Reduce soil erosion & rivers lost to deforestation
This article discusses using micro-capture to mitigate damaged and water scarcity suffering caused by deforestation. Deforestation can be the root cause behind many water scarcity situations. The solution is applicable in larger context where micro-weirs can be used to provide a reliable water source for people suffering from water scarcity even in areas with very little rainfall. The solution is best suited for rural and smaller villages where water scarcity is expensive to solve due to missing infrastructure and low incomes but at sufficient scale it can solve part of the problem for larger cities such as São Paulo.
Deforestation and Water Scarcity
Rhett Butler does a great job of describing how deforestation causes soil loss, high silt loads, ruined hydro-electric projects, silt filled reservoirs and downstream rivers that dry up. Deforestation causes the loss of tree roots which help hold soil together and slows water down so it can be absorbed. This causes the water to run off quickly with little being absorbed. Fast moving water rapidly erodes soil while down stream rivers flood during heavy rain and soon dry out.
A major impact from the loss of tress is loosing their ability to buffer and slow the flow of water which used to ensure consistent water availability down stream. Reduced infiltration in the deforested areas means there is less water available in the soil so new trees find it more difficult to survive.
Many of the areas affected are described with water scarcity but the real problem is they are loosing the water downstream before it can be used. This is tragic because it is relatively easy and relatively inexpensive to fix.
We need help from charities. We also need people who are affected and willing to try something new . Together we can help solve this man-made water scarcity problem while helping to restore the environment Joe Ellsworth.
Help the People affected by Deforestation
We are most interested in the farmers down stream who loose their ability to grow crops when they loose consistent access to water. In particular we are researching low impact ways to restore mitigate the impact of deforestation while also helping to improve the ability of poor rural farmers to survive in water scare regions.
Treating the real problem
The main impact of deforestation is reduced ability to buffer water causing rapid run-off then then the most direct solution is restore the ability to slow the runoff from deforested land. If we can slow the water then the soil that has eroded has a chance to settle.
If we can hold the water in place closer to where it falls then it has a chance to soak into the soil and eventually filter down and recharge aquifers. Increased soil moisture and pockets of retained soil create an opportunity for the forest to start to re-establish itself.
Enterprising farmers were able to use micro-capture approaches to support agriculture in the Negev desert over 1,000 years ago. The Negev is an incredibly dry area so if it works there a similar approach can work almost anywhere.
The concept is simple but how you approach implementing the solution can make it relatively easy or incredibly difficult.
Even in areas with very little rainfall the process can work. A storm that drops 15mm (0.59 inch) of rain only needs the rainfall from 70 square meters to fill the a 250 gallon reservoir for a micro-weir assuming some of the water soaks into the surface soil. This reservoir will refill very time it rains 15mm. If you are a philanthropist who want to help please contact us.
Micro-capture can solve the problem
Our approach seeks to slow the flow of water off these deforested areas by capturing the runoff in weirs (micro-reservoirs) each holding 250 to 3500 gallons. With enough of these micro-weirs we can capture the sediment currently being lost down river. The weirs can slow the water so it has as chance to soak into the ground water system. Since the average weir is less than 3 foot tall and they are made mostly by had using rocks and sand they are low cost and low impact.
Our hope is that by maximizing water absorbed into the ground while also slowing the flow of the water out of the affected region that it will restore more consistent flow to downstream rivers.
Our true motivation is that these micro capture reservoirs will eventually fill with silt and provide nice soil and consistent water for new trees to re-establish seed forests. The larger weirs can be used to grow wet crops like rice.
In very warm climates can be beneficial to add a floating barrier over the surface of the water to minimize evaporation losses since we want to maximize the amount of water that soaks into the ground. This can also be done by minimizing the surface area of the reservoir exposed to the air which would favor deeper reservoirs that cover more surface area.
In many locations it would be better to stop the deforestation in the first place but there are scenarios such as South Africa where deforestation was a deliberate choice because invasive species were actually reducing river flow via to massive Evapotranspiration losses. If we can’t stop the deforestation; we can alleviate some of the worst effects. Modern research from the FAO has indicated that water buffering effects of forests have sometimes been overstated. This may means that at sufficient scale our micro-weir program can deliver greater water buffering capacity than the forest did originally. We would rather see our approach added to the existing forest to increase the forests water buffering capacity.
