Spatiotemporal variations of water quality parameters in selected semi-arid young reservoirs in Tigray Regional National State, northern Ethiopia

Abstract

Abstract The health status of aquatic ecosystem is depended on the physicochemical and biological characteristics of water which provides significant information about the available resources for supporting life. This study aims to assess spatiotemporal variation of water quality parameters in selected young reservoirs in Tigray. Depth-integrated water samples (surface, middle, and just above bottom) werecollected bimonthly (three times during the wet and dry seasons) at each sampling siteswith a heart-valve sampler. Variation between the wet and dry seasons was examined using the independent t-test, and one-way ANOVA was used to analysis the differences among sites. We showed a significant (p < 0.05) seasonal variation in temperature, pH and transparency in all the reservoirs investigated. Kalema reservoir was recorded with highest mean value of temperature, chlorophyll a and conductivity. Mean value of pH hasa spatially significant difference (p<0.05) inall the study reservoirs except Kalema. None of the physicochemical water quality parameters in Kalema reservoir exhibited spatially significant (p>0.05) variations. Dissolved oxygen and pH showed spatially significant variation ( p < 0.05) in Mihtsab Azmati and Seisa reservoirs. A significant correlation ( p < 0.01) was recorded between temperature with turbidity, chlorophyll a, transparency and conductivity. The physicochemical parameters of the reservoirs showed distinct temporal and spatial variations. The result obtained in this study is very important as baseline information to know the ecology of reservoirs for future reservoir management. Further detailed studies that include total phosphorus, total nitrogen, etc., are needed to suggest the trophic conditions of the reservoirs.