I feel totally lost with my hole that i dug on karst earth. Please help!

It is often said to just do things instead of getting lost
reading things, so my excavator friend did something and now
i do not know how to handle things.

So i will try to elaborate as detailed as i can what the situation is,
and i really hope i can be pointed into the right direction:

First of all, i tried to find some literature on creating/maintaining springs ( https://permies.com/t/135539/Book-water )
with some fine books suggested (thanks again here), but none of it deals with springs,
expect for one figure in Brad Lancasters "Harvesting Rainwater for Dryland and Beyond", Volume 2, 2nd Edition
on one page.

These few senteces in the book are replicated here for reference,
as my site is geographically very similar to what is pictured in the book:


Now to my site, it is located in the mediterrean just little less than a mile
north-east from the adria between two mountains rather close to the valley bottom.



Usually croatias coastal areas are very dry and rocky .
Geologists refer to it as Karst (see https://en.wikipedia.org/wiki/Karst )
Few species can make it through the summer, which are hot and dry.
When there is rain in Summer, it a lot in a short time.
Winter rains however are ample.

In earlier times croatians build rock terraces to be able to hold debris and farm
at least a litte, but most calories came from fish and plants that thrive with litte earth and water
like figs or grapes.

So the area pictured here is somewhat exceptional as it is a valley bottom so the runoff from the
surrounding mountins accumulates making it grow green grass even in the summer.

However the habit of building terraces to hold dirt is also practiced here, as the upslope sides
of the roads are fortified with dry-stone walls - usually around one metre high - and have earth accumulated
to the height of the wall. There are also dry-stone walls between some parcels to gain more level ground.

So historically this place was one of the more fertile stripes of land in the area,
but as most food is imported from the easier to farm countryside this land is used as pasture for cow and goats.
(Damn those goats! Ate my damn raspberries! )

Current trees and shrubs are mostly some hardy trees of the Acer genus,oaks, common hornbeam, blackthorn, a lot of blackberries and some dogrose.
Occasionally there is a fig, persian walnut or a grape. Ground cover is mostly grass with some clover, dandelion and crocus.

In summer my earth was dry and hard. Like in "broke-my-shovel-hard" hard.
As there is this slope and the earth is hard ground the water rushes just over it in the big rain events.

So the perliminary goal of my actions was to do some earthworks that would allow,
to have more humidity in the earth. My parcel is a little less than 1/4 acre so my options are limited.





We did a test dig with an excavator in august this year that i will dub "Excavation site 1",
to see how deep the earth is before we hit rock bottom. We gave up after about 1,5 metres
as the earth was so hard/compacted that the excavator only digged out a handful of earth in each pass at this depth.
However the earth (more like reddish clay) was glossy from humidity at this depth, which is cool, as this means
that the correct trees can access water even in summer.
Also it was really hard and smooth where the excavator passed, sort of impossible to scratch with fingernails.

As we had some rain lately the hole filled up:




So fast forward to recent events:

My excavator friend visited me again and was eager to start digging.
The most obvious thing to do, was to dig a hole in the uppermost part of the property where the water from the nothern parcel overflows.
This northern parcel is seperated from mine with a dry-stone wall and about 2" higher in elevation than my parcel.
I dub this hole "Excavation site 3" (sorry for misleading nomenclature), and the earth we found there was totally different than in the other hole:
Firstly it had a thicker distinctive black layer of topsoil (around 20 centimetres) and below was brown soil,
which does not seem to have such a high clay content. I will probably just sink some sort of rainbarrel there
to catch water for irrigation purposes.


My excavator friend wanted to dig more holes,
so encouraged by the experience with excavation site 1 (holding water) we started digging a hole
in a existing depression to get a small pond.

This depression was a mistery to me since i bought the parcel,
i even had sleepless night thinking about whether it could be a former riverbed from ancient times
that has filled up with sediment when the romans cut down the area maybe 2000 years ago.

When you look at the satellite picture where i marked "Excavation site 2" you see a small slghty darker
stripe that is about 1-2 metres wide and slightly deeper
than the surrounding area. It is proturding about 20 metres from "excavation site 2" to the
nort-west-west before it hits a dry-stone-wall/road, where the
road is about one metre below the parcels elevation.
The depression also proturdes a couple of metres to south-east-east from "excavation site 2"
right TROUGH the treegroup/dry stone wall that is the border between my parcel and the neighbor.
So the depression is probably not man-made.

