Updated December 1998
By D. Lantieri, J.P. Gastellu-Etchegorry
63 pp, 4 figures, 17 photos
RSC Series No. 65, FAO, Rome 1993.
A rapid analysis of development projects identified and prepared by FAO's Investment Centre (IC) in 1990 and 1991 suggests that from a technical point of view, the use of remote sensing information, either on a large scale with the most air-photography, medium scale with SPOT and Landsat TM satellite data and/or smaller scale with Landsat MSS satellite data, could potentially benefit 35 to 50 percent of the development projects prepared. In many cases, projects to which remote sensing could be applied involve a combination of subjects/thematic applications. The most frequent subjects are listed below in descending order:
Different constraints govern the use of remote sensing techniques in the identification and preparation stages of project design.
Identification: this phase lasts six weeks on average, six months at the most for World Bank projects and two months at the most for other development bank projects; it produces serious time constraints for acquiring and using remote sensing documents. At this stage small to medium-scale information (1:2,000 000 to 1:250,000) is usually required with few thematic details, mainly on land use and possibly land potential, and covering rather wide areas of several hundred thousand square kilometres. Remote sensing studies can be implemented during this phase only in the rare cases where timing would allow it which means more than two months, when imagery is already available, and when there is no reliable thematic map. Cost of this type of remote sensing study should not exceed US$ 0.50/km2. In the majority of cases when less than two months are available, input from remote sensing experts is likely to be restricted to an inventory of available satellite imagery, and to some background technical and budgetary decisions on the possible use of remote sensing technology at a later stage.
Preparation: this phase, coming between identification and appraisal, usually lasts two to six months. It usually requires medium- to large scale information (1:200,000 to 1:25,000) with a number of thematic details, on one or several sub-areas selected from the identified study area covering a few dozen thousand square kilometres. Cost of medium-scale remote sensing studies is somewhat variable according to the thematic interest (land-use/land-potential/land-changes), the scale and the type of output required (draft map, printed map, digital data base).
It ranges on average from US$ 0.50 to US$ 6/km2, and in exceptional cases can be higher. These costs could be covered by the preparation phase budget or, if necessary for the more costly studies, by the development project itself. Timing might be too tight for certain studies involving considerable mapping. In these cases, studies might overlap with appraisal or loan negotiation, or spread into the first phase of implementation of the development project. The input of the preparation mission will therefore be restricted to the preparation of a remote sensing document proposal and arranging the provision of necessary funds.
The analysis of remote sensing for the IC's activities is preceded in this brochure by an overview of technical principles and a discussion on the technical capability and costs of remote sensing for land and resource surveys and particularly for land use inventories, crop mapping, agricultural statistics, agricultural potential, irrigation management and monitoring, forestry, fisheries, degradation assessment and protection of the environment and topography. It is also shown that costs involved depend more on the scale and the level of output digital or analogue than the thematic application itself. Some particular emphasis was given to satellite remote sensing considering its recent importance. Thus, cost efficiency of satellite remote sensing increases when data are required over average areas larger than 1,000 km2 within a short time and at a medium scale of information, (1:50,000 to 1:200,000) and also when emphasis is put on the monitoring of activities. The analyses are illustrated with the presentation in the last section of 17 case studies that were implemented with the assistance of satellite remote sensing by a number of organizations in the developing world. Each case study indicates the context, methodology, outputs, costs and delivery times for the information generated, and the potential for wider application of the particular remote sensing technique that was used.
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