A preliminary investigation of the erodibility of the Ramla valley catchment system

Abstract

The issue of soil erosion is becoming a serious problem worldwide. However, few studies have been conducted on this topic in the Maltese Islands. This aim of this study was to investigate soil erosion in the Ramla valley catchment system through baseline geographical data. This is the first study conducted on soil erosion in the island of Gozo. It is also the first study conducted in Malta and Gozo in which raster imagery was used for RUSLEbased calculation of erosivity. In this study, it was possible to investigate whether the rate of soil erosion within the Ramla valley was increasing. Observations were done by the use of remote sensing, the Geographical Information System (GIS), the System for Automated Geoscientific Analyses (SAGA), and Light Detection and Ranging (LIDAR). During this study, soil analysis was conducted in order to investigate the soil texture and their organic matter within the Ramla valley system and to update the soil map produced by Lang (1960). In the soil analysis, the soil texture resulted to be different from those Lang had reported. Consequently, two Revised Universal Soil Loss Equation (RUSLE) models were produced, one using soil type data from the soil analysis of this study, and the other using data from Lang‟s map. This was done in order to investigate the average annual soil loss over seven years. The results of these two RUSLE models varied as the soil classifications were not the same. The slope length-gradient, rainfall-runoff erosivity, crop and vegetation cover and the support practice of each field were very important factors when considering soil erosion. Both RUSLE models indicated problematic areas along the Ramla valley system, namely, in- Nuffara hill and the upper part of the Nadur slope. This study recommends a national agricultural practice assessment, maintenance of rubble walls and terraces, the launching of educational campaigns regarding soil conservation, the study of more catchment areas, and the creation of a WEPP model for the Maltese Islands.