Assessment of groundwater quality is vital for the sustainable safe use of this inimitable resource. However, describing the overall groundwater quality condition—particularly in a mining basin—is more complicated due to the spatial variability of multiple contaminants and the wide range of indicators found in these areas. This study applies a geographic information system (GIS)-based groundwater quality index (GQI) to assess water quality in a mining basin. The study synthesized nine different water quality parameters available—nitrate, sulphate, chloride, sodium, magnesium, calcium, dissolved mineral solids, potassium, and floride ( ${\mathrm{NO}}_3^{-}$ , ${\mathrm{SO}}_4^{2-}$ , ${\mathrm{Cl}}^{-}$ , ${\mathrm{Na}}^{+}$ , ${\mathrm{Mg}}^{2+}$ , ${\mathrm{Ca}}^{2+}$ , DMS, ${\mathrm{K}}^{+}$ and ${\mathrm{F}}^{-}$ )—from 90 boreholes across the basin by indexing them numerically relative to the World Health Organization standards. The study compared data from 2006 and 2011. The produced map indicated a lower GQI of 67 in 2011 compared to 72 in 2006. The maximum GQI of 84.4 calculated using only three parameters ( ${\mathrm{Mg}}^{2+}$ , ${\mathrm{K}}^{+}$ and ${\mathrm{F}}^{-}$ ) compared well with the GQI of 84.6 obtained using all nine parameters. A noticeable declining groundwater quality trend was observed in most parts of the basin, especially in the south-western and the northern parts of the basin. The temporal variation between the GQIs for 2006 and 2011 indicated variable groundwater quality (coefficient of variation = 15–30%) in areas around the mining field, and even more variability (coefficient of variation >30%) in the south-western and eastern parts of the basin.

Globally, the variation of groundwater levels is increasingly overwhelming due to over exploitation resulting from population growth. The dynamic nature of socio-economic activities in Moroto District such as agriculture, settlements and increased trends in irrigation technology has been well-known worldwide as common parameters triggering groundwater variability. Nevertheless, determination of groundwater levels for groundwater management and development purpose is a challenge due to spatial variability in levels across Moroto District. In this study, geostatistical technique in Geographical Information System (GIS) was used to analyze spatial variability of water levels in the study area. The analysis utilized ordinary Kriging method to predict the spatial variation of groundwater levels for 189 measured boreholes. The resultant groundwater level variation map generated using Gaussian model depicts change in groundwater levels varying significantly across the study area dropping by 12 m to 50 m. Significant variations of groundwater levels were observed in the western, central and south eastern part of the study area which are highly populated areas and therefore, the potential of overexploitation. Generated map can be used as first-hand information for decision makers and water managers in management of groundwater resources in Moroto District.

The relationship between microbial communities and mineralogical/mechanical changes was studied regarding the biodeterioration of Portland cement (PC) and calcium sulfoaluminate cement (CSAC) in a wastewater treatment plant. An in situ experiment was conducted by submerging 12 independent PC and CSAC specimens in a sand-trap structure for 10, 30, 75, 150, and 240 days. The microbiological analyses of the 16S rRNA genes of bacteria and Archaea from the biofilms and the geochemical analysis were performed on the studied specimens. The results showed that while there were characteristic changes in PC specimens over time, CSAC specimens showed few biodeterioration effects. The dominant bacteria identified from the biofilms of specimens belonged to the classes of Gammaproteobacteria (8.4–32.4%), Bacilli (1.6–21.6%), Clostridia (4–15.4%), Bacteroidia (2–18.8%), Desulfovibronia (0.5–19%), Campylobacteria (0.4–26.8%), and Actinobacteria (1.8–12.8%). The overall relative abundance of the bacteria linked to biodeterioration processes increased to more than 50% of the total bacterial communities after 75 days of sewage exposure and was found to be strongly correlated with several PC deterioration parameters (e.g., mass loss, calcite and ettringite minerals), whereas no significant correlation was revealed between these genera and CSAC characteristics.

This study examined the adaptation and diffusion of biogas technology in Dar es Salaam, utilizing various data collection methods, including surveys, laboratory analysis, field observations, and interviews. Data collection methods and techniques included lab analysis using American public health association (APHA) standard methods, interviews, questionnaire administration The data analysis was undertaken using statistical package for the social sciences (SPSS) with a sample size comprising 100 community heads from Mburahati, 50 biogas technology adopters, 50 non-adopters, and 16 key informants. The findings disclosed that 40% of respondents learned about biogas technology through their friends and neighbours who had already adopted it, while 6% discovered it through exhibitions. A majority (54%) acquired information from other sources like seminars, biogas researchers, extension officers, and technicians who had adopted the technology. The most influential factor affecting the adoption of biogas technology was the community's income level, accounting for 50.4% of all factors. Inadequate funds were a significant challenge for 75% of respondents, and 64.05% hadn't attended training sessions or seminars related to biogas technology, despite their importance. The study also found that neutral pH levels enhanced anaerobic digestion efficiency, leading to efficient biogas production. Efficiency rates varied among case studies, with the International School of Tanganyika achieving rates between 93.52% and 99.35%, Mburahati DEWATs ranging from 82.15% to 98.24%, and CCBRT ranging from 81.98% to 99.61%. These variations in anaerobic digestion efficiency were likely due to the low solid content in the selected substrates or effluents. In conclusion, the study revealed a low level of biogas technology adoption and diffusion in Dar es Salaam. To enhance this process, the government should review and establish a supportive environment for the advancement of this technology.

A graphical abstract for assessing meteorological, agricultural, and hydrological drought characteristics, trends, propagation in a semi-arid catchment showing input data, methods and results. Semiarid catchments in Tanzania are vital for livestock grazing but highly vulnerable to recurrent drought. This study characterizes meteorological, agricultural, and hydrological droughts (1984–2022) across 3-, 6-, and 12-month timescales, using the standardized precipitation index (SPI), standardized streamflow index (SSI), and standardized soil moisture index (SSMI), respectively. Normalized Difference Vegetation Index (NDVI) anomalies were used as a proxy for pasture condition. Results indicate a unimodal rainfall regime (November–April) and persistent dry-season water deficits (June–October) driven by high evapotranspiration. Short-term droughts (SPI-3 and SSMI-3) occur frequently (0.9–1.8 events year−1), whereas SSI-3 are less frequent but longer-lasting (duration: 5–16 months). Long-term trends are weak overall, although a significant decline in streamflow is observed at the catchment outlet. Propagation is strongly timescale-dependent: short-term rainfall deficits rapidly translate into soil moisture anomalies in lowlands (SPI-3 to SSMI-3, lag 0–1 month, r ≈ 0.5–0.6), while SSI reflects cumulative multiseason deficits. NDVI responds most strongly to SPI-3 and SSMI-6 (lag 0–2 months; r up to 0.48), indicating rapid pasture sensitivity. These findings highlight a narrow early-warning window for forage decline and support adaptive strategies including timely destocking, rotational grazing, and improved dry-season water management to enhance resilience under increasing drought variability.