Kevin Elmore wrote:Jim,
How big is your property? Surely you can direct more water into a pond than what lands on your roof. I don't know if your rainfall info is right or not, but another question is how much irrigation water will you require during the year.
Michael Cox wrote:Without speaking to your pond sizing, you might take a look at what water you can divert from above your property line to feed your pond. Look for where water might run down a road, or a contour where you could put a slightly off contour swale/ditch to divert surface flow towards your pond. I'm pretty sure that Hemenway's book looks at things like harvesting water from roads before it is lost into drains. Any hard surface can be used to collect water; not just a roof line.
Do you notice flowing surface water during heavy rains?
Angela Aragon wrote:Jim. Drip irrigation typically is done for finite periods in the early morning and late afternoon to maximize soakage and minimize evaporation. For example, you might run a schedule of 2 X per day for 30 minutes each. That is one hour of water use per day. How much you use during that hour depends upon the system you put in (size of tubing; number of ports) and the drip rate you set.
I was planning on building a pond on my property to run a drip irrigation setup until I considered that, for about the same cost, I could put in a couple of large water tanks. So far, it is working fine and I have not had to worry about pond leakage or evaporation.
Your situation might be different. In my case, I focused first on things that would maximize water retention in the area where i put my market garden - putting rows on contour, using compost to create raised planting beds, etc. My rows on contour are for access, not planting. This creates the effect of having mini-swales. This strategy has enabled me to run my drip irrigation setup at a relatively low drip rate and conserve water.
Caveat: I only have had this going for a year, so it is too early to pronounce it a success. However, I am optimistic .
Gilbert Fritz wrote:It is unlikely that a whole year's water would be available to put into the pond at any given time; water would be used/ evaporated continuously. So you would have to calculate average inputs/ outputs month by month and see what the largest cumulative total would be, and then add some extra to account for unforeseen events.
carly bee wrote:look into data that local agencies have collected- NC state research/extension, local NRCS office, etc. you may need to adapt to permaculture concepts, but the data and equations available through these public agencies should help with sizing. nc state in particular is known for being pretty progressive (in SE) in the designed-ponds field (rainwater/retention ponds, etc.)
maybe this will help you get started http://iswm.nctcog.org/training/Ponds_Class_082913/Ponds_handouts_combined.pdf