Flattening the Curve

In the weeks ahead, we will be posting observations, insights, and lessons that are to be found in relation to water, infrastructure, and leadership during the COVID-19 crisis.    

This visual that we all now share describes the intended effect of social distancing guidelines. By reducing the rate of transmission, we can slow the spread of the virus in hopes of keeping the number of people that need to be hospitalized at any given time below the total capacity of a community’s hospitals.

The diagrams we use to talk about slowing and reducing runoff in the world of water management are nearly identical. A hydrograph describes the volume of water flowing through a channel or running off from a given area over a period of time. Each rain event, just like with an outbreak of disease, registers a distinct curve on the hydrograph. A community can “flatten the curve” of the hydrograph with a lot of trees, open green spaces where water can soak into the ground, and features like stormwater harvesting tanks, gardens, and landscapes that are designed to safely hold large volumes of water. These conditions slow the flow of water so that there is less water at any given time entering a community’s stormwater system.

In New Orleans, where drainage pump stations are vital for removing water from neighborhoods when it rains, you can draw a dashed line on the hydrograph to represent the finite capacity of the city’s drainage pumps stations, just like the dashed line in this COVID-10 diagram represents the capacity of a community’s health care systems. Flattening the curve means reducing the surge of patients to hospitals, or reducing the surge of water to pump stations, so that hospitals/pump stations are not overwhelmed. As we know all too well, when pump stations are overwhelmed, water backs up in the city’s pipe and canal network, and our neighborhoods flood.

These parallels suggest possibilities for how we might talk about some of our most pressing water management issues, as they relate to quantity, time, and systems capacity. With COVID-19, even a highly abstract “flattening the curve” diagram has been effective in building public awareness and knowledge, and shaping action.