Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
Present state, changes and quality of Sologne and Brenne, two 
French large wetlands, studied with the MSS and TM Landsat data 
Michel Lenco 
Ministry of Environment, Quality of Life Delegation, Neuilly s/Seine, France 
Jean-Pierre Dedieu 
Company SFERES-Teledetection, Montrouge, France 
ABSTRACT : This work was undertaken to give original informations to local administrative and scientific autho 
rities as an assistance to decision. At first, from Landsat TM and MSS data, the study yields cartographical 
(at 1/50.000 scale) and numerical informations in 23 classes on the present state and the late 1975/84 changes 
of the watershed land cover of two french large wetlands. Secondly, Landsat TM data processing in supervised 
classification have afforded mapped informations about depth, aquatic vegetation, turbidity and outer tempera 
ture of the ponds in ascertaining thresholds in channels 5, 1, 2, 3 and 6. 
RESUME : Ce travail a été entrepris pour fournir des informations originales aux autorités administratives et 
scientifiques locales en tant qu'aide à la décision. En premier lieu, à partir des données Landsat TM et MSS, 
l'étude donne les informations cartographiques (à l'échelle de 1/50.000) et numériques en 23 classes sur l'état 
actuel et les changements récents 1975/84 de l'occupation biophysique du sol du bassin versant de deux grandes 
zones humides françaises. En second lieu, des traitements des données Landsat TM en classification supervisée 
ont apporté des informations cartographiques sur la profondeur, la végétation aquatique, la turbidité et la 
température de surface des étangs en procédant à des seuillages dans les bandes spectrales 5, 1, 2, 3 et 6. 
1. INTRODUCTION 
The aims of the study carried out in 1985 was to know 
the present state and the late changes of ecozones 
and land cover of the watershed and the water areas 
of Sologne and Brenne, which are two large wetlands 
of 130,000 and 145,000 ha extent respectively, situa 
ted in the center of France below the Loire river. 
There are several schemas both to bring out and pro 
tect these two natural media where the changes were 
important during the last ten years owing to hunting 
and fishing or maize cultivation development, 
and cattle breeding withdrawal. The remote sensing 
seemed a good tool to give cartographical, quanti 
tative and qualitative data on these humid areas as 
an aid to the decision. The study was managed in col 
laboration with local administrative and scientific 
authorities. 
2. METHOD 
Two Landsat data recordings were used, a 7/27/1975 MSS 
tape and 6/17/1984 TM tape. An improved and restored 
false color image was elaborated for each date at 
1/50.000 scale. After restoration, the ground resolu 
tion (pixel) was 50 x 50m in the first case, and 30 
30m in the second one. The three wavelenghts choosen 
to establish the two restored images were 4, 5.and 7 
for Landsat MSS, and 2, 4 and 5 for Landsat TM. 
The second image was interpretated to study the 
land cover of the two watersheds with the support of 
topographical, geological and potential vegetation 
maps and a sampling of photographies drawn out of the 
last national coverage at 1/30.000 scale. It was pos 
sible to obtain a classification with 23 items (see 
hereafter results). Landsat TM data appeared interes 
ting to detect easily meadows, cereals, conifers, wa 
ter surfaces and wetlands with the level of the soil 
humidity in the classes. Some difficult points needed 
a control on the ground, during the mapping proces 
sing : classification of wet vegetation on humid 
areas near water surfaces. 
The changes since 1975 were distinguished by compa 
rison of interpretated TM data with corresponding MSS 
data called on a screen in a processing station. 
Between the two dates a perceptible increasing of 
ponds in number and surface and a rise of the draina 
ge to develop the maize cultivation were noticed. The 
interpretated map was treated on computer to get sta 
tistics in hectorage for each class and changes. 
The channel 5 of 1984 Landsat TM data gives the possi 
bility to draw out the water surfaces and the wave 
lengths 1,2, 3 and 6 allow to study the characteris 
tics of water surfaces (depth, nature of the bottom, 
turbidity, aquatic,vegetation and temperature) in se 
lecting thresholds" in supervised classification with 
a discriminant analysis, because some ponds are regu 
larly analyzed and watched by local scientists and 
administrative authorities and were used as ground 
data. It was possible also to observe on the ground 
some ponds in june 1985 at the same period of the year 
that the catch of TM data. In the middle infra red, 
the channel 7 has brought nothing more than channel 5 
to study the water surfaces. 
* some ratios 
3. RESULTS 
3.1 Classifications for mapping at 1/50,000 scale 
LAND COVER CLASSIFICATION 
code category 
1- Building areas 
VI urban, dense 
12 urban, mean and few dense 
13 urban, diffuse 
14 urban hold (industrial areas...) 
15 bare soil, quarry, building yard 
2- Agricultural areas 
21 arable land 
22 fields in copse (arable land and grassland) 
23 wet meadows 
24 reaped grassland and dry grassland 
25 orchards, vineyards, nurseries 
26 draining areas and areas in changing 
3- Natural areas 
31 hardwoods (oaks species,...) 
32 softwoods (pines) 
33 mixed forests 
34 cuts 
35 reafforestings (in conifers)