I also have a wetlands that I'm restoring (the previous owner dug ditches through it and put in culverts: http://www.permies.com/t/49656/grey-water/Wetlands-Duck-Poop-Previous-Owners) to hold more water and to grow edibles like cattails, service berry and arrowhead. I plan on burring some wood deep in the wetland to hold more moisture there for a longer time. Since there are all these ditches, which are also connected to my house, the water runs off most of my land and gets stored in the wetlands.
One important thing to note is that, if you don't already have designated wetlands, you might want to avoid digging ponds and making them unless you want them to be turned into "protected wetlands" that you can't do much on. Large pond digging also requires permits. 1/3 of my property is government protected wetlands... though obviously the previous owner did not protect them too well. At this point, I'm just trying to make them look more natural so I don't get fined for them having been destroyed.
Another thing I have is rainwater catchment, though it is lamentably pretty small. I have a 55 gallon drum that is attached to one of my gutters on my 1500 sqft metal roof. This actually fills up pretty fast, and even in our very dry summer, I was able to take 5 gallons a day to water my ducks with the rain barrel only going dry once.
I think a main thing to remember about water catchment her in the Pacific Northwest, and elsewhere too, is the importance of storing water in the ground and letting it peculate down to the aquifers. Having our aquifers and wells dry up is no good, and maintaining wetlands so that the water has a chance to peculate down is very important...though also annoying when legally you're not supposed to do anything with it other than passive recreation around the wetlands.
Once you capture all the water you want in ponds, water features and cisterns then it's a mater of fast & clean exit via an established water way (if you have access to one).
Established water ways such as creeks or very small seasonal creeks have already removed top soil, slit and started to cut into the sides. Some rocks usually appear at this point, you can drop large logs/rocks into small creeks casing small shallow pools to form as habitats (make sure you are not preventing fish from migrating). Natural water ways are the best solution for clearing off excess water without damage to one's land.
Walk your property during heavy rains to see if there are any places where you have water logged areas. You may want to consider planting water loving plants or making a shallow depression for growing rice.
Remember in areas like the PNW, digging deep will call to water that normally would not be a problem. For example, a guy dug 3' down-slope trenches along his dirt road to help keep water off the road, however this deep trench pulled a lot of water from deeper soils and created a large rushing flow that ended up in his down-hill neighbors property in the form of a bog. Most of this water should have been left submerged in the soils = slower moving. So deeper isn't better when all the land surrounding is water logged. A water/soil engineer suggested the guy fill in the ditch leaving about 10" in depth. Just enough to collect water at or near the surface of the road and no more. That did the trick, and the neighbor now doesn't have a wet-land.
Scott McBride wrote:Most of what I read about water management was written about areas with little rainfall and where water conservation is of utmost importance. The west slopes of the northern Cascades where I live is not such an area. Different sources put this area at around 50 inches of rain annually. So, I am wondering what systems or strategies other Cascadians are using to manage excess water. We have plans for rainwater catchment and grey water irrigation systems to help in the dry months. What else is going on out there? What do you do with all of this water? Is it something that you manage or do you let it run downhill? Interested in any an all discussion. Thanks!
I have been struggling with this at my place near Olympia WA. I have a seasonal stream that transports water off my property and feeds a large wetland and later a named stream just downstream of my place. The seasonal stream is fed by a large pond and a fairly large catchment area that is concentrated into a culvert that marks the start of my seasonal stream.
This time of year all the soil is saturated - even at the top of the hills surrounding the stream if I dig down about a foot or two I will hit water and the hole will fill up and stay that way for the entire wet season. My soil is almost all heavy clay. So this time of year I need to keep the plants from being flooded and also make sure there are no landslide risks - luckily the slopes on my hills are not very steep.
In the summer months the clay soil becomes fairly dry and hard. But down where the seasonal stream flows the natural vegetation seems to indicate that the water table is still fairly close to the surface. Up on the hills I would like to have water features that would help the land stay hydrated through the summer.
The issue of course is that the water features that would help during the late spring and summer months are likely to not be much use during the rest of the year. Now if the water features just filled up and sat there passively with the extra water flowing off the property through the seasonal stream that would not be an issue. But I worry about holding water in swales or ponds on the slopes given how saturated the soil is already during the winter. Based on this concern I'm going to implement my water features in a couple of phases.
Phase 1: Focus on the seasonal stream and building the organic material content of the soil on the slopes. This phase will involve planting shrubs, trees and other plants on the slopes to increase the overall stability and the organic material content of the soils. I will also start digging ponds in a couple relatively flat points along the stream channel to help retain water. Some of these ponds will be fairly large and I may also place some features to slow the water in the stream down between the ponds. These features will likely be a mix of large rocks and willow stakes that should slow the water down and spread it out a bit.
Phase 2: Continue building the organic material content of the soil on the slopes and also start building swales and a couple small ponds on the slopes. The thought is that by this time the soil will have been improved and stabilized enough during phase 1 that the slopes could support a system of swales with a couple small ponds in a couple key spots. Trees would be planted along the swales to help with stability. Some of the swales might be connected to the ponds along the seasonal stream and would serve to bring water from the stream to other parts of the property. I'm picturing the structure of a leaf where the stream is the central vein and the swales are the branching veins that bring nutrients to and from all the areas of the leaf.
Phase 3: Continue to build the organic material content of the soil. This phase would never end and would continue to improve the water holding capacity of the soil and improve the stability of the slopes.
My hope would be that the system would be stable during the wet times with the extra water being moved off the property through the seasonal stream. But I also hope that by installing a network of swales and ponds that I can keep the water table high enough during the summer months to ensure my plants have all the water they need. I'm also hoping that by focusing on increasing the organic material content of the soil I can greatly increase the amount of water the soil can hold. Finally, planting a large number of trees and shrubs should also help keep the land hydrated during the summer and also reduce any flooding issues I might have during the winter months. My ultimate hope is that I can transform the seasonal stream to a year round stream or at least have water in the ponds along the stream all year. This would be a strong indicator that I had successfully increased the water table.
From what I have read about how our area is expected to change overtime I would highly suggest that anyone living in this area plan for the winters to get wetter/warmer and for the summers to get dryer and hotter. If these predictions are accurate we have a major challenge on our hands to hold as much of the winter rains as possible for the summer months while not flooding or eroding our lands in the process.