Land Resources Information Systems A Source of Information and Basic Tool for Modelling and Monitoring Land-use and Land-cover Changes

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1 1 Land Resources Information Systems A Source of Information and Basic Tool for Modelling and Monitoring Land-use and Land-cover Changes Otto SPAARGAREN and Vincent VAN ENGELEN ISRIC International Soil Reference and Information Centre, The Netherlands Abstract Geo-referenced databases containing information on aspects like terrain, soils, land use, climate, vegetation, degradation and conservation, etc., have proven to be an excellent tool for land use planning, for monitoring changes (positive or negative), and for modelling and scenario research. SOTER is such a land resource database. The identification of areas of land with a distinctive, often repetitive, pattern of landform, lithology, surface form, slope and soil is underlying the SOTER methodology. Tracts of land distinguished in this manner are named SOTER units, and each SOTER unit thus represents one unique combination of soil and terrain characteristics. To obtain a broad characterisation of tracts of land in terms of complementary characteristics, the SOTER database does include files on climate, vegetation and land use. Several SOTER applications have been developed for modelling, i.e. SWEAP for water erosion models, SOTAL for automated land evaluation, SOSA for soil salinity studies, while the development of a SOTER Wind Erosion Program (SWEAP2) is underway. For crop production simulation WOFOST has been applied. A system-independent Viewer program allows for display of thematic maps with associated attributes. A variety of studies using SOTER databases have been carried out at various scales. Examples are given erosion/crop production models, the assessment and monitoring of the status of human-induced soil degradation, soil vulnerability mapping and assessment of soil carbon stocks. Once standardised baseline data are available, specific outputs can be produced for the development of scenarios and recommendations, like on soil conservation/land husbandry, organic matter and soil fertility management, land suitability, etc. The countries in East Asia could benefit from experiences with standardised land resources information systems established elsewhere in the world. 1. Introduction General land use concerns are, on one hand, related to issues of environmental protection, impact on biodiversity, use and preservation of specific biotopes (e.g. coastal areas, wetlands, sloping lands and primary forest). On the other hand, land use aspects focus on food security (production, availability, access, marketing and attainability), using either capital intensive, high external input or labour intensive, low external input agriculture management options. It is difficult -if not impossible - to completely distinguish these from each other. By improving agricultural efficiency in one area for instance, neighbouring natural and/or more fragile areas can remain untouched. Land use concerns are also related to increasing urban and rural populations, enlargement of agricultural areas at the expense of forestland, and encroachment of urbanisation and industrial activities on agricultural land. Also issues related to energy sources (fuelwood and "bio"-fuels) and waste product management (crop residues and urban organic refuses) play a role. It must be emphasised that all these issues should be considered in a larger context, also involving various socio-economic factors.

2 2 2. The SOTER methodology Land (of which soil and terrain form part) incorporates processes and systems of interrelationships between biophysical and social phenomena evolving through time. The identification of areas of land with a distinctive, often repetitive, pattern of landform, lithology, surface form, slopes and soil is underlying the SOTER (SOil and TERrain Digital Database) methodology (Van Engelen & Wen, 1995). Tracts of land distinguished in this manner are named SOTER units, and each SOTER unit thus represents one unique combination of soil and terrain characteristics. A SOTER database consists of two major components: a Geographic Information System (GIS), which stores and manages the geometrical aspects, and a Relational Database Management System (RDMS) for the handling of attribute data. So far, SOTER uses predominantly ArcInfo as GIS and dbase IV as RDMS. The major differentiating criteria to establish SOTER units are applied in a step-by-step manner, each step leading to a closer identification of the land area under consideration. In this way a SOTER unit can be defined progressively into terrain, terrain component and soil component and, consequently, an area be described by its terrain, its terrain components and its soil components. The level of spatial disaggregation at each step in the analysis of the land depends on the level of detail or resolution required and the information available. The reference scale of SOTER is 1:1 million, but it has been successfully applied at larger scales, varying from 1:500,000 to 1:50,000. SOTER is a land resource database. For many of its applications SOTER data can only be used in conjunction with data on other land-relevant characteristics. To obtain a broad characterisation of tracts of land in terms of complementary characteristics, the SOTER database does include files on climate, vegetation and land use. The climate file is in the form of point data, whereas the vegetation and land use information is provided at the level of SOTER units. However, for specific applications, information on these characteristics should be obtained from specialised databases such as a climatic database. This also applies to natural resource data (e.g. groundwater hydrology) and socio-economic data (e.g. farming systems), which do not form part of the SOTER database. 3. SOTER applications Several applications have been developed, either as SOTER specific programs or as adaptations of existing models. To the first group belong the SOTER Water Erosion Assessment Program (SWEAP; Van den Berg & Tempel, 1995) and the SOTER Salinity Status Program (SOSA; Rotmans, 1997). The development of a SOTER Wind Erosion Program (SWEAP2) is underway. The second group contains such varied applications as land evaluation by means of the Automated Land Evaluation System (Rossiter, 1990) for SOTER (SOTAL; Mantel, 1995) and crop production simulation such as World Food Studies (WOFOST; Van Diepen et al. 1989). A system-independent Viewer program allows for display of thematic maps with associated attributes. 4. Some studies using the SOTER database 4.1 Erosion/crop productivity studies An example from Northern Argentina A case study on the impact of erosion on the productivity of land use systems has been made using SOTER data available for Northern Argentina (Mantel & van Engelen, 1997). In the study the potential yield was calculated for the dominant soils of each SOTER unit suitable for the specified land use, before and after an erosion scenario of 20 years.

