Fresh water supplies are becoming increasingly scarce due to population growth, inadequate clean and fresh-water resources, economic growth and social change impact on human preferences, and climate change.
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One-third of the world's population is affected by water stress and shortages, which leads to a lack of access to fresh water. It is crucial to investigate sustainable methods for collecting and distributing fresh water among the general population to protect the worldwide water reserves.
Fog Harvesting for Enhancing Water Usage Efficiency
There are various ways to increase water usage efficiency and productivity from traditional water resources such as surface water in lakes, rivers and reservoirs. These resources are insufficient to fulfill human demands. Therefore, some unconventional water resources to reduce the gap between water demand and supply must be investigated.
Fog is an overlooked source of fresh water. Harvesting of fog water requires a low maintenance system, low cost, and a passive way of attaining clean drinking water in areas with higher fog concentrations.
Fog water can supplement rainfall for tree planting in dry regions. It can be life-saving in dry, remote and semiarid areas with tropical or subtropical climates affected by huge shortages.
How Does Fog Water Collection Work?
The mechanism of collecting fog water is straightforward. The wind pushes the fog through mesh exposed to the atmosphere. A portion of the fog droplets are deposited on the mesh material upon impact.
Fog droplets build up as they accumulate, combine, and convert into bigger droplets and finally flow into a storage tank through the gutters in the mesh material. Various fog collector designs are available with different mesh materials, dimensions, and shapes.
How Much Water Can Be Collected by Fog Collectors?
Standard Fog Collector (SFC) assesses how much fog water can be collected at specific locations.
Schemenauer and Cereceda provided a detailed description of the creation and application of this flat mesh panel. The SFC is mounted perpendicular to the wind direction, is linked to the incidence of fog, and has a surface area of 1 m2 with a base elevation of 2 m.
Fog collection has traditionally been carried out using the Large Fog Collector (LFC). It also works on the same principle as SFC but is considerably more significant in size. The mesh is typically 10 meters wide and 4 meters high. The mesh's lowest edge should be as high off the ground as feasible with the gutter attached (usually 2 m), as it results in increased fog collection.
The mesh of the SFC design is stretched over a stiff frame. In the case of LFC, the mesh is supported by a cable framework firmly attached to two vertical poles.
Water accumulates on the mesh and drips downwards into drainage at the bottom of the net piped to a storage reservoir or tank. The typical daily water production rates from the typical fog collector vary from 300 to 1,000 liters, with daily and seasonal variations. Larger fog droplets, faster wind speeds, and narrower collecting fibers/mesh width all increase collection efficiency.
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Advantages of Fog Collection
Fog water can be used as a source of clean drinking water and as water for reforestation. It can also be used for domestic and agricultural purposes.
Atmospheric water is pure, free of harmful microbes, and appropriate for instant irrigation.
Water obtained using fog collecting equipment complies with World Health Organisation (WHO) requirements.
The technology's installation and maintenance have a minimal environmental impact. Construction of fog harvesting technology is reasonably easy and can be carried out on-site once the parts and technical supervision have been acquired.
Simple skills are needed for the construction of the fog collector, and once the system is built, it does not require any energy to run. Since mountainous regions, where inhabitants frequently live in remote conditions, are particularly well-suited for fog harvesting, capital investment and other costs are typically minimal.
Disadvantages of Fog Collection
Fog harvesting systems rely on a water supply that is not always dependable because fogs can appear at any time. However, some regions do tend to generate more fog.
It can also be challenging to estimate the amount of water collected at a specific place. Unless a pilot project is first conducted to evaluate the possible water rate yield in the region under consideration, this technology poses an investment risk.
Need for Reforestation for Enhanced Fog Collection
Deforestation has greatly influenced the natural fog cycle. Trees can be self-sufficient in an ecosystem because they can catch fog water that seeps down to their roots. Due to continuous deforestation, fewer trees are available to capture the fog water.
Deforestation is causing climate change and dry seasons all over the world. The loss of ground-covering plants due to changes in the natural hydrological cycle results in arid, heated landscapes more prone to erosion. Deforestation-related disruptions of the fog cycle can have long-lasting effects on surface water runoff and groundwater recharge.
Human involvement is required for these regions to recover as new plant growth is impossible without the extra water intake from fog drip typically provided by existing plants. Hydrological and ecological restoration of these regions is only possible with human involvement.
The newly planted trees will be able to survive the fog drop and become natural fog collectors. When fog drip returns to an area, it will help to restore the local ecosystem by recharging the groundwater and lowering the erosion rates.
Fog water in regions where fog is common can be used for reforestation and irrigation.
References and Further Reading
Klemm, O., Schemenauer, R. S., Lummerich, A., Cereceda, P., Marzol, V., Corell, D., ... & Fessehaye, G. M. (2012). Fog as a fresh-water resource: overview and perspectives. Ambio, 41(3), 221-234. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3357847/
Andrews, H. G., Eccles, E. A., Schofield, W. C. E., & Badyal, J. P. S. (2011). Three-dimensional hierarchical structures for fog harvesting. Langmuir, 27(7), 3798-3802. https://pubs.acs.org/doi/abs/10.1021/la2000014
Schemenauer, R. S., & Cereceda, P. (1994, May). Fog collection's role in water planning for developing countries. In Natural Resources Forum (Vol. 18, No. 2, pp. 91-100). Oxford, UK: Blackwell Publishing Ltd. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1477-8947.1994.tb00879.x
Lummerich, A., & Tiedemann, K. (2009, October). Fog farming: linking sustainable land management with ecological renaturation in arid areas by means of reforestation. In Conference on international research on food security, natural resource management and rural development (pp. 6-8). https://www.researchgate.net/publication/257479318