Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
257 
Spectral signature of rice fields using Landsat-5 TM 
in the Mediterranean coast of Spain 
S.Gandia, V.Caselles, A.Gilabert & J.Melia 
Department of Thermology, Faculty of Physics, University of Valencia, Spain 
ABSTRACT: This work gives the first results of a study carried out in an agricultural area of the Spanish Mediterranean coast using 
Thematic Mapper images. Three cover types, rice, citric - vegetable orchard and urban area are classified in the zone by using a 
vegetation index. Bands 4 and 5 seem to be more suitable for a possible classification of two varieties of rice. 
Key words: Thematic Mapper, vegetation index, rice plants. 
RESUME: Ce travail donne les premiers résultats d'une étude réalisé dans une zone agricole de la côte méditerranéenne espagnole en 
utilisant des images du Thematic Mapper. Trois types de couverture du sol (riz, agrumes-legumes et une zone urbaine) ont été classées. 
Les canaux 4 et 5 semblent les plus convénianu» pom une distinction de deux variétés de riz. 
Mots clés: Thematic Mapper, index de végétation, cultures rizières. 
1. INTRODUCTION 
The application of radiometric measurements to the study of the 
spectral response of rice has originated a number of publications. 
A fair amount of the experimental measurements have been 
ground-based radiometric ones and have mainly addressed to 
establishing correlations among parameters of an agricultural 
interest such as production, influence of the use of different 
fertilizer treatments (Patel, 1985), (CCE.1978), (Berg, 1980), 
etc. Air - flight images as well as images carried out from 
satellites, especially with the Landsat MSS have also originated 
frequent works (CCE, 1984). 
The Thematic Mapper (TM) sensor of the Landsat 5 provides 
better achievements with respect to the MSS which gives it a 
greater potentiality in regards to thematic mapping techniques. In 
regions with high ground parcelation the increase of spatial 
resolution from 80 m (for the MSS) to 30 m (for the TM) is 
essential. In the same way, the inclusion of new spectral bands, 
B1 (0.45 - 0.52 pm), B5 (1.55 - 1.75 pm) and B7 (2.08 - 2.35 
pm) allow a more complete definition of spectral signatures. The 
increased quantization level of 6 bits (0 - 63) to 8 bits (0 - 255) is 
very important in areas where besides high parcelation, different 
agricultural cultivations alternate with urban areas. D. L. Toll 
(Toll, 1985) carries out an important study comparing the 
different characteristics of TM and MSS sensors for land cover 
classification. 
The present work gives the first results of rice studies carried 
out in an area of the Spanish Mediterranean coast from 
measurements supplied by the satellite Landsat 5 (TM). 
2. STUDY SITE DESCRIPTION AND DATA USED 
Approximately a third of Spanish rice production is obtained at 
the south of the city of Valencia (Spain) which is an area 
eminently agricultural. The area of cultivation (about 15.500 ha) 
expands along the lands bordering the lake "La Albufera" and the 
proximities of the outfall of the Jucar river, "Ribera Baixa". This 
is a high populated area where rice cultivations alternate with 
citrics and vegetables. The lands dedicated to the cultivation of 
rice are slowly but constantly decreasing because they are being 
substituted by orchards and citrics. The map of figure 1 shows 
the referred area and the two studied zones. 
But this seaboard stripe is also undergoing a strong urban 
pressure characteristic of tourist areas. Similarly La Albufera lake 
and its surroundings is an area of general interest due to the 
alterations produced in the natural environment. 
The heterogeneity of land cover types besides the big ground 
parcelation impose the use of satellite measurements with high 
spatial resolution for the classification of the ground. 
In this study two neighbouring zones of about 7 km 2 each 
have been chosen (figure 1). The lower one (Sueca) 
representative of the different land cover types: rice, citric - 
Figure 1. Training sites located in the Mediterranean coast of 
Spain. 
vegetable orchards and urban areas and has been defined in order 
to separate these three land cover classes. The upper zone (La 
Albufera) mainly contains rice fields. The work has been 
centered in this area in order to study the spectral response of 
rice. 
In both zones, reference parcels have been chosen, with the 
caracteristics shown in Table I. The varieties Bahia (91%) and 
Sequial (8%) cover almost exclusively the whole production.The 
net efficiency is about 6500 kg/ha. Parcels with other varieties 
(Rubino, Pierina and Lido) have been taken in order to study 
reflectivities. These latter parcels are considered experimental 
from a production point of view. 
The citric - vegetable class presents a great internal variability 
due to the different degree of vegetated cover of the ground. In 
these class other types of cultivations such as vegetables have 
been included in order to discriminate them from rice.