CHAPTER 3 DATA AND METHODOLOGY
3.1 Characteristics of Study Area
The study area has special characteristics of topographical parameters, LULC, and the climate. In addition, characteristic of landslides in the study area occurrences in Cameron Highlands are explained as well.
3.2.1 Limits of Study Area
The study area is part of Titiwangsa mountain range. The area covers 30 km x 30 km (about 900 km2) that conforms to the coverage of 1: 25000 topographic map, published by Department of Survey and Mapping Malaysia. As shown in Fig. 3.1, the study area mainly includes main part of Cameron Highlands district, Pahang state, and eastern part of Kinta District, Perak state. Small part of study areas are occupied by Gua Musang district, Kelantan state, and Batang Padang district, Perak state, which are located at the Northeastern and Southern of the topographic map respectively. The boundary coordinates of the study area are presented in Table 3.1 in
three formats namely, 1) RSO (Rectified Skew Orthomorphic) which is the projection system use for topographical mapping in Malaysia, 2) geodetic system and 3) Universal Transverse Mercator (UTM) system.
Fig. 3.1 Location of the study area
Table 3.1 The Coordinates of the study area corners
Upper left coordinates Bottom right coordinates RSO X: 360000 m Y: 510000 m X: 390000 m Y: 480000 m Geodetic : 1010 13‘ 48‖ 40 36‘ 29.1‖ : 1010 30‘ 4.3‖ : 40 20‘ 16.4‖
UTM North 47 747417.5 E 509730.8 N 777615.51 E 479934.06 N
3.2.2 Topography, LULC and Soil of Cameron Highlands
The study area is located at mountainous terrain. The elevation ranges from 80 meter to 2100 meter. The lowest height is located at lower left of the map which is rubber plantation area located in Perak state. The highest elevation is at top of Mount Irau, followed by the top of Mount Berincang that is 2110 m and 2031 m above mean sea level respectively. The average height is 1108 meter indicating that the study area is deserved to be called as highlands area. About 60% of the total of study area is located at elevation above 1000 m.
Batang Padang
Gua Musang
Cameron Highlands Kinta
Lipis Peninsular Malaysia
30 km
30 km
According to slope classification by Omar, et al. [9], the slopes at the study area are mainly dominated by the critical slopes that range from 200 to 350 and occupies 47% of the total area. About 33% of the study area has moderate slopes that range from 120-200 and 200-410. The remaining areas are considered as flat (18%) with slopes that range from 0-120 and areas with the steepest slope (4%) that range from 410-880.
LULC of the study area is dominated by forest (92%) followed by cropland (7%) and built up (1%). The corresponding areas are 833.6 km2, 61 km2 and 5.5 km2 respectively. This information was extracted from topographic map constructed using aerial photo acquired in 1981. In recent condition, these portions of LULC have surely changed. Investigation performed by TNBHidro-Sdn.Bhd. [152] showed that the development of cropland and built up increased significantly. The number of open land and crop land has expanded significantly in Bertam and Telom catchments, two areas in Cameron Highlands. The increase of these two land uses implicitly means the decrease of forest areas.
The soil in Cameron Highlands is generally sandy and easy to erode as reported by Van der Ent and Termeer [216]. Having this soil type combined with critical slopes and high rainfall intensity, the potential of landslide occurrences in Cameron Highland becomes higher.
3.2.3 Climate of Cameron Highlands
The annual rainfall of the study area is quite high ranging from 2412 mm to 3172 mm based on Malaysia Meteorological Department (MMD) data record acquired from 2000 until 2005 as shown in Fig. 3.2. The monsoon system plays an important role in controlling rainfall distribution. As explained by Guha [149], the Northeast monsoon that falls between November and January brings heavy rainfall over Malaysia, particular in the east coast of Peninsular Malaysia (PM). In the western part of PM, the rainfall intesity is lesser than that of the eastern part. Meanwhile, during the southwest monsoon period that falls between April and May, less rainfall occurred in PM compared to that of northwest monsoonal period. The hottest and driest days take
places during inter monsoon period. On the contrary, heavy rainfall with high intensity takes place in the northern part of PM.
Fig. 3.2 Monthly averaged rainfalls of Cameron Highlands (2000-2005)
Comparison between rainfall data of MMD and monsoonal periods shows that the peak of heavy rainfall started early before northeast monsoon period. The rainfall intensity starts to increase from September and decreases on January. The intensity of rain reaches its peak on October as indicated by the maximum number of rain days by 26.5 days per month averaged over 5 years of rainfall data. As the consequence, the amount of rainfall in October, which is 381.6 mm, is the highest one for the entire year. During southwest monsoon, the rainfall intensity reaches its peak on April with 22.5 rainy days and 318.3 mm rainfall amount. This number is slightly smaller compared to that of northeast monsoon period. There are two driest seasons which takes place during inter monsoon periods indicated by low rainfall intensities. The peaks of these seasons occur on February and June and the rainfall intensities are 117.6 mm and 141.8 mm respectively. Meanwhile, there is an agreement between monthly rainfall amount and the number of rainy days.
