Official Website of the Municipality of Villasis

            North                :                  City of Urdaneta
            East                 :                    Municipality of Asingan
            West                 :                    Municipality of Malasiqui
            Southeast          :                   Municipality of Rosales
            Southwest         :                    Municipality of Alcala

The whole southern loop of Villasis is traversed by the 17 km. stretch of the Agno River.

Table 1. Area and geographical location

Sources: Municipal Atlas & Maps of Bureau of Coast and Geodetic Survey
                  National Mapping & Resource Information Agency (NAMRIA)
                  Villasis Cadastral Survey
                  Old Municipal & Barangay Maps

2. LAND AREA
Based on the Cadastral Survey and updated Tax Mapping of Villasis as submitted by the Assessor’s Office, the total land area of the municipality is 7,581.61 hectares or about 1.5 percent of the total land area of the province. About 91.63% of which is agricultural land scattered all over the municipality. The rest are residential, commercial and industrial lands. It has twenty-one (21) barangays including the five (5) zones in the Poblacion. The municipality is predominantly rural, about 31.80 % of its total population is in the urban area. On the other hand, about 68.20 % is in the rural area.

3. TOPOGRAPHY
The general terrain of Villasis is generally flat and leveled having a 0 - 3% slope. This is within slope category “A” that is useful for paddy rice culture.

Areas located along the boundaries with Urdaneta and Malasiqui which is more popularly known as UNCALLAB because the area consists of the barangays of Unzad, Capulaan, La Paz, and Labit have rolling terrain with a maximum elevation of 78 meters above mean sea level (AMSL) located in Unzad. Based on the Bureau of Coast and Geodetic Survey map, the slopes are not so steep enough to classify as above 3% having an average slope of only 1.5%. There are however few sections in the area that have slopes ranging from 3 - 8% and to even as high as 15%. The plains have an average elevation of 24meters AMSL, the lowest at 18 meters AMSL around the vicinity of Amamperez which is nearby downstream of the Agno River.

4. DRAINAGE AND SURFACE WATER
Major water surface is the Agno River found in the southern boundaries of Villasis. There are several inland tributaries that both serve as natural drainage system and as a source of irrigation water. Major flood basin is located at Amamperez-Barangobong depression having an elevation of 19m. AMSL. During floods these areas are normally submerged unsuitable for rice and other crops. The major tributary is the Payas de Americano now called Tangat crisscrossing the town diagonally from Asingan exiting to Sileng-Sileng creek at the eastern portion of Amamperez eventually drains its water into Agno River at Sta. Rosa, Malasiqui. A 5.00 kilometers long lateral of the National Irrigation Administration irrigation canal was constructed at the northern portion of the municipality but due to some technical problems, it could not adequately supply irrigation water and sometimes not operating throughout the year.

5. CLIMATE
5.1. General Climate
The climate of Villasis is simply characterized into wet and dry seasons. The wet season occurs during the month of May to October while the dry season is usually from the months of November through April.

5.2. Temperature
The average temperature is 27.70° Celsius which is moderately hot but could reach to as high as 35° during the summer months. The lowest temperature is usually recorded during the month of January which is 24.9°. Temperature range of the municipality does not vary much with the surrounding towns.

5.3. Rainfall
The average rainy days are 15 days a month yielding an average precipitation of 390.67 millimeters. It is observed that August has the most number of rainy days which has 20 days per year average.

5.4. Humidity
Average relative humidity is 76 percent, the lowest being at 68 percent and the highest at 85 percent. April, the hottest month, recorded the lowest humidity. Humidity is high during the rainy months of June, July, August and September.

5.5. Prevailing Wind Direction
In the months of January and April, the prevailing wind direction is at 90 percent towards the Northeast and 10 percent towards the West. In the month of February, March and May, it is observed at 90 percent towards northeast and 10 percent towards west. During the month of June and July, prevailing wind direction is at 65 percent northeast and 35 percent towards west. While during the months of August, September, October wind direction is at 60 percent northeast and 40 percent west and on December, wind direction is at 75 percent northeast and 25 percent west.

