Experimental setup
Due to the richness of the soil and water conservation techniques in Cape Verde, and their omnipresence in the entire island and specially in the Ribeira Seca catchment, covering all the variability of climatic regions, from the sub-humid to the arid, a nested approach was designed, including a network of climatic and hydrological structures and sensors, which include automatic rainfall gauges and water level recorders.
In addition, due to the profusion of soil and water conservation techniques, several techniques are implemented in the field to monitor the effectiveness of those S&W conservation techniques. This include the use of semi-quantitative transects to quantify the presence of erosion features and soil characteristics that may enhance or mitigate soil degradation and erosion processes. In addition, minidisk infiltration capacity measurements and rainfall simulations using the rainfall simulator model of Cerdá et al (1997) is used to provide quantitative information for each Soil and Water Conservation Technique.
The measurements of soil erodibility during the dry and wet seasons, and along the different agricultural stages will then be assessed at the local scale, that will then be compared with the data at catchment scale.
Two water level recorders and a rainfall gauge are already operational since the 2009 wet season, at the Longueira Catchment outlet and at the João Teves area, which includes all the sub-catchments, with the exclusion of the Godim, semi-arid sub-catchment. Several other rainfall gauges and water level recorders will be installed before the next wet season.
In addition, a semi-quantitative survey of the more representative soil and water conservation techniques was already performed and will be published soon. At the moment several dozens of rainfall simulation measures and infiltration capacity measurements were already held, and are currently being processed.
The participatory process pinpointed afforestation and the use of vegetative barriers as the more promising soil and water conservation techniques. Nevertheless, in addition to these techniques, several other are being monitored, such as half moons, small stone terraces, large stone terraces, several associations of stone terraces with vegetative barriers, several species used as vegetative barriers, etc. During the next years until the end of the DESIRE project, an effort will be made to increase the number of measures and cover the existing variability in what concerns climate variability, management practices and soil and water conservation techniques.