3 3 Various steps were taken in the procedure: 1. The expert model SOTAL was used to discriminate between the land units considered suitable and unsuitable for the type of land use. The selected Land Utilisation Types (LUT s) were characterised by 11 land use requirements and evaluated by matching these with the given land qualities. 2. The erosion risk assessment model SWEAP was used to determine the hazard for erosion. The erosion risk units were translated into a scenario for loss of topsoil over a 20-year period for the land use under consideration. 3. The crop simulation model WOFOST was used to calculate the potential yield of the selected crop under the current agro-ecological conditions and after 20 years of simulated soil erosion. The defined Land Utilisation Type (LUT) was mechanised, medium to high input wheat, which is one of the dominant types of arable farming in the northern part of the country. About 25% of the area under study is considered unsuitable for the chosen LUT, on the account of moderate to strong alkalinity (ph > 8), low rootable soil volume, or coarse textures, the rest being moderately or only marginally suitable. High silt contents and long slopes, however, are the cause of the high risk for erosion in more than half of the area suitable. The predicted loss of topsoil in the 20 years of erosion simulation varies over the area, with some 40% of the land loosing some 10 cm or more and more than 45% loosing between 25 and 50 cm of topsoil. Based on the calculated crop production levels it is possible to estimate the yield decline caused by the simulated effects of water erosion. The general picture of the area shows that highest crop production potentials (over 6 t/ha) are found around the capital Buenos Aires, decreasing to the north and the west to levels between 2 and 4, locally between 1 and 2 t/ha. The erosion scenario shows that in the high yield producing areas generally a yield decline of less than 25% can be expected, with localised areas with an expected yield decline between 25 and 50%. In other areas a similar trend is observed, although in the moderate production class relatively larger areas may be affected by a yield decline between 25 and 50%. Figure 1 illustrates the nutrient-limited yield decline for wheat after a simulated 20 years of soil erosion. This picture is important for politicians and decision-makers in this region, which now can anticipate on a possible decrease in food production near such highly populated areas as Buenos Aires. Linking with socioeconomic models makes it then possible to foresee the effects on food prices, e.g. by taking into account larger transport distances, migration to the urban areas resulting from closure of marginal farms, etc., as well as taking actions to counteract the scenario, e.g. by introducing and promoting measures to control erosion. 4.2 Assessing and monitoring the status of human-induced soil degradation An example from South and Southeast Asia Soil degradation reduces agricultural productivity and so provokes encroachment of land users into natural areas and marginal lands. In South and Southeast Asia sustainable management of land resources is becoming a major challenge to the national governments, in view of the increasing population pressures and rapidly growing economies. Other land resource problems relate to encroachment of rural communities in natural forest areas, water availability and sanitation problems, conflicting land uses, etc. Recently, an assessment was effected by ISRIC in collaboration with national institutions in the region of human-induced soil degradation in S and SE Asia at a scale of 1:5 M (ASSOD), at the recommendation of the Third Expert Consultation of the Asian Network on Problem Soils methodology (Van Lynden & Oldeman, 1997). It is based on a modified GLASOD 1 methodology and illustrates the impact of soil degradation on productivity in the region. 1 Global Assessment of Human-induced Soil Degradation (ISRIC-UNEP, 1991)