The temperature range is 14.50C (minimum) - 22.40C (maximum) according to the data from Worldclimate [217] averaged from 1966-1975. This area is also called cloud forest due to the existence of mountains intercepting circulation of air, forcing it upward where it cools and water vapor condenses into cloud. The clouds that
0.0 5.0 10.0 15.0 20.0 25.0 30.0
0.0 100.0 200.0 300.0 400.0 500.0
Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.
Number of Days
Rainfall (mm)
Months Rainfall
Number of Raindays SW Monsoon
Inter Monsoon
NE Monsoon NE Monsoon
Source: MMD [33]
frequently exist in the study area cause a problem in data acquisition using optical remote sensing technique.
3.2.4 Geology of Cameron Highlands
The geology of the study area mainly consists of granite. The primary granite type is acid intrusive granite formed in the Late Triassic period. The granite is divided into a medium to coarse grained, porphyritic, biotite granite as mentioned in Van der Ent and Termeer [216]. The porphyritic biotite granite is found abundant in the study area. The conditions of granite rocks vary. Some of them are covered with sandy soil mixed with peat; some are studded with Granite boulders; and some are covered with loamy soils and beds. Granite looks decaying in some places with colors vary from deep red, yellow to almost white. The color of the weathered overlying soil also varies from deep red, light yellow and pink. Along fresh cut slope, the different color of weathered underlying soil. Discontinuity exists within granite rock that ranges from 0.3 to 1 meter.
Alluvium rock type also exists in the study area. This rock type consists of deposit of clay, silt and sand left by flowing water in a river valley or delta. This type of rock typically produces fertile soil. Another existing rock type is Schist, a kind of metamorphic rocks. In the study area, schist is the oldest rock. It was intruded by granite so that schist is normally situated at the upper part of lithological boundary. A detail explanation of geology of the study area can be found in Bakar and Madun [218] and Jamaluddin [219]. There is undifferentiated which is described in geology map as sedimentary rock.
3.2.5 Landslide Occurrences in Cameron Highlands
The main source of landslide occurrences record was obtained from Malaysian Public Work Department (Jabatan Kerja Raya, abbreviated as JKR) report documented in JKR [220]. Table 3.2 shows the summary of landslide occurrences in Cameron Highlands from 1961 to 2007 and the corresponding rainfall intensity. The number of
road related landslide is higher (57%) compared to non-road related one (43%). A more meaningful illustration on relationship between landslide and rainfall intensities is already shown in Fig. 1.3 of Chapter 1. Starting from November to January, high intensity of rainfall driven by Northeast monsoon is followed by the high number of landslide occurrences. Meanwhile, during southwest monsoon with lower rainfall intensity than that of northeast, the number of landslide occurrences is lower as well.
On July and August which are the hottest and dries months, there are no landslide occurrences.
Table 3.2 Number of landslide occurrences in Cameron Highlands (1961-2007) Monthly Average Rainfall
(mm) Landslide Type
Month
Landslide Occurrence
Number
Malaysia Cameron
Highlands Non-road related
Road related
Jan 5 92.1 141.8 2 3
Feb 1 109.3 117.6 0 1
Mar 1 245.6 200.8 1 0
Apr 2 318.3 289.8 1 1
May 3 236.8 260.5 2 1
Jun 3 194.8 157.8 0 3
Jul 0 180.5 141.8 0 0
Aug 0 203.2 171.8 0 0
Sep 1 270.4 240.8 1 0
Oct 10 381.6 340 5 5
Nov 6 325.2 316.5 2 4
Dec 5 258.9 222.4 2 3
Total 37 Total 16 21
Percentage (%) 43 57
Source: JKR [13]
Among the areas that experiencing landslide events according to JKR [13] and Chan [148] record are Tanah Rata/Brinchang (6 cases), Ringlet (3 cases), Tapah- Cameron Highlands road (8 cases), Kampung Raja (2 cases), Tringkap (1 case), Kuala Terla (5 cases), Lata Iskandar (1 case), Blue Valley (1 case), Simpang Pulai- Cameron Highlands (5 cases) and Gua Musang-Cameron Highlands road (1 case).
According to Chan [148], landslides in Ringlet (1961), Kampung Raja (1966) and Tanah Rata-Brinchang road (200) are considered as the killing landslide that killed 16 people for the first case and 6 people for the last 2 cases. Meanwhile, a landslide at
Pos Selim, located at Simpang Pulai-Kampung Raja road near Perak-Pahang boundary, was considered as a big massive landslide occurred in 1999 with wide coverage. There were no people killed but the total economic loss costs about RM 354.6 million. The total cost includes such as fatalities, injuries, distance related transportation cost, time related transportation cost, time related productivity cost, and restoration cost. Fig. 3.3 shows two conditions of landslide at Pos Selim at KM33 of Simpang Pulai Kampung Raja road recorded in 2001 and 2006.