Remote sensing and GIS contribution to the detection of areas susceptible to natural hazards in the Safi area, W-Morocco

Abstract

The quality , data amount and information content of GeoInformation Systems (GIS) dealing with natural hazards and vulnerability assessment has increased considerably during the last decades. Meanwhile many countries have implemented such a GIS for the public use, whereby satellite imageries before and after disasters form important layers within these GIS. In the scope of this research adaptation strategies are developed by presenting an approach in which Geographic Information Systems, used together with remote sensing data, contribute to the analysis and presentation of information, especially required for the increasing geo-hazards in Morocco, such as earthquakes, mass movements and flooding using mainly free available, existing data for contributing to a GIS integrated data base.

Seismic Hazard Analysis along Koyna Dam Area, Western Maharashtra, India: A Contribution of Remote Sensing and GIS

“…The term lineament is a neutral term for all linear, rectilinear or slightly bent images, which are often expressed as scarps, linear valleys, narrow depressions, linear zones of abundant watering, drainage network, peculiar vegetation, landscape and geologic anomalies [39,41,42]. Lineaments represent, in many cases, the surface expression of faults, fractures or lithologic discontinuities.…”

“…The emphasis was laid on lineament mapping, because it can contribute to: (1) developing the inventory and analysis of faults and fracture patterns relevant to surface water infiltration and rock permeability; (2) detecting subsurface influence on macro-seismic intensity; and (3) inferring the subsurface, structural influence on earthquake-induced secondary effects, such as slope failure. The visibility of linear features depends on specific properties of satellite systems, such as their spatial and radiometric resolution or acquisition time [41,42].…”

“…The sum of all factors/layers that can be included in the GIS provides information of the susceptibility to amplify seismic signals. The analysis method and integration rules can easily be modified in the GIS architecture as soon as additional information becomes available [42].…”

Remote Sensing and GIS Contribution to the Detection of Coastal Slope Failure in the Safi Area, Morocco

“…These images were evaluated in order to map visible scarps and erosional features on the cliffs (Fig.7). The different image products were merged among each other for enhancing the evaluation feasibilities [14,15,16]. Especially NDVI-vegetation -and NDWI-water index images were used for the identification of cliff areas with lower photosynthetic activity of the vegetation or with higher soil moisture, factors influencing the susceptibility to slope failure.…”

“…The long-term impact of coast-near, subsurface karst-hydrologic drainage networks, caves and dolines on slope failures has not yet been investigated in detail. Dissolution processes along fracture and fault zones near and below the cliff sites can lead to slope instabilities [14], [15] and [16]. The karst water flow into the sea can be monitored on IKONOS-scenes of the Safi area (Fig.16) in yellow colours with fan-shaped outline.…”