Posts Tagged: flood cycle

The city of Los Angeles acts as a natural flood basin where the surface flows that come from the Santa Monica and San Gabriel mountain ranges travel across the city to reach the Pacific Ocean.  This natural system experiences an occasional 100 year flood, where water reaches extreme levels. In 1938, the city experienced the ‘first’ catastrophic flood, which killed more than 100 people and damaged over 1,500 homes.

This event was deemed Southern California’s deadliest flood of the 20th century and was the catalyst in channelizing the river systems within Los Angeles County.By 1938, the “wild west” character of Los Angeles was quickly disappearing due to the rapid pace of urbanization.  The population in Los Angeles grew rapidly from 1900 to 1930; there were 102,500 residents in 1900, and by 1930, the census counted 1,238,048 residents.   In historic photos from this time, supplied by the U.S. Army Corps of Engineers, large river beds make up the landscape, formed by the natural paths of the water. Up to this point, few concrete channels had been built and methods of erosion prevention such as gunite banks, pipe and wire, rock paving and rock mattresses were commonly used to tame the rivers.

During early March of 1938, five days of continuous rain fell on Los Angeles.  Erosion controls that were in place could not hold the high level of water coming from the mountains.  In downtown Los Angeles, Broadway Avenue became a small lake and truck beds were strapped on top of motorboats to carry workers in and out of the area.   The Academy Awards were postponed for a week due to excessive flooding.  It was unlike anything the city had experienced before.

In the two decades following the 1938 flood, the concrete channelization of the rivers was a major infrastructure project that altered the ecology and identity of the waterway systems.  The transformation, documented by the U.S. Army Corps of Engineers, depicts the phasing of the waterways becoming a single use infrastructure system, which was designed for the sole purpose of discharging stormwater as quickly and safely as possible.

These images show a vast infrastructural and natural water system heavily ingrained within the urban environment.  The majority of the time, the channel sits idle, absent of vegetation and a barrier for neighborhoods.  Preventive flood measures are necessary yet can there be a more sustainable solution?

In analyzing the potential for multifunctional infrastructures, understanding the natural systems like the flood cycles of the Los Angeles watershed, is an important first step to finding real solutions.