Thursday, August 31, 2017

Coastal floods from rain get worse as the drop to sea level gets smaller

Something that isn't getting mentioned but should about Hurricane Harvey - gradient determines drainage speed, and higher sea level means less gradient and slower drainage. And of course you have zero gradient and zero drainage when you hit sea level, which is six or seven inches higher than it was when Houston was founded. Not an inconsiderable amount when the coast is as flat as Houston's is, and that'll get worse. This issue and Roger Pielke Jr's refusal to recognize it was one of my earlier interactions with him, back in the day.

Maybe on to a cheerier idea:

Distributed renewable generation + power storage = disaster resiliency

It's a good thing that this is gradually happening, and it's a point I was making two years ago in support of Silicon Valley cities banding together to buy their own electric power supply. It's not just good for the environment, it's about disaster preparedness. More crucial facilities can stay open if they have their own power sources or draw it from a smart grid. More people can stay home instead of evacuating if the refrigerator still operates to keep food and medicines cold, and if a stove can boil water. A bit at a time we're getting closer to this type of preparation for disaster.


Fernando Leanme said...

Within the Houston city limits the creek banks overflow at 70 to 85 feet over sea level. If we use open channel flow equations it's easy to sea level change does have AN impact in flow capacity. However the worst impacts come from subsidence and non compliance with flood control regulations. I own property in north Harris, and that flood control district designs the system to preserve private houses. This requires that parks, and some commercial areas, be allowed to flood. In our case the clubhouse, the pool, the children's park, tennis courts and the club parking lot were flooded, but only one house got a small amount of water.

The solution for Houston appears to be better enforcement, widening the bayous downstream of the city, and placing a combination drainage canal and underground storm sewer form Addicks to the Brazos River. For the long term the sea level rise will be a more serious problem for Brazoria and Galveston counties, which are much lower, but they also have lower population.

I've seen a lot of baloney written blaming global warming on the damage, but that's typical propaganda. In 1963 Hurricane Flora stalled over eastern Cuba, and dropped 100 inches on Santiago. That killed one of my cousins, whose village was covered up by a landslide caused by the huge amount of rain and deforestation.

Anonymous said...

The retired guy from the Harris County Flood Control District claims subsidence has a nearly zero net effect.