In arid and semi-arid areas, human health and economic development depend on water availability, which can be greatly compromised by droughts. In some cases, the presence of natural contaminants may additionally reduce the availability of good quality water. This research analyzed the water resources and hydrochemical characteristics in a rural area of the central Main Ethiopian Rift Valley, particularly in the districts of Shashemene, Arsi Negelle, and Siraro. The study was developed using a census of the main water points (springs and wells) in the area and the sampling and physico-chemical analysis of the water, with particular regard to the fluoride concentration. In many cases, fluoride content exceeded the drinking water limits set by the World Health Organization, even in the absence of anthropogenic contamination. Two different aquifers were recognized: A shallow aquifer related to the eastern escarpment and highlands, and a deep aquifer in the lowland areas of the rift valley on the basis of compositional changes from Ca–Mg/HCO₃ to Na–HCO₃. The distribution of fluoride, as well as pH and EC values, showed a decrease from the center of the lowlands to the eastern highlands, with similar values closely aligned along an NNE/SSW trend. All these data contribute to creating awareness among and sharing information on the risks with rural communities and local governments to support the adequate use of the available water resources and to plan appropriate interventions to increase access to fresh water, aimed at the sustainable human and rural local development of the region.

The wide range of gypsum facies observed all over the world and the strong heterogeneity that may be present even within a single facies often cause an inhomogeneous mechanical response that, if neglected, may be particularly dangerous in the framework of underground excavations. In addition, gypsum is particularly sensible to the presence of water. The high relative humidity conditions often registered in underground gypsum quarries may imply an additional worsening of mechanical properties. In the present study, the strength and the creep response of a natural gypsum rock facies are investigated, considering the influence of material heterogeneity and relative humidity conditions. The heterogeneity of the material, quantified with MIP and SEM analyses, is observed to strongly affect the mechanical response. To this intrinsic mechanical variability, the influence of an external parameter as the relative humidity is observed to generate an additional reduction of material strength and to increase the creep strain rate in the long-term tests. The effect of all these elements in the underground quarry framework is discussed and a constitutive model of these experimental results is provided.

The measure of local strains of geomaterials under the application of an external load is significant to the study of mechanical properties of rocks. The application of image analysis methods (i.e. digital image correlation analysis) offers the possibility to have pointwise measures of local strains on the entire surface of the samples. Strain contributions in the different areas of the samples can be highlighted and diversified. In this study the methodology was tested on gypsum rock. Image analysis was conducted by means of Ncorr, an open-source two-dimensional digital image correlation Matlab software. The processing of consecutive images acquired during the execution of uniaxial compression tests allows for the identification of strain distributions and concentrations. The test was repeated for different angles of orientation of the anisotropy. If properly calibrated, the method may be used to highlight the influence of textural features of the rock materials, such as – in this case − anisotropy, on the mechanical behaviour. Features such as the localisation of the strain, the load thresholds that lead to the opening of the first microcracks and the way they reorganise to create the failure surface may be intensively investigated.