Remote Sensing and GIS Contribution to the Investigation of Karst Landscapes in NW-Morocco

Barbara Theilen-Willige,Mohamed Chaïbi,Abdessamad Charif,Halima Malek,Fatima El Bchari

doi:10.3390/geosciences4020050

Barbara Theilen-Willige, Mohamed Chaïbi + Show 3 more

Open Access

https://doi.org/10.3390/geosciences4020050

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Journal: Geosciences	Publication Date: Jun 23, 2014
Citations: 40	License type: CC BY 3.0

Affiliation: Technische Universität Berlin, Cadi Ayyad University

Abstract

Remote sensing and geographic information system (GIS) methods were used for karst research in the coastal area of Northwest Morocco near the city of Safi in order to identify karst landscapes, to describe karst features and to detect geological structures relevant to karst development. The aim of this study was to investigate the use of different satellite data, such as Landsat, RapidEye and IKONOS imagery, as well as ASTER- and SRTM-derived digital elevation models (DEMs) for the analysis of karst features. Dolines were identified by visual interpretations based on high resolution satellite imagery and aerial photographs. Digital image processing of the satellite data, such as deriving vegetation and water index images, helped to identify regions with relatively higher surface water input, where karstification processes might be more intense than in surrounding areas. ArcGIS-integrated weighted overlay tools were used for this purpose as well by aggregating of morphometric, causal factors (lowest and flattest areas) influencing the susceptibility to higher surface water input. Lineament analysis based on the different satellite data contributed to the detection of near-surface fault and fracture zones with potential influence on dissolution processes in sub-terrain waterways.

Highlights

Karst as a type of landscape found on carbonate rocks or evaporites is characterized by a suite of landforms comprising springs, dolines, caves, collapsed sinkholes and carbonate depositional landforms [1,2,3]
The multi-level approach focuses on the pre-processing and exploration of individual datasets, followed by data integration and investigations in a geographic information system (GIS) environment, combining digital elevation models (DEMs), satellite imagery and ground-truth
The approach consists of the following steps: (a) Morphometric analysis of the investigation area based on SRTM- and ASTER-DEM data; (b) Inventory and mapping of dolines by visual interpretation of aerial photographs and high resolution satellite imagery and mapping of karst features from digitally-processed satellite images; (c) Detection of areas with relatively higher surface water input based on the weighted overlay of causal factors influencing the susceptibility to higher surface water input; (d) Detection of linear features with possible relation to subsurface structures, such as fault and fracture zones or fold structures

Summary

Introduction

Karst as a type of landscape found on carbonate rocks (limestone, dolomite, marble) or evaporites (gypsum, anhydrite, rock salt) is characterized by a suite of landforms comprising springs, dolines, caves, collapsed sinkholes and carbonate depositional landforms [1,2,3]. This karst landscape type is well developed in the coastal area near the city of Safi in West Morocco (Figure 1). The occurrence of karst phenomena and their continual evolution can pose serious problems related to subsurface stability and may require caution in the maintenance and planning of infrastructure, especially in urban areas, such as Safi. Karst is a sensitive environment, which imposes specific management constraints on environmental domains, such as water protection, problems of pollution or site conservation

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