Marikina City is a valley with with the elevated Antipolo, San Mateo and Quezon City all lying around its boundaries. Even with the presence of the Marikina River, it's not enough to handle the additional downpour of water from nearby areas when it rains and even if it doesn't heavily rain in Marikina City, some places could be subject to flooding due to rushing waters from the mountains.
One of the commonly flooded areas is the stretch of Katipunan Road in Concepcion Dos. This main artery serving as a shortcut from Sumulong Highway to Marikina Heights is subject to flash floods during the rainy season. The waters usually are knee-high during initial flash floods but could go up to waist level at its deepest during extreme weather conditions.
Katipunan Road has been a problem flooding area for decades. Two hospitals, namely, SDS Medical Center and Immaculate Concepcion Hospital, are right at the center of the flood which stretches from the corner of Tangerine St. to Rainbow St. The floods extend to Aquamarine St. and Russet St. rendering them virtually impassable to light vechicles.
The major improvement through the past years is that the flash flood easily disappears in 1-2 hours as soon as the rains stop. Being a main road though, it causes a major standstill as motorists park their cars at the Katipunan-Sumulong road while waiting for the waters to subside. Let's hope Marikina doesn't experience much flooding this rainy season.