tanama,
I'm not certain that your berm idea is going to work. It appears that the water will collect behind the berm, pour out the sidewalk side of the berm and seek the lowest point which is your driveway. But, perhaps coupled with your other 'fixes' which you do not elaborate you may be on the way to solving your problem.

To answer your questions directly. On the berm itself you can plant any perennials or annuals that appeal to you. Look for varieties that will withstand hot afternoon sun. Carpet roses-(good choice), verbenas, creeping phlox, cosmos, petunias, marigolds...all sorts of choices are available at the box stores.

As to planting in the berm ditch itself. Japanese iris (Iris Kaempferi) is the the type that will endure the situation you describe. Their extensive root system will seek moisture within the berm itself. Perhaps medium sized shrubs might be a better choice such as Inkberry (Ilex glabra), Summersweet (Clethra alnifolia), or Bayberry (Myrica pensylvanica).

Nandina, thanks for your plant suggestions! The more I'm reading, the more I'm thinking that a berm isn't the best direction to go. I actually want the water to do what you describe - go to the street (we have no sidewalk) side of the driveway and flow out from there, because it appears (from a quick test involving simply pouring out a bucket of water) that the water will head towards the storm drains when it reaches the street, not go back up into my driveway.

But I'm reading more and more that getting a berm to really "take" without it washing away (including washing away things I've planted there) is tricky.

I'm investigating how it would work to put in a raised bed with a french drain at the bottom -- back of the bed a few inches above the neighbor's lot level, acting as a dam when we have a normal rain. Then if it's a hard rain, instead of the runoff from my neighbors yard filling up my driveway or the raised bed, the drain can direct it to the street.

It is difficult to understand the sources of water from the pic, but it is clear that the road is one source (pic) and that the neighbors downspouts (your desc) are another.

You could make a berm, as shown in your plan, that slopes towardthe street. That may catch the downspout water and direct it to the road. You could create a ridge between your property and the road pavement to keep water that is on the road from entering your property.

But, it all is worthless if the water has no where to go, as appears to be the problem, once it gets to the bottom of the road (which appears to be somewhere very near your house. Then the water is going to rise to that level no matter what path it takes to get there.

The bigger problem appears to be that the water has no place to go more than where it came from. The person back by the fence appears to be in deeper water than where the cars are parked. If that is the case, the water drains in that direction from your driveway (until it has nowhere to go, then it builds up?). It is quite apparent that your lot is lower in elevation than the road since the road is not under water.

Does the road start to go up hill in front of your house, or does it continue down hill? If it continues down hill, there is hope.

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From the looks of the photo (especially if this is a reoccurring event) this is a civil engineering problem -- not a landscape design problem. A viable, effective solution also seems to be far beyond the scope of the average homeowner.

IronBelly

I'm thinking it wasn't a good idea to use the pics of last year's flooding, because that was very much NOT a typical event. It's also clear that in the interest of trying to not bog down my question with too much information, I left open too much for interpretation.

There is a storm drain located just around the lower left corner of the flood picture. Clearly it's not working well, and I'm addressing that with public works. The storm drain directly across the street works great.

Much of the water on my property actually comes from the far side of my property, not shown in this picture -- if you went through the gate that's behind my granddaughter in that flood picture and walked straight over to the other side of the fence, the lot on that direction is very large, and there is just enough slope from back in there yard to way over by the side street shown in the pic that when we have a hard rain you can go in the yard and watch the water rushing over my yard. So it's actually exactly oppposite from what it looks like -- water doesn't come in from the street, it comes from the opposite side and stops at the street. Another of the problems we're addressing is grading the back yard to try and get THAT neighbor's runoff to stay in their yard.

What happens during a "normal" very heavy rain (as opposed to the 12" we got the day of last year's flood) is that the water comes from all directions and tends to pool right where you see my granddaughter standing, which is at the top end of an old swale which goes to the storm drain - that's why it seems so deep there: she's standing in the deepest part of the swale. But that swale has gotten built up with dirt over the years as you get closer to the drain, and so the water backs up there at the gate. Getting that swale dug back out is yet another of the things we're addressing.

Here are some pictures that show the area dry:

The right side of our driveway, showing the difference in height between my neighbor's property and my driveway.

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The same side of the driveway, taken from next to the shed.

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This is the left side of the garage, where water pools the most during a hard rain. If you look through the gate to the fence in the background, the lot behind that fence is where much of the water flows from. FYI, the gutter was installed today - it used to have the downspout back by the gate, right where the problems were the worst, so we put in a new one that discharges on the opposite side, and someone is coming out this week to route it to a drywell.

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So, to summarize:
We have water coming from the far side of our yard, flowing across our yard. We're grading there to cut that down.

We have an insufficiently functioning storm drain. We're working with Public Works.

We have an old swale that no longer is sloped the way it should, so water stops there by the side of the garage. We're digging that out and reshaping it to let water flow the way it's supposed to.

AND we have a neighbor to the side of our driveway whose lot is significantly higher than ours, and whose downspouts are tied into pipes that discharge right at our property line so that most of his roof runoff comes onto my property. There is no code preventing him from doing that and I'm not willing to drag him into civil court, so I'm trying to deal with it on my side of the property. THAT aspect of our stormwater problems is what my original email was all about.

Sorry for confusing things so thoroughly by not explaining all the sources for the flood waters I showed, and for not making it very clear that this picture is NOT our typical problem; I had mistakenly thought it would be a good picture just to illustrate the difference in height of my property vs. this rear neighbor's lot, now I realize it confused things considerably.

Maybe I should just ditch this thread and start all over...