Geo - Physical Environment

1.1.        Location and Boundaries:

            The municipality of San Jose de Buenavista is located at the Southwestern portion of the province of Antique.  Located at 10 degrees 45' North Latitude and 122 degree 56' East Longitude.

 

Map 1: VICINITY MAP

 

1.2.        Topography

San Jose de Buenavista has no massive mountain ranges within its locality, but it has irregular masses of geologic domes and rolling hills situated at both the northeastern and eastern sides of the town proper or the poblacion area, which is known as the Binirayan Hills, and  on the northern part of the municipality, specifically in Barangays San Pedro, Durog, Pantao, and  Igbonglo known as the Pantao Hills and the San Pedro Hills.  These are basically extensions of the Antique Highlands of the Western Cordillera System of Panay Island. Alongside the rolling hills are relatively extensive lowland areas that dominate the western portion of the municipality.  These are the San Jose coastal plains that extend toward the Sulu Sea.

The municipality also has level to smooth and rugged to steep slopes. These slope categories are A (0-3%), B (3-8%), C (8-18%), D (18-30%), and E (30-50%).  Generally, the  rolling hills characterized by moderately undulating terrain with some steep slopes are confined mostly to the north and northeastern portions of the municipality covering the barangays of Pantao, Supa, Catungan-Bugarot, Inabasan, Durog, Cansadan-Tubudan, and Bariri which are planted either by tree crops such as bamboo, coconut, and sugar cane. Moving westward and southwestward, slope diminish to 0-3% (A) and 3-8% (B) which are either level to nearly level to gently sloping to gently undulating or rolling areas which then makes this portion of the topography available to rice and corn production and allocated for fishing activities. And this is located mostly in the barangays of San Pedro, Mojon, Magcalon, San Fernando, Badiang, Funda-Dalipe, Atabay, Madrangca, Mala-Iba, San Angel, Maybato Norte, and Maybato Sur.

            The municipality has level to smooth and rugged to steep slopes.

Slopes category, San Jose de Buenavista.

Code

Range (%)

Description

A

0-3

Level to nearly level, very gently sloping to gently sloping

B

3-8

Gently sloping areas with land sloping in one general direction. Gently undulating and gently rolling land. Sloping is more than one general direction.

C

8-15

Moderately undulating and rolling land sloping in many directions. Steeply undulating and rolling land sloping in more than one general direction.

D

15-30

Strongly sloping

E

Above 30

Very steeply sloping land in many directions to many mountains and hilly areas.

Source:MPDO, San Jose, Antique ,1991

             DENR , San Jose, Antique, 1992

1.3.        Hydrology

San Jose de Buenavista is dissected by two major river systems: the Sibalom River System and the Malandog River System, and the minor creeks and streams that traverse the entire  municipality and which are identified as possible sources of irrigation water. The Sibalom River System was once used as a boundary that separates San Jose from Sibalom, but since the river recently changed its course, it has dissected San Jose in Barangay San Pedro where its river delta is located. As for the Malandog River, most of San Jose’s major creeks and streams are tributaries to this river system that come all the way from its adjoining creeks in the municipality of Sibalom and some areas within the municipality itself.

The Sibalom watershed system helps facilitate the different agricultural activities in San Jose de Buenavista by providing water for irrigation through the Sibalom-San Jose Irrigation System. The Sibalom watershed covers a total watershed area of 62,964.62 hectares (57,780 square kilometers) and influences not only San Jose but also the municipalities of Sibalom, San Remigio, and Belison.  As of this report, the Antique Integrated Area Development (ANIAD) Foundation proposed that a minor artificial watershed be built in the municipality.  This watershed project that they propose is the Lugutan-Igbonglo  Micro Watershed to be built in Barangay Igbonglo.  This project is currently under evaluation.

1.4.        Geology and Soil

San Jose de Buenavista has a very simple geologic structure marked by the combination of relatively little quantities of igneous, sedimentary, and metamorphic materials.  Limited types of geologic formations that consist of different types of earth materials like andesite tuffs, dacites, or breccias have been identified.   The youngest geologic formation found in San Jose de Buenavista is the Quaternary Alluvium that is a result of depositional processes during the Holocene Period. It covers the coastal plains in the south and southeast portions of the province.

