Topography and Slopes
A rugged and undulating terrain is common in all slopes from the foothills of Sierra Madre Mountain Range (SMMR) down to man-made lake and down to Laguna Lake. Cavinti is situated in the foothills of SMMR and its topography is a longitudinal traversing of many minor ridges and drainage basins (valleys).
The terrain of Cavinti can be best described as having a gently rolling to steeply undulating landform. Most of the lakefront areas are generally flat. The highest elevation computed using digital elevation model (DEM) is 501 meters located in Barangay Lumot near the boundary of Quezon Province and the lowest is 21 meters located in Barangay Anglas near the boundary of Municipality of Pagsanjan, Laguna.
Based on derived slope using GIS, the slope of the area ranges from 0% to more than 50% slopes. About 29.84% (6,404.22 has) of the total land area of the municipality has slope 0-3%; 31.20% (6,757.52 has) of the municipality has slope 3-8%; 17.76% (3,843.20 has) are within the maximum economically buildable slope range of 18%; and only 16.11% (3,487.24 has) belong to steep slope classification.
The municipality of Cavinti falls under the Type IV category of the Philippine Climate Corona Classification, which has rainfall more or less evenly distributed throughout the year. This climate type resembles the second type more closely since it has no dry season.
Temperature – The annual minimum temperature in Cavinti is recorded at 21.9oC; a maximum temperature of 28.6oC and annual mean temperature of 25.2oC. Warmest months in Cavinti are April to June, while wettest months are October to December. Coldest months are January to March, when lowest monthly mean temperature have been recorded at 20.7oC in January.
Rainfall – Heavy rainfall is observed from June to December. The month of November has the heaviest rainfall with normal readings of 460.4mm precipitation.
Wind Patterns – Recorded wind velocity is 1 knot and average cloudiness is 6. Peak wind velocity is observed from November to February with a prevailing direction of North East.
Soil Types and Suitability
There are three types of soil in the municipality. The Luisiana Clay Loam, Mountain Soil (undifferentiated), and Paete Clay Loam. Luisiana Clay Loam which is 28.88% (6,250.98 has) found most in the south-west portion of the municipality, the whole barangays of Banco, Bulajo, Duhat, Poblacion, Labayo, Udia, Layug, Sisilmin, Tibatib, West Talaongan, East Talaongan and Inao-awan; almost of barangay Anglas; half of barangay Bukal; portion of barangays Sumucab and Lumot. Undifferentiated Mountain Soil which is 65.74% (14,228.64) found in the whole area of barangays Paowin and Cansuso; and almost of the barangays Lumot and Sumucab. Paete Clay Loam which is only 0.06% (12.56 has) found in the boundary of barangay Anglas and municipality of Pagsanjan.
Table 14 indicates the type of soil, its characteristics and the common crops grown. Luisiana Clay Loam which is formed from the physical and chemical weathered products of igneous rocks (of basalt and andesites). Its relief varies from undulating to rolling and mountainous causing variation in the degree and extent of soil erosion hazards. This soil is generally suitable for paddy rice, tree crops, diversified crops and grazing. Depending in its slope characteristics, soils under this type is best for growing crops such as coconuts, buri palm, pandan, sugarcane, upland rice, corn, bananas, sweet potatoes, pineapple, lanzones; and suitable for commercial and non-commercial forests. Basically, Luisiana Clay Loam is conducive to agricultural production.
Paete Clay Loam belongs to the Paete Soil series’ soil formation. It is derived from the physical and chemical weathering of igneous rocks of basalt and andesites. The profile characteristic of this soil is moderately deep to deep reddish brown granular clay loam to clay. Its external drainage is rated good to excessive while fair to poor internally. This soil is not suitable for paddy rice, generally not suitable for diversified crops and marginally to moderately suitable for tree crops.
Based on scientific studies by PHIVOLCS, areas were found to be fronted by very steep canyons and stretches, literally cliff edges, they are susceptible to landslides. Considering the slope characteristics and geologic structure of the municipality, Cavinti is subject to erosion particularly along the steeper areas.
Soil erosion is a natural process. It becomes a problem when human activity causes it to occur much faster than under natural conditions. Based on GIS computed data from BSWM, Cavinti has 12.90% (2,791.96 has) of total land area that is classified as Severe Erosion located near the vicinity of lakes in barangays Lumot, Paowin, Cansuso, Bukal and Sumucab; 12.10% (2,618.83 has) of municipal land area has moderate erosion located in various location; 35.64% (7,712.44 has) has slight erosion and 34.05% (7,368.95) has no erosion. Generally, 25% of the municipal land area should be handled with carefully planned erosion control management practices and intensive/complex soil conservation practices.
Geologic and Hydrogeologic Hazards
Majority of the municipality which is 73.91% (15,996.18 has) of the total land area based on Mines and Geoscience Bureau (MGB) Landslide Susceptibility Maps of Paete Quadrangle (7271-I), San Antonio Quadrangle 3363-III), San Pablo Quadrangle (7271-II), Mauban Quadrangle (3362-IV) classified as “moderate susceptibility to landslide”.
The 12.24% (2,649.09 has) of the total land area of the municipality found in the barangays of Anglas, Banco, Tibatib, West Talaongan, East Talaongan, Poblacion, Labayo, Udia, Bukal, Sumucab, Cansuso, Paowin and Lumot is classified under “high susceptibility to landslide”. Only 8.53% (1,846.91 has) of the total land area is classified as “low susceptibility to landslide”.
Dense population and settlements along the slopes everywhere in the municipality are also the present major problem of the government of Cavinti. Unless seismically-designed slope stability measures are adopted along the slopes and embankments, threat of landslides among a large population will be avoided.
In terms of flooding hazard from MGB, Cavinti has only 5.64% (1,196.27 has) of the total land area that is identified as “high susceptibility to flooding” of which 96.63% are located near the man-made lake. Out of 19 barangays, portions of the six (6) barangays fall to this classification namely: West Talaongan, East Talaongan, Inao-awan, Paowin, Cansuso, and Bukal.
Meanwhile, barangays such as Anglas, Tibatib, Poblacion, Duhat and Layasin have portion fall in the “low to moderate susceptibility” classification which is approximately 51.78 has or 0.24% of the total land area of the municipality.
Generally, due to its geographical location, Cavinti is safe in terms of flooding hazard.