Land Degradation Assessment in the Dry Areas of Tunisia Case Study: Wadi Koutine Watershed

Soil erosion processes remain the principal environmental issue in the arid regions, such as the southern part of Tunisia. Erosion is a real threat not only for soil conservation but also for the sustainability of water harvesting techniques (cisterns, check dams). The quantification of soil loss in Koutine watershed depends on many factors such as human activities, climate variability, topography (slope), and soil resources. The objective of this study is to examine the influence of topography (slope), short-term exceptional rainstorm intensity, and soil texture on erosion at field scale (less than 1 ha). The data used are from field measurements and a survey of sedimentation in 25 cisterns (6 Fesguia and 19 Majel) and erosion simulation in 37 individual sites. Data were collected over a four (04) year period from 2015 to 2018. By combining the two sources of data, we aim to improve the understanding of the erosion processes and to delineate important links between field rainfall (less than 200 mm), topography and soil characteristics, and sediments deposited in the small sediment settlement basins. The results are based on local and spatially distributed observations. The standard deviation values of soil loss/sediment yield (SY) was about 6%.