My main work for over a month has been the flood study for the headwaters of Little Osage Creek in Centerton, Arkansas. I’m way behind on the project, and am soon to be over budget (in part because the project included a flood study of the headwaters of McKisic Creek as well; yet the budget is 80 percent consumed). I let this project sit almost a year, then got a promise from another department in the company to piggy-back it on one of their projects along the West Branch of Little Osage Creek. Somehow they didn’t do it, saying they never claimed they were intending to. So I had to take it back into my work load, dust off my “tools”, and get the job done.
As of today, I am really, really close. I have completed a complicated computer model for calculating the flood flows. This model includes 18 detention ponds, some 21 subbasins, and a number of stream runs (called “reaches” in the vernacular). I have run this model for the 100-year storm, and had believable and predicted results. Next, in a separate program, I merged the existing FEMA stream geometry model with the CEI stream geometry model (the one my project was supposed to piggy-back on), filled in the 600 foot gap between them, corrected a considerable number of errors in both, added missing culverts, added needed cross-sections that were left out of the FEMA model and due to which the model never should have been approved, and finally, today, ran a successful stream geometry model together with the flood flows from the other model. I have an answer!
I still have some tweaking to do. The results (i.e. the flood elevation, which drives the spread of the flood waters) are not as favorable as I would like, so I have to look some more at it and see if anything in the merged geometry is too conservative. If so, I might be able to reduce both. If not, the City will just have to live with the calculated flood elevation and spread.
When I started the study I had some goals in mind as to how to improve the situation on the existing flood maps, which contained obvious errors along with some things that drastically changed from the previous flood map, but which may or may not have been errors. One of the obvious errors will be gone on the new map; the other looks like it will remain. That’s not a final answer, but it’s most likely.
Why am I writing this? Today there has been an emotional release with the success of these models. I still have much to do on the project, including model tweaks, calculating flows for other storms, writing a technical report, making a presentation before an unhappy city council, putting an electronic and print submittal together for FEMA, and then working through the (probable) six month FEMA approval process. But with the successful model having all missing links plugged, no obvious errors, and believable results, the release is at hand.