Figure 6. Landcover map in the Tyrma region as a result of
extrapolating the decision-tree’s classification model. Orange areas
denote the places classified into wetland (Mari ). Similarly,
green areas denote forest, and purple areas denote grassland. Areas
enclosed by color and black lines show the catchment areas of the
sampled rivers.
3.2 River water chemistry (dFe, DOC, EC) and their relationship with the
coverage percentage of wetland (Mari ) in the watersheds.
Using the produced landcover map (Figure 6), the coverage percentage of
wetland (Mari ) in the sampled river watersheds was calculated.
This result is shown in Table 1 with the results of dFe, DOC, and EC.
The range of dFe concentration in the five large rivers was 0.12–0.38
mg L–1, with
dFe being especially high in the Yaurin and Gujik Rivers. The range of
DOC concentration was 13.4–19.0 mg L–1, and similar
to dFe, DOC concentration was higher in the Yaurin and Gujik rivers than
in other large rivers. EC in the large rivers was low on average and its
range was 3.90–5.63 mS m–1. The range of wetland
coverage was relatively high in the Gujik Basin at 34.8%, but there was
no significant difference among other large rivers of 14.7–16.5%.
Alternatively, the small rivers showed more variety of water chemistry
compared with the large rivers: they showed quite wide ranges for dFe
concentration of 0.02–0.54 mg L–1 and DOC
concentration of 7.4–29.5 mg L–1. EC in the small
rivers was also in a wide range of 2.89–14.00 mS
m–1. The coverage of wetland in the small river
watersheds was 1.5–55.9%, especially higher in the rivers of the Tyrma
River system (Rivers 9–19 in Table1) than those of the Gujal River
system (Rivers 1–8 in Table1).