When it used to rain like no tomorrow, engineers turned muddy rivers into concrete flood control channels.

Designing a shopping mall? Leave plenty of space for the parking structures.

In a blink of an eye, both of those icons of the Southern California landscape are changing. It’s not raining much and malls are succumbing to Amazon and other online shopping dot-coms.

In the next five to 10 or 20 years, green ride-hailing services and personal electric cars will be dominating the streets — and cities aren’t adapting. The state faces a severe shortage of places to charge electric vehicles, whether the cars are owned or shared, says a new report from the U.S. Public Interest Research Group Education Fund, PennEnvironment Research and Frontier Group.

“There will soon be a tipping point where we need to expand our number of electric vehicle charging stations,” said Alana Miller, one of the authors of the report “Plugging In: Readying America’s Cities for the Arrival of Electric Vehicles” and policy analyst with Frontier, a think tank based in Denver.

Though sales of EVs and hybrid plug-ins started slowly, they are picking up speed.

Sales nationwide increased 38 percent in 2016, and 32 percent in 2017 Half of all electric vehicles nationwide are in California. Sales have risen every year for the last five years.

Last year saw the introduction of the Chevrolet Bolt, a car that more than doubled the mileage on a single charge to about 240 miles yet kept the cost around $35,000 without incentives. In addition, others, such as the VW e-Golf and the electric Smart car brought prices even lower, while hybrid plug-ins graduated to the minivan with the Chrysler Pacifica. If Tesla manages to produce new Model 3s for the 400,000 on the waiting list, that would be a game-changer.

With breakthroughs in electric trucks, soon there will be no vehicle class without an electric drive option. General Motors plans on launching 20 EV models by 2023, while Ford is going electric, too, with its plans to invest $11 billion in battery cars, eyeing a goal of 40 models by 2022.

These are no longer “compliance car” numbers that automakers produce to check off the list. In California, Gov. Jerry Brown announced a new goal of 5 million EVs by 2030. Bloomberg New Energy Finances predicts half of all new cars in the world sold by 2040 will be electric vehicles.

While many folks charge using a Level 1 charger — another name for a standard, three-pronged 110-volt outlet — most public stations are Level 2, 240-volt chargers that can add 50 miles of charge in two to four hours. Fast chargers (Level 3) add 100 miles of range in an hour, but they are very rare.

The companion report focusing on California estimated a severe shortfall of public plugs in Los Angeles. By 2030, L.A. will have about 450,000 EVS but has only 1,456 public plugs. It needs 8,180 Level 2 chargers in workplaces and 4,834 in public places (shopping center lots, public streets).

So despite Mayor Eric Garcetti’s green incentives, L.A. is falling way short on helping turn the transportation tide to electric, where there are no tailpipe emissions and where greenhouse gases from electric power is much, much less than from burning gasoline, i.e. fossil fuels.

On a positive note, the report points out that L.A. has installed 100 smart poles with charging ports on city streets — right at the curb. The power poles are there! So new conduit is not needed.

For people who live in denser areas (apartment, condos) and must park on the street, these would be ideal for charging.

Without more of these, people will hesitate to buy electric. More EV stations would help solve what’s called the chicken-and-egg problem.

Miller says cities and utilities should no longer consider them a frill but rather a necessity.

Steve Scauzillo covers transportation and the environment for the Southern California News Group. He’s a recipient of the Aldo Leopold Award for Distinguished Editorial Writing from The Wilderness Society. Follow him on Twitter or Instagram @stevscaz or email him at sscauzillo@scng.com.