Indicators and Information Requirements for Combatting Desertification
97
Working Group 1: Climate and remote sensing related
The problem which has to be solved is the scaling between global modelling and
local impact. The downscaJing from global models requires additional techniques
to include topography and vegetation and small scale circulation systems which are
available from different studies but not used in a systematic way. Similarly, the
studies of regional and local effects need regional expertise which may be available
but is not yet organized enough.
A Mediterranean/North African GEWEX (Global Energy and Water-cycle
Experiment) is proposed for which main requirements are:
• Measurements in representative areas necessary to provide input data for models
and to validate model results.
Satellite data bridge from isolated measuring sites to larger land-surface units.
A GEWEX has to be build upon a networked scientific community able to
provide the logistic support for experiments as well as regional expertise. Some
ground stations should in any case be selected as "anchor stations" for satellite data.
At these stations surface properties should be measured such as albedo, net
radiation, carbon dioxide and water exchange between surface and atmosphere, state
and density of vegetation, as well as subsurface quantities such as the piezometric
level, soil moisture profiles and root depth precipitation, evaporation, river run-off,
maps of "functional land-cover types". Time series of Satellite data must be
extended to 20 years minimum.
Working Group 2: Soil, water, and vegetation related
Concerning water resources, there are major gaps with respect to data and
information relating to the monitoring of water use, the use of water for irrigation
and for public water supply.
Data should be collected at a variety of scales in catchments where all the
collateral data relating to land use change, vegetation, soil and climate are available,
as well as information on socio-economic and policy drivers. Too often critical data
sets required to interpret results are missing.
With particular reference to soil, particularly valuable are observations related
to the dynamic features of soils such as various aspects of soil structure (including
surface crusts, bulk density and roughness), soil chemistry and nutrient dynamics
and various soil biological indicators. Soil moisture amounts, fluctuations and
distributions were also considered to be important.
It was stressed that these data and the indicators that will be derived from them
should be specifically targeted at :
the reconstruction or rehabilitation of soils that are already degraded
the prevention of degradation in areas that are likely to be threatened.
deriving indicators that could provide early warning of degradation.
Concerning methods, it was thought that low-cost simple field tests or
measurements should be given priority. Detailed DEMs are very important for
erosion modelling.
97
Working Group 1: Climate and remote sensing related
The problem which has to be solved is the scaling between global modelling and
local impact. The downscaJing from global models requires additional techniques
to include topography and vegetation and small scale circulation systems which are
available from different studies but not used in a systematic way. Similarly, the
studies of regional and local effects need regional expertise which may be available
but is not yet organized enough.
A Mediterranean/North African GEWEX (Global Energy and Water-cycle
Experiment) is proposed for which main requirements are:
• Measurements in representative areas necessary to provide input data for models
and to validate model results.
Satellite data bridge from isolated measuring sites to larger land-surface units.
A GEWEX has to be build upon a networked scientific community able to
provide the logistic support for experiments as well as regional expertise. Some
ground stations should in any case be selected as "anchor stations" for satellite data.
At these stations surface properties should be measured such as albedo, net
radiation, carbon dioxide and water exchange between surface and atmosphere, state
and density of vegetation, as well as subsurface quantities such as the piezometric
level, soil moisture profiles and root depth precipitation, evaporation, river run-off,
maps of "functional land-cover types". Time series of Satellite data must be
extended to 20 years minimum.
Working Group 2: Soil, water, and vegetation related
Concerning water resources, there are major gaps with respect to data and
information relating to the monitoring of water use, the use of water for irrigation
and for public water supply.
Data should be collected at a variety of scales in catchments where all the
collateral data relating to land use change, vegetation, soil and climate are available,
as well as information on socio-economic and policy drivers. Too often critical data
sets required to interpret results are missing.
With particular reference to soil, particularly valuable are observations related
to the dynamic features of soils such as various aspects of soil structure (including
surface crusts, bulk density and roughness), soil chemistry and nutrient dynamics
and various soil biological indicators. Soil moisture amounts, fluctuations and
distributions were also considered to be important.
It was stressed that these data and the indicators that will be derived from them
should be specifically targeted at :
the reconstruction or rehabilitation of soils that are already degraded
the prevention of degradation in areas that are likely to be threatened.
deriving indicators that could provide early warning of degradation.
Concerning methods, it was thought that low-cost simple field tests or
measurements should be given priority. Detailed DEMs are very important for
erosion modelling.