Assessment of hydrological drought indices in drought prone areas provides useful information for accurate and sustainable water resources management. However, meteorological drought estimation in ungauged basin remains less studied. The main objective of this study was to compare the ability of Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) to reproduce historiological drought within Massili basin. To this end, monthly historical rainfall and temperature time series spanning from 1960 to 2021 have been collected from the national agency of meteorology. R programming language has been applied to display Boxplots in order to identified the temporal dispersion of the rainfall indices. Then the Spearman correlation was applied to illustrate the relationships between the SPEI and the SPI. The results shows that both SPEI and SPI exhibit consistent behavior in observed drought within the Massili watershed. Dry conditions prevailed during the period 1980–1990, 1990–2000 and 2000-2010. Severe wet conditions prevailed in years 1984, 1985,1998 and 2002. In all time scale the SPEI and SPI are characterized by high correlation. The Spearman correlation coefficients value is above 0.7 with the highest correlation value detected between SPEI-24 and SPI-24 (0.97). This study may contribute to better understand the drought patterns within the basin for water resources planning perspectives.

In the landfill bottom liners design process, geotechnical tests of long duration time are often conducted to ensure the presence of reactive clays and to assess their hydromechanical properties. This study aims to show the interest of the rheometry of clayey suspensions as an alternative tool for identifying clays and determining the shear strength of bottom liners. An experimental protocol, using a six-speed rotary viscometer, was first implemented on bentonite suspensions on the one hand and kaolinite suspensions on the other. The results show that to have similar shear strengths (between 1.0 and 25.4 Pa), the concentration ranges used for these two types of suspensions must be totally different: between 600 to 1200 g/L for kaolinite and 30 to 90 g/L for bentonite, confirming the usefulness of rheometry as a tool for identifying clays. Furthermore, results from rheometry tests also show an increase in the shear stress of kaolinite suspensions when there are made with leachate; such results are in agreement with geotechnical shear tests conducted on compacted samples. This study is of practical use for environmental geotechnics professionals because it offers an alternative to traditional geotechnical tests.

Faced with the loss of biodiversity, particularly plant diversity, due to anthropogenic pressure, particular ecosystems such as inselbergs can constitute refuge areas. The objective of this study is to determine the conservation potential of plant biodiversity on inselbergs in Burkina Faso. A comparative study was carried out between inselberg’s vegetation and the surrounding plains vegetation. In each of these vegetation types, stratified and random sampling was adopted and data were collected in plots of 900 m² for the woody stratum and 100 m² for the herbaceous stratum. The specific diversity was evaluated through the effective numbers of Hill of order Q = 0; 1; 2. The Hill index does not vary between inselbergs and plains and thus reflects a strong similarity in floristic diversity between the two ecosystems. Sorensen’s similarity coefficient also shows a similarity in terms of floristic composition between inselbergs and surrounding plains. In inselbergs, relict species that have disappeared from the surrounding plains of some phytogeographic sectors occur. The flora of inselbergs is also characterised by indicative species of anthropized ecosystem absence. However, these species are present on the surrounding plains. Indeed, the flora of inselbergs is characterised by 11 endemic species. Inselberg’s vegetation is characterised by unique plant communities such as rock pools and Afrotrilepis pilosa mats. The exploitation and mortality rates of woody plants are significantly higher on the surrounding plains than on the inselbergs. The flora and vegetation of inselbergs show the absence of indicator species of disturbed ecosystems. They present endemic and relict species and stable woody stands. Due to the steep slope, lack of suitable soil for agriculture and sacred status of someones, the inselbergs constitute a refuge for plant species and thus contribute to the conservation of biodiversity like the protected areas.

