Water Balance and Groundwater Quality of Koraro Area, Tigray, Northern Ethiopia

Achieving the Millennium Development Goals (MDG) has been given a paramount importance by both Regional and Federal Governments in Ethiopia. In this direction some stations in Hawzen Woreda, Tigray Regional state, extremely poor, have been selected as model areas to test the achievement of the MDG. This paper focuses Koraro Tabia (or Station), one of the millennium villages where shortage and bad quality water is a challenge. Water balance and the hydro chemical characteristics of groundwater have been investigated in order to assess the water potential and quality in the area. Hydrometeorological information has been used to calculate water balance parameters and the recharge amount. Accordingly, the mean annual rainfall, actual evapotranspiration, bare land evaporation, runoff and groundwater recharge was found to be 548.5 mm, 431.3 mm, 372 mm, 71.33mm and 56.7mm respectively. Twelve water samples were collected from hand dug wells and springs located in different lithologies and were tested for major anions, cations, and some trace metals in Ethiopian Geological Surveys Central Geological Laboratory. Mean electrical conductivity of water samples from different sources varies significantly. The mean electrical conductivity for the hand dug wells is found to be 5170 µS/cm and that of springs is 209 µS/cm. Piper diagram revealed that groundwater in the hand dug wells is of sodium sulfate type and spring water are calcium bicarbonate type. The results indicate that groundwater from the hand dug wells is of very poor quality with high salinity and sulfate content and does not fit for human consumption. Therefore, it is recommended to avoid water for drinking purpose from hand dug wells constructed in shale dominated areas and in the alluvial deposits underlain by shale. Moreover, groundwater recharge is also insufficient in the area due to the impervious shale unit. Hence, an adaptive management method is suggested for efficient use of water and a mechanism to isolate the bad quality water while trying to construct water supply scheme for drinking in the area. Key words: Groundwater, Water balance, Water quality, Koraro, Ethiopia

The Positive Effect of Micro-Dams for Groundwater Enhancement: a Case Study around Tsinkanet and Rubafeleg Area, Tigray, Northern Ethiopia

The government of Tigray Regional State, Northern Ethiopia has been conducting a massive construction of micro-dams (small reservoirs) in order to decrease the rainfall dependency and alleviate food insecurity in drought prone areas of the region. Tsenkanet and Rubafeleg reservoirs are examples of this endeavor. The purpose of this investigation is to evaluate the role of these micro-dams in enhancing the surrounding groundwater by artificial recharge. In this study the physical characteristics of the reservoir are discussed including the groundwater surface water relationship with respect to water level elevation and also hydro-chemical composition. Six water samples have been analyzed. Samples are taken after rinsing the plastic bottles with distilled water and the sample to be taken. One surface water sample from each reservoir and one groundwater samples from each well next to each reservoir has been collected. Moreover, one sample from spring and one from river has been analyzed. The chemical composition of the reservoir water and the surrounding groundwater seem to suggest a similar origin and to be resulting from similar hydro-chemical processes. The chemical composition of all samples is found to be of the CaHCO3 type, which could be explained as resulting from precipitation water in which the mineral calcite has been dissolved. Both the topographic evidence and the water level monitoring data has confirmed the feeding of the reservoir to the near by shallow groundwater system. Quantifying the amount of groundwater accretion by the use of modeling and water balance method is recommended. Keywords: Groundwater, Surface water, Topography, Water Level, Type, Hardness, Class

Drinking water quality from rural handpump-boreholes in Africa

Groundwater provides a vital source of drinking water for rural communities in many parts of Africa, particularly in the dry season when there are few safe alternative sources. This paper summarises results from a study (n = 428) assessing dry season water quality, both microbiological and inorganic chemistry, in handpump equipped boreholes (HPBs) across the Ethiopia Highlands (n = 142), Malawi (n = 162) and Uganda (n = 124) using a stratified, randomised sampling design. This study seeks to examine general water quality by randomly sampling rural groundwater supplies across larger areas with different geology and climate. The majority, 72%, of HPBs surveyed provide good quality dry season drinking water as defined by WHO drinking water quality criteria. Within this overall picture, the most notable constraints were from thermotolerant coliforms (TTCs), which exceeded the WHO drinking water guideline of zero colony forming units (cfu/100 ml) in 21% of sites (range 0–626 cfu/100 ml). TTC contamination was found to have a significant and positive correlation with annual average rainfall (ρ = 0.2, p = 0.00003). Across all three countries, WHO health based chemical drinking water quality values were exceeded at 9% of sites and were found for manganese (4%), fluoride (2.6%) and nitrate (2.5%); arsenic concentrations were below the guideline value of 10 μg l−1 (range 400 μg l−1) found in drinking water sources in Uganda challenges the decision by WHO not to formalise a health-based guideline for Mn. While the overall level of microbiological contamination from HPBs is low, results from this study strongly suggest that at a national and regional level, microbiological contamination rather than chemical contamination will provide a greater barrier to achieving targets set for improved drinking water quality under the UN-SDG 6. Efforts should be made to ensure that boreholes are properly sited and constructed effectively to reduce pathogen contamination

Contribution of physical factors to handpump borehole functionality in Africa

Handpumps are the main water supply for rural communities across sub-Saharan Africa. However, studies show that >25 % of handpumps are non-functional at any time. We present results from a systematic field study of handpump borehole functionality. The study was designed to investigate the contribution of physical factors to functionality outcomes, including; hydrogeology, borehole configuration, and handpump components. To achieve this, we deconstructed and examined 145 handpump boreholes in Ethiopia, Uganda and Malawi. Pumping tests showed that 19 % of boreholes were located in aquifers with transmissivity below the minimum required to sustain a handpump. Water levels, measured during the dry season, had a complex relationship with borehole configuration and transmissivity. The handpump cylinder was <10 m below the water table at 38 % of sites, which increases the risk of the handpump running dry during intensive use and/or in areas of low transmissivity. The water column was <20 m at 23 % of sites and screens were <10 m long at 29 % of sites and often sub-optimally positioned in the borehole. Borehole depth had no clear relationship with functionality. Using multinomial regression and four functionality categories (functional; unreliable; low yield; unreliable and low yield) as dependant variables, we found that transmissivity is a significant risk factor for the classification of handpump boreholes as low yield. The configuration of the borehole (e.g. cylinder position, screen/casing configuration and water column) is a statistically significant risk factor for the classification of handpump boreholes as unreliable. Handpump components were in poor overall condition but rising main pipes were a particular problem with 53 % of galvanised pipes corroded and 82 % of uPVC pipes damaged, with implications for handpump performance. Our study highlights the importance of; understanding aquifer properties, investing in borehole siting, construction (including supervision) and commissioning, and improving the quality of components and maintenance of handpumps