Télédétection et ressources en eau/Remote sensing and water resources
19
the objective of the application, the scale and the platform: always avoid privileging the tool over
the theme, avoid carrying out excessive digital analysis on the image if it doesn’t contain the
required information. The cost factor should also be integrated in the choice of the platform to be
used. Aerial photography and satellite images are usually a source of complementary information
to be used with caution.
Remote sensing and the management of rural space
Another presentation (Patrick) proposes the integration of environmental information obtained
from two complementary sources: remote sensing and the indigenous knowledge of local
populations. Remote sensing provides a view at a given moment, while local populations integrate
the knowledge of local conditions over a number of years. The presentation suggests integrating
indigenous knowledge into an expert system. This method, particularly original in its attempt to
combine global information with the local knowledge, needs further testing before its feasibility
can be evaluated.
THEME 2: HYDROLOGICAL MODELLING AND THE DEFINITION OF PARAMETERS
In this section, it is possible to identify two main themes: a descriptive and mapping theme,
followed by a modelling one. The objectives of the presentations in this section may be described
as follows:
Description and mapping
• determination of the hydrological characteristics of soils: quantitative mapping of parameters
that vary over time (soil types, vegetation, crops, surface conditions and runoff index);
• determination of the elements of water balance: quantitative mapping of parameters that vary
over time (humidity, evapotranspiration, temperature);
• objective division of space into hydrological units.
Hydrological modelling and interpretation
• collection of spatially distributed information to be used as a support for modelling;
• analysis of the connections between environment and its functions: search for descriptors of
environmental mechanisms,
• detailed analysis of hydrological behaviour: renewed interest for the internal hydrological
functions of watershed.
Description and mapping phase
Hydrological characteristics of soils
A number of presentations described the activities carried out in the framework of an FAO
project for the estimation of discharge in Sahelian regions, and particularly the tests carried out
on the utilization of remote sensing for the improved estimation of discharge from small
watersheds. The surface feature mapping in Sahel (Lamachere and Puech) was also described.
These activities start from the assumption that, thanks to a number of peculiarities, the Sahelian
region is favourable for the development of remote sensing tools used for assessing the origin of
19
the objective of the application, the scale and the platform: always avoid privileging the tool over
the theme, avoid carrying out excessive digital analysis on the image if it doesn’t contain the
required information. The cost factor should also be integrated in the choice of the platform to be
used. Aerial photography and satellite images are usually a source of complementary information
to be used with caution.
Remote sensing and the management of rural space
Another presentation (Patrick) proposes the integration of environmental information obtained
from two complementary sources: remote sensing and the indigenous knowledge of local
populations. Remote sensing provides a view at a given moment, while local populations integrate
the knowledge of local conditions over a number of years. The presentation suggests integrating
indigenous knowledge into an expert system. This method, particularly original in its attempt to
combine global information with the local knowledge, needs further testing before its feasibility
can be evaluated.
THEME 2: HYDROLOGICAL MODELLING AND THE DEFINITION OF PARAMETERS
In this section, it is possible to identify two main themes: a descriptive and mapping theme,
followed by a modelling one. The objectives of the presentations in this section may be described
as follows:
Description and mapping
• determination of the hydrological characteristics of soils: quantitative mapping of parameters
that vary over time (soil types, vegetation, crops, surface conditions and runoff index);
• determination of the elements of water balance: quantitative mapping of parameters that vary
over time (humidity, evapotranspiration, temperature);
• objective division of space into hydrological units.
Hydrological modelling and interpretation
• collection of spatially distributed information to be used as a support for modelling;
• analysis of the connections between environment and its functions: search for descriptors of
environmental mechanisms,
• detailed analysis of hydrological behaviour: renewed interest for the internal hydrological
functions of watershed.
Description and mapping phase
Hydrological characteristics of soils
A number of presentations described the activities carried out in the framework of an FAO
project for the estimation of discharge in Sahelian regions, and particularly the tests carried out
on the utilization of remote sensing for the improved estimation of discharge from small
watersheds. The surface feature mapping in Sahel (Lamachere and Puech) was also described.
These activities start from the assumption that, thanks to a number of peculiarities, the Sahelian
region is favourable for the development of remote sensing tools used for assessing the origin of