Hydrogeochemical and bacteriological analysis of ground water quality for water supply and irrigational uses: a case of guder town

Abstract

Groundwater refers to all the water occupying the voids, pores and fissures within geological formations, which originated from atmospheric precipitation either directly by rainfall infiltration or indirectly from rivers lakes or canals. The current concern of world is the issues of water pollution with chemicals. The study was conducted to analyze ‘hydrogeochemical and bacteriological suitability of groundwater for water supply and irrigational uses in Guder town. Here, Ground water quality suitability for domestic purposes, for irrigational uses, and groundwater type were analyzed. Using purposive sampling technique nine samples of water were taken from different sample points. Field and laboratory based measurement were conducted. The following physicochemical and bacteriological parameters were analyzed following standard methods for the analysis of water and wastewater: The average values of groundwater quality parameters of the study area were: Temperature (22.9⁰C), turbidity (16.9NTU), pH 7, TS (1326.9mg/L), TDS (741 mg/L), EC (1164μS/cm),TA (410.9mg/L ),Na⁺ (306.4 mg/L), K⁺(29.5mg/L), Ca²⁺(106.8mg/L), Mg²+(91.7mg/L), TH(198.5 mg/L), Fe²⁺(1.3mg/L ),SO4 2- (88.95 mg/L), F- (0.94mg/L),NO3 - (5.2 mg/L), Mn²⁺(0.27mg/L), As³⁺ (0.001 mg/L), Cl- (17.8 mg/L), HCO3 - (410.9 mg/L), CO3 2- (0 mg/L). The average values of the following physicochemical parameters of were above WHO permissible guideline values such as: EC, TDS, HCO3 - , TA, Ca²⁺, Fe²⁺, Mn2+ , Na⁺, K⁺, TS ,Turbidity, FC, and TC. The rest parameters of: pH, NO3 - , As³⁺, CO3 2- , CO3 2- , and Cl- , average values were below and in (WHO, 2011) guideline values. The maximum values of Mg²+ , SO4 2- and TH were recorded at BH1 of the source for water supply. Bacteriological analysis results were: FC (9.1MPN/100) and TC (14MPN/100). Water type of the study area was determined by using Aquachem version 4software. The water types of the studies area of BH1, SP6, R8, and R9 were Na-Mg-Ca-SO4 types which is dominant types. The rest sample points of: SP4, and SP5, Na-Mg-HCO3 water types and finally BH2 and HW7 of Na-HCO3 water types were detected. Groundwater suitability for irrigational uses was analyzed by irrigational indices of: SAR (100%) suitable, %Na (55.6%), PI (55.6%) in permissive range. However the values of SSP (77.8%) in doubtful range, and MH (62.34%) were unsuitable. In general the study was concluded that the physicochemical and bacteriological property of groundwater of the study area was unsuitable for domestics and irrigational uses. Therefore Guder town municipal water supply office and concerned body should: design and construct treatment plant; use chlorination treatment; build cascading aerators to remove Iron; construct laboratory center for monitoring the groundwater quality continuously.