Assessment of the Water and Sediment Quality of Tropical Forest Streams in Upper Reaches of the Baleh River, Sarawak, Malaysia, Subjected to Logging Activities

Abstract

The study of the impact of logging activities on water and sediment quality of Sarawak forest streams is still scarce despite Sarawak being the largest exporter of timber in Malaysia. This study was aimed at determining the water and sediment quality of forest streams in Sarawak and the potential impact of logging activities. In situ parameters were measured, and water and sediment samples were collected at six stations before rain. Additionally, water quality was investigated at three stations after rain. The results showed that canopy removal resulted in large temperature variation and sedimentation in the forest streams. Lower suspended solids were found at stations with inactive logging (<2 mg/L) compared to active logging (10–16 mg/L) activities. The highest concentration of total nitrogen and total phosphorus in water and sediment was 4.4 mg/L, 77.6 μg/L, 0.17%, and 0.01%, respectively. Besides, significantly negative correlation of sediment nitrogen and water total ammonia nitrogen indicated the loss of nitrogen from sediment to water. Water quality of the streams deteriorated after rain, in particular, suspended solids which increased from 8.3 mg/L to 104.1 mg/L. This study reveals that logging activities have an impact on the water quality of Sarawak forest streams particularly in rainfall events.

Influence of Rainfall on the Physicochemical Characteristics of a Tropical River in Sarawak, Malaysia

“…' The improved parameters included DO and AN, whereas pH and TSS deteriorated after rain. After the rainfall event, the worst classification of the parameter in the river was TSS, where there were three stations classified as Class V. The deterioration in TSS was also reported in the Batang Baleh, where the TSS changed from Class I to Class III and/or IV after rain [26].…”

“…The Batang Baleh in Sarawak that was subjected to logging activities also showed significantly higher TP concentration after rain [26].…”

“…In general, stations 2, 3, 5, and 6, which were subjected to logging activities, showed high turbidity and substantial suspended solids during both trips, indicating that the logging activities had increased the sedimentation of the area [25]. Similarly, the Baleh River in Sarawak, which was subjected to logging activities, also showed elevated turbidity and TSS values, particularly after rain [26]. In the present study, comparatively, stations that were located near to the longhouse tend to show lower turbidity and suspended solids.…”

Assessment of Near-Bottom Water Quality of Southwestern Coast of Sarawak, Borneo, Malaysia: A Multivariate Statistical Approach

“…The positive loadings on turbidity and NO 2 − -N are associated with the presence of suspended solids whereas the negative loading on salinity in PC2 suggests that freshwater inflow was a key factor in suspended solids variation. The Sarawak forest is subjected to high timber harvesting pressure rendering sedimentation problem in its forest streams [8,[35][36][37]. Logging activities in the surrounding area have caused sedimentation and increased suspended solids level in the river and subsequently into the coastal area.…”

“…Although deterioration of the coastal environment due to increasing population and urbanization is noticeable in Sarawak [6], the study conducted on Sarawak coastal water is scarce. Aquaculture and domestic sewage with high nutrients content is being discharged directly into rivers [7] while deforestation for timber production and agricultural development has increased soil erosion and inputs of fertilizers in Sarawak River [8,9], all of which could lead to increased sedimentation and eutrophication in coastal areas.…”