Abstract Three pilot systems of a constructed wetland were assessed to advance the urban reuse of greywater for household gardening in areas of the world representative of Africa's Sahel (one unplanted and two planted with local species, namely Andropogon gayanus and Chrysopogon zizanioides). Principal component analysis showed planted systems provided higher removal efficiencies than the unplanted system and A. gayanus performed better for treating most water quality parameters. As expected, removal efficiencies for suspended solids (SS) and chemical oxygen demand (COD) were greater than 90% in all filters. The removal of five-day biochemical oxygen demand (BOD5) was, however, significantly greater in the filter planted with A. gayanus than in the unplanted control. For plant-beneficial parameters such as nutrients (NO3−, NO2−, NH4+, and PO43−), the removal in the planted filters was significantly higher than in the unplanted filter (>90% versus 73%–78%). The reduction of fecal coliforms was significantly greater in the two planted systems and exceeded 2.5 log10 removal. Analysis of the microbial water quality characteristics showed the concentration of fecal microbial indicators would achieve WHO guidelines for restricted irrigation with retention of some embedded nutrients, thus reducing pressures on areas experiencing climate variability, water scarcity, and land degradation.

In this work, we present a numerical study of the thermal behavior of a hollow block with or without phase change material (PCM) in the Sahelian zone.
 The PCMs used in this study are RT27 paraffin and hydrated salt with a melting temperature of 27°C and 29.9°C respectively and a latent heat of fusion of 179kJ/kg and 184kJ/kg. The equations obtained were adimensionalized then discretized by the finite element method and solved on the COMSOL software. We were first interested in the study of the thermal phase shift, the damping and the evolution of the temperature at the level of the internal wall. In a second phase, we conducted a comparative study between hollow block containing PCM and other construction materials (adobe, BTC and BLT) used in Burkina Faso.
 The numerical results obtained show that the temperature of the internal wall of a hollow block containing RT27 is lower than that of a hollow block without PCM, hollow block containing hydrated salt, BTC, BLT and adobe with respectively a temperature difference of 8.354°C; 3.39°C; 5.79°C; 3.97°C and 3.92°C and the difference in terms of phase shift is 1h18min, 6min, 24min, 42min and 6min for the hollow block containing RT27, the hollow block containing hydrated salt, BTC, BLT and adobe.
 Therefore, the integration of PCM in building materials increases their thermal inertia.

As a Semi-arid country, Burkina Faso is highly vulnerable to climate-related disasters such as drought and flood. Analyzing drought signature is therefore a key factor in advocating climate change adaptation at the local scale. In this study, Spatiotemporal trends of drought were conducted for the period 1960–2021 within Massili Basin using the standardized precipitation and evapotranspiration index (SPEI) package in R. The non-parametric method (Mann–Kendall) was then used to test for a monotonic trend, whereas the magnitude was estimated using Sen's method. Accordingly, the result revealed that during the period 1960-1979, the mean value of SPEI varies from 0.06 to 0.71; over 1980 to 2009, the mean value of the SPEI varies from -0.08 to -0.88 and for the last decades (2010 to 2021), the mean value of the SPEI ranges from 0.05 to 0.75. Normal to middle wet conditions is thus observed over the periods 1960-1979 and 2010-2021 while the period (1980-2009) depicts a middle drought condition. The Mann-Kendall test results show a decreasing trend of SPEI-3 and SPEI-24 with a Z value of - 0.784 and -0.530 respectively. A slightly increasing trend is observed for SPEI-6 and SPEI-12 with Z ranging from 0.598 to 1.917 respectively. The magnitude of the decrease is indicated by the sens’ slope value, which is -0.0014 for SPEI-3 and -0.00010 for SPEI-24 while the magnitude of the increase ranges from 0.00011 for SPEI-6 to 0.00037 for SPEI-12. This study highlights the importance of examining past drought features to obtain essential information to assist in designing and implementing efficient water resources management strategies over the Massili Basin.

Abstract In this article, we consider the infinite dimensional linear control system describing the population model structured by age, size, and spatial position. The control is localized in the space variable as well as with respect to the age and size. For each control support, we give an estimate of the time needed to control the system to zero. We prove the null controllability of the model, using a technique avoids the explicit use of parabolic carleman estimates. Indeed, the method combines final-state observability estimates with the use of characteristics and L∞ estimates of the associated semigroup.