Roads a major (problematical) part of the water infrastructure of society.

One of the keys to restoring the water cycle, is help the rainwater infiltrate better into the soil and land. This can be done through slowing, spreading, and sinking the water with swales, terraces, check dams, soil organic content increase, mycelia, and plant debris.

An impediment to rainwater infiltration exists, that is not often talked about. And that is roads - roads in the wilderness, roads in cities, and roads leading into cities.

As an example, there are large pieces of mainly wild, mountainous land, sometimes privately owned, on the west coast of the US, that have forestry or logging roads going through their property. These roads sluice the water off the property before it gets a chance to infiltrate the land. When large rains come they gain velocity as it races down the slopes, and will often carve out a rivulet landslide through parts of the road. Many of these lands are finding that year by year the creeks and springs on them have less and less water. If the rains could more effectively infiltrate the land, these creeks and springs would have a lot more water.

Many towns and cities around the world are experiencing flooding. The roads act as highways for water from higher altitudes to funnel into towns below. In the towns, the water can gain so much velocity that it shovels cars around like little toys.

So what are we to do this problem of roads and water? Some of the solutions that begin to make headway on this issue, are creating swales next to roads to guide the stormwater off of it, and other stormwater absorption strategies.

The Chinese, faced with many of their cities flooding out, has implemented a sponge city program, where they have wetlands and rain gardens next to roads, and have used permeable roads to allow the rainwater to seep into the land below. Brad Lancaster (of harverstingrain.com ) has pioneered the idea of making curb cuts in road to help guide the water off the road onto the plants on the sidewalk.

Roads take up a lot of land area. A study of Los Angeles, San Jose, Phoenix, Brooklyn, Houston and Miami roads by Adam Millard Ball found that the roads, averaging 55 ft wide, took up 18% of the cities studied, with some districts being as much as 30% of the total land area. [1] This creates problems for the water cycle. If our continents were still wild, rain would come down, and get absorbed by the soil and vegetation. Some of it would descend to replenish the aquifers, and some of it would be transpired back up to add to the water vapor in the air, to create rains downwind. With the paving over of our cities, there is less groundwater, and there is often less rain inland [2], even while causing the increase of extreme rainfall events because urban heat alters the flow of atmospheric water [3]

Decreasing the amount of land area that roads take up would help. We can look at re-greening 1% to 5% of our roads as an initial goal. This would help with floods. If we re-greened some of the roads in the city areas, then that re-vegetated area could absorb some of the in-flowing onslaught of stormwater during floods. If we turned back into nature some of the roads leading into the cities, it could lessen amount of floodwater reaching urban areas. Re-greening 1% to 5 % of our roads would also help with drought, as then more rainwater can be absorbed and then re-transpired to help add to the ocean vapor blowing inland to create rain.

The problem is our society is still increasing the amount of roads it has. We are still in urban development phase. The more we want to develop, the more roads we have, and the more roads we have, the more traffic wants to flow to urbanize more land. Our society has to look deeply in our cultural relationship to roads.

Roads are affecting the weather and making climate change worse. The destruction of nature by increasing urban sprawl is one of primary causes of climate change, along with carbon emissions, and modern agricultural systems (with their disruption of soil and water cycles). Vegetation allows the land to transpire and cool itself, in a similar way that sweat cools the human body. Vegetated lands are usually quite a few degrees cooler than similar asphalted or concretized land. Urbanization is creating urban heat domes that alter pathways of jetstreams, and water vapor flow in the atmosphere, that leads to more extreme rainfall, extreme droughts, and extreme heat events. Urbanization is stopping the moisture hopping path of water inland, through the small water cycle, so the rainfall cannot be absorbed into the earth, and then evapo-transpired back out to blow further inland.

Companies like Tesla while hastening a much needed transition away from oil, is still increasing our road usage and urban spread. So while Tesla helps climate change by reducing carbon emissions, it will also increase climate change in the long run by increasing urban sprawl, and messing with our water cycles. So we need to facilitate companies like Tesla coming in and making oil based vehicles obsolete, but then we need to look at phase two of the plan, and look at how we lessen the amount of Tesla and similarly produced electric vehicles in the long run.

There are different groups, towns, movements helping us find a way forward to a less car dependent future. The city of Ghent in Belgium, made a transition to a car-free culture, and found it could convert a lot of its road and parking lots into more natural vegetation. There is a Depave movement in Portland, that helps people and businesses depave roads, parking lots, and yards. Strong Towns is an urban movement in the USA that has one of its objectives to help transition our society to a less car intensive culture. In Barcelona, roads have been blocked off to create community superblocks. Shenzhen in China is creating car-free sections of the city. There are groups like Transition Towns that are working to relocalize our economies and rebuild local community, so that people and trucks do not then have to travel as much and as far to find the things they need.

Roads are both a transportation infrastructure and a water infrastructure. Our society needs to understand that it is both, in order to make saner decisions for the future. We cannot only focus on roads as a transportation infrastructure. Civilizations depend on proper water flow. Civilizations have ended because they have destroyed their relationship with the water cycle [4] We need more research and design thinking about how to integrate our society’s roads into the water cycle.

References:

[1] “Indentifying the amount of urban space occupied by roads” https://www.eltis.org/in-brief/news/identifying-amount-urban-space-occupied-roads

[2] Millán, M.M., Estrela, M.J., Sanz, M.J., Mantilla, E., Martín, M., Pastor, F., Salvador, R., Vallejo, R., Alonso, L., Gangoiti, G. and Ilardia, J.L., 2005. Climatic feedbacks and desertification: the Mediterranean model. Journal of Climate, 18(5), pp.684-701 https://journals.ametsoc.org/view/journals/clim/18/5/jcli-3283.1.xml

[3] Millán, M.M., 2014. Extreme hydrometeorological events and climate change predictions in Europe. Journal of Hydrology, 518, pp.206-224 https://www.sciencedirect.com/science/article/abs/pii/S0022169413009384

[4] https://science.nasa.gov/science-news/science-at-nasa/2009/06oct_maya