https://www.cato.org/publications/commen...-wont-work
A wall would probably be less easily damaged by man or nature. But in at least some areas, its impassibility could also become a maintenance liability. Border Patrol agents have told Fox News that a border wall would still “have to allow water to pass through, or the sheer force of raging water could damage its integrity, not to mention the legal rights of both the U.S. and Mexico to seasonal rains.” In 2011, for example, a flood in Arizona washed away 40 feet of steel fence
Much of the current fencing can be easily mounted with a ladder or from the roof of a truck. In some cases, border crossers can scale the fence without any additional equipment. One viral video from 2010 shows two women easily climbing an 18-foot steel bollard-style pedestrian fence in less than 20 seconds. Smugglers can even drive over the fence using ramps, a fact that was discovered only when a couple of foolish drug entrepreneurs managed to get their SUV stuck on top. (They took the dope and split.)
Fences or walls obstruct crossers’ paths, cutting off a straight shot into the interior of the country. But a barrier is not the permanent object that some people imagine. Natural events can knock down parts of a border fence. One storm in Texas left a hole for months. Fences and walls can also erode near rivers or beaches, as the one in San Diego did. And they can be penetrated: Some fencing can be cut in minutes, and the Border Patrol reported repairing more than 4,000 holes in one year alone. They neglected to mention whether that number equaled that year’s number of breaches.
If not over or through, some crossers may opt to go under. Tunnels are typically used more for drug smuggling, but they still create a significant vulnerability in any kind of physical barrier. From 2007 to 2010, the Border Patrol found more than one tunnel per month, on average. “For every tunnel we find, we feel they’re building another one somewhere,” Kevin Hecht, a Border Patrol tunnel expert, told The New York Times last year. A wall would likely increase the rewards for successful tunneling as other modes of transit grow more expensive.