We focused on smaller weirs because:
Small weirs can be constructed from mostly rocks and sand by hand. This means they can be built by the people who will receive the most immediate benefit. They can be inexpensive which allows a lot of them to be build.
It is important to impound the water as high on the hills as possible because this is where you want to retain the soil. Each well placed weir will eventually fill with damp soil which is ideal for starting the next generation of trees. We want lots of small pockets of trees scattered over the entire area.
Small weirs are well suited to have overflow form one fill the next. The water will percolate into the soil and eventually filter it’s way down hill in springs that are probably dried out now. The flow is delayed in a way similar to what was done by the forest tree roots.
By creating a series of weirs working from the higher elevation down the it allows storage of very large amounts of water at low risk and low cost. No single weir contains enough water to cause much damage so it also spreads the risk out. When water soaks in it tends to spread out in in the soil below it. We want lots of smaller infiltration zones recharging the aquifer rather than a single huge one.
Each layer of weirs as you work down the hillside retains more soil on the hill where you want it rather than having it end up clogging large reservoirs. This value along can pay for a very large micro-weir system because replacing or dredging out larger reservoirs is very expensive.
While this approach can help most immediately with areas that have significant deforestation problems it can also deliver similar benefits in many areas experiencing water scarcity.
How we help solve the problem.
A major problem with placing small weirs is figuring out where to put them. As a result many are placed in the most obvious spots in well defined valleys. This is OK but it is almost too late because the soil may have already been moved for miles. There is also such a large volume of water by that point that you need well engineered structures and large reservoirs to hold the content. These larger projects are fine and most likely beneficial but they are also quite expensive, highly political and they require long planning, approval and funding cycles. Since these sites already likely contain a creek or river they can be covered by wetland regulations which can further delay implementation.
We believe that we should catch the soil as close to the point of erosion as possible. We also think we should build the weirs on land that is normally dry and we want to keep them small enough that they can be built by hand using locally available materials such as rock and sand. This is the reason we choose a size range fro 250 to 3500 gallons.
Find the sites to install the small weirs can be challenging. Our solution is a new kind of software the allows a farmer, forest manager or erosion control officer to circle a small area of their land on a map and we will find all the locations where a small Weir would collect the amount of water they have targeted. Once they tell us how much rain falls in that region we can determine where to build the weirs. In very dry areas with little rainfall the weirs are farther apart. In areas with lots of rain the weirs are close together.
Our software uses NASA elevation data to determine where each drop of rain will most likely drain. It looks at elevation data in 30 meter squares by comparing elevations of surround squares it can figure the most probable drainage path. We can use this data with estimated absorption by ground to figure out where to place the micro-weirs.
It is actually better to model the weirs so that each major storm will fill the reservoir. That way we storm delivers fills the weirs and gives the water time to soak in before the next storm. The weir reservoirs can be smaller and there can be a larger number of them yielding more places for the forest to re-start. The exception condition may be strong but short monsoon climates where we need to model the storage based on a few weeks of rain because the storms arrive close together.
We can probably obtain a grant to finish building the software in the USA but need to find locations where the output would be used and useful. If you represent a charity or NGO please offer your assistance.
We need some enterprising farmers who have lost access to water due to deforestation who would be willing to give the weir idea a try. We need a group of users ready to use the system. Ideally several groups of users before we are likely to obtain the grant. If you know rural farmers in poor countries who would benefit from participating the please introduce us to them.
This approach can work for any location where you have a farmer who has lost access to water or is having crops fail due to drought. It works best if there are surrounding hills they could access or if their field is on a hill so we have natural flow paths for the water. If you know farmers in these conditions who would benefit please refer them to us.
A perfect scenario is a village nestled in a valley surrounded by hills they have legal access to use. If those hills are barren or sitting idle due to drought then even better. If the village has farmers unable to support their families due to reduced crop yields the system can be highly beneficial. If the village is facing problems with wells failing during the summer but still receives during some seasons and some years then the system can be a lifesaver. In this instance the village unites and may build several hundred to several thousand micro-weirs. The village farmers can plant drought tolerant forage trees in the upper weirs and use the lower weirs to support rice and fish farming. The main benefit to the village is the immense amount of water that is retained on the land and soaks into re-fill their aquifer. This may be enough to ensure wells that currently fail during the summer have enough water year round. 500 of the larger 3500 gallon weirs in an area that receives 500mm of rain can deliver 1.75 million gallons of water per storm to the the local aquifer. Assuming the average storm drops 20mm of rain only needs about 750 sq meter of land to capture that much water. The key of our software is we can show them where to build the micro-weirs for each 750 sq meter of land across the hills surrounding their village. If you know a village that could benefit then please introduce us. They are the perfect users who could help us obtain the grant to finish the software.
