even more thoughts...
9/16/20 (11:46 a.m.)
Topic Today: Typhoon Mangkhut:
As you know by now, the loss of life (11 dead at the time I write this) and the amount of damage to property (estimated to be $5 billion) caused by Hurricane Florence is tragically high. I sincerely hope that if you are one of those who lost a loved one, that you find peace and comfort in the days that follow. If you have lost property, I also hope that you have found safe lodgings and that you are able to rebuild your life quickly.
Half-a-world away…”Super Typhoon Mangkhut” (the most powerful storm yet this season (https://www.sciencealert.com/not-just-hurricane-florence-far-stronger-super-typhoon-mangkhut-about-to-hit-philippines-china) has left 13 people dead and more than 4 million without power. Unlike Hurricane Florence, Typhoon Mangkhut is not done wreaking death and destruction, as it is now heading toward China and Viet Nam. Although the financial damage to property in each country in it's path will be far less than the damage caused by Hurricane Florence, the humanitarian impact is expected to far exceed that of Hurricane Florence; there is an estimated 37 million people living in the projected impact zone.
Many of the people who live in these areas will be vulnerable to mudslides and flooding exacerbated by the impact of urbanization that has occurred over the past 30 years. Last month I attended a presentation on the aftermath of Typhoon Mirinae that hit Viet Nam in 2009. The study of one town in the affected area (Nhon Phu) conducted by Michael DiGregorio of the Asia Foundation in Ha Noi revealed that due to the construction of new dikes, houses, buildings, industrial zones, raised roads, raised rail lines, the addition of concrete/asphalt streets, and the deforestation that occurred as the town grew and acquired new land, the natural flood plain had been significantly altered. Tragically, this alteration led to the loss of 8 peoples' lives in Nhon Phu (over 69 in the province). What happened was that all of this urbanization led to the formation of many new, deeper, "flood cells" up stream that each took a longer time to fill; thereby delaying the advancing water's progress. In the past this water would have passed almost unimpeded within 4 to 8 hours after the rainfall began and the advancing water flow would have given the townsfolk plenty of warning that the water in the mountains was coming. This warning would have allowed for the evacuation of the town in advance of the flooding, however, in 2009 as each "new" cell filled and reached capacity, larger and larger quantities/volumes of water were restricted, delaying the overflow to the next cell. At a point after midnight, approximately 20+ hours after the first water cell began filling, the vast majority of these cells failed and the dammed up water began it's rapid journey toward the sea. Historically, water flood depths in town were about one foot, however, the addition of new buildings and structures acted as natural dams, restricting and redirecting water flow. This resulted in water levels quickly rising to over 10 feet - all at night when people were asleep. The contribution of deforestation on mudslides and unabsorbed water likely needs no explanation. In two villages downstream from Nhon Phu (located near to, or on the coast) many more died that night and in the early morning hours. Some of the bodies were never recovered having been swept out to sea.
As with all storms of this nature, the predicted path of Typhoon Mangkhut changes rapidly. For now, at the time I write this, it looks like Mangkhut will pass just north of Ha Noi, however, as the U.S. Embassy notes: “You should also have an emergency plan in place before the approach of a typhoon, as even areas far from the coastline can experience dangerous winds, tornadoes, mudslides, and floods.” Ha Noi is about 100 kilometers (50 miles), give or take, from the nearest coastline, so they say we will likely have strong winds, lots of rain, and some major flooding.
Roughly translated, Ha Noi means “within rivers”. The name was chosen because the city is located between two major rivers: Red River and Nhue River. The elevation is about 30 ft above sea level so all the rain that hits the mountains will pass our way! Check out google map for the satellite view and you’ll see the rivers and how the mountains funnel down toward Ha Noi. Ha Noi is one of the fastest growing cities in the world and the infrastructure is not keeping up with the growth. I’ve seen the streets here flood to a depth of over 10” following a 2 hour downpour. Can’t imagine what will happen with 2 days of heavy downpour... I’ll try to post to my blog in the days to come.
So, until the next post, it's time to button down the flaps and see what happens during my first major weather event here in Ha Noi, Viet Nam. Honestly, I don’t know what to expect.
Take good care everyone!