Muralitharan Jothimani

Rapid urbanization frequently outpaces sanitation infrastructure, leaving vulnerable residents without essential services. This study develops and applies a GIS-based spatial decision-support framework combining multi-criteria decision analysis (MCDA), the Analytical Hierarchy Process (AHP), and network-based accessibility analysis to assess location suitability and prioritize public toilet development in Addis Ababa, Ethiopia. Eight spatial criteria, population density, proximity to public activity nodes, road connectivity, distance from existing facilities, land use/land cover, slope, soil characteristics, and proximity to rivers were standardized on a 1–5 suitability scale. A field inventory of 339 georeferenced facilities, constraint masking, network service-area analysis, and sensitivity analysis produced three principal findings. First, accessibility is severely deficient: only 25.07% of residents (822,514 of 3,280,422) live within the normative 500 m walking distance to public toilets; 74.93% lies beyond it. Second, provision is maldistributed: the highest-density population class records a provision ratio of 0.90 against 1.39 in the second-highest, with Addis Ketema and Yeka each serving ~ 13,400 residents per facility. Third, expert weights are internally consistent (CR = 0.0152), with demand and accessibility criteria receiving 79.2% of total weight. Suitability mapping classified 20.46% of the city (87.97 km²) as high/very-high suitability. Overlaying suitability with service deficits and building-footprint constraints delineated a priority development envelope of 25.43 km² (5.91% of the city). Robustness testing across alternative weights and thresholds demonstrated stable spatial priorities (Jaccard similarity 0.60–0.97; AUC = 0.864). This framework provides municipal planners a transparent, reproducible basis for prioritizing sanitation investment, whilst acknowledging that tenure screening, community engagement, disability-responsive design, and environmental compliance remain essential.

1. Groundwater is a critical freshwater resource that supports public health, agricultural production, and economic development, particularly in environments where surface-water sources are seasona...

Groundwater is the principal source of domestic and irrigation water in Limuna Bilbilo Woreda, East Arsi Zone, Ethiopia. The study was conducted to evaluate groundwater quality using the Water Quality Index (WQI), GIS, hydrochemical facies analysis, irrigation-water indices, lithological interpretation, and statistical analysis. Eighteen groundwater samples from ten springs and eight boreholes were analyzed for 21 physicochemical parameters. The suitability of drinking water was determined using the weighted arithmetic WQI method based on WHO and Ethiopian standards, and irrigation suitability was determined using EC, TDS, SAR, Na%, RSC, PI, MAR, and Kelley's index. The WQI results indicated that 61.1% of the samples were excellent, 27.8% good, 5.6% poor, and 5.6% very poor for drinking. The majority of groundwater sources were suitable for irrigation, though some boreholes had local sodium and magnesium hazards. The Ca-Mg-HCO3 water type was the most dominant hydrochemical facies, associated with recharge, mineral weathering, and water-rock interaction. The results provide a baseline for groundwater monitoring, aquifer protection, and water-supply planning in rural volcanic terrains.

Soil erosion and land degradation are the main environmental challenges disturbing ecosystem services, agricultural productivity, and community livelihoods in Ethiopia. The Southern Main Ethiopian Rift is one of the regions experiencing high levels of soil erosion and land degradation, driven by active geological processes and anthropogenic activities. However, the contribution of these geological processes to salinization and their subsequent impact on soil erosion and land degradation in the region remains poorly understood and insufficiently studied. This study was conducted to assess and map the spatial patterns of soil erosion and land degradation vulnerability in the salinized and hydrothermally stressed region of the Southern Main Ethiopian Rift using integrated multi-source earth observation data and machine learning frameworks. Landsat, Sentinel-2, SRTM DEM, CHIRPS rainfall data, soil data, and field observations were integrated with Google Earth Engine and GIS platforms to analyze existing biological, chemical, and physical indicators of land degradation. Land degradation indicators like soil erosion, land use/land cover (LULC), soil-adjusted vegetation index (SAVI), Normalized Multi-Band Drought Index (NMDI), land surface temperature (LST), salinity, and soil erosion were computed using respective approaches and integrated to produce a land degradation vulnerability map of the study area. The results show that large portions of the study area are moderately to highly vulnerable to land degradation. The major driver of land degradation in the study area is salinization, which increases surface runoff and sediment removal through surface crusting. The annual soil loss values for the area range from 25 to 100 t ha-1 yr ^-1, with about 10.69% of the area under moderate to very severe erosion risk. Accordingly, the land degradation vulnerability map shows that 1.68%, 50.15%, 38.14%, 6.31%, and 3.72% of the study area fall into the very low, low, moderate, high, and very high vulnerability categories, respectively. The land degradation vulnerability (LDV) model demonstrated strong validation performance, with an overall accuracy of 92.34%, a Kappa coefficient of 0.87, an F1-score of 0.948, and an ROC-AUC of 0.901. These validation results demonstrate the accuracy and reliability of the LDV model for mapping land degradation vulnerability. The findings indicate that soil salinity, surface soil loss, and elevated land surface temperature, together with anthropogenic pressures, are the primary drivers of high land degradation risk in the study area.

The Afar Triple Junction, where the Arabian, Nubian, and Somali plates diverge, is one of the most volcanically and tectonically active region on Earth. However, the east–west and vertical deformation field across the Erta Ale volcanic segment remains poorly constrained because previous InSAR studies have largely focused on individual volcanoes or line-of-sight deformation, limiting the characterization of horizontal and vertical ground motions across the entire segment. Here, we derive cumulative horizontal (east–west) and vertical displacements across the Erta Ale volcanic segment using a four-year (2022 to 2025) Sentinel-1 InSAR time series. Time-series analysis and two-dimensional decomposition were performed using the open-source LiCSBAS version 1.17 software to separate ascending and descending line-of-sight observations into horizontal and vertical displacement components. Deformation time series were generated for all six volcanoes to identify temporal trends and episodic deformation and to interpret the underlying magmatic and tectonic processes. The results reveal widespread subsidence across all volcanoes during the study period. Erta Ale and Alu Bagu exhibit westward horizontal motion, whereas Hayli Gubbi, Geda Ale, Alu Dalafilla, and Bora Ale show eastward displacement. The opposing horizontal motions produce an east–west separation of approximately 110 mm between Erta Ale and Hayli Gubbi, consistent with active rift extension. This 4 years intrusion-dominated separation and the long-term Red Sea spreading rate refer to different temporal scales and are therefore compared only qualitatively. The largest subsidence occurred at Erta Ale (−301.49 mm) and Hayli Gubbi (−271.37 mm), which is consistent with caldera-floor collapse and magma withdrawal associated with the mid-2025 dike intrusion event. The spatial variability of the horizontal and vertical deformation fields indicates the combined influence of shallow magmatic processes and regional tectonic extension. These results provide the first comprehensive characterization of east–west and vertical deformation components across the entire Erta Ale volcanic segment and offer new constraints on tectono-magmatic interactions and the ongoing evolution of the Afar Triple Junction.

1. Crime is a complex socio-economic issue that negatively impacts a country’s economy and lowers the standard of living for its citizens (Adugna & Italemahu, 2019). It not only results in financia...