The next major steps are to build the web site using the NASA data and our algorithms so a person can pick a location, draw a box around their property, their village or their town, specify their criteria for weir size and show them where to build their micro-weirs. Please help if you have the means.
How farmers can use Micro-Reservoir System
By building The general idea is that they would install several dozen small weirs and a few large ones. in one ravine and then use a single larger one that now receives a slow but consistent flow. They can then grow rice and aquaculture fix in the larger weir.
- Fuel and Forage: They can grow fuel and forage trees in the upper weirs. This is critical because this concentration of water can deliver edible fodder even during sever droughts. This means they can keep their goat when other farmers are forced to sell at distressed prices.
- Food & Vegetables: They can grow vegetables around the middle weirs or grow bamboo to sell in the middle weirs.
- Water loving crops: The larger micro-weirs also provide little zones where flooded crops like rice can be grown and can support aquaculture. They may need to line the reservoir area with plastic to retain the water for fish but water tolerant forage trees like cottonwood and willow can just be planted in the reservoir area.
- Choose their shape: The farmer can tell the system if the want the smallest possible reservoir area or want to spread the water out. This allows them to choose the weir structure that fits their target crop. We tend to prefer perennial crops that produce edible fruits just in case the rains are late arriving.
- Personal Well: The micro-weirs are generally designed to allow water to percolate into the surrounding soil. The farmer has a choice to line several of their reservoirs with a water impermeable plastic or clay so that weir can retain the water for months. They can dig out the reservoir, add a roof and have a nice emergency supply of water during the next drought. We have found that burlap with lime, cement and sand make a very inexpensive matrix for cement so a 1/2″ layer is water-poof, very durable and fairly inexpensive for use in buried tanks.
Large Scale Benefits
- Installing weirs high and working down provides many benefits but the main hydraulic benefit is they increase the hydraulic pressure from the freshwater flowing down. In some locations this can reverse salt water intrusion into freshwater lenses of islands.
- Depending on the local aquifer water absorbed up in the deforested hills can flow for many miles to the wells servicing the city. This can increase the life and reduce pumping costs for municipal wells.
- Recharging local water tables is nearly always a good idea. At the very least it means people living in rural areas will experience failure of their wells or boreholes less often. This reduces the cost for the government and NGO to haul in water. In some locations the micro-weirs may be cheaper to install the micro-weirs that will work for decades than it is to haul in emergency water for a single summer. You do need to plan ahead but that is a small price to pay for massive savings.
- A dramatic reduction in silt load can be delivered inexpensively while also improving the quality of life for people living up stream. This can reduce the rate at which major reservoirs fill up with silt thus preserving their storage capacity. This preserves both their hydro-electric and water storage capacity. Building new reservoirs can cost billions of dollars while dredging silt out of existing reservoirs can also be very expensive. Stopping the silt upstream using micro-weirs is far less expensive.
- Villages can concentrate capital in ways single families can not. This means that villages can install hundreds of the larger weirs then pump them together to deliver pressurized water to the village stand pipes. This makes it easier to install secondary filters and even have a zone where water can be treated with ozone before dispensing so it comes out of the stand pipe with antiseptic qualities to help sterilize containers.
Helping poor farmers fund their Weirs
We would like to be able to help farmers who need new weirs build what they need. In many areas these farmers make less than $10 per day but they can not afford to take the time to build their weirs. It also helps to have a small amount of material like plastic film to line the weir so the water stays inside.
In many cases a small weir can be completed in a couple days. Even 3500 gallon weir can normally be completed in less than 3 days by 3 motivated able bodied workers. This places the cost for a large weir at about $90 in labor and probably $20 in supplies. A small weir can cost under $20 for labor and $8.00 in parts or $35 in parts for one used as a cistern. The cost changes by country or region so this is only a ballpark. It would be easier but not essential for them to have a large wheeled cart to help carry the rocks.
