TITLE:
Adequacy of Water Use Resources for Drinking and Irrigation, Study Case of Sarh City, Capital of Moyen-Chari Province, CHAD
AUTHORS:
Edith Kadjangaba, Djimako Bongo, Mekila Le Bandoumel
KEYWORDS:
SEQ-Eau, Water Quality, Consumption, Irrigation, Physico-Chemical and Bacteriological Parameters
JOURNAL NAME:
Open Journal of Modern Hydrology,
Vol.13 No.1,
December
2,
2022
ABSTRACT: Our objective is to evaluate adequacy of water for consumption and
irrigation. We collected nineteen water samples from 21 to 26, May 2017.
Twenty-two physico-chemical and bacteriological parameters were taken into
account, electrical conductivity, pH, total hardness, bicarbonate, nitrates,
sulfates, chlorides, calcium, sodium, magnesium, potassium, dissolved oxygen
and biochemical oxygen demand, chemical oxygen demand, total coliforms, Escherichia Coli, and fecal coliforms.
To evaluate water intended for consumption, average values measured parameters
were compared to [1] for quality water drinking and we evaluated overall
quality of water by means of simplified SEQ-Water grid. Concerning irrigation
water, evaluation is based on interpretation of quality parameters of
irrigation water that we have calculated; among these parameters we can mention
the percentage of sodium, rate of sodium absorption, ratio of magnesium
adsorption, residual sodium carbonate. Kelly ratio, Corrosivity ratio and
Permeability Index. Results show that surface water is weakly mineralized
compared to groundwater and presents a good chemical quality; however, it is
slightly altered by presence of organic pollutants. The overall assessment of
groundwater quality shows that about 47% of water sampled varies between
average quality and very poor quality for consumption. This poor quality is
mainly due to presence of nitrates in water, whose content sometimes exceeds
the limit authorized by [1]. From a bacteriological point of view, germs of
faecal origin such as Total Coliforms, Escherichia
Coli and Faecal Coliforms contaminate all groundwater points sampled. They
are of poor quality and unfit for human consumption without prior treatment. We
also evaluated the quality of water used for irrigation using 6 parameters. The
results show that all of our water points are suitable for irrigation,
according to the values of CSR and Kelly ratio. The same is true for the
permeability index, which shows that all samples fall into class I and II type
to indicate their suitability for irrigation purposes. According to [2] all
waters are excellent quality for agriculture; and for Richard diagram, 89.5% of
waters are generally suitable for irrigation and 10% are generally not suitable
for irrigation without prior dilution with low salinity water.