Physiography and Terrain
San Juan is composed entirely of undulating low grade tuffaceous plateau of soil. This means that it has the depth and stability to carry almost any type of construction and it has the ability to absorb and hold water.
Most of San Juan’s terrain is gently rolling with a predominant slope of 2 – 12%. However there are flat areas with a slope of 0 –1% scattered along the western boundary and other parts of the city. Except for these flat areas, the physiography and terrain of San Juan make it ideal for urban development.
Flood and Earthquake Risk
Being in the heart of region’s central plateau, the city is free of earthquake damage risks.
However, areas along the western boundary rimmed by the San Juan River are sometimes visited by floods are barangays Salapan, Balong Bato, Progreso, Rivera, San Perfecto, Batis and sometimes Kabayanan.
Of the city’s 5.94 square kilometers total land area, about 63.5% square or 3.77 square kilometers are residential, 16% or 0.95 square kilometers is road network 8.9% or 0.53 square kilometer is commercial, 6.7% or 0.40 square kilometer is institutional and the remaining 4.9% or 0.29 square kilometer is industrial.
Approximately, 10% of San Juan has been rendered unfit for development due to high flood risk and level slope. However, the remaining 90% has very good capacities for urban development.
Based on the proposed land use, the land area intended for commercial use rose significantly to 0.99 square kilometer, representing 17% of the town’s total land area intended for commercial use rose significantly to 0.99 square kilometer, representing 17% of the town’s total land area. Land area proposed for institutional use also expanded to 0.42 square kilometer, accounting for 7.1% of the total. On the other hand, land area designed for residential and industrial uses were reduced to 3.54 and 0.05 square kilometers, respectively. Meanwhile, the land area for road network is still the same at 0.95 square kilometer.