We think the process will scale best if one farmer can obtain a grant to build his 10 or 15 weirs so he can afford to pay himself and a couple neighbors to do the work. Then his neighbors can get their grants and build their own.
We would like to build a brokerage where villages, farmers and small cities can post their project. Show where they want to build their weirs and describe why they need them. They will hopefully include use cases showing some of the people they will help. The brokerage will provide the meeting ground where people in the USA interested in crowd funding can provide grants or low interest loans to build the project.
There are still lots of things to figure out such as how to deliver the money to the farmer. How to ensure they get a good deal on the supplies. How to help local charities introduce the farmer to the opportunity. How to track the work and report results. How to release the money only as they complete the prior weir. How to avoid abuse, How the farmer can pay back their loans, Where the process is legal or illegal, etc.
We will seek a grant to build the brokerage and integrate it into the maps. We would also seek a grant to start the process of reaching out to local churches and charities who can help promote and manage the program on a local basis. We see this as stage three. The first stage is to make the web site with the weir locator available while stage 2 is supporting as many languages as feasible from the site.
Please help us. We need grants to finish developing the software. Even more important we need referrals to farmers living in water scarcity areas where there is some rain. We may be able to help improve their ability to feed their families while solving some issues like soil erosion along the way.
Some areas are the easiest to fix.
The combination of reduced ground water absorption combined with fast runoff combine to destroy the livelihood of farms downstream who depend on a consistent supply of water. It was somewhat surprised when I started to receive inquiries for our larger A2WH machines from relatively rain rich areas like Mauritius, Columbia, Nicaragua and Brazil. After doing some research I found that even during drought conditions most of them receive adequate rain but man-made issues are casing them to loose water when it is available down stream and not have any left when it is needed.
Preventing deforestation would be best but since I don’t know how to stop that. The next best thing seems to be to deliver mitigating solutions that can deliver profound humanitarian benefits at a reasonable cost while establishing conditions to restore some of the damaged land.
The good thing about these areas is that a micro-capture process can help restore things quickly. because they receive a lot of rain. This allows the micro-weirs to refill their aquifers, drastically reduce soil erosion loss, level out river flows, Improve water availability during all seasons and reduce food insecurity during drought. In these rain rich climates this can happen quickly compared to deserts where it will take longer.
This requires getting the word out, Recruiting local churches and charities to help, Providing education and delivering our software to those who need it. In many cases it will actually be the local charity that coordinates and plans building he weirs but those charities need to know about the approach. If you can help then please do so.
Women walking for miles to obtain water
Our original mission started with the idea of delivering technlogy that could help women get out of the business of walking miles to obtain water. This is true for Women who stand in queues for hours to obtain water and those who can never sleep because they don’t now when water will be available.
We built some really cool technlogy to extract water from air but so far it has been too expensive and to bulky to deliver it where the women needed it. We still believe that women and especially children who are walking miles to obtain water is a horrible waste of human potential that nearly guarantees the female child pulled out of school to carry water will never escape poverty. If we can keep female teenagers in school they at least have chance of obtaining sufficient education that they can become engineers, nurses or doctors. This is essential to break the local poverty cycle.
The Micro Weir concept is our next installment in our ongoing quest to eliminate the need to for women to carry water. It will solve the problem in many areas even dry areas but it may not work in all areas more because of land rights than technlogy. If the woman is living in a village surrounded by hills then when the village builds their weirs it may fix her problem and if so it is the best solution because it solves the problem for many people.
Many of the affected women during could walk to a hill that is closer than their existing water source where they quite often walk 5km each way. They normally report needing to walk to obtain water during the dry season and they need an average of 6 gallons per day. Using 5 months for the dry season this means each woman needs about 900 gallons but lets round it up to 1,200 gallons to be safe. Even during the dry season most areas receive some rain but lets assume we need to store the full 1,200 gallons during the wet season. We need a drainage area covering 500 sq meter or 0.124 acres. for a storm that drops 10mm of rain to fill a 1,200 gallon reservoir depending on how much soaks into the surface soil. Using these numbers a single hill covering 50 acres could deliver water for 403 women even during the worst drought because even during a drought year most areas will receive at least one storm that delivers at least 10mm of rain.