So yeah, big mistery...but still it seemed like the best spot for a litte pond.

So here are pictures right before we started digging:





Unlike the earlier excavation, this site had almost no rocks in it, despite being
only 10 metres away. And after only 70 centimetres we hit a yelowish clay layer.
Usually we have red-brown earth with high clay content, so this is the next strange thing.
From what i can tell, this is the type of clay you want so seal you pond with,
i could easily form little "sausages" with it.

After another pass of the excavator the upslope(nothern) side of the hole suddenly had water shooting through it:






It came from between these rocks:



After some time the water stopped flowing, however if we removed some
of it, it started flowing again.
As i remeber Seep Holzer saying in one of his videos that a small spring
is really easy to lose with the wrong actions we stopped excavating here.

So here i am...lost and confsed, wondering if i already fucked up, or what the next
step should be.



I am aware that you cannot answer my questions via internet, but still i want to state them here:

Is the hole in excavation site 1 watertight and does hold rainwater, or is it fed from somewhere else in the area,
i.e. does it reflect the current groundwater table after the big rain evetns we had lately?

Are the rocks in Excavation site 2 a spring? If so, how can i make it useable?

PS: The subforum "ponds" does not seem right to me, but i is the closest i found.

Have you spoken with any old timers in the area?
They may be very helpful.

John C Daley wrote:Have you spoken with any old timers in the area?

Yeah, they remember that some decades ago the land was worked and there were no trees.
They also said what will thrive here (Figs, Olive, Almonds, Apricots, Cherry) and that
Plums won`t work as there is not enough humidity.
If i want to plant potatoes, i would have to get them out of the earth by July, otherwise they will be cooked (in the earth).

Every single person i spoke with also told me to get rid of the volunteer trees that are sprouting all over the place,
and to rip out the medium-sized trees and the shrubs as they are "worthless" and will "mess up" my place.
Usually they would tear off some twigs/leaves of the trees while saying this, while i was biting my tongue not to comment
that action (internal voice:"NOOO!!! STOP IT!!! I VALUE THIS VEGETATION!").
The area was mowed every year before i took control of it, which why there where no volunteer trees before.
I personally value those volunteers as i think they will help shade the earth and their roots will help the water to penetrate.

But those old-timers where childern when the land was worked, it has been pasture for decades.

Regarding humidity, i was told that the adjacent valley in the north-east is more humid and even forms dew.
(there is a river flowing through that other valley and it is farmed, mostly with grapes)

So now looking at a heightmap and seeing the existing water features there,
there former riverbed theory seems not impossible as an explanation of the misterious depression in the area.

My background in Australia is Civil Engineering.
That makes me inquisitive.
Where is you land actually located I may do some research as well.
How big is the depression you speak of? And why do you think its a river bed?
Archeologists may have better information.
Are there properties set up in a similar way in the same area?
Do you plan to live there or just grow food?
regards

I see you are in Croatia, where its very dry. Is that correct?

For what its worth, I dont think you damaged a spring.

More likely, you found a shallow underground runoff.

It might mean you could have a wet weather pond in that spot, but it would likely dry up some (or all) in summer.

You have both contour and soil types to experiment with. Have fun with it. Keep going and trust your instincts. Paul's video on world domination gardening has enough info to give direction on both. I recommend it.

And I love your take on the volunteers trees. But do look around and see which ones take over but dont produce food. Got autumn olive?

All the best

Where I live and have grown up, here in the southeastern USA its very common to dig out a spring by hand and build a spring house to protect it. The spring house can be a sort of catchment for the water. Sometimes springs are not much more than a seep, but if dug out (usually by hand) they can be harvested using a spring house and a cistern.

Your old timers are telling you the truth about the trees that aren't producing. I tend to keep a few hardwoods for shade, but I clear most of the trees and plant trees that are fruit and nut producers. Those old timers are just looking at available space.

I've also come across some of these spring like features when digging some small earthworks, and I always get excited when I see them.

Sometimes water would come up from the bottom, as I reached a depth that I'm guessing water flowed underground. Other times I would hit a spring like area when digging out the side, and water would just start trickling out at a pretty steady pace until it eventually slowed down or filled up the small pool.

Looks like a really neat piece of land, best of luck!

