Bataan is located in the southwestern part of the Central Luzon Region. It lies approximately at coordinates 120° 15' to 120° 40' latitude and 14° 20' to 14° 50' longitude. It is bounded on the north by the provinces of Zambales, on the northeast by Pampanga, on the west by South China Sea, and on the east by Manila Bay.
The climate in Bataan is categorized under Type I. There are two distinct seasons: the rainy season and dry season. The rainy season starts on the month of May and ends up around the month of October. The rest of the year is dry with occasional rains dispersed widely throughout the province. Occasional typhoons visit the area especially during the months of June to September.
Bataan is a mountainous land mass, dominated largely by uplands, hills, and mountains,covering 80.9 percent of its whole area. The lowlands and plains, which comprise 19.1 percent of the land area of the province, are generally flat, gently rising towards the hills. These areas comprise most of the agricultural portion of Bataan, found along the northern and eastern coasts facing Manila Bay.
The province is drained by numerous rivers and small streams with very few meanders radiating and sloping from the mountain groups down to the sea draining the whole area efficiently. There are more than one hundred rivers in the province which are very important not only for irrigation but also for purposes of navigation and fishing.
The whole province of Bataan can be classified broadly with one volcanic terrain. Most of the highest elevations are considered parts of the collapsed caldera forming a ring-like structure with the suspected mouths, Mount Natib and Mariveles. Other high peaks are most likely the satellite vents of major volcanic craters presently occurring and dikes along the upper and mid-slopes of the volcano. Bordering these morpho-landforms are lava fields and flow plains with deep incision, steep cliffs, occasional gorges, and minor cascades.Coastal areas are classified by typical marine land forms such as beaches, ridges, swales, and foreshore sand bars.
Basically, Bataan is tectonically sitting directly on top of an active subduction zone, which centers along the Manila trench. It is believed that this zone was responsible for the Early Pliocene to Early Holocene period of volcanic activities giving rise to varied depositions of volcanic rocks in the whole peninsula.
There are three (3) rock strategic units exposed in the area, namely: quaternary pyroclastics (QP), quaternary plug (Qp) and quaternary alluvium (Qal).
Quaternary pyroclastics occupy the rolling to hilly ground with infrequent deep incision in several sections of creeks and rivers. It is composed of volcanic breccias, tuff and tuff breccias, and lahars.
Quaternary plug is made wholly of alticandesites rock.
Quaternary alluvium occupies the low- , lying areas which include the beaches and plains. These deposits are derived from weathering and erosion of older volcanic rocks that were later transported and deposited along stream channels.
The presence of a chain of volcanoes in the Zambales -Bataan region, including the currently active Mt. Pinatubo, may put the province under threat of volcanic eruption. Mt. Pinatubo, some 40 kms. to the north, deposited a relatively thin but widespread ash cover over the Olongapo -Subic- North Bataan area during its last eruption. Similarly, the smaller, dormant volcanoes are Mt. Sta. Rita and Mt. Malasimbo.
These tectonic elements are probable earthquake generators that would trigger ground- shaking and ground displacement. Bautista, et.al. (1992) have conducted probabilistic estimate of peak ground acceleration. For the Bataan area, a ground acceleration value of 0.1 g (1 times the force of gravity) within a 50-year return period was estimated. In the same study, Bautista, et.al. suggested that the risk of tsunami along the coastal areas of Bataan cannot be discounted since tectonic features around Bataan are capable of generating tsunamegenic earthquakes. Historically, the occurrence of a tsunami in Bataan that has been last recorded was on December 7, 1677.
Based on the distribution of earthquake epicenters in the whole archipelago, the strongest is, in fact, the eastern section, i.e. Eastern Mindanao, Samar, and Leyte. However, other relative active parts are the vicinities of Lubang Island -Mindoro, the East Luzon Trench, Casiguran Fault, Digdig Fault, and the northern segment of the Philippine Fault Zone, all of which are within the 150-km. radius of the province.
Coastal marine waters support a dynamic ecosystem and contain valuable natural resources that are important to the coastal community. The inseparable relationship between land use and water quality are major issues in the coastal zone.
The Bataan coastal area is receiving drainage from immediate watersheds through tributaries and major river systems. Large amounts of waste drain into the coastal waters from domestic discharges.
With rapid increase in population and industrialization within the coastal area, water quality is expected to deteriorate. Contamination of the Bataan coastal and marine waters will continue to increase with the inevitable population and economic growth. The sources of contamination that eventually lead to marine pollution are domestic and industrial wastes, agro-chemical loading, siltation/sedimentation, toxic and hazardous wastes, and oil pollution.