Quantification of groundwater exploitation and assessment of water quality risk perception in the Dar Es Salaam Quaternary Aquifer, Tanzania

This study quantified groundwater exploitation and assessed water quality risk perception in the Dar es Salaam quaternary aquifer through a socio-economic survey. Annual total groundwater exploitation was estimated, using the daily per capita consumption of groundwater derived from the household survey. A logistic regression analysis was performed to ascertain the influence of sex, marital status, education level, employment, income, and cost of water on groundwater quality risk perception. It was revealed that most residents of Dar es Salaam use groundwater as a main source of water supply. The results of this study further showed that 78% consider groundwater as a reliable source. Averting strategies for insufficient quantity of groundwater consist of minimizing less necessary water uses, while for poor quality, buying bottled water and water treatment by boiling and using chemicals. The chance for water quality risk perception is 0.205 times greater for married than unmarried household heads, and it is 623 times higher for employed versus unemployed household heads. To get an overall view of the importance of groundwater for domestic needs in Dar es Salaam it is imperative to combine a time series data of groundwater and surface water exploitation

Indigenous Knowledge Systems for Climate Change Detection and Adaption Planning in Mountainous Areas in Tanzania

The study was carried out to gather perceptions and experiences of the Uluguru mountains communities on climate change and its impacts, and to understand their traditional innovations in detecting climate change and coping with the impacts. It took place in three villages of Luale ward namely Luale, Masalawe and Londo in Mgeta division, Mvomero district. Participatory research methods were employed in generating the perceptions, information and experiences about climate change, its impacts and community based adaptation strategies. Climate-related hazards were identified using traditional knowledge, skills and experiences. Historical timelines developed by the local people themselves revealed an increase in the frequency of drought incidences and shifting rainfall seasons, with unprecedented wildland fires devastating the study area. Community-based coping strategies as a response to the observed climate change impacts were also identified. However, the coping strategies practised by the traditional communities are mainly oriented towards survival, not continuous, motivated by crisis, reactive, often degraded the available resource base and are usually prompted by lack of alternatives. Therefore, local communities and traditional people in general need the support of the international community to continue their role as traditional caretakers of marginal and fragile ecosystems, at the same time, building their capacities to adapt to the impacts of the current and future changes of global and local climates using more proactive approaches integrated into their indigenous knowledge base. KEY WORDS: Climate change, Traditional communities, Indigenous knowledg

Open-Source Software Application for Hydrogeological Delineation of Potential Groundwater Recharge Zones in the Singida Semi-Arid, Fractured Aquifer, Central Tanzania

This research article published by MDPI, 2020This study attempted to delineate and map potential groundwater recharge zones of the Singida, semi-arid, fractured crystalline basement aquifer using open source remote sensing and GIS software. Various thematic maps such as lithology/hydrogeology, soil, land-cover/use, slope, lineament density, drainage density and rainfall distribution were integrated in QGIS software. Vector input layers were rasterized and resampled using QGIS wrap projection function to make sure that the grid cells are of the same size. Reclassification using SAGA and GRASS reclass algorithms in QGIS was carried out to realign the factor classes in a consistent scale, and reclassification to a scale of 1 to 5 was carried out to harmonize the results. The study identified a number of potential areas for groundwater recharge, groundwater exploration, groundwater development and potential areas for artificial groundwater recharge. Potential groundwater recharge zones for the Singida semi-arid fractured aquifer are restricted to areas with high lineament density, cultivated areas, grassland and flat to gentle slopes. The potential of groundwater recharge is also observed in areas with low drainage density. The delineated zones provide a good understanding of the potential recharge zones, which are a starting point for recharge zone protection. This blended approach can be utilized for carrying out suitability analysis using the weighted overlay analysis approach. Areas designated good and very good are recommended for artificial recharging structures as an alternative technique for enhancing groundwater recharge through rainwater harvesting. This will help to augment groundwater storage in this semi-arid environment

Using hydrogeochemical facies and signatures for groundwater characterization and evolution assessment in aquifers with contrasting climate and geology in Tanzania