There is a major fault system along the western side of Antique.  This is  believed to have  been created  by the collision of the Panay micro-plate and the Palawan block and runs in a northeast-southwest direction and is known as the Tablas Fault System.

            Different types of soil categories are found in San Jose de Buenavista and are differentiated in terms of its parent material and types and methods of deposition. The soil types found in the municipality are (1) Beach Sand; (2) Sta. Rita Clay; (3) Magcalon Sandy Loam; (4)  Umingan Sandy Loam; (5) Sta. Rita Sandy Loam; and (6) Hydrosols. These major soil types are classified according to texture, type of formation (alluvial/deposited), structural nature, and consistency. Table No.  IV shows these different soil categories while Table No. 5 gives the different soil categories by barangay.

Beach Sand covers approximately 155.246 ha. or 3.49 percent of the land area of San  Jose de Buenavista. Mostly found along the coast on the western fringes of the municipality, it has a fine texture and a light brown to grayish-white coloring.  It is mostly composed of gravel and sand.

            The Sta. Rita Clay, whose granular structure are coarse, covers about 1,551.246 ha. Mostly found on the eastern and southeastern portions of the municipality, its color ranges from dark brown to black and becomes soft when moisture is introduced. This soil type has a moderate to excessive external drainage with poor to fair internal drainage.  Because of its capability to hold large quantities of water, which is a characteristic of most clayey soils, the cultivation of rice is suitable for this type of soil but proper cultivation practices should be employed.    

The Magcalon Sandy Loam covers the largest soil type in San Jose de Buenavista,  covering a surface area of approximately 1,855.389 ha. or 41.70 percent of the total land area.  It encompasses the whole south-central portion of the municipality including the main poblacion area. The Magcalon Sandy Loam has a dark-gray to reddish-brown color and is an organically rich mixture of clay and sand, suitable for the production of tree crops, especially fruit trees like coconut and mango.

The Umingan Sandy Loam, mostly found on the northern portion of the municipality, is accumulations from the alluvial process of the Sibalom River, making it well drained and covers about 211.985 ha. Because of its capability to accommodate air and moisture than the other soil types, the production of rice and other field crops like corn and vegetables is encouraged. It is also a deep and easily worked soil .

The Sta. Rita Sandy Loam, which covers the northeastern and southeastern portions of the municipality, is basically a mixture of clay and sand which when mixed with loam gives evidence  to past flood events. It encompasses an area of 631.307 ha. or 14.19 percent of the total land area of the municipality, and it is best suited for the production of tree crops.

            The Hydrosols found primarily in most parts of Maybato-Sur located near the Malandog River, has a brackish aqueous A horizon and a B-horizon which has a light brown to gray color. It is also slimy and has numerous undecomposed organic debris. It has an area of 45.016 ha. and because of its substantive water depth, it serves as a good medium for the growth of algae and aquatic plants which  serve as a good food source for some aquatic and marine organisms.     

 

            Different types of soil categories are found in San Jose de Buenavista and are differentiated in terms of its parent material and types and methods of deposition.

Soil Categories, San Jose, Antique

Code

Type

Description

Land Area

(in has)

% of total Land Area

B

Beach Sand

It has a fine texture which has a light brown to grayish white in color. Composed mostly of gravel and sand found along or adjacent to coastal waters.

155.246

3.49

SS

Sta. Rita Clay

Surface Soil is from black to dark brown, soft when moisture is introduced. Its granular structure is coarse.

1,551.057

34.85

M

Magcalon Sandy Loam

It is an organically rich mixture of clay and sand with a dark-gray to reddish brown color.

1,855.389

 

41.70

U

Umingan Sandy Loam

Best for the production of rice and other field crops. It can accommodate air and moisture.