I find springs and groundwater confusing too. If you dig too deep, you can lose water because it can find a way deeper into the rocks. Then one has created the situation that you lose water that would otherwise seep through the soil on terrain below the dug hole. Seal it well at all times i guess. People use pigs for that if that's any help.
A spring would be ideal. My understanding is that if you hit one it is water coming to the surface under pressure from higher areas. They can keep going all summer and when harvested at all times they can blow out all the debris that is blocking the "pipes" and become stronger. That would be a jackpot. I guess that's what you're looking for. Ideally high at your terrain, in that case you could use it to create a meandering stream of interconnected ponds feeding own surrounding soil as long as the spring keeps feeding it. Shade out the ponds and blocking winds will be helpful stretch their existence into the hot summer. Any interesting nitrogenfixing shrubs you can plant like Goumi and Seabuckthorn? Maybe Italian Alder, which can withstand more drought than regular Alders..
Any way i don't agree with the elders at all that you have to cut all the trees which don't produce fruits or nuts. They attract wildlife,insects, birds and all which will fertilize your land. Some shrubs might be annoying, like Maythorn or Sloaberry, for their thorns which can puncture tires, but they're good to keep wild animals out of places where you grow trees in the middle of them. Maythorn known as the oakmother in middle ages in England, removing it was punishable by being whipped.
As well you can use trees for firewood and if no need use them to chop n drop or make wood chips. As well they suck up water from deeper layers and sweat it out through their leaves. Meanwhile bonding with mycelia and feeding soil life while blocking sun and wind..Trees produce soil. Good luck..

So i feel like i should give some updates on what happened since last october.

John C Daley wrote:I see you are in Croatia, where its very dry. Is that correct?

It depends what you call dry...there is over 2 metres of rain, which comes reliably every year.

However its distribution over the year is not so reliable. This year we had quite some rain late into may with a 40 day Drought+Heatwave in june,
and moderate rainfalls afterwards. This is considered a wet summer, it is not unusual to have no rain for serveral months during the summer.
When it rains, there is chance that it rains a lot, especially in winter.

Now you think of croatia as a dry country, because of its geology.
Most of the coastal area is bedrock only slightly covered with a little soil, if there is soil at all.
Said bedrock ist karst, therefore any water that reaches it will perculate through the ground and either show up(unfiltered!) somewhere else in the landscape,
or run into the adria.

So yeah most of coastal croatia is bone dry during the summer, but i am in a special location.
Karst geology features very fertile valleys called "dolina" (pl. doline). Sediment accumulates there resulting in paritally extremly deep soils.
I am located in such a valley.

So i have enough dirt to turn into soil to hold water.
Currently water pools on the surface and runns of.
Note that the water in the following pictures is actually flowing downslope!
This is not "standig water", it is moving, but the is so munch of it coming from upslope that it
gives the impression it is standing.





Also note that axcavation site 1 & 2 totally fill up with water during those winter rain events.
I have yet to measure for how long they hold water, but i think i remember it being filled for a good part of the winter,
but it also rained for a good part of the winter.





Excavation site 1 & 2 fill up to the rim with water when it rains heavily,
while excavation site 3 drains faster. Excavation site 3 surrounded by trees and there is generally softer more forrest-like soil.
The soil also seemed to have less clay and almost no rocks in it, compared to excvation site 1 & 2.


I have also hand dug a small hole to be sure it is not groundwater-table. The earth was moist, but it filled with water from the surface.
The presence of wells indicates a clay layer, as can be seen in the pictures of Excavation site 2.

So basically every hole i dig will fill with water and should help to charge the groundwater table.

Also after some thinking i realised that diggin excavation site 2 was probably the biggest mistake i made on the plot (so far).
It was already an depression, so water an debris should have accumulated there, creating the most fertile spot on the plot.
And idiot me had it dug up to the clay layer.

Furthermore i should have listened to the landscape/vegetation more. The are just upslope of excavation site 2 seems a bit wetter
then the rest, as there were mosses growing. Now i suppose that there is a shallow clay layer which used to hold water close to the surface,
but i damaged the layer downslope effectively draining this feature.

I am seriously considering throwing some dirt back into excavation site 2.

2 metres of rain, wow!
We get about 500mm.
Filling in excavation spot #2 can be done, a lesson learned.
There are a few ideas that come to mind;
- have you got a general plan for what you want to create on the land?

If you want to retain moisture on the property these concepts will help.
- contour plough the land to create small openings  and bumps in the soil to catch, and hold flowing water.
- consider growing vetch on the contours to again create catch dams for soil and water