why don't you try Sedum?
there are some varietes that can grow fast and literally grap the soil up.

Also another good choice is Hypericum.There are varieties suitable for ground cover.They are shorter and can survive almost every difficulty

You don't say whether you get frost in your location, but some good ground covers that are low growing and fast spreading with reduced water needs might include some of the South African iceplants such as Lampranthus spectabilis, Drosanthemum species, trailing Gazanias, or the Australian Myoporum parvifolium. All of these can be planted out as rooted cuttings from flats and will quickly fill in if planted out after the start of winter rains, but well before it gets hot and dry. All will be better if they get some irrigation in summer to keep them looking their best. You might also consider some mediterranean natives such as low growing cultivars of Rosmarinus officinalis, which are also available as rooted cuttings here in flats in California. Some of the Rockroses lend themselves to bakn plantings, with Cistus salviifolius var prostratus as one of my personal favorites. Some of the dwarfer growing native Euphorbia species could also work.

In my experience with Hypericum calycinum here in California, this looks much better if shaded and well watered, if not, it looks pretty awful in mid to late summer. Another Mediterranean native often used as ground cover is Vinca major, but this also looks and grows best with some shade.

Good luck with your project, and if you use shrubby types of plantings, you can space these out more widely and just drip irrigate individual plants rather than having to water the whole slope. I'd also suggest heavily mulching the whole slopes to control weeds and help conserve water.

We garden in North-West Crete on a reasonable slope in the limestone foothills of the White Mountains. Full sun and limited water for irrigation are the order of the day.
In our area a never-fail plant is the Hottentot Fig/Highway Ice Plant/Pigface(!)/Sour Fig (Carpobrotus Edulis). This has a long flowering period and makes rapid growth - the only snag is you may be overrun with the stuff after a year or two! Also the Cape Daisy/South African Daisy (Osteospermum) may do the job and has hundreds of varieties to choose from.

We need to talk!!! DRYSCAPES does this - we suggest portulaca and lampranthus if afar, or other smaller lampranthus and sedum if close up. Come over and visit sometime - or check out dryscapes.eu and dryscapes.com

Here is a link that might be useful: dryscapes

lampranthus, portulaca or sedums
'throw on then walk away' over winter, not hard to root autumn or spring, following a few basic rules
Do not try in summer!!!

Also,there are many sedums - not all good. BEWARE!

Here is a link that might be useful: water less plants

YES I TOTALLY AGREE!!!! OUR BANK WAS A PROBLEM TOO, IT WAS A CLAY SOIL THAT KEPT 'SLIDING' WITH THE HELP OF THE DRYSCAPES TEAM WE GOT A MIXTURE OF PLANTS THAT WE PUT ON THE BANK.... A YEAR LATER THEY ARE COVERING THE SOIL WELL. AND I HAVE TO ADD THAT AFTER THE TORRENTIAL RAINS THAT WE HAVE RECENTLY HAD THERE HAS BEEN NO LANDSLIDE LIKE WE EXPERIENCED LAST YEAR. DRYSCAPES WEBSITE WELL WORTH A VISIT!!! ALSO SAW THEM ON LIVINGINSPAIN.TV.... VERY INFORMATIVE