Admittedly this water is not as clean as a well sanitized deep borehole managed by UN but there are lots of 50 acre hills and the UN water can be miles away with hours long lines. The water is certainly cleaner than pulling it out of a random puddle that may be 10 meters from a latrine and it will generally be above the village so contaminated affluent will be less likely to enter her cistern. By adding a relatively inexpensive filter it will be safer than most of her alternative water sources. It will be reliably available even during extreme drought. She may still need to walk but hopefully a much shorter distance.
Our software can show them every near-by location where they could build a 3500 gallon weir that is closer than the water source they currently use. Many of these 3500 gallon weirs can be built in 3 days by 3 able bodied workers but lets be conservative and say it will take the single woman 30 days to build her weir. The magic of the software is use the natural land profile so you don’t have to do as much work.
To make this possible we need to provide her with 6 gallons of water per day for 30 days while she builds her Weir and tank. She will also need about $220 in materials although that can be reduced. We also need to ensure the village can grant the access for her to use the hill and that we can preserve her right to use the reservoir she constructs for several years. Perhaps the hardest aspect will be how to ensure her water is not stolen. All of these things represent work and would need local charity help
Her weir is a little different because we want to retain all the water up to 1200 gallons and we want to keep it as clean as possible. We need a 1200 gallon tank that is probably 1 meter deep by 4.6 meter long and 1 meter tall. We estimate the woman can build such a tank using our burlap and cement lamination technique for a cost under $120 in materials. Using a 6 mill plastic liner would be cheaper but not last as long. The lid for the tank could be made using simple sand casting techniques and our burlap cement matrix. She would need a simple screen to keep the worst debris out of the tank and a spillway to handle overflow. In an idea system we would have her weir able to hold another 3,000 gallons in addition to the tank so she could grows some vegetables right around the weir. We would love to see the tank treated with a solar powered ozone trickle along with a good filter before the water is allowed into the tank but that would add $120 to the cost and we would still need a final filter. I would prefer an inexpensive string wound filter followed by a 1 micron water cartridge followed by a quality backpacking filter. In reality the backpacking filter should be adequate although it’s life could be extended by pre-filtering. Assume the filter will need to be replaced once a year at a cost of $15.00.
- Extending the software to analyze the land surrounding the Weir candidates to try and find the location where a small move of the weir could retain the water with a smaller structure.
- We also need to enhance the software to understand typical infiltration so we can deduct that from runoff water estimates.
- Augment the data source to include average storm rainfall data where possible so users do not need to provide it.
- The NASA data is good it could still be better. We can build drone planes that gather the elevation data using ground based radar at a much finer resolution and even more accurate heights. A key value is low level drone can yield better data for true ground level rather than canopy level. A small drone can gather the needed data for a village sized area in a couple days but it takes fairly specialized systems that do not currently exist off the shelf. We can develop this drone but it will require considerable effort and lots of testing.
- One question is do you have any idea who owns the land shown in the plane view of deforestation caused soil erosion in Madagascar? Some of our ideas work best when farmers willing to put it the effort could use that land. It is a win, win because it slows soil erosion while helping recharge the water table. Inturn the framer gets a crop they probably could not have obtained otherwise due to lack of water.
I tried to order these most important first.
- Micro-catchment water harvesting potential of an arid environment
- Micro-catchment water harvesting for desert revegetation
- Micro catchment used in Negev desert to allow farming in desert
- Enhancing Sustainable Production at the Landscape Level by CRS.org these guys are using these techniques at fairly large scale. Great picture of the kind of micro-levee I had in mind.
- Green Water management handbook rainwater harvesting for agricultural production and ecological sustainability
- Water Harvesting and Soil moisture retention – Similar thinking to my own but I disagree with their premise of doing the harvesting on the hills. You want to slow the water down falling down the hills so you have a chance to use it.
- Micro Basins quick overview
- Water harvesting techniques for sustainable water resources management in catchments area During wet season Cimanuk River in West Java where water shortages are common has a flow as high a 600 cubic meter per second and only 20 cubic meter per second during the dry season. This represents 36 million liters per minute of water. Some of this could have been retained upstream and used to recharge the water table.
- FAO water catchment several techniques.
- Runoff farming manual and guide
- Good description of mechanical ways to reduce soil erosion from new zealand.
- An easy introduction to deforestation and how it causes soil loss and river loss.
Thanks Joe Ellsworth
CTO of Air Solar Water