LAND DEGRADATION STUDIES.
It is important to know the present status of land degradation before embarking on
any land use plan. It is also important to know the causal factors associated with each
land degradation type. The present status of human-induced land degradation was
assessed for the whole world at 1:10 million scale (UNEP/ISRIC 1990). It shows areas
where land degradation takes place, also causal factors for each degradation type are
mentioned. It can be used as a warning to take necessary action. But because of its
small scale, the map cannot be used for local land-use planning activities. Following
the concept of GLASOD (Oldeman et al. 1990), ISRIC (1997) came up with a map of
the status of human-induced soil degradation in South and Southeast Asia (ASSOD).
It is an improvement of the original map, with somewhat more detail. It is thus
important to map land degradation issues at watershed or subwatershed scale for
planning of mitigation works. It is equally important to make hazard assessments and
derive scenarios to answer ‘what if’ questions in order to optimize land-use planning
activities. For this, tools, techniques and methods should be developed.