So, an opportunity has opened up following recent big storms. We had a clump of large pine
trees blown down which made a right old mess but opened up a lot of light and
land that I could do "something" with.
Current land arrangement
This land is at the North east of the property, and is still partially shaded by the remaining trees to the south, although with the damage already done by the storm we would probably be able to take the rest down and replant with smaller fruit trees.Annoyingly it is not quite the highest point - the flat land where we do our veggies (it was leveled at some point in the distant past) is the absolute highest spot, so we can't gravity feed to water our annuals.The land slopes somewhere between 1 in 15 and 1 in 20Upslope is large conventional ag field - complete with poor soil, fertilisers, but due to the shape of the land rainwater catchment from the field doesn't look massive.The area is a crazy mix of selfseeded trees - mostly young willow which has been coppiced once, but also yew, elder, pine and ash. No trees that we would especially miss now the big pines are down. How do I go about killing off approximately 200 willow stumps so we can plant something more productive? We can't have livestock in this area at the moment because of all the yew.
The soil is quite clay rich in a thin layer, but once you dig deeper you hit chalk (we sit on a few hundred meters of chalk here) so rainfall that sinks in eventually disappears to the aquifer around 40m below. I'm not sure exactly how deep the clay/soil layer is here as I've never dug in this area of the garden.
Planning
My vague thinking at this point is to build a
pond near to highest boundary, but sufficiently far down that we can use a swale/ditch to direct rainfall from more of the property - currently water that is lost without servicing any of our productive areas. We'd probably get a
swale ditch/berm about 40m along the contour, to supply a dam that might have a length of around 10m.
Down slope of this I'd install a series of two or three staggered swale/berms and establish a larger fruit orchard and perennial garden area.
The pond itself could house ducks + fish, and provide gravity feed irrigation to the fruit orchard below, as well as drinking water for livestock in a field below the orchard area. For a lot of the year no irrigation is needed here in the damp uk, but in the summer months we often irrigate using sprinklers - very time and water inefficient. We already have a borehole to supply drinking and irrigation water from the deep aquifer so when we need to irrigate this section of the garden I could simply pump bore water in and let the nutrient rich duck poo filled pond water overflow in to the swales (or use a buried pipe and valve in the dam wall).
Questions
There is no surface water in this area, other than that in lined ponds. The chalk does a good job of soaking everything away, so despite heavy rain and saturated top soils there is no surface water. In the bottom of the valley is a woe-water river, which is spring fed from the aquifers when they are sufficiently charged. This is a good half mile from our property and a long way down hill.
Do we have a hope of being able to sufficiently water proof this pond to be able to hold water year round, or does the chalk beneath rule out dam construction?How do I tell if the soil there is of sufficient quality to form a good wall/seal. I presume I need a certain ratio of clay? Our soil also has odd chunks of flint and chalk.Should I just plan to use a pond liner from the outset? The whole area will not be massive I think.