Mujong 13/2/2015 1:00 pm Raining Table 2: Summary of in situ parameter at the tributary station of the Batang Baleh.
A total of 15 tributary stations were selected along the Batang Baleh from upstream to downstream direction (Table 1).
Tributary stations were relatively shallow in the study area, ranging from 0.15 [+ or -] 0.09 m to 3.10 [+ or -] 0.00 m (Table 2).
The pH value of tributary stations fluctuated along the Batang Baleh with the lowest and the highest pH values observed at station 5 and station 6, respectively.
The extremely high values of turbidity and TSS observed at the tributary stations of the present study were substantially higher than those recorded at the tributaries of the Baram River where the highest turbidity and TSS were about 468 NTU and 320 mg/L, respectively, and they were also attributable to logging activities [18,19].
Chl a concentration ranged from 0.02 [+ or -] 0.00 mg/[m.sup.3] to 1.36 [+ or -] 0.21 mg/[m.sup.3] at tributary stations of the Batang Baleh (Table 3).
Significantly higher (p value [less than or equal to] 0.05) BO[D.sub.5] concentrations were observed at tributary stations
Tributary stations at the upper part of the Batang Baleh were mostly classified as Class II and/or III whereas tributary stations at downstream region were classified as Class I and/or II.
Similar to BO[D.sub.5], the N[O.sub.2.sup.-]-N + N[O.sub.3.sup.-]-N concentration was also significantly higher (p value [less than or equal to] 0.05) at tributary stations that were located at upper part of the Batang Baleh than those at the lower part of the river.
Cluster analysis (CA) was applied to detect similarities among the tributary stations of the Batang Baleh.