JAG l Volume 3 - Issue 1 - 2001 The role of GIS and remote sensing in land degradation assessment and conservation mapping: some user experiences and expectations Godert W J van Lynden and Stephan Mantel International Soil Reference and Information Centre (ISRIC) , P.O. Box 353, 6700 AJ Wageningen, The Netherlands (phone: +31 471 71 l/735; fax: +31 317 47 17 00; email: vanlynden@isric.nl; website: http://www.isric.nl) KEYWORDS: land degradation assessment, soil and water conservation inventories, GIS, remote sensing ABSTRACT Planning strategies for sustainable land management require solid base line data on natural resources (soils, physiography, climate, vegetation, land use, etc.) and on socio-economic aspects. GIS and remote sensing have an important role in linkage and analysis of such data, in particular for detection (direct or indirect), extrapola- tion and interpretation, area calculation, and monitoring. More specifically, GIS and/or remote sensing has been or could be used: (1) to identify physiographic units; (2) to serve as a common (phys- iographic) base map for assessments of different kinds of soils, degradation, and conservation; (3) to overlay data layers for differ- ent map units; (4) to make area calculations; (5) to link spatial data with non-spatial but more detailed attribute data; (6) to make geo- referenced information easily accessible to non-GIS users; (7) to “bridge the scale gap”, ie, upgrade experimental results from small plots to larger areas; (8) to present data in map and other graphic format; (9) to map (temporal and spatial changes in) land cover and land use; and (IO) to identify areas of degradation. Located in the Hindu Kush-Himalaya (HKH) region, the International Centre for Integrated Mountain Development (ICIMOD) is in an excellent posi- tion to apply GIS and remote sensing in an integrated context, eg, to make a comprehensive inventory of natural resources, degrada- tion status and risk and an inventory of conservation measures being applied, using internationally accepted standardised method- ologies described in this paper. INTRODUCTION At the local level, various studies and projects in the HKH region have investigated soil conservation activities or causes of degradation. Far less attention has been paid to national or regional inventory of land degradation, despite the possibilities such inventories could offer for conservation and development; nor has enough atten- tion been paid to the basic data required. According to Messerli et al [1993; p.161 for instance, “Information on soils in the Hindu Kush-Himalayas is very weak”. Denniston [I9951 states that “A fundamental impedi- ment to raising mountains on the agenda of policy mak- ers is lack of knowledge, combined with pervasive scien- tific uncertainty about the planet’s most complex land- scapes. Data on mountain areas - whether economic, social, or environmental - are usually incomplete when they exist at all”. The use of GIS and remote sensing for monitoring soils and geomorphic processes has a special importance in the mountainous and remote HKH region. Due to the difficult terrain and its remoteness, field data are often scarce or lacking. Remote sensing and GIS can play an important role in extrapolating existing data and filling the gaps between them. Without an integrating methodology, identification of viable technological and institutional options for the sustainable development of mountain areas will not be possible [ICIMOD, 19991. Moreover, as stated in the Second Regional Collaborative Programme of the International Centre for Integrated Mountain Development (ICIMOD): “Geo-referenced databases have become powerful tools in decision-making for sustainable development, but it is now time that a shift be made from the formerly ad-hoc and isolated development of data- bases to a more structured and easily accessible and com- patible system” [ICIMOD, 19981. The extreme conditions of the high mountain regions jus- tify a specific approach that recognises the significance of particular mountain parameters. Jodha & Shrestha [in ICIMOD, 19941 refer in this respect to the mountain per- spective as an “understanding and explicit consideration of specific mountain conditions and their imperatives while designing and implementing interventions in these areas”. These specific conditions also include non-bio- physical aspects, namely poverty, low level of education, health and poor infrastructure inter alia. The lack of a mountain perspective underlies the majority of failures of conventional development projects in mountain areas. This is also reflected in mapping scales. Where smaller scales might be adequate for general planning purposes in flatter land, the geographic diversity of mountain ranges requires a methodology at more detailed scales, eg, larger than 1:250,000. Valley conditions differ wide- ly from those on higher and steeper adjacent slopes, and 61