6. Extracts from Background Paper

SATELLITE MONITORING AND AERIAL PHOTOGRAPH ANALYSIS FOR EARLY WARNING OF MIGRATION RISKS

Dr. Susanne Groten

Early warning of migration risks factors on continental to national level is possible to some extent based on monitoring of climatic conditions, crops and vegetation. For this, meteorological satellites are used, especially NOAA, providing vegetation index image series. For the inventory of problem areas, e.g. detected on NOAA images, Landsat and SPOT satellites are giving useful background information, especially, if integrated with biophysical, administrative and socio-economic data in a Geographic Information System (GIS). A number of indicators can be derived from remote sensing for estimating the pressure on natural resources and the vulnerability of population to environmental risks. Estimations of the possible quantitative effects of the problem on agricultural, rangeland production and food security can be obtained by GIS modeling. At inter-village level, enlarged aerial photographs can be used to map land claims by different villages or clans, if necessary without visiting the terrain. For areas claimed by neighbouring villages or groups, a solution can be found at an early stage, before escalation of latent conflicts.

Locating a potential problem zone using meteorological satellites

The identification and the exact location of a problem is the first step towards finding solutions. If the location is only vaguely or wrongly known, management actions may be counter effective: e.g. relief supplies to areas, which have no, or no severe food shortage will lead to a disruption of local market prices and discourage local food producers. From vegetation index images of the NOAA satellite a number of products can be derived by GIS modeling, which may be used to estimate migration risks:

* Vegetation index anomaly ® drought and risk of flooding, pests
* Map of the number of consecutive anomaly years ® depletion of reserves
* Delay of the start of the growing season ® failure of sowing

Inventory of problem zone by retrieval of information in a GIS data base

For an irregular anomaly area, information may be obtained through queries in the GIS data base, either as information aggregated per (administrative) map unit or per pixel by moving the cursor on a map displayed on the computer screen. Information in the map can be linked to other maps with the same coordinate system, and to table via the key columns. Examples of retrieval of background information are:

® Administrative and infrastructure information

* average density of population per pixel > total population of potential problem zone(s)

* administrative zones, settlement names > number of inhabitants of settlements

* composition of population in terms of % age classes, social groups...

* road infrastructure > distance to roads > number of (non)accessible population

* relevant point infrastructure linked to tabular “attribute” information: hospitals, schools, deep wells, food stocks...

® Biophysical information

* soil types > relative fertility, erosion risks, vulnerability of degradation, behaviour in wet/dry condition (for transport)...

* vegetation types > relative availability of fuel wood, local medicines, forage

* rainfall/meteo-data > normal rainfall, variability, rainy period (accessability)

® Agronomic, land use and economic information

* % crops grown in area > subsistence and cash crops, food habits

* crop calendar > activity calendar during growing season, difficult periods

* area suitable for cultivation > land to man ratio > population pressure

* average agricultural income from cultivation

* average income from other sources

* % normal budget allocation, requirements for essential aspects like food, housing, school fees, agricultural inputs.

For including in the GIS data base, a selection of minimum set of standardized indicators should be made per country and region, taking into account available data sets, but also area specific ones depending on the varying nature of the problems. The establishment of schematic data models can help to decide, which data sets and formats would be relevant.

Verification and analysis of information

Before any (false) alarm is given, available information should be cross-checked, because all data, including remote sensing can contain errors.

Impact assessment through GIS modeling

Through GIS modeling of national vegetation index data, quantitative estimates can be done for a number of possible effects:

· impacts on agricultural production
· impact on rangeland production
· impact on food security and migration risks: coping ability and vulnerability index
· other effects:

- estimation of wood energy production/consumption
- estimation of water consumption/availability for men and animals (feasible?)
- estimation of impact of food production on capacity of households to pay school fees
- estimation of locust risk areas with NOAA

Organizing follow up and detailed monitoring

Monitoring creates knowledge and knowledge creates responsibility to take action. Therefore it is essential that a follow up is organized after risk assessment, first for preventive action, and if not possible otherwise, for problem mitigation.

Based on these early warning data, planning of possible interventions should be done, such as:

- relief operations in temporary problem areas
- economic measures to stimulate or regulate trade between surplus and deficit areas
- destocking of animals with least disturbance of the markets
- structural preventive land use planning

Before undertaking action, it is however advisable to monitor developments locally, identify the most vulnerable groups and to understand the problem perception of local people.

Monitoring for prevention of structural migration risks at sub-national level

Conclusion: Early warning of migration risk factors on continental to national level is possible to some extent based on monitoring of climatic conditions, crops and vegetation. For this, meteorological satellites are used, especially NOAA, providing vegetation index image series. For the inventory of problem areas, e.g. detected on NOAA images, Landsat and SPOT satellites are giving useful background information, especially if integrated with biophysical, administrative and socio-economic data in a geographic information (GIS). A number of indicators can be derived from remote sensing for estimating the pressure on natural resources and the vulnerability of population to environmental risks. Estimations of the possible quantitive effects of the problem on agricultural, rangeland production and food security can be obtained by GIS modelling. At intervillage level, enlarges aerial photographs can be used to map land claims by different villages or clans, if necessary without visiting the terrain. For areas claimed by neighbouring villages or groups, a solution can be found at an early stage, before escalation of latent conflicts.