I am developing a two acre property, with some existing great features. We have a seasonal creek that runs about 8 months out of the year, and a pond on site that fills when the creek runs. The house sits in the middle of the property, with about a 2% steady grade from the rear property line to the front. The front yard is about 3000 sq feet of gentle slope away from the house, toward the driveway and creek (the driveway crosses the creek with a small bridge). The front yard gets good sun, so I'm interested in making it into a food growing space. We've already developed the back yard into a great food production area, with multiple hugelkultur beds that are rocking our socks off every summer with great yields. The front, however, is something I've wanted to handle more carefully, so I haven't touched it yet. It is the prettiest spot on the property, bordered on one side by a nice pond with a splashy waterfall and flowerbeds on the other. This part of the property is the first thing people see when they enter, and is also visible from the community roadway.
My idea is to develop a series of swales on contour, leading across the front yard away from the house, toward the creek. I thought it would be a good way to catch the roof runoff from the house, and ameliorate the incredible mud that develops in the spring and fall from heavy rains. Apparently every ten years or so, though I haven't experienced it yet, the creek outruns its banks and floods the entire property and the neighbor's garage, so I'm thinking some kind of water management would prevent those disasters, as well.
In addition to the swales on contour, I'd like to add another small pond to the end of the yard fed by the swales above it, (as well as being fed by a spillway from the larger existing pond), then another series of two or three swales below the small pond, eventually leading back into the creek.
What do ya'll think of this idea? I'd love some input. Earthworks projects scare me a little, so I want to make sure this idea is well fleshed before I start digging. I had a PDC grad friend of mine say, "Almost everybody I know who has done earthworks ended up regretting them terribly!". Yikes!
Did your friend who doesn't know anyone with successful earthworks tell you why they failed and how they might have been done better? Frankly, their statement seems a little bizarre to me, considering the important place earthworks have in permaculture. We've had a few earthworks done and so far we're thrilled; just wish we could afford more of them!
What kind of growing area are you looking to create? Swales are primarily a tree growing system, so if you don't want trees or large bushes in your front yard you might look at going a different direction with this area. Such a small area could be easily sheet mulched and converted into a really good, versatile growing area. The sheet mulch will drastically reduce your need to irrigate and you could use this area in many different ways effectively for growing food. Perennial bushes, shrubs, herbs, etc. would do really well in a system set up this way. I guess it really just depends on what you are wanting to accomplish with this area and what you want it to look like.
You mention that the creek can every 10 years flood the whole property, that's I think one of the main things to keep in mind. When land gets flooded the water must go somewhere doing the least amount of damage, while if possible have some good effects as well. If the water gets really wild it will also carry lots of debris with it. The Geoff Lawton video mentioned above stresses that you can design your landscape to avoid damage. In Bill Mollison's designers manual (on page 103) he shows some flood plain wall type or tree line patterns that can pacify the water flow, to help deposit debris in a controlled way.
If people regret earthworks I think it tells you that those were build without either proper prior observation, or without proper construction. Building swales or ponds without a good overflow designed in will lead to blow outs or bursting walls in wet years and/or during severe storms or rain events. Or in dry years they might not catch a lot of water and appear useless. Any swale or dam/pond is made to catch excess rain and to prevent erosion from such heavy rains. Observe your land during heavy rains so you know how the water flows before you design any into your landscape.
A final point is your driveway, because it's a hardened surface it will have runoff even in milder rains. Check out where the water runs off the road to see if you can capture it there.that's by far the easiest way to get some water into a swale. I hope this helps.