Water management through decentralization, harvesting, cleaning and ‘down-up distribution’. Survival on Earth, begins and ends with water, its usage and the responsibility of maintaining it as a resource available to all. Solving the problem of managing water, would be a starting point to getting around to all the other massively ‘wicked problems’ of the world.
I was thirsty today while out grocery shopping. I was hesitant to get myself water until I got home, where drinking water is run through a particulate filter, carbon filters, chemical filters, UV light, boiled and finally put through a ceramic filter. Call our family paranoid, but even after all this, the water still holds a very faint taste and calcifies the electric kettle.
This, in a city where water is brought in from various reservoirs, treated and then piped to users. Its all very organized, given the scale of distribution and the numerous points of leakage and seepage.
Imagine the plight of people who don’t have access to treated and filtered water. The problems with our current sources of water are many.
- Rivers & streams: Polluted by effluents and dirty runoff (see: Top 10 most polluted)
- Reservoirs, lakes and ponds: Accumulation points for poisons, garbage, human and animal waste (see: An article on this)
- Groundwater: Concentration of chemicals due to industrial and agricultural runoff (See: Wikipedia & read this)
Essential to all people and animals.
The most convenient and inexpensive way to get ‘nearly’ pure water is from rain. Massively distributed rainwater harvesting could be the way to quickly bring usable drinking water to every individual, with enough left over for animals.
Think about how grid-tied consumer solar/wind systems work. Now extrapolate this to water. If every house, building, rooftop or elevated surface were to necessarily capture rainwater (after a built in first-rain flush), enough could possibly be saved for everyone’s needs. Consider this: A tiny 45 square meter roof (~484 sq ft), could capture a good 35,375 liters (9,345 gallons) of water, even in an arid region with minimal rainfall of up to 500 ml (~30 cubic in); places like Central Texas (US), Central Rajasthan (India), Almería (Spain), Western New South Wales (Australia), The Sahel Belt (Africa) and Northwestern Argentina (South America).
Napkin calculations: A person requires approximately two liters of water a day. Assume everyone’s really thirsty all the time and consumes three liters of water a day; then, each person would require about 1,100 liters of water a year. Even if one-third of all rooftop water is wasted, a 45 square meter roof/surface could adequately supply drinking water to 21 people for a year. To sort out the entire world’s current drinking water needs, we’d require 349,820,714 roofs (45 sq ft). Rounded, that’s 350 million rooftops of a mere 45 sq mtrs needed.
India alone may have 45.6 m usable residential roofs (244,688,900 occupied residences of which 62% are concrete/pacca; SRC). If we assume 30% of concrete structures have roofs (with the remaining being assumed as apartments) we arrive at 45.6 m residential roofs.
Globally, I believe we’d have 350 m residential rooftops to average out to the requirement and meet the need with a low criterion of 500 ml average rainfall. Consider that, rainwater harvesting initiatives would cover high rainfall areas too.
Technologically, micro-rainwater harvesting at scale is feasible. The challenge would then be to push excess capture in a series of centralization flows, where water can be stored cleanly and later redistributed as needed. Central collection from micro arterial points can be triggered over existing distribution networks, by reversing the flow with pumps at the first point or collection/consumption. If a local storage tank is kept full, pumps would be required to reverse the flow back into the distribution system. Measurement could be done locally via pressure sensor (adjusted to the capacity of the holding tank) and sensor data could be remotely sent back to a central point for big-data analytics, water distribution automation and overall management at individual, local, regional and global levels.
This kind of scaling would require connecting entire regions to each other (across countries) and the construction of very large pure water reservoirs committed only to drinking water supply. Distribution and usage along with capture and centralization would need to be automated to ensure water is distributed or sourced uniformly right down to the individual usage level.
Potable water for animals
This is a vital consideration if we’re to take along all creatures along with us. This would require the creation of swales (permaculture concept) along height grades in all places to slow (and sink) surface water, the linking of swales to each other so that they’re directing water to catchment tanks dug into the ground, and to lakes artificially enlarged and deepened. The swales would need to be in areas not utilized for residences, agriculture or industry.
Water capture tanks, ponds and lakes would need to be populated with natural water plants so that they continuously absorb nutrients which flow into the water-bodies; keeping the water clean and drinkable by animals. A system of interconnection would be needed between water-bodies which are at the same elevation. Overflows from these would then need to be directed via swales to the next level of water capture systems. Water remaining in the swales would seep into the soil providing for the needs of plants around the swales and would recharge groundwater.
Essentially, for a while, large portions of the global population would have to be engaged in digging catchment ponds, lakes and the swales needed to slow and direct water. People along with machines of course.
Water for commercial and agricultural use
Like what we’ve covered earlier, water for agricultural or industrial use would need to be captured and stored, but locally in large holding tanks or reservoirs. The size of the holding area would depend on the use & need.
There are various examples from across the world where agricultural communities have benefited across swathes of areas, with individual farmers taking direct control of their water management. Within farms, about a quarter of all area should ideally be dedicated to holding water. Half of the holding area would need to be kept with an absorption barrier which would ensure enough water for the farm’s use if held without it seeping into the ground. The half which allows water seepage would recharge the groundwater of the local area.
If all farmers in an area did this, entire regions would transform within a short period of time. The need would be to undertake labor organization at the local level with the ability to transport people and machinery to places within the region/s which fall behind, so that all farms across entire countries can avail of facilities.
Farmers in many countries aren’t overly well off, so much of this water harvesting infrastructure may need to be undertaken with public funds, made available for free or through social programs of time donation. Ideally, this should be undertaken through a ‘poorest-first’ model.
Water usage at the farm level would need to be calculated carefully, so as to arrive at an annual series of crops which utilize the available water. The cultivable area would also need to be calculated. The assured water would guarantee a ‘specific’ amount of crop that the farmer would be able to generate, and the type. This, clubbed with data and demand/supply software, could be used to put out requests to farmers on what they should opt to grow.
The area/s beside the portion of rainwater capture tank which allows grown absorption, could be dedicated to planting fruit, nut and spice trees or plants. This would provide perennial plants which would provide an additional resource.
Industries too would capture water through a similar system, either individually or as a group. The rainwater harvesting needs would again be split between tanks, one which ensures adequate water availability for the industry’s annual use. The second tank would act as a backup source of water but would be aimed at recharging groundwater.
With most rainwater harvesting initiatives covered so far, a portion of harvested water would need to be dedicated to recharging groundwater, to increase water table height. Gravity measured variations in groundwater (See: Global map)
show a massive problem across India, South Asia, the entire Central African belt, most of South America, and portions of Alaska and Canada. The rest of the world is approaching critical variations.
To get ahead of this problem before it escalates into a catastrophe, massive water retention projects need to be commenced and implemented. Swales, holes, ponds, lakes and water sinking initiatives are urgently needed. At scale.
Some examples of water management at scale
China, Loess Plateau
35,000 square kilometre watershed management program
District level rainwater harvesting initiative at the local farm level
Local area watershed management