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6 6 The base map for ASSOD is the draft physiographic map for Asia at 1:5 million compiled by ISRIC and FAO using the SOTER methodology. Three major physiographic items are used to structure this base map, viz. Major Landform, Hypsometry and Slope Class. The various types of soil degradation are entered in the database as major type and subtype. A third entry is used where appropriate to add details on the type of soil degradation. Important modifications in the ASSOD approach with respect to the GLASOD approach are that the status assessment of soil degradation is expressed in terms of impact on productivity, and that the rate of degradation is given more importance. Figure 2 illustrates the status of human-induced soil degradation in Eastern Asia. A clear outcome of the ASSOD inventory was the importance of water erosion in the region, with agriculture and deforestation being the major contributing factors. Extensive soil and water conservation programmes in the various countries are being or have been implemented but with only limited results, often because they were too much technology focused and too little farmer-oriented. Therefore, site-specific technologies developed either through experimentation by NARs and IARs, or by farmers themselves (indigenous knowledge) need to be inventoried, so that success stories can be extrapolated to other areas with similar agro-ecological and socio-economic conditions and failures can be avoided. This geographic inventory of soil conservation approaches and technologies is an established activity of the WOCAT 2 programme, which at the same time offers a framework for systematic evaluation of soil and water conservation activities. Another finding of the ASSOD project was the high occurrence of soil fertility and organic matter decline, generally as a result of over-exploitation of the soil resource for agriculture. This fertility decline forces farmers to abandon their fields in search of new fertile land, thereby often encroaching on neighbouring marginal or natural forest areas. The use of organic fertilisers, crop residues, animal manure and other biomass, on farmland should be optimised. Intensification of agricultural production will further require an increased use of inorganic and organic fertilisers. Balanced soil fertility recommendations are thus urgently needed and can be assessed once the soil and terrain information database is established. The usefulness of such studies is that they form a departing point for monitoring the status of land resources, which give decision-makers and planners a clear handle to develop policies and implement measures to remedy soil and land degradation, and thus secure food production. 4.3 Soil vulnerability mapping An example from Eastern Europe The capability of a soil to be harmed in its ecological functions its vulnerability varies with climate, soil type, land use, the chemicals involved, and the degree of loading with these contaminants (Batjes & Bridges, 1993). Once degraded, for example by water erosion, heavy metals or acid deposition, the ecological functions of soil will return only slowly. Thus, knowledge of the currently degraded land and areas potentially at risk (vulnerable land) is critical for sustainable development and the formulation of conservation or remediation technologies. Currently ISRIC is co-ordinating a project on the Assessment of Soil and Terrain Vulnerability in Central and Eastern Europe (SOVEUR), a project carried out in collaboration with soil survey institutes in Belarus, Bulgaria, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Moldavia, Poland, Romania, the Russian Federation up to the Urals, Slovak Republic and Ukraine. The project is to develop an environmental information system (EIS) for a geo-referenced assessment of the status of human-induced land degradation, with particular attention to issues of soil pollution, and of soil vulnerability to delayed-pollution at a nominal scale at 1:2.5 million (Batjes & Bridges, 1997). 2 World Overview of Conservation Approaches and Technologies, co-ordinated by the Centre for Development and Environment, University of Berne.