211.985

4.76

SC

Sta. Rita Sandy Loam

Mixture of sand and clay which is mixed with loam particles evidence of past flood phenomena

631.307

14.19

H

Hydrosol

Brackish aqueous A horizon and slimy, light brown to gray clay B

45.016

1.01

Source: Bureau of Soils, Antique, 1991

Soil Categories by Barangay, San Jose de Buenavista

Number

Soil Categories

Barangay

1

Beach Sand

Maybato Norte, San Angel, Mala-iba

2

Sta. Rita Clay

Cansadan-Tubudan, Supa, Catungan-Bugarot, Inabasan, Bariri

3

Magcalon Sandy Loam

San Pedro, Mojon, Magcalon, San Fernando, Funda-Dalipe, Badiang, Atabay, Madrangca, Barangays 1 - 8

4

Umingan Sandy Loam

Durog

5

Sta. Rita Sandy Loam

Pantao, Igbonglo

6

Hydrosol

Maybato Sur

Source: Bureau of Soils, Antique , 1991

Map 2: SOIL MAP

 

1.5.        Climate

            San Jose de Buenavista’s climatic pattern belongs to Type I of the Modified Coronas Classification in which it has distinct periods of wet and dry - wet during the months of June to November and dry from December to May. Its temperature regimes are hot and humid in summer while cool nights are experienced in December and January.

             San Jose de Buenavista is also influenced by two important monsoons that hit the Philippines annually. The monsoon is the seasonal inflow/outflow of air masses moving from/to the water and land bodies due to the differences in pressure systems between the Northern and Southern Hemispheres. The southwest monsoon (Habagat) is experienced from June to September. Winds would originate from the southeast coming specifically from the high-pressure system over the Australian continent and reverses direction coming from the southwest upon reaching the equator.  The time of the SW monsoon also coincides with the period when typhoons are most prevalent in the country.  The other seasonal wind flow is the northeast monsoon (Amihan) that occurs from November to mid-February with winds originating and diverging from the northwest coming from a high-pressure system in Siberia. When these winds reach the North Pacific Ocean, they reverse their direction and blow towards the Philippines from the northeast.  In addition, orographic barriers like the Sierra Madre in eastern and southern Luzon and the Western Cordillera of Panay Island block the NE monsoon from reaching Antique thus lessening the possibilities of precipitation making conditions dry and cool during this period.  Typhoons may also occur during this period but less prevalent. 

           The municipality may exhibit similar regimes of temperature and precipitation characteristic of the town of Valderrama, Antique where the climatic data obtained were recorded.  According to the climatic data presented in Table III-3, the heaviest amount of rainfall were observed in the months of July and August with an average precipitation of 618 mm.  The month of February has the least amount of rainfall with an average of 8 mm.  In terms of temperature, the hottest mean temperature of 290C was recorded in the months of April and May, while January and February have the coolest mean temperature of 260 C. San Jose may exhibit slight modifications from the observed climatic patterns in Valderrama, therefore, its climate may not really deviate much from what have been recorded.

 

1.6.        Mineral Resources

Antique province is endowed with substantial quantities of different types of minerals.  However, San Jose de Buenavista is somewhat spared of these minerals as compared with the other municipalities of Antique, for only some metallic minerals are present. And of these metallic minerals, only chromite and manganese deposits are found in San Jose de Buenavista and both are explored.

The type of chromite deposits found in San Jose de Buenavista is extensively magmatic.  It comes in a stockpile and has an average grade/chemical analysis of Cr2- 20.3-45.40%, Fe- 12.99%, SiO2- 7.03%, and Al203- 7.23%, and it appears in podiform type (Ophiolite-hosted). On the other hand, the manganese deposits are sedimentary materials that have an average grade/chemical analysis of Mn- 12.69%, 13.86% and 22.61%, and SiO2- 71.07%, 70.23% and 45.61%. The manganese deposits also have a sedimentary origin in overlying Ophiolite and supergene deposits derived from weathering. The presence of chromite and manganese deposits in San Jose de Buenavista may be due to the fact that the municipality rests upon the Ophiolite Zoneof the geologic cross section of Western Panay which also houses the municipalities of Sibalom, San Remigio, and San Joaquin and contain very important minerals like copper, chromite and manganese.