Hydrochemistry of MADA irrigation water

K. Sani

Abstract

The MADA irrigation water samples were collected from Sg. Padang, Alor Gunung, Sg. Tajar, Sg. Sala (2) and Sg. Sala (3) from May 1983 to January 1984. The pH, salinity, N, P, K, Na Ca, Mg, Cl, SO₄ HCO₃, total suspended solid and total dissolved solids status were determined. The study concluded that MADA water could be classified as good quality freshwater, suitable for irrigation. Its chemistry was the product of precipitation and dilution mechanisms of the rainfall, and seawater influences. The water could be divided into two types. The first type contained Na and Cl as the dominant ions due to its proximity to the sea. The second type from the inland areas had about equal dominance of Na, Ca and Mg from the cation composition, and Cl, SO₄ and HCO₃ from the anion composition. MADA water was slightly acidic with pH values of 5.82-6.47. The water was also slightly mesotrophic with average N:P of 2.0. Inland areas had low salinity values i.e. 0.05-0.09 dS/m while those near the coast had higher salinity, 0.53-0.70 dS/m. The concentration of dissolved solutes in most MADA water was low thus making the water safe for irrigation purposes.

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