5.6. Typhoons and Flood Occurrences
Villasis is not spared from typhoons that strike the eastern part of Pangasinan. Records in the past will show that there are about three to four typhoons that directly cross over the municipality annually. The place is also affected by other typhoons that cover the country’s whole area of responsibility. Flooding normally occurs during an abnormally heavy downpour which affects more the eastern portion of the National Highway that includes the Poblacion, San Nicolas, Lomboy, Parts of Piaz and Caramutan, Lipay and Bacag. This is a result of drainage bottleneck at San Nicolas Bridge which drains all the floodwaters from these areas but is too inadequate to contain the flow. This problem is aggravated by the siltation of the creeks at the downstream due to constant erosion of surface soil from the upstream areas and also due to the clogging brought about by construction of illegal fish pens and illegal tilling on the creeks by farmers.

6. SOILS
Soil in Villasis represents a wide range from young soils to recent alluvia's deposits too old in the hilly part of the town.

6.1. Soil Types
    The following are the characteristics of soil types in Villasis:
»    predominantly sandy loam underlain with sand and gravel normally with good to excessive drainage conditions.
»    predominantly clay loam to clay.
»    predominantly silt types are found in Villasis, namely:

6.1.1. San Manuel Sandy Loam
This cover one barangay which is situated in the easternmost part of the municipality and this is barangay Piaz.

6.1.2. San Manuel Fine Sandy Loam
This soil is characterized by fine river silt (lab-ok) and is common to the Barangays along the Agno River.

6.1.3. San Fabian Silt Loam
This covers the major part of the municipality comprising agricultural plains.

6.1.4. San Fabian Clay Loam
This covers the western part of the town including the barangays of Capulaan, Unzad, Labit and La Paz.

6.2. Soil PH Level
PH value of the soil in Villasis can be classified in just two levels: Strongly acidic and moderately acidic. The strongly acidic areas can be found in the hilly areas of UNCALLAB whose soil type is clay loam. This can also be traced in some parts of Piaz. All the rest of the land area is moderately acidic

6.3. Soil Potassium Level
Potassium content of soil in Villasis varies from low (with less than 100 parts per million (ppm) content) to medium (101 to 150 ppm) and high (with more than 150 ppm). Low potassium soils can be found at the skirts of the UNCALLAB area. Medium potassium content lies in the barangay near or along the Agno River, parts of Barraca, San Nicolas, Lomboy and San Blas.

6.4. Soil Phosphorous Level
This can be broken down into two categories, low and medium phosphorous level. Low phosphorous level (at less or equal to 10 ppm) can be found at the UNCALLAB area and the barangays along the Agno River. All the rest has medium level of phosphorous content (11 to 20 ppm).

6.5. Soil Organic Matter Level
Organic compounds in soil determine its fertility as this is needed by plants to grow and yield crops. Various levels of organic matter are dispersed throughout Villasis with the medium level at the higher elevations of the UNCALLAB area. Low level of organic matter can be found in the wide plains especially in the middle section of the town. Very low level of organic matter can be traced in the extreme eastern part of the town and parts of San Blas, San Nicolas, Barraca and lower slopes of Unzad.

6.6. Land Capability and Suitability
Soils in Villasis are best suited for rice, corn, vegetable and fruit trees. Soil profile is predominantly sandy loam surface underlain by sand and gravel.

7. VEGETATIVE COVER
Villasis is generally planted with rice, corn, root crops and vegetables. Portions of UNCALLAB hill are planted with permanent trees such as mangoes, fruit trees and non-bearing forest trees. Sandy portions along the Agno River were planted with ipil-ipil trees, bamboos, root crops, peanuts, corn and other kinds of agricultural crops and trees.

8. NATURAL AND MAN MADE RISK AREAS
8.1. Natural Risk Areas
The July 1990 earthquake was the most severe earthquake ever to hit the municipality in recent memory. Located just very near the epicenter which is somewhere Cabanatuan, Nueva Ecija, the intensity was registered to be at 7 at the Richter scale. Such an earthquake magnitude however did not cause as much damaged to structures as in other cities except that it had collapsed three spans of the historic Don Teofilo Sison Bridge virtually cutting link between Region I to Manila and the rest of Luzon.

