Indicators in the study sites

Table of Contents

1. Compilers and contributors
2. Introduction
3. Climate indicators
4. Water indicators
5. Soil indicators
6. Vegetation indicators
7. Water runoff indicators
8. Forest fires indicators
9. Agriculture indicators
10. Cultivation indicators
11. Animal husbandry indicators
12. Land management indicators
13. Land use indicators
    1. Land abandonment
    2. Land use intensity
    3. Period of existing land use
    4. Urban area and rate of change
    5. Distance of low elevation lands from the sea shore
14. Water use indicators
15. Tourism indicators
16. Human characteristics indicators
17. Institutional indicators
18. Conclusions
19. References

Urban area and rate of change

Urban area and rate of change of urban area are two interrelated indicators, which are connected with the indicator of impervious surface discussed above. The extent of urban areas and rate of expansion are factors affecting soil sealing. Urban areas are widely expanded along the Mediterranean coastline in the last decades removing fertile soils from agricultural production and causing tremendous effects on ground water recharge, flooding, brackish water intrusion in aquifers, soil salinization, processes related to desertification. Furthermore, the current spreading of urban areas in wild lands has significantly affected frequency and extent of forest fires. This generates high ignition hazard from human activities to forest fuels, and high risk of forest fires affecting housings and other urban structures. Some countries have developed regulations to reduce fuels in the perimeter of the urban area and to use less flammable building materials in houses. Last summer (2009) a great forest fire occurred around the Athens urban area for which the main driver of destroying the pine forest was the illegal expansion of housing into the forest. Such a forest fire is expected to have tremendous effects on soil erosion rates, flooding of lowland, degradation of natural vegetation, and land desertification.

The extent of urban area has been expressed in % or ha of soil sealed by built-up structures within agricultural and/or semi-natural land cover units over the studied territory (urban area/total study area). It has defined by using ortho-photomaps or remote sensing image analysis. The following classes have been identified: (a) extent <2%, (b) extent=2-5%, (c) extent=5-10%, (d) extent=10-20% and extent >20%.

The rate of change of urban area is expressed as the area covered over certain time. Its approach is to compare and combine mapping methods based on field surveys and remote sensing image analysis for an efficient geo-referenced identification and quantification of the extent of dispersed built-up structures within semi-natural/agricultural areas expressed in ha/10 years/10 km² of territory. The following 4 classes of change of urban areas have been defined: (a) very low (<5 ha/10 years/10 km² of territory), (b) low (5-10 ha/10 years/10 km² of territory), (c) moderate (10-20 ha10 years/10 km² of territory), and (d) high (>20 ha10 years/10 km² of territory).

As Table 11 shows, data for these indicators were collected only in 9 study field sites corresponding to Boteti Area-Botswana. The urban area for this study site covers less than 2% of the territory, while the rate of expansion is estimated to less than 5 ha/10 years/10 km² of territory.