Index methods for the assessment of surface water quality: the case study of Oued Fodda dam, in the Northwest of Algeria

In this study, the assessment of surface water quality of Oued Fodda dam was carried out by using the physicochemical and organic data recorded during the period from 2009 to 2016, which were measured monthly near the water intake in this dam. The basic parameters (pH, EC, TDS, O2, Mg2+, Ca2+, Na+, K+, Cl−, NO3−, HCO3−, SO42−, BOD, COD, OM, NH4+,NO3−, NO2− et PO43−) are used to determine organic water pollution and water quality for different uses, such as irrigation and industrial purposes. The evaluation of the suitability of surface water for irrigation purpose was done by the basic criteria such as sodium hazard (% Na), residual sodium carbonate (RSC), sodium adsorption ratio (SAR), and water quality index for irrigation (WQII). All these index methods indicate good water quality in this dam, which can be used to irrigate all kind of plants without real problem on agricultural yield rate, and without a problem of sodium and salinity hazards or permeability on the irrigated soils, mainly if an adequate drainage systems will be installed. The assessment of organic water pollution index (OWPI) indicates variation of water compounds concentration from month to another, that is due to multiple anthropogenic activities, and natural processes on upstream of this dam. The water passes from low pollution in the period of water inputs to moderate pollution in the period of reduction of water volumes in the dam. The fitness of water for industrial purpose by index methods (LSI and RSI) reveals an alternation between water quality from slightly to heavy corrosion (corrosion will proceed) unhindered by scale formation, generally, in the period of water inputs, and water quality of little scale forming with little to significant corrosion, which can be observed inside pipe, generally, from on the period of water volume decease.