“Tropical” Storm Chantal Produces Extreme Flooding in July Along the Haw River NC

July 15, 2025
Bill Dunson

: Tropical storm Chantal forming off the eastern coast of SC/NC

: Tropical storm Chantal makes a direct hit on my Haw R home

: A satellite view of Chantal and its track over te US mainland

: The Haw river flooding at 32.5 ft followed by a minor peal of 26.5 ft at the Haw River NC gauge

: A list of minor and major floods shows that 29 years ago there was a very similar peak at 32.8 ft

: The Haw river looking upstream from the Union Bridge next to our house during the flood

: A picnic area with a car port was turned into a pretzel by the flow

: My favorite giant elm tree probably 100 years old was spared

: One of my favorite giant hackberry trees was toppled into the river by collapse of the bank

: Strange orange deposits along the collapsed banks seem to iron oxides formed when reduced ground water encountered the air

: A group of unusual green dragon plamts were knocked over but I tied them up so they will produce fruits

: A pearl crescent butterfly visits a purple coneflower

: The inside wings of a male spicebush swallowtail

: The outer hindwing of the male spicebush swallowtail has a distinctive double row of orange spots

: The female black tiger swallowtail is another member of the pipevine mimicry complex

: The more common yellow morph of the tiger swallowtail on a purple coneflower

: A remarkable predatory robber fly has captured a paper wasp as prey

: A ruby throated hummingbird and its specialized coral honeysuckle nectar source

: The male brown cowbird is native but is a nest parasite on other birds

: The beloved if noisy Carolina wren often nests inside buildings

: My perennial garden is at its peak in July

There is an old saying, “you can run but you cannot hide!” I had just returned July 5 from a short trip to FL to continue to clean up after the devastating hurricane Milton which had a huge storm surge of sea water which flooded my house there. A tropical storm named Chantal had just formed in the Atlantic off the NC/SC border. The problem with these storms is generally not high winds but very high rainfall which can cause catastrophic flooding. You can see from the bright red color of the first radar image that massive amounts of rain were developing offshore. In the second radar image the storm has moved inland on a northerly track and my Graham NC location is shown by the central blue dot. During the passage of the storm we received more than 10 inches of rain as did the watershed to the north. The third satellite image shows the storm clouds and a storm track. The USGS Haw River gauge showed a huge peak in river level of 32.5 feet on July 7 with a secondary peak of 21.5 feet on July 10. Although some called this a “1000 year flood,” such is definitely not the case. Indeed there was a slightly higher flood peak at the same gauge of 32.8 feet in 1996, just 29 years ago (see table taken from USGS records of the same gauge). One thing that is certain is that flooding must be increasing with time as more and more of the watershed is made impermeable, resulting in a more rapid runoff of rain water. Indeed the time it takes for the Haw River to return to base flow of about 3-5 feet is quite rapid, illustrating how the watershed has lost most of its original ability to hold rainfall for a period and buffer the effects of flooding due to heavy rainfall.

It is not surprising that this severe flood had devastating effects on the floodplain. A photo is shown of the muddy river just upstream of the Union Bridge adjacent to our house. Water extended far into the floodplain and caused extensive damage to vegetation, river banks and any existing human structures. A photo is shown of a picnic area which had a metal car port, two tables and various chairs, all of which were swept away or destroyed. The crumpling of the metal carport by the river current was especially impressive. A huge American elm tree directly on the river bank did not collapse; this tree is126 feet tall with a circumference of 14.25 feet; it is estimated to be 80-100 years old. A very large hackberry tree right on the river’s edge fell in as the bank collapsed; it was 76 feet tall with a circumference of 9.25 feet. I estimate its age at 75 years and have been surprised that such large trees survive as long as they do immediately on the edge of the river. Some other vegetation such as paw paw trees was almost all blown down by the current. Some small plants such as the green dragon fell over but when I tied them up to a stake it appears they will survive and continue to ripen fruits.

One very interesting anomaly along the collapsed river banks was bright red/orange material associated with ground water flow from the truncated sandy banks. It seems most likely that these deposits are iron precipitates which were previously reduced by the very low oxygen of ground water but became oxidized in the air to iron oxides that are brightly colored.

Despite the large amount of rainfall in a short period I continue to see butterflies at flowers. This pearl crescent was sipping nectar from a purple coneflower. A male spicebush swallowtail came often to flowers of butterfly bush. Given that the caterpillars of this species feed on the poisonous spicebush, its coloration would seem to be a case of Muellerian mimicry along with the pipevine swallowtail. Note that the outer surface of the hindwing of the spicebush swallowtail has two rows of bright orange spots, a distinguishing characteristic. Another member of this mimicry complex often seen in my yard is this female black tiger swallowtail, here shown feasting on flowers of Joe Pye weed. Note that you can see individual blue scales on her wings. A comparison is shown with the more common yellow tiger swallowtail morph which is here attracted to a purple coneflower.

I am a bit of a nut for hibiscus type flowers and enjoy watching bumblebees feeding inside the rose of Sharon. This non-native plant has not been invasive in my experience but I do dead head the seed heads to eliminate that possibility. This wild type flower has white petals with a dark red center which is considered to be a “nectar guide” which helps insects find the center of the flower. Bumblebees are generalists and forage on a wide variety of flowers and another is shown here collecting nectar and pollen from a spectacular Mexican sunflower or Tithonia.

In my recent walks I came across a very interesting example of insect predation. My photo is shown of a robber fly which has caught a paper wasp. Isn’t it amazing that a fly can kill a wasp? Paper wasps are one of the major predators of larval butterflies in our yard in Florida so I am happy to see them being controlled by another insect.

I have a large display of coral honeysuckles which can attract hummingbirds when they are in bloom. At the moment there are quite a few blooms and you can see that a ruby throated hummingbird has come for nectar. This is a classic example of a specialist pollinator which only visits flowers with copious nectar supplies and usually a long narrow corolla tube that is red. A native bird that is not so welcome is this male brown cowbird which is handsome but is an egg parasite. The female lays eggs in other birds nests which is a natural evolutionary process but somewhat obnoxious to our human values! We prefer to see the common Carolina wren which makes nests in our garage, takes care of its own young and sings perhaps too much and too loudly!

I always look forward to July since it is the peak time for certain native perennial wildflowers which I plant in a small garden. I am faced with a massive amount of yard work in our 50 acres so prefer perennials to annuals since they are less work. Many of these bloom prolifically and are a beauty to behold and attract many pollinators.