Design for Aveleiras – Part 1: Scale maps and climate data

The first stage in the permaculture design process is to understand what you have, and for this purpose I have drawn up a scaled garden map for the top terraces (I will follow-up with a full-map on our next visit), and researched climate data for the area.

Month max temp. min temp. Sunshine (hours) Rainfall (mm) Days of rainfall Monthly mean wind speed
Jan 14.5 2.7 93.5 37.3 10 6.7
Feb 16.4 3.9 75.5 74.8 9 9.2
Mar 19.3 4.6 90.5 76.7 7 8.7
Apr 20.7 6.7 107.5 14 8 8.7
May 23.8 9.4 101.3 89.8 7 8.3
Jun 28.4 12.3 135.8 13.8 3 10.5
Jul 32 14 154 5.8 1 9.8
Aug 32.2 13.6 149.3 4.2 1 9.8
Sep 29.5 12 116 17.1 4 8.9
Oct 23.7 9.4 85 56.2 8 7.8
Nov 18.4 6.2 70.5 89.5 8 8.1
Dec 15.3 4.6 78.3 47 10 7.8
Annual 32.2 2.7 1194.7 526.2 76 6.1

In general there is hot, dry summers and cooler, wet winters, so water storage will be important. This will be done in two ways – the first is storing water from roof spaces in tanks to be used for intensive vegetables, seedlings etc. during the summer. The following chart highlights the seasonal water harvest possible. Assuming the vast majority of tanked water will be needed only in summer, tank capacities can be calculated to ensure they cope with the rainfall but are not too large, wasting both space and the resources needed to produce the tanks.

Water capture (L):
Month Rainfall (mm) Main roof Flat roof Outbuildings Total
Jan 37.3 1440 506 399 2346
Feb 74.8 2888 1015 801 4704
Mar 76.7 2961 1041 821 4823
Apr 14 541 190 150 880
May 89.8 3467 1218 961 5647
Jun 13.8 533 187 148 868
Jul 5.8 224 79 62 365
Aug 4.2 162 57 45 264
Sep 17.1 660 232 183 1075
Oct 56.2 2170 762 602 3534
Nov 89.5 3456 1214 958 5628
Dec 47 1815 638 503 2956
Annual 526.2 20317 7139 5634 33090

It’s often surprising just how much water capture is possible even with modest roof sizes. The calculation above is roof space (m2) x rainfall (mm) x runoff coefficient = amount captured (L). The runoff coefficient is determined by the material the water in harvested from. In the above case it is a tiled roof, estimated to be 0.9 (90% of rain falling on roof will run-off into gutters, rest will evaporate etc.). If you were harvesting from a lawn (perhaps storing the water in a pond) simply substitute roof space with lawn space, and the runoff coefficient will be around 0.60, depending on the rain falls (the heavier the rain the bigger percentage of rain will runoff, hotter weather = higher evaporation rate so lower runoff coefficient). A few common coefficients are highlighted here.

The best place to store water, for the purposes of a healthy landscape and food production, is undoubtably in the soil. Plant roots will slow the groundwater flow, reaching down to access water that may have fallen months ago. Earthworks, such as swales/ditches and ponds help water infiltrate into the soil, rather than run over as sheet flow. This will hydrate the landscape and can even negate the need for any additional irrigation in some cases, particularly trees that have deeper roots. Seedlings and shallow-rooted plants will always struggle in drought so some collection in tanks is still nessecary depending on your needs. The additional bonus is less flood damage, as by increasing percolation rates through tree planting or earthworks creation you will slow down the water flow.

To determine the best water capture strategy I have been using the bible of water storage – Brad Lancasters amazing book Rainwater Harvesting. He also has a website – https://www.harvestingrainwater.com/ – with plenty of his knowledge and guidance readily shared. Alongside our water tanks we plan to have several ponds, as a great wildlife habitat and peaceful area to sit and ponder, while slowly hydrating the surrounding trees and plants. A series of swales will link the ponds and water tanks via the fruit trees, ensuring maximum irrigation is done with very little input. The linked system will aerate the ponds and at times create the lovely sound of flowing water. To minimise evaporation swales will be mulched with forest debris (leaves, sticks etc.), also allowing easy access over them so they can double up as pathways.

The finer details of the water system will be decided after more observation on the ground, but the rough idea is highlighted visually below. Beyond a solar-powered pump, hopefully used just once a week, the entire system will be gravity-fed and made using earthworks to negate needs for any pipes. Sheet-water flow from rain higher up the hill will also be diverted into this irrigation system.

Water map

Scale map

As mentioned we currently have mapped just the top few terraces accurately, as these will be the main areas for more labour-intensive pursuits such as annual vegetables, cottage garden, raising seedlings etc.

Scaled garden map (opens in new window)

Now the outline is there, and permanent features such as trees to be retained, buildings etc. are highlighted, I can calculate where to place design elements such as ponds, water tanks, veg beds, fruit trees, pathways etc. in a way such that our physical effort is minimised and production, biodiversity and joy are maximised. By this I mean companion planting, linked habitats (wildlife likes to move, need to consider the basic needs of food and shelter!), quiet areas, easy access to places visited often, visual shield from less desired views and many other considerations. Better to make these choices now before even lifting a spade, to save having to change things later. Of course the design will evolve over time, but if I have a general feel in the back of my mind my current actions won’t get in the way of future plans.

The next stage is concept designs for the different areas of the garden – for instance we’d love a forest garden (fruit trees interplanted with ground cover plants, climbers, and herbs – an edible garden mimicking a woodland structure) above the house and a cottage garden (beautiful flower displays rich in interest for insects intermingled with edible plants for us) to the west, as this is the entrance to our home. Meandering paths will help slow down our pace of life, while a shaded corridor (roses and fruit climbers) will still ensure easy access to the house for when speed is more essential! More blog updates will follow with these individual areas, and our initial thoughts, advice and comments welcomed!

We will also be doing lots of research on the species we want to plant, after all here in the Lake District we contend with high rainfall, cool wet summers and long winters, a far cry from summer drought and mild winters. The real work will of course be in real-life observation, trials and evaluation, but books and websites always offer a fantastic starting point for those of us (me included) not wishing to spend our days reinventing wheels.

Please stay in touch and use the comments section below to ask more about anything that sparked some curiosity within – I have whistled through many concepts that may be alien, or (small probability, no higher than 95%) I may have even made some mistakes!

 

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