New application of GIS and statistical analysis in mapping the distribution of quaternary calcrete (Tensift Al Haouz area, Central Morocco)

Abstract

Quaternary calcretes are widespread in soils of many regions of the world especially in semi arid and arid areas. Their development has been studied worldwide for more than a century involving various disciplines and resulting in large amounts of data concerning their evolution. In this article, the geographical distribution of calcrete has been studied by combining Geographical Information Systems (GIS) and statistical analysis. In this paper, we present a qualitative approach that incorporates topographic, geological, hydrogeological and climatic data as well as field observations. After getting all four parameters, they were divided into classes and an index value has been assigned to each of them according to influence degree on calcrete development. Finally, all the parameters are superimposed to prepare the final map of calcrete distribution. The multivariate statistical analysis techniques used were principal component analysis and cluster analysis. Both methods were performed to discuss the potential relations among the investigated parametres (CaCO3 (%), Palygorskite (%), slope (%)) and calcrete evolution.The qualitative approach adopted provided a distribution map predicting the possible areas where different calcrete forms might occur and allowed to elucidate the degree of influence of environmental factors on the evolution of calcrete. The accuracy of this method has been estimated by comparing it with 52 cross-section data from the field. This approach proved to be successful in this study. The results of statistical analysis confirm the results obtained using GIS method and highlight the influence of the studied environmental factors on the spatial distribution of different types of calcrete.