The earthquake also caused big fissures running along the Agno River basin and along the inland portion along the dikes - building up pressure in the subterranean soil bed that caused the release of mud and water called liquefaction. These fissures leveled a sizable length of the Agno Flood Control Dike particularly worst along the Amamperez-Macayo, Alcala portion, a section in Puelay, and slightly damaged some portions of the dike along Lipay, Caramutan and Piaz. These southern areas of Villasis are the most susceptible to earthquake damage. The geologic substructure along the Agno River is the weakest as evident in the thick layer of sandy soil.

8.2. Man-Made Risk Areas
During the seminar held last June 26, 2002 in San Roque, San Manuel, Pangasinan, sponsored by the San Roque Power Corporation, the participants were briefed about the worst case scenario of a dam break up. The San Roque Multi-Purpose Dam is the fourth largest dam in Southeast Asia to date. Its reservoir has a storage capacity of 530 million cubic meters for power generation, irrigation and flood control purposes at its maximum surface elevation of 280 meters AMSL. That’s besides the 140 million cubic meters of active storage reserved for flood control purposes at the maximum exceptional surface elevation of 290 meters AMSL. The dead storage volume totals 320 million cubic meters, thus the total storage volume of the reservoir is nearly 1 billion cubic meters1. In a dam break event, all these water volume threatens to flood 85% of the central plains of Pangasinan.

Accordingly, a dam break-up has only a slim 1 in 1000 chance (equivalent of once in a thousand years) of occurrence considering the

Fig. 11. The San Roque Dam Reservoir and the central plains of Pangasinan as shown in satellite picture. The reservoir can be seen as already filled with water.

Photo courtesy of http://www.crisp.nus.edu.sg

technology involved in its construction. However, accident can happen no matter how remote the chance is considering that it is just 8 kms. from the nearest earthquake fault line, the San Manuel Fault Line, according to the discussion made. The participants were assured however that the dam can withstand intensity 7.9 earthquakes in a Richter scale

The dam becomes operational last September of 2002 so the seminar was held purposely so that all municipalities along its flood path could come up with their own disaster preparedness plan as soon as possible. Judging from the aerial plan of the danger zone (See Fig. 11 and Map G22) those that live very close to the dam have a very slim chance to escape a deluge. Villasis by the way is just an hour to two hours away from the rushing tidal wave of reservoir waters. In fact only those living in UNCALLAB areas can be declared safe from the flash flood. One to two hours of advance warning from the dam authorities is surely not enough to muster all resources for evacuation. It will surely be a disaster that only a miracle could save a lot of lives and property. More on this is discussed in Chapter II.D, Environmental Management Sector.

Likewise, the Agno Flood Control Dike is also considered to be both beneficial and destructive. It has effectively served its purpose of preventing floodwaters from flooding the plains of Villasis every time excess water from the upstream Binga and Ambuklao dams were released in the past. After the July 1990 earthquake, the earth fill dike proved to be a weak structure which took several months to be repaired. It is quite fortunate by that time that there had not much swelling of the Agno River but there were occasions when it almost overflowed its banks after the sudden releases from the two upstream dams. The dike is mainly made up of side-burrow sandy-loam fills which renders it very impervious and easily erodes. It is also rarely maintained although most of the slopes now are eroded and some road widths becoming very narrow. The effect of the coming operation of the new San Roque Dam still remains to be seen. Since the dam reservoir can hold more rainwater including released waters coming from the upstream Binga and Ambuklao dams, water releases thus become more seldom. But with the dam’s bigger reservoir, it takes longer and more water to be released once the impounded water has reached it maximum capacity.

But as early as now, many are wondering that in the first year of operation of the San Roque Dam, flooding has become more frequent and the flooding has become more severe in the northern part farther from the Agno River. The City of Urdaneta has experienced its worst flood in memory and flooding easily occurs on an average rainfall in surrounding towns including Villasis. Whether this new phenomenon is caused by the San Roque Dam directly or indirectly, or by combination of other factors, we will never know unless in-depth studies shall be conducted.