by OO Falowo, V Oluwasegunfunmi, Y Akindureni, W Olabisi and A Aliu
Original Research
The natural quality of groundwater is controlled by aquifer hydrology, geochemistry, and the geology. The principal objective of the study was to estimate and characterize the water quality parameters of groundwater using World Health Organisation (WHO) for drinking purpose. In view of objectives of the study, groundwater quality assessment was carried out in selected 67 water wells in Akure, Ondo State, Nigeria. The analyzed parameters are electrical conductivity, pH, oxidation potential (Eh), acidity, total alkalinity, total hardness, temperature, total dissolved solids (TDS), turbidity, calcium (Ca2+), magnesium (Mg2+), Sodium (Na+), potassium (K+), chloride (Cl-), bi-carbonate (HCO3-), sulphate (SO42-), and nitrate (NO3-). The temperature of the groundwater varies from 25.9 – 30.8°C with a mean of 27.9°C. All the water samples are colourless, odourless, and tasteless, with clear appearance. The recorded pH varies from 5.2 – 7.0 and characterized by an acidic condition. The EC of water samples is in the range of 53 - 874 μS/cm (avg. of 189.8μS/cm). The water type is a recharged water, with value of TDS ranging from 40mg/l to 424 mg/l, and an average of 96.7 mg/l, indicative of fresh water. The cations and anions satisfy the WHO standard for drinking purpose with about 95% compliance. The sequence of the abundance of the major ions is in the following order: HCO3-> Cl-> SO42-> NO3-for anions, and Ca2+> K+> Na+> Mg2+ for cations .The calculated values of WQI vary from 22% to 60%. The study area is widely (90% areal coverage) characterized by “Good water” in the range of 26 – 50%, with hardness varying from soft to very hard water. The “Excellent water” is only associated with Sample S-34 in the northwestern part of the study area, while “Bad water” fall (S-21, S-28, S-57, and S-65) within a small portion of biotite granite and migmatite geologic units.
American Journal of Water Resources. 2019, 7(2), 76-88. DOI: 10.12691/ajwr-7-2-5
Pub. Date: July 23, 2019
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by EA Ochungo, GO Ouma, JPO Obiero and NA Odero
Original Research
Water Quality Index (WQI) computation method based on quality parameters’ selection, assigning of weights, creation of sub-indices and calculation of the aggregated quality value has been used for many decades from the early 1960s to check on the pollution stati of watersheds. Today, due to rising water demand in the face of increased drought induced water shortage challenges and rampant pollution of the water sources, consumers augment their needs by using groundwater resources like in the case of Langata sub County in Nairobi city-Kenya. Little however, has been done to assess the overall potability of groundwater quality here. Accordingly, in the present study, a Water Quality Index (WQI) was developed by Weight Arithmetic Water Quality Index (WAWQI) method to fill that identified gap using a five categories’ grading scale, viz. excellent (A), very good (B), good (C), fairly good (D), suitable (E) and unsuitable (F). To realize this, chemical parameters’ concentration ranges were defined on the basis of the Kenyan Standards (KS) and International Standards of World Health Organization (WHO).Subsequently, a total of eight chemical parameters were selected based on their level of occurrence in borehole commissioning data obtained from Water Resource Management Authority’s database of the area viz; K+, Na+, Ca2+, Fe2+, F-, Cl-, SO4-2 and Ec (µS/cm). Out of a total of 137 boreholes, only 39 had complete eight chemical parameters. These 39 boreholes’ water quality assessment is taken in this study as a true representation of the entire area’s groundwater quality. The individual concentrations were spatially plotted using Surfer Software’s digital terrain model (DTM) which produced contoured maps in different chroma saturations including the overall aggregated concentration to facilitate scale ranking. The WQI for the study area is 53.18 in a scale of 1 to 100, with one being excellent. In this case, the groundwater quality was ranked as grade ‘C’. WQI calculation method is known to improve the understanding of water quality issues by integrating a suite of data into a single value which describes the status of water quality. WQI is very useful for the water management authorities because it facilitates their informing of the public on water quality in a simplified form.
