The Bonnet Carré Spillway, a crucial flood control structure located in St. Charles Parish, Louisiana, has a distinct and readily identifiable geographical footprint. Understanding its map requires appreciating its function: to divert excess floodwaters from the Mississippi River into Lake Pontchartrain, thereby protecting New Orleans and surrounding areas.
Visually, the map of the Bonnet Carré Spillway showcases a broad, rectangular swath of land. It stretches roughly six miles from the Mississippi River southward towards Lake Pontchartrain. This area is primarily composed of a controlled floodway, characterized by low-lying land deliberately designed to be inundated with water during high river stages. The map distinctly highlights the Mississippi River’s proximity, usually depicted as a powerful, meandering blue line edging the northern boundary of the spillway.
The key feature of the map is the “weir,” a long, concrete structure punctuated by hundreds of wooden pilings. These pilings are strategically removed when the Mississippi River reaches critical flood levels. The map accurately shows the weir’s location along the northern edge of the spillway. When the pilings are pulled, water flows over the weir and into the floodway.
The floodway itself, as depicted on the map, is not uniform. It consists of natural bayous, canals, and open fields. The map usually displays a network of waterways within the floodway, indicating the natural drainage patterns and how water will flow through the system towards Lake Pontchartrain. These waterways, often shown as smaller blue lines, are vital for efficiently directing the floodwater and minimizing erosion.
The southern boundary of the spillway is defined by the shoreline of Lake Pontchartrain. The map illustrates how the floodway funnels the water directly into the lake. The size and shape of Lake Pontchartrain, a large brackish estuary, provides the necessary capacity to receive the diverted water without causing significant flooding issues in adjacent communities.
Surrounding the spillway, the map reveals the contrasting landscape of developed areas and preserved wetlands. To the east and west, one can see indications of residential and industrial areas. The map emphasizes the importance of the spillway in protecting these communities from the devastating effects of Mississippi River floods. Furthermore, the map may highlight areas designated as wildlife preserves or managed for recreational use, demonstrating the spillway’s coexistence with ecological considerations. This interplay between human development and environmental protection underscores the spillway’s complex role in the region.
Modern maps of the Bonnet Carré Spillway also often incorporate layers showing elevation data, which further clarifies the topography of the floodway and how water moves across the landscape. GIS mapping platforms may even include real-time data about river levels and the operational status of the spillway, providing critical information for emergency management and community awareness.
