I use shredded cedar bark mulch under my driplines and it never washes away.

I have an even cheaper solution - I just use my broom to sweep it back off the sidewalk into the flower beds.

I don't mean to keep a blatant advertisement up at the top of the discussion list, but if you have that much mulch washing away in the rain - maybe you have bigger problems, like drainage?

Here's an article kind of on-point

Growing Greener Lawns
Soil Scientists Stabilize Fire Ravaged Topsoil With New Technology

July 1, 2008 Chemists and engineers designed a technology that protects soil. A polymer encased in recycled paper bonds to positive ions in soil to form clumps. These clods of dirt break up the hard surface that can form following a fire, promoting the absorption of water, which stops soil from being flushed away during a heavy rain. This process helps promote the plant growth that will keep the topsoil in place over the long term.

Every summer, wildfires consume thousands of acres of vegetation, threaten wildlife and set the stage for mudslides that can wreak even more havoc. Now, scientists have developed a new kind of soil technology that could stabilize those areas and help them grow again. And now, there could be an added bonus for anyone trying to keep their lawn greener this summer.

For homeowner David Feschuk the challenge is keeping his lawn green through a long drought. "I don't want the grass to die and at the same rate I want to be able to conserve water to not overwater the grass and have the water run off," said Feschuk.

For the forest service, it's bringing back a scorched mountainside after a devastating wildfire. Now, a new kind of soil technology offers solutions for both.

Now soil scientists in Wisconsin have developed a way to turn office waste into a product that can stabilize the soil Recycled paper is dried and combined with chemically made polymers and other ingredients. When mixed with soil, the ingredients are attracted together -- like a magnet -- creating a net. Industrial engineer Mike Krysiak, Industrial Engineer & President of ENCAP, calls it AST Â advanced soil technology.

"Advanced soil technology is about engaging the soil to do the work -- stops erosion, helps with better water penetration," said Krysiak.

Dropped by aircraft, the product, called Pam 12 is now being used by the forest service to stabilize burn areas.

Researchers say that same technology is used in soil-binding lawn products that don't wash away, and won't damage the environment. They've even developed a new kind of seed watering technology that actually tells you when it needs watering.

It's new technology designed to reduce paper waste, save water, restore burned hillsides and make your world a little greener.

WHAT IS ADVANCED SOIL TECHNOLOGY? AST is the term used for the product that helps stabilize fire-ravaged soil against erosion. It consists of polymers encased in recycled paper which bond to positive ions in the soil. This process forms clumps, breaking up the hard surface that can form following a fire. This promotes the absorption of water, stopping rain from flushing away soil. This process promotes the plant growth that will hold topsoil in place for the long term.

RUNNING WILD: Weather is a key factor in starting and spreading wildfires -- particularly drought, which dries out vegetation. Trees, underbrush, dry grassy fields, pine needles, dry leaves and twigs can all cause and spread forest fires because they burn faster, like kindling, than large logs or stumps. The more fuel that is present, the more intensely the fire will burn and the faster it will spread. When the fuel is very dry, such as after a long drought, it is consumed much faster, and the fire is much more difficult to contain. As the fire spreads, it generates heat that evaporates the moisture in potential fuel materials just beyond it, making it easier for those to ignite. Wind can also help spread a forest fire, and is the most unpredictable factor. Winds supply the fire with extra oxygen and push it across the land at a faster rate. Because the wind generally flows uphill, fires also travel faster up a slope than downhill. Wildfires can even generate their own winds, called fire whirls, which resemble tornados. They arise from the vortices created by the fire's heat, and can be so strong they have been known to hurl flaming logs and burning debris over long distances.