INVESTIGATION OF SURFACE WATER RESOURCES AND IMPACT OF WET COFFEE PROCESSING EFFLUENT ON THE WATER QUALITY PARAMETERS OF CHICHU RIVER, SOUTHERN ETHIOPIA

Abstract

Investigation of surface water resources and its quality were one of the crucial tasks for better planning and management of the scarce resources. Pollution of surface water resource via discharge of industrial effluents is a concern today. Thus, the main objective of study was to investigate surface water resource and impact of wet coffee processing effluents on water quality parameters of Chichu River, Southern Ethiopia. To estimate surface water resource; hydro-meteorological and spatial data were collected and analyzed via SWAT model. To examine water quality parameters; samples were collected from twelve sampling point and analyzed for pH, EC, temperature, turbidity, and DO at onsite level, while TSS, TDS, COD, BOD, N-NH+ 4, N-NO3, and PO4 3- at laboratory. Result of sensitivity analysis shows; eight parameters were sensitive to the SWAT model. Performance indicators for calibration and validation of the SWAT model shows, good fit of which R 2=0.69, NS=0.53 and R2=0.71, NS=0.56 respectively. Since the Chichu River is ungauged, calibrated parameters were transferred from gauged Walame River to estimate water resource. Accordingly, annual surface runoff and total surface water resource corresponds 13.81 and 32.53 Mm3 respectively. Total water yield is 1066.17 mm, indicates Chichu River catchment has excessive water resource potential. A significant (p<0.05) variations were identified in the quality parameters at sampling site and points. Very acidic pH (4.03±0.48); high organic load of which BOD (631.4±71.58), and COD (1960.07±63.5); much deteriorated DO (0.85±0.4); huge nutrient load of which N-NH+ 4 (17.5±0.98), P-PO4 3- (19.67±1.3) and NO3-N (17.5±0.6); and very high floating and dissolved materials TSS (4076.87±90.7), TDS (2417.23±25.4), EC (1565.9±62.9 µS/cm), and turbidity (917.43±93.4 NTU) were obtained in the DSP of S4. Except for USP of S1, all studied quality parameters were highly deviated from the surface water quality standards. And during processing period, significant quantity (0.6MMC) of river’s available water were directly polluted via releasing of untreated coffee wastewater. In turn, it was found that the downstream water quality were undesirable for drinking, agriculture, and environmental uses during this period. Generally; Chichu River catchment has plenty water resources, but a significant proportion of this water is highly polluted via indiscriminate discharge of effluents from MWCPPs, such that the concerned government bodies and NGOs should develop mechanisms for water resource planning and management