Abstract This study aimed at characterizing groundwater evolution using hydrogeochemical facies and signatures in two basins with contrasting climate and geology, one in the central part and the other in the eastern coast of Tanzania. The Kimbiji (humid, unconsolidated) aquifer is covered by an unconfined layer in the upper parts and a confined layer in the lower parts, with strong artesian flow characteristics while groundwater in the Singida (semi-arid, consolidated) aquifer occurs in weathered shallow layers and in fractures of basement rocks. Fieldwork involved water sampling from precipitation, deep and shallow boreholes, springs and surface water from rivers and lakes in the two study areas. These were specifically conducted for hydrogeochemical analyses to unravel hydrogeochemical facies and signatures in the two aquifers. Physico-chemical water quality parameters [i.e., pH, electrical conductivity (EC) and total dissolved solids (TDS)] were measured in situ using HANNA HI 9829 Multiparameter Analyzer. Standard procedures for water sampling, preservation, transportation, and chemical analyses of major ions were conducted as documented in previous studies. Samples were carried and stored at 4 °C prior to their shipping and analyses at Water analysis and testing in environmental regions (WATER) laboratory in Iringa, Tanzania. The mechanism controlling groundwater geochemistry were revealed by assessing the reactions between groundwater and aquifer minerals. Chloro-Alkaline indices (CAIs) were used to study cation exchange processes between the groundwater and its host environment at stagnancy and/or during groundwater travel. The Gibbs ratio 1 values were found to range from 0.26 to 0.94 and Gibbs ratio 2 values ranged from 0.11 to 0.95. The majority of the samples irrespective of the contrast in climate and geology were observed to fall in the rock–water interaction zone. This is attributed to chemical weathering processes where the dissolution of rock forming minerals takes place. Some samples exhibited replacement of Na+ by Ca2+ or Mg2+ (S18), loss of Na+ through precipitation of evaporate rocks (S11, S13, S16, S19), and water flowing through crystalline rocks (S1, S2, S4, S6, S8, S10, S12, S13, S14, S21). The ratio Na+: Ca2+ > 1.0 (S1, S4, S8, S10, S12, S14, S17, S18, S19, S21) explains base ion exchange while the ratio < 1 implies a reverse ion exchange (S2, S6, S11, S13, S16).The Ca2+: SO4 2− + HCO3 − ratio < 1.0 connotes groundwater flowing through a normal hydrological cycle (S1, S4, S8, S10, S12, S14, S17, S18, S2, S6, S11, S13, S21) and a ratio greater than 1 is an indication of Ca2+–Cl− brines (S16, S19). The HCO3 −: Cl− hydrogeochemical signatures divided the Singida aquifer into upper water flow course, where groundwater recharge occurs (S52, S54, S56, S57, and S58) and the discharge zone, (S53, S59, S60, S61) which is a lower groundwater flow course. Interestingly, the Mg2+ + Ca2+: Na+ + K+ ratios as well confirmed that the Singida aquifer is a lower groundwater flow course (discharge zone). The greater than 1 Na+: Ca2+ ratios confirm the dominance of base ion exchange in the Singida aquifer as it has been explained by the CAIs and the Piper diagram. The Gibbs diagrams revealed that the hydrochemistry of groundwater in the Kimbiji and Singida aquifers are mainly in the rock weathering region, affirming that there is high dissolution with rock forming minerals. This is thus one of the main controls of groundwater mineralization in the two study areas. The similarity of hydrogeochemical signatures between a distant surface water body, Lake Inkhanoda and Mwankoko borehole in the Singida aquifer is an indication that there is a discernible interaction between groundwater and surface water, further revealing that the Singida aquifer is fed by sub-regional and regional groundwater flow systems

Integrated Geospatial and Geophysical Approaches for Mapping Groundwater Potential in the Semi-Arid Bukombe District, Tanzania

The rapid growth of civil societies coupled with population influx due to the artisanal mining industry in the Bukombe district (BD) has triggered a high demand for water resources. The daily consumption of water resources in the district surpasses the supply from available surface water sources. Thus, the situation has raised the demand for groundwater resources as an alternative. Despite the importance of groundwater resources, no current studies have spatially assessed groundwater potential to locate optimal points for borehole development. This study intended to investigate and map the groundwater potential areas (GWPAs) in the semi-arid BD using remote sensing (RS), the geographic information system (GIS), and the analytic hierarchy process (AHP) to help local communities access clean and safe water. Rainfall, geology, slope, drainage density, land use/land cover and lineament density were prepared to delineate the map of GWPAs. The map was categorized into poor (0.21%), moderate good (51.39%), good (45.70%) and very good (2.70%). Finally, the GWPA map was validated using Vertical Electrical Sounding (VES), 2-D sections and a drilled borehole. The validation results confirmed that the applied approach provides significant results that can help in planning the sustainable utilization of groundwater resources

The role of development projects in strengthening community-based adaptation strategies: the case of Uluguru mountains agricultural development project (UMADEP)-Morogoro-Tanzania

This study was trying to find out whether the designing and implementation of the Uluguru Mountain Agricultural Development Project (UMADEP) has taken into account the hazards, impacts and risks associated with climate change and the local coping strategies of their project beneficiaries, since its inception, 17 years ago . Data were gathered using the Community-based Risk Screening–Adaptation and Livelihoods (CRiSTAL) tool, complemented with a series of semi-structured and structured interviews containing both close and open-ended questions. The Vulnerability and Capacity Assessment (VCA) method was also used in identifying resources, capacities and vulnerabilities which pertained to different livelihood settings in the study area. The study found out that coping strategies applied by affected people in the study area vary from one community to the other, depending on level of education, income, household size and agro-ecological zone. Ranking of the identified livelihood resources revealed that natural resources are very crucial in adapting to climate change. Generally, the results indicate a moderate influence of project activities towards enhancing adaptive capacities of the surrounding communities, with the observed positivity of the project activities towards community-based adaptation being more of a coincidence than a planned state-of-affairs. Lack of training to development project officers, managers and planners on the importance of integrating climate change management during the early stages of project development was clearly depicted as a key hindrance to mainstreaming climate change into development planning.This article is available at http://www.internationalscholarsjournals.or