7 7 The methodology to develop this environmental information system combines the SOTER approach (Van Engelen & Wen, 1995; Batjes & van Engelen, 1997) with the expertise gained in the assessment of the status of human-induced land degradation (Van Lynden, 1997). Furthermore, the project activities include the development of methodological guidelines for the assessment of the vulnerability of soils to selected categories of pollutants (Batjes, 1997), and the application of these methodological guidelines, by country, to create georeferenced databases on (1) soil and terrain units and (2) soil degradation and pollution status. This will subsequently be used, in combination with other data sources, to assess relative soil vulnerability, and to determine areas considered at risk from re-mobilisation of specific contaminants. The project is still ongoing and specific outputs cannot be shown yet. It is hoped that the final output, the environmental information system, will enable governments in policy formulation at regional and national level, for instance by identifying areas considered most at risk. The project will also contribute to strengthening cooperation between national environmental organisations in Central and Eastern Europe and Western Europe. 5. Conclusion Land resources information systems (LRIS), i.e. multi-layered, geo-referenced databases containing information on aspects like terrain, soils, land use, climate, vegetation, degradation and conservation, etc., have proven to be an excellent tool for land use planning, for monitoring changes (positive or negative), and for modelling and scenario research (Mantel & van Engelen, 1997). Linkage of biophysical with socio-economic information (from other databases) will strengthen the application of database work to help solve the resource management problems. Once standardised baseline data are available, specific outputs can be produced for the development of scenarios and recommendations, like on soil conservation/land husbandry, organic matter and soil fertility management and land suitability. The use of globally accepted methodologies in data collection, storage and retrieval, e.g. the SOTER methodology developed at ISRIC during the 1980 s, also enables the exchange of information and experiences with other regions. Such a standardised approach is already being used in other parts of the world, e.g. LASOTER in Latin America (FAO et al, 1998), and the countries in East Asia could benefit from these experiences if a similar approach is taken. 6. References 1) Batjes, N.H. (1997): Methodological Framework for Assessment and Mapping of the Vulnerability of Soils to Diffuse Pollution at a Continental Scale (SOVEUR Project). Report 97/07. International Soil Reference and Information Centre, 2) Batjes, N.H. and E.M. Bridges. (1993): Soil Vulnerability to Pollution in Europe. Soil Use and Management 9, pp ) Batjes, N.H. and E.M. Bridges (eds). (1997): Implementation of a Soil Degradation and Vulnerability Database for Central and Eastern Europe: Proceedings of an International Workshop (Wageningen, 1-3 October 1997). International Soil Reference and Information Centre, 4) Batjes, N.H. and V.W.P. van Engelen. (1997): Guidelines for the Compilation of a 1:2,500,000 SOTER Database (SOVEUR Project). Report 97/06. International Soil Reference and Information Centre, 5) FAO-ISRIC-UNEP-CIP.( 1998): Soil and Terrain Database for Latin America and the Caribbean. CD-ROM Land and Water Digital Media Series 5. Food and Agriculture Organization of the United Nations, International Soil Reference and Information Centre, United Nations Environmental Programme, and Centro Internacional de la Papa. Rome. 6) ISRIC-UNEP. (1991): World Map of the Status of Human-induced Soil Degradation: An Explanatory Note. International Soil Reference and Information Centre and United Nations Environmental Programme,

8 7) Mantel, S. (1995.):The Automated Land Evaluation System applied to SOTER, with an example from West Kenya. Working Paper and Preprint 95/03. International Soil Reference and Information Centre, 8) Mantel, S. and V.W.P. van Engelen. (1997): The Impact of Land Degradation on Food Productivity Case Studies of Uruguay, Argentina and Kenya. Volume 1: Main Report. Report 97/01, International Soil Reference and Information Centre, 9) Rossiter, D.G. (1990): ALES, a Framework for Land Evaluation using a Microcomputer. Soil Use and Management 6, pp ) Rotmans, A. (1997): SOSA, A Computer Program for Soil Salinity applied to SOTER. Draft. International Soil Reference and Information Centre, Wageningen 11) Van den Berg, M. And P. Tempel. (1995): SWEAP, A Computer Program for Water Erosion Assessment applied to SOTER. Documentation version 1.5. SOTER Report 7. International Society of Soil Science, 12) Van Diepen, C.A., J. Wolff, H. van Keulen and C. Rappolt. (1989): WOFOST: a Simulation Model of Crop Production. Soil Use and Management 5, pp ) Van Engelen, V.W.P. and T.T. Wen. (1995): Global and National Soils and Terrain Digital Databases (SOTER), Procedures Manual (revised edition). United Nations Environmental Programme, Food and Agriculture Organization of the United Nations, International Society of Soil Science and International Soil Reference and Information Centre, 14) Van Lynden, G.W.J. (1997): Guidelines for the Assessment of Human-induced Soil Degradation in Central and Eastern Europe (SOVEUR Project). Report 97/08. International Soil Reference and Information Centre, 15) Van Lynden, G.W.J. and L.R. Oldeman. (1997): The Assessment of the Status of Human-induced Soil Degradation in South and South east Asia. United Nations Environmental Programme, Food and Agriculture Organization of the United Nations and International Soil Reference and Information Centre, 8