Help with dam placement.

I have a topographical map of the site https://www.dropbox.com/s/f4ep7v8czuz2s31/halihazir_egrili_tum.pdf?dl=0
I have also attached it below.

İ want about 9000 cubic meters of water storage. I'm thinking of building 2 ponds and 1 dam also back folded swales around every 13 meters.

I have to build them because we only get about 300 mm rain per year (mostly flash floods) and I want to grow food crops and fruit trees in a forest garden. There is no other water source. Also I would like to create a habitat for birds frogs etc..

What are your ideas? Any advise will be apprecitated.

I failed to mention that the flood water enters the property at the top in the North. And I want to passively irrigate my crops and flood my swales via the dam . So here is how I would roughly do this. http://imgur.com/dOSUVXr

The coordinates of the site 35.260567,33.229861

Ok, so your water flows from north to south.
Is this some type of creek bed or hollow?
The west side seem to rise steeply, so does the southern east side.

Flood water feeding in at 266.62

Dam 264.55 to 264.84

West spillway to west pont 265
East spillway to east pond 265.27

West pond around 264.73
East pond around 265.44

crops
264.84 to 264.68

What I do not understand is you only have around two feet from level of flood water feeding in to the area you plan to dam.
For every foot you increase the height of the dam you will be flooding land above you.
So we are talking some really shallow dams here.

Ponds are about the same level as the crops. So you have to pump water, unless you are depending on dam and ponds providing enough soil moisture.

You could dig a pond at the dam and sink some concrete boxes to anchor each side of the dam. This would let you hold water at the dam itself in a pond.
This would let you use wind or solar to pump water uphill to a water trough or connected barrels. You have enough ground on the east side to put up a posts to hold a water tank or barrels five to six feet above the ground. You can then use gravity flow to your plants.

If the flood flow is high enough you could use a ram pump.

One thing I do not see is spillway for overflow. Where does water go when dam is full and lots more flood water is still coming. Need a way to divert around your crops.

Alex,

My guess is that the topo numbers are in meters since he is in Cyprus. Definitely more depth than you first assumed, but the rest of your thoughts are still on target.

Yusuf,

I like the concept of swales that you show. They should help to slow, spread, and soak water into the soil.

A couple of questions I have after looking at the site in Google Earth:

1. Was this depression formed by machinery sometime in the past?
2. How does water cross the north road? Low water crossing or a culvert?
3. How does w ater leave the property to the south? Looks like white rocks damning the exit chanel.

Kevin

Could someone make a graphic of the dam placement? Thanks!

Hello Kevin

Here's a picture of the North side. Theres a concrete structure where the land ends in the north I can only imagine it was built for erosion control. Right above the concrete structure is the road. This is where the water runs into the site. No culvert. Hasn't been any water running into the site from here this year as it's been a drought year. Heres a picture.

I don't believe the depression was created by machines. A local fellow said the villagers used to wash their clothes in the water on the land right by the concrete structure. No sign of that water now. Although it does look like water has come through here at some point. You can clearly see its path.

Also looked at Old satellite pictures through Google earth. Lots of evidence of water flow. I have personally been observing the land since September 2015

There is the same concrete structure on the south side of the property where the water exits. Heres a picture

Hi Alex

I want to use 265 on both sides as a spillway. I'm thinking of diverting extra flow of water in to ponds on each side and the off the land via exit in South along 265.

To achieve the dam storage I want to excavate and dig down to make my dam deep and narrow to minimise evaporation. This is how I will solve the small difference in height between the water entrance and dam depth.

Not entirely sure how I will divert the water into the dam/pond completely yet. Any ideas on the best way to do this.

Back flooding swales is critical as soil is a vertisol. It is important to keep moisture levels optimal in soil as it is prone to deep cracking which would damage tree roots.

Our aim is to turn this over grazed over worked barren land into an abundant system.

Yusuf,

Thanks for the pictures as they really help to see what the concrete looks like. I think you are correct that they were placed for erosion control. Looking at the area around you in Google Earth it is clear the there has been erosion control work going on for a LOOOOONG time in the area. Everything is placed along the channels to slow down the water. When you follow your drainage south for ~1.4 miles there is a large stand of trees growing. Have you ever been down to see what type of tree they are? Obviously they can grow in your area and might be useful in your forest as well.

You might think about excavating for your pond immediately below the northernmost concrete dam so your water is impounded as high on your property as possible. The upper concrete dam will help break up the energy of flowing water, and gravel/silts should settle out of water to the north of the concrete dam before flowing into your pond.

Are your topo numbers in meters like I thought? Just want to make sure.

Kevin

Now that I know what you are trying let me throw you a curve.
During flood water you will get high volume and likely silt and particulates.
This ground looks really played out.
It is possible to divert particulate laden water to area where silt and particulates can settle out.
think of terraced rice paddies.
It may be possible to divert the lower layer of water where the particulates will be to shallow pond or terraces so you can build up layers.
Thing how old gold boxes diverted bottom flow.

The other way is just to let dam fill with silt and stuff than after flood waters pump muck to your terraces or plant rows.

Since your map is likely metric you should have enough room on the east side for terraces.
You can build a water wheel that will use the flood flow to raise water to a higher height for your terraces.
A good water wheel can move silty water also. So long as you can keep the flow up enough to keep particulates from settling till they get to your terraces.

If not build the terraces, pump the muck.

Well there are methods using terraces, sediment basins, etc. that may help.
Erosion seems to be an issue in your area from the pictures.


Native American methods for conservation and restoration of semiarid ephemeral streams
http://www.uwyo.edu/esm/faculty-and-staff/norton/papers/norton3.pdf

http://www.nazarethvillage.com/site-archaeology/terraces/

Introduction to Alley Farming
http://www.fao.org/wairdocs/ilri/x5545e/x5545e04.htm

Bench Terrace Design Made Simple
http://tucson.ars.ag.gov/isco/isco12/VolumeIV/BenchTerraceDesignMadeSimple.pdf

A review of the effect of terracing on erosion both pro and con views
http://eusoils.jrc.ec.europa.eu/projects/scape/uploads/103/Dorren_Rey.pdf

Sediment and Desilting basins
http://www.dot.ca.gov/hq/construc/stormwater/SC-02.doc

Design Manual for sedimentation control
http://www.osmre.gov/resources/library/ghm/designManual.pdf

Hi Kevin

Yes I also noticed the trees below the water channel.I actually took a hike along the channel to go see it.

It was planted about 15 years ago. It's donated land in honour of a teacher who died of cancer. I saw evidence of old drip irrigation lines which are all long gone. Mainly pine trees and some eucalyptus trees. They look like they are doing OK on their own. Which is good.

Yes I also want to collect the water in the North but not sure about the shape of it or how to excavate it exactly.

The topo map is in meters .

Thanks again

Have you looked at Brad Lancaster's book "Rainwater Harvesting for Drylands Volume 2"? It provides a great deal of information about various earthworks which can be made with hand tools.

http://www.harvestingrainwater.com/ lots of free info on website