expectation of the NDVI analysis and the condition of the river during dry and wet months . The oldest image that could be acquired was from November 2 , 2007 . However , the images could not be utilised due to cloud cover . The images used for this analysis were taken from May 29 . 2011 until July 13 , 2019 .
Generally , from this analysis , the river in the area of study expanded up to 20 metres in width during the wet or rainy months which usually start in September . During the dry months , which usually start in February , the river is only two to three metes in width . This analysis also showed the shift in the river course which seemed to shift towards the north . Some parts of the river had even shifted out from the cadastral river reserve as surveyed in 1985 . Figure 3 shows the comparison between the river located near the study area for the years 2013 and 2019 .
( ii ) Normal Difference Vegetation Index ( NDVI ) The 31 lots were included in the study and each lot was approximately one to two hectares in area . These were analysed to acquire the average NDVI value for each individual lot . From the analysis , it was observed that the lowest NDVI value was
Figure 3 : Comparison of the river locations for the years 2013 and 2019 .
recorded on April 23 , 2005 with a value of 0.34 and the highest on February 28 , 2020 , with a value of 0.74 .
Based on Figure 4 , the NDVI values from the year 1988 have an average of 0.54 . This may be due to the new oil palm that had been planted in the same year . The NDVI values for the land scheme then steadily increased and was consistent with the growth of the oil palms . However , there was an exceptionally large decrease of NDVI values on April 5 , 2005 . This condition was mostly due to drought that occurred in West Malaysia which impacted Sg . Kerian at Selama with a flow of 6.9
Figure 4 : NDVI trendline of oil palms in land scheme from year 1988-2020 .
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