Klem1, Thank you for information on Hugelkulter method. I had never heard of it. As I am reading about it and it completely makes sense. Wood will take time to break down, allowing time for young roots to solidify at a raises position. More importanlt this apprach is long term solution and I can start small. Based on advise in this forum,

I have been already experimenting with mound planting since last one year and those plants so far have done well but I am concerned about this location since deluge will be a lot and these two shrubs roots will want to go deeper.

I will post few photos later today. Fortunately concerned area is not too big.

A handy device for handling storm water is a water level. It's more accurate than economy priced transits and economy transits aren't cheap. Sounds like your main problem is inconsiderate neighbor diverting storm water into your yard instead of to public storm drains in street and alley. In case you aren't aware,home foundations on soil with high clay content suffer damage from sudden flooding of surrounding surface.

The neighboring house (source of water) is at a higher elevation. Our house is at the bottom of the totem pole. Many of our neighbors are affected.I am told there has been a sudden rise of water table in the last 6-7 years.

But here are the images. (Excuse the weeds .). Mock orange planted in June and now the mound has reduced by 4 inches or so.

Here below you can see the fence in background the source of water from neighbor. Mock orange is at center right and Weigela is at center left and both at the end of slope. The rose of sharon far right in background planted many years ago has survived the deluge since it is at 8 inches or so elevation from the mock orange.

Some comments did not get added. Adding again.

I just feel the mounds for the two plants are not big enough for the plants to survive as the roots will go further down into the soil. Would you agree ?

I'm not qualified to predict how those plants are likely to do where they are located. After hearing how much slope is in grade I have to wounder if berm(s) and/or swal(s) could help. This being a neighborhood wide situation requires far more than photos and secondhand observations. Has the community put their heads together on this?

I should mention that neighbor behind the fence has a pump to drain water to street drain that gets turned on once a month during winter. Neighbor on left has planted water loving plants. Problem is excarbated only during rainy months december to end of march, rest of the year stays quite dry. Thanks.

Well your original plan to keep those plants feet out of water seems reasonable.

Here is a wider view. The sump on left was added few years ago, did not help much. Plants added down the slope all on lhs are all water loving plants. One experimental hosta planted last year on a mound did do well.

I am overjoyed to find out that all my plants hosta, mock orange and weigela managed to survive the winter swamp condition and have all returned. Truly the raised planting has worked and definitely is a great technique. However, I do plan to replant the mock orange again at the same location this fall with further raised mound because the mound has reduced by over 50%.

Glad to hear the plants are still hanging in there,best of luck going forward.

Do you have access to leaves? I'd be piling them deeply on all the bare ground..

Yes in fall I would have enough leaves. Beyond that, this time I am planning to lay small sticks and branches at the base of the mound. The woody sticks and branches will take much longer to disintegrate, allowing enough time for the roots of the young shrub to get thicker and stronger to support the weight of the growing plant. The mound may not reduce much with this approach. Finger crossed. It will be interesting experiment. :)