Deriving rainfall distribution map in monsoon period using inverse distance weighting (IDW) spatial interpolation technique
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Date
2017-06
Authors
Nazatul Amira Binti Abu Safian
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Abstract
Rainfall data is generally recorded as observational data from meteorological rainfall station networks. These rainfall records are regularly incomplete due to their recorded period or inadequate stations. The rainfall measuring stations in the Northern Region of Malaysia is sparse as there are only nine (9) stations covering Perak, Penang, Kedah and Perlis. It is therefore insufficient to characterize the highly variable precipitation and its spatial distribution. The main objective of this final year project is to evaluate a spatial interpolation method, namely the Inverse Distance Weightage (IDW) that will estimate rainfall in areas where rainfall cannot be measured using data from meteorological stations. Spatial interpolation is the process of using points with known values to estimate values at other unknown. Consequently, this project establishes the spatial relationship between 2008 and 2011 flash flood occurrences in Perak and Perlis with monsoon seasons that produce heavy rainfalls. At the same time, comparison was made for 2016 as the control data where no flash flood occurs. From the study, it was found that the IDW method being experimented provides better and reliable solutions to rainfall pattern study. The amount of rainfall distribution during 10 of September 2008, flash flood in Bukit Merah was 28.4mm based on the nearest meteorological station in Lubok Merbau. It registers small intensity class of rainfall because the amount of rainfall less than 96mm/day. The amount of rainfall data on the 11th September 2011 was moderate based on the classification of rainfall (i.e. 100.8mm). Clearly, research found out that rainfall intensity for both flash flood occurrence indicate no relationship with monsoon period. Lastly, this technique has the potential to be used as spatial reference model for mapping future rainfall estimation work.