context of the area concerned. Evaluations for unrealistic land use options should
be avoided. The assumptions underlying evaluation differ by region and are often
implicit. To avoid misunderstanding and to assist in comparisons between different
areas, such assumptions should be explicitly stated.
v. Suitability refers to use on a sustained basis. The aspect of environmental
degradation is taken into account when assessing suitable land uses. Land uses that
are highly profitable in the short term but cause physical limitations or hazards
in the long term are classed as not suitable for such purposes. For any proposed
land use, the probable consequences for the environment should be assessed as
accurately as possible and taken into consideration in determining suitability.
The sustainability principle provides a balance to the economic emphasis in the
Framework.
vi. Evaluation involves comparison of more than a single kind of use. Evaluation
is only reliable if benefits and inputs from any given kind of use can be compared
with at least one, and usually several different, alternatives. If only one use is
considered there is the danger that, while the land may indeed be suitable for that
use, some other and more beneficial use may be ignored.
Concepts and procedures
Land evaluation is the process of the assessment of land performance when the land
is used for specified purposes. It involves the execution and interpretation of surveys
and studies of landforms, soils, climate, vegetation and other aspects of land in order to
identify and compare promising kinds of land use in terms applicable to the objectives
of the evaluation. To be of value in planning, the range of land uses considered should
be limited to those relevant within the physical, economic and social context of the area
considered, and the comparisons should incorporate economic considerations.
The Framework uniformly defines concepts related to land evaluation. Definitions
of land, land mapping unit, major kind of land use, land utilization type, multiple and
compound land use, land characteristics, land qualities, diagnostic criteria, land use
requirements, limitations, land suitability, land suitability order, class, subclass, unit
and potential suitability classification as outlined in the Framework can be consulted
in the glossary (Annex 1 of this document). Most of the principles and concepts of the
1976 Framework remain valid; some need amplification (Chapter 3).
The procedures described in the Framework are detailed and complex, but in
many cases not all activities or procedures are needed for the specific goal of the land
evaluation. The main groups of activities in a land evaluation are:
¾Initial consultations, concerned with the objectives of the evaluation, and the data
and assumptions on which it is to be based
¾Description of the kinds of land use to be considered, and establishment of their
requirements
¾Description of land mapping units, and derivation of their land qualities
¾Comparison of kinds of land use with the types of land present
¾Economic and social analysis
¾Land suitability classification (qualitative or quantitative)
¾Presentation of the results of the evaluation.
Although the various activities are necessarily listed in succession, there is an element
of iteration in the procedure – there may be a considerable amount of revision to early
stages consequent on findings during later stages. Once the land use potential has been
Land evaluation – towards a revised framework
8
determined, land evaluation can be used as a strategic tool for land use planning (FAO
1993; Rossiter 1996).
Chia sẻ với bạn bè của bạn: |