Under water (or woodah, if you speak Baltimorese)

July 24

We're in the middle of a week that has experienced record rainfall with over 9" falling locally by the end of the week (some nearby areas reportedly >15"). I was curious what the mandala looked like, whether the stream could hold all of this water. Apparently not, though this isn't particularly surprising. The mandala's in a floodplain and shows signs of past flooding like debris piled against the upstream side of trees. The soil is also different from uphill as it contains much more silt and sand and is less rocky, a pattern expected from flood deposits. I suspect that the anticipated elevated soil nutrient status here is also due to these stream deposits and perhaps from erosion of organic matter and topsoil from uphill.

Today, the stream is high but still within its bank. It is muddy brown, carrying lots of sediment. The mandala's vegetation has largely been flattened by overflow and looking pretty pitiful. The lush understory is missing in action but I suspect that it will return with a vengeance as the forest dries and the sun returns for a few days. I suspect that the monsoon-like rains of a few days ago flooded the mandala. There are fresh piles of natural and anthropogenic debris strewn through the area and especially against several of the larger trees. The trail to the mandala contains standing water and the floodplain on the other side of the stream contains new overflow channels, some still flowing. This wetness of this week, the prolonged soil saturation, the flooding - all of this has me wondering about the effects on the mandala's inhabitants, from the soil biota to the mammals and birds. Certainly the more mobile animals are seeking drier habitats away from the stream. Certainly some smaller organisms have been washed downstream and perhaps others from upstream deposited here. Certainly some also met their demise. Although I don't have data on community diversity or species abundances, it will be interesting to watch the resilience of the mandala as waters subside and the mandala dries.

Stream panorama

All of this rain and the flooding that's dominated the local news this week brings several things to mind. First, what's going on downstream? All of this water, debris, and sediment are being washed downstream through the Gwynns Falls watershed to the Baltimore Harbor. A oft-related issue in Baltimore is the leaking sewage whenever it rains more than a little. The City's Department of Public Works reports that 45 million gallons of stormwater-sewage mix has leaked this week. Not only gross but with ecological impacts of nutrient and pathogenic consequences. Second, where's this week or month fall historically? This has been with wettest July on record with nearly 17", far exceeding the average rainfall of bout 4", and is the second wettest month on record (the wettest month was attributed to a major hurricane's precipitation). And we've already received the average annual total for the year. Several other records were broken too and are nicely summarized here: Baltimore records via the Baltimore Sun. So why'd this happen? My simplistic meteorological understanding is that a frontal system stalled over the Mid-Atlantic due to a high pressure system to the east and this resulted in a persistent conduit of tropical moisture being drawn north and dumped in a consistent north-south pattern for much of the week. Is this global weirding at work? I'll just say that the pattern fits. Regardless, I'll be sure to wear my rubber boots next time I visit the mandala.

Maryland State Climatologist Office (we're in the middle of the largest dark green blob)