Summary
At Cape Verde, the threshold for sustainability is a very narrow, due to the frequent droughts, the low rainfall volumes and the increasing population pressure. Since men needs are complex and multiple, the management of the scarce resources is problematic. Nowadays, the hash climatic condition, the scarce resources and the increasing population needs, makes sustainable development and conservation of resources an almost impossible task.
The Ribeira Seca basin has been for several years a study area for various programmes and projects in the fight against degradation of the land and water. Some of those projects were: FIDA in 1994, ROSELT in 1994, PDH-INGRH in 2001, and the Quantification of Erosion at the Hydrographic Basin Scale since 2004. One of the reasons of this large interest for this basin is that the land degradation is considered severe due to the practice of dry pluvial agriculture, which facilitates and enhances soil erosion, and the irrigated agriculture, which aggravates the soil and water salinization downstream.
Due to the interesting results achieved in these projects, the socio-economical and ecological importance of the basin (it includes all the Santiago bio-climatic areas), and the severe population pressure upon the natural resources, Ribeira Seca was selected as a Hotspot for the DESIRE project.
Two scales of analysis were selected, due to the characteristics of the terrain, the high population density, and the profusion in number and kind of the soil and water conservation techniques in place. One scale of analysis is an integrative one, at catchment scale. With this purpose, two water level recorders were placed in two of the main headwater sub-catchments of Ribeira Seca. The second is based on a local assessment of soil and water degradation processes, especially in locations where soil and water conservation measures occur, in order to test their efficiency. This approach is based on rainfall simulations, infiltration capacity measured with a minidisk, and semi-quantitative measures of soil conditions, with special emphasis to soil erosion features. This second approach aims at obtaining the maximum of detail on the various management practices and especially on soil and water conservation techniques, such as terraces, half moons, check dams, vegetation stripes, contour tillage, etc. The conjunction of the two approaches in a nested multi-scale monitoring strategy is expected to give an improved insight into the desertification problems, much more than using a single scale approach.
