Reduced Impact Logging (RIL) introduced in some places has been reported to improve harvesting efficiency and environmental impact e.g. better design of skidtrails, less waste wood, reduces forest damage and cost. In this study, the effect of RIL on hydrological aspects was examined to assess its impact on direct runoff, streamflow, suspended sediment and unit hydrograph of the catchment, comparing RIL with conventional logging (CL) and an unlogged (UL) control. Compared to the control, the ratio of water yield to rainfall increased by about 53% with RIL and 98% with CL treatment after a period of 3 to 4 months following logging. Direct runoff with RIL remained similar to the control but increased by about 140% with CL treatment. Compared to CL treatment, the mean maximum suspended sediment concentration (Cmax.) levels can be reduced by more than six times and the daily suspended sediment load (S) by almost half if RIL treatment is implemented. The ratio of Cmax and S under UL, RIL and CL treatments are about 1 : 5 : 32 and 1 : 6 : 11 respectively. The main cause of erosion and sedimentation was soil damage due to compaction by harvesting machinery and soil cover reduction. RIL treatment is capable of reducing the runoff coefficient about half than that of CL: mean runoff coefficients for UL, RIL, and CL treatments are 0.027, 0.045 and 0.095 respectively. Unit hydrograph models for the two replications of each treatment showed shape consistency (e.g. time to peak is shorter with UL than RIL and CL treatments) and could be used to predict direct runoff from the related catchments. Finally, the study showed that supervision of harvesting - including planning and post logging treatment has an important role in reducing logging impact on hydrological behaviour.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:640557 |
| Date | January 2001 |
| Creators | Anwar, Syaiful |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/14747 |
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