Environmental Engineering Reference
In-Depth Information
Farmers use fallow periods to restore the fertility of the soil. The early period
of fallow, which is called
forbe
regrowth, is a good indicator of soil fertility.
Another vegetative parameter used is the presence of twigs/shrubs and creepers.
High amounts of these indicate good soil fertility.
Comparison of traditional and scientific methods of assessment
Water quality
Traditional assessment of water resources is dependent on a number of factors.
They include flow rate, the presence or absence of sand in the water or stream,
and absence of vegetative cover trees and shrubs around it. Regarding water qual-
ity, parameters used include the colour of the water, the amount of foreign matter
in the water, and the taste. By contrast, the scientific approach is based on labo-
ratory experimentation using the parameters in Table 3.3.
It is observable from Table 3.3 that the parameters for assessing water quality
from the scientific point of view are many and varied. On the other hand, trad-
itional assessment is limited to only physical characteristics such as odour,
colour, and taste.
Table 3.3 Scientific indicators of water quality
General Temperature
Oxygen (O
2
)
Oxygen saturation
Suspended matter radioactivity
Tritium
Inorganic compounds Calcium (Ca
2
)
Magnesium (Mg
2
)
Total hardness
Total dissolved salts
Organic compounds Chemical oxygen demand (COD) mg/l
Potassium permanganate mg/l
Colour
Odour number
Eutrophic compounds Ammonia (NH
4
)
Nitrate (NO
2
)
Nitrate (NO
3
)
Total phosphate (PO
3
PO
4
)
Metallic elements Iron
Manganese
Bacteria (microbiological)
Faecal coliforms
Coliform organisms
Streptococcus faecalis
*
Source:
Standard Methods.
AWWA/APHA/WEF (1992)
*
The Oxoid Manual
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