Physical and Chemical Diagnosis of Lower Sebou River for Agricultural Use(GHARB - Morocco)
Abstract
In the present study, it is proposed to characterize the physicochemical of the water of the Lower Sebou sub-basin in the Gharb region used mainly in irrigation. The physicochemical characterization of the raw waters of the Sebou revealed that this river is very loaded with mineral and organic matters and have a wide variation in the chemical composition: *the electrical conductivity (EC), varies between a minimum of 629μS/cm and a maximum of 2370 μS/cm; *the average pH is between 8 and 8.77. The pH is slightly basic but remains acceptable according to standard; *the ammonium concentration varies between 0.04 and 2.66 mg/L; *concentrations of nitrates NO-have a maximum value of 196.9 mg/L and a minimum value of 0.24 mg/L; 3 *the concentration of ion Cl-has a maximum value of 385.53 mg/L and a minimum value of 145.55 mg/L; *for sulfate ion SO --, the maximum concentrations is 359.29 mg /L and the minimum value is 37.62 mg /L; 4 *the maximum and minimum bicarbonate ion concentrations are 362.34 mg / Land 75.64 mg /L; *calcium Ca2+ ion contents range from 220.4 to 97.6 mg /L; * for magnesium ion Mg2 + the maximum concentration is 124.08 mg / Land the minimum value is 17.28 mg/L; * Na + ion concentrations in water range from 2530 mg /L to 51 mg /L; *K + ion concentrations in surface waters range from 17.55 mg /L to 2.54 mg /L.
In conclusion, this study shows that the waters of the lower Sebou have a high mineral load but remain within the limits of the Moroccan irrigation standard. The waters of the Sebou are too polluted and we recommend that all domestic and industrial wastewaters should be treated appropriately to reduce the nuisance to the receiving environment and to compensate for the loss of this coveted and prized water resource.
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Introduction
Water quality is defined by physical, chemical and biological parameters, but also by its use. Thus, water unfit for human consumption can be adapted to irrigation, fish farming or to cool industrial circuits [1-3]. The rational management of water resources in the Kenitra Gharb area has become the main issue for local decision-makers to adopt a fair policy and which takes into consideration the importance of this resource and the challenge of increasing water resources. The Sebou river and its tributaries drain an area of 34000 km2. It extends for more than 600 kmstarting in the Middle Atlas under the name of Guigou river. It opens in the Atlantic to Mehdia, through its estuary 35 km in length. The rise of marine waters being stopped at the level of the guard dam, immediately downstream of Sidi Allal Tazi city [4]. In addition, the Sebou river is home to many pollutant spills from a variety of sources. The Sebou watershed, an extremely important area from a socio-economic point of view, is one of the most affected areas in Morocco. The existence of two of the main agricultural plains of the country as well as the multitude and diversity of industrial units and urban wastewater effluents in the major cities of the basin (Fez, Allal Tazi, Mechraa Bel Ksiri, Dar Gueddari, Kenitra), not to mention the uncontrolled dumping of household waste, which are the main causes of the deterioration of the quality of Sebou waters.
In our present study it is proposed to examine the physicochemical surface water of the lower Sebou sub-basin. This characterization of the levels and concentrations of the organic and mineral loads of Sebou raw water consists of a monitoring of the pH, ECelectrical conductivity, sodium, chloride, sulphate, calcium, magnesium, potassium, bicarbonate, ammonium and nitrates.
Conclusion
Adjacent agricultural activities occur well in the waters of the Lower Sebou sub-basin by significant concentrations of nitrates and sulphates which enter the water stream by runoff and leaching of nitrogenous and phosphorus fertilizer and phytosanitary products [26-27]. The upstream-downstream distribution of physicochemical parameters, reflects deteriorated situations of water quality in salts and chlorides in relation to the rise of marine saline waters.
The present work has revealed the poor quality of the waters of the lower Sebou but remains incomplete and needs to be deepened by analyzes of trace heavy metals and pesticides to provide the scientific and technical bases for decision-makers [28-30].