Drainage Network Analysis: Implication to Tectonic Interpretation of Sarawak

Landforms in Sarawak are results of a complex tectonic evolution. The tectonics in this region has greatly influenced the drainage system. Sarawak which is made up of complex geological and structural settings due to the multiple tectonic events is an ideal study area to investigate the tectonic activities that shaped the landforms of Sarawak besides the fact that there has been lack of regional scale study conducted in the area because of the dense forest. Digital elevation model (DEM) of Shuttle Radar Topographic Mission (SRTM) is the primary data that is used to perform the analysis. Based on the stream order analysis, the drainage networks in Sarawak are characterized into the first until the sixth order, based on the Horton-Strahler scheme. Watershed basin analysis is performed by identifying the area drained by a stream section and its tributaries and a total of 97 watershed basins are characterized. Based on the results from watershed analysis, drainage basin area which refers to the area of a given watershed is calculated. The density of the drainage basin is also calculated to study the sum of the drainage lengths divided by basin area. The tectonic interpretation is performed by generating profiles of certain drainage networks. The irregularities and anomalies identified on the drainage longitudinal profiles give the information required to study the tectonic processes that occurred in Sarawak. The findings from the profiles are further supported by more analysis and evidences obtained from the cross section of the drainage network as well as from field observations.