 to 0.86 mm. These results
indicate, that the representation of the hydrological cycle by hydrological modelling may be improved by the integration
of appropriate remote sensing data.
KEYWORDS: Landsat, Vegetation, Sensors, Data archive systems, Earth observing sensors, Remote sensing, Time series analysis, Agriculture, Satellites, Point spread functions
The aim of this study was to evaluate the potentials and limits of remote sensing time series regarding change analysis of
drylands. We focussed on the assessment and monitoring of land degradation using different scales of remote sensing
data. Special interest was paid on how the spatial resolutions of different sensors influence the derivation of vegetation
related variables, such as trends in time and the shift of phenological cycles. Hence, a comparison was performed using
high and medium resolution sensors and their suitability for monitoring land degradation will be evaluated.
Long time series of Landsat TM and NOAA AVHRR covering the overlapping time period from 1990 to 2000 were
compared for a test area in the Mediterranean. At local scale additional information was delivered by a multi-seasonal
land use/cover change detection (LUCC) analysis. The test site which is located in Central Macedonia (Greece) is mainly
characterized by long-term, gradual processes mainly driven by grazing and the extension of irrigated arable land.
Land use conversions or changes of land management practices are primary drivers of global environmental change.
'Natural experiment' situations, where some conditions vary, but other potential land use determinants remain relatively
constant, offer unique opportunities to study land use change, its drivers and feedbacks on human-environment systems.
The Chalkidiki peninsula in Northern Greece is an ideal test case to study recent land use transformations and socio-economic
changes (e.g. resulting from accession to the EU) against a stable reference area. Of the three peninsular legs of Cassandra, Sithonia and Athos, the latter harbours the 'Autonomous Monastic State of the Holy Mountain', a sovereign and isolated monastic state. Apart from subsistence agriculture around the monasteries, it represents a
Mediterranean ecosystem in a state virtually unaffected by modern human use. We have used a time series of 22 fully corrected
Landsat-TM and ETM+ data to study land use/land cover change on the
peninsula, and related the results to a similar study in the adjacent County of Lagadas. A diachronic land use change analysis based on SVM classification was conducted using two three image-pairs. Where natural and semi-natural vegetation formations remained stable, trends were calculated using a pixel-wise linear trend analysis of SMA-derived vegetation cover estimates. Results were interpreted using auxiliary data and in relation to the Athos area. Changes were
found to result from discontinuation of extensive land use in Cassandra and Sithonia in favour of intensified agricultural
use and the expansion of tourist activities, complemented by land abandonment in less attractive areas.
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