American Journal of Water Resources. 2019, 7(2), 62-75. DOI: 10.12691/ajwr-7-2-4
Pub. Date: June 04, 2019
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by Bama Nati Aïssata Delphine, Niang Dial, Gbané Mahama, Ouedraogo Ibrahima, Boube Bassirou and Ngnepi Toukep Elvire Vanessa
Original Research
Smart-Valley is an inexpensive, sustainable and participatory lowland development approach, developed by Africa-Rice in order to increase the resilience of small-scale rice producers to rainfall variability effects. The approach is based on these farmers’ knowledge of their lowlands. Smart-Valley has already proven itself in West Africa's coastal countries. In these coastal areas, smart valley bunds are designed with only lowland land. But in sudanian climatic zone, the runoff is sometimes violent. Will bunds with lowland lands be resistant? Hence, this study aimed to test and adapt smart valley bunds designed for West Africa coastal areas to sudanian ecology. Twenty ha in four lowlands, five ha by site, were developed during the months of May-June 2018 follows smart valley approach. However, rubble stones were used to reinforce the main bunds and drainage channels were made if needed. The study showed that on half of the sites, the small holders farmed their lowland without carrying out any water management bunds. Smart valley adapted technology is not suitable for all the sudanian lowlands because this approach was success 75% in lowlands tested. But, in these area where smart valleys is adapted, bunds done by rubble stone slow down runoff, increases infiltration and retains a standing water that reduces the effects of pockets of drought during crop production.
American Journal of Water Resources. 2019, 7(2), 58-61. DOI: 10.12691/ajwr-7-2-3
Pub. Date: June 04, 2019
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by Ranojit Kumar Dutta, Jun Ma, Baishakhi Das and Defu Liu
Original Research
A bottom curtain weir (BCW) is a hydraulic structure that acts as a barrier to the flow and diffusion of heat across the width of a water body. Algal blooms occur frequently in the largest tributary of Xiangxi Bay (XXB) of the Three Gorges Reservoir (TGR). A laterally averaged two-dimensional hydrodynamic and water quality model was used to simulate BCWs, including water temperature, hydrodynamics and chlorophyll-a concentrations, for XXB. The numerical models show that BCWs are a much more attractive, much less expensive and time-saving algal bloom controlling technique for subtropical reservoirs. The developed model was calibrated using data collected in XXB from January to December 2010. The maximum chlorophyll-a concentrations observed were 125-154 mg/m3 according to sampling sites such as XX09, XX06 and XX01. Overall chlorophyll-a concentrations were markedly reduced by 4-44% as a function of BCWs height and location. A seasonal algal bloom reduction rate of more than 37% was observed in summer. In some periods, such as May 27-31, June 2-4, June 16-18, August 16-18 and August 23-24, BCWs with heights of 3 m, 5 m and 7 m reduced algal blooms by up to 99% at XX09 and XX06 in XXB. Therefore, the proposed BCWs can reduce algal blooms and improve water quality to save domestic water and aquatic ecosystems in XXB of TGR.
American Journal of Water Resources. 2019, 7(2), 50-57. DOI: 10.12691/ajwr-7-2-2
Pub. Date: May 23, 2019
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by Ranojit Kumar Dutta, Jun Ma, Baishakhi Das and Defu Liu
Original Research
Algal blooms occur frequently in Xiangxi Bay (XXB), which is one of the largest tributaries of the Three Gorges Reservoir (TGR). Floating curtain weirs (FCWs) are hydraulic structures that act as a barrier to divert density currents and diffuse heat across the width of the water body. Numerical modeling of FCWs is become a widely accepted method for controlling algal blooms. A laterally averaged two-dimensional hydrodynamic and water quality model (CE-QUAL-W2) was used to simulate the effects of FCWs, including those on water temperature, hydrodynamics and chlorophyll-a concentrations, for XXB. The developed model was calibrated using data collected in XXB from January to December 2010. The results indicated that the maximum chlorophyll-a concentrations observed were 74-154 mg/m3 at the XX09, XX06 and XX01 sampling sites. The performance of the FCWs suggests that the overall chlorophyll-a concentrations are markedly reduced by more than 85% as a function of the FCW heights and locations. Seasonally, an algal bloom reduction rate of more than 62% was observed in the summer. FCWs with heights of 3, 5, and 7 m reduced algal blooms by up to 99% at XX09 during March 26-28, April 24-27, July 18-26, August 5-20, and 23-28, and September 3-8 and 12-16, respectively. Therefore, the proposed FCWs can reduce algal blooms and improve water quality to save domestic water and aquatic ecosystems in XXB.
American Journal of Water Resources. 2019, 7(2), 42-49. DOI: 10.12691/ajwr-7-2-1
Pub. Date: May 23, 2019
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