Rainwater harvesting for groundwater replenishment is an essential technique for combating water scarcity, as it captures and stores rainwater to recharge underground aquifers.
 |
| Artificial Rainwater Reservoir |
 |
| Natural Rainwater Reservoir |
The clean water scarcity is a growing challenge being faced throughout the world mainly due to drought, population growth, usage habits and rapidly increasing undesired consumption by communities.
Is the World Running out of Clean Water?
According to World Resource Institute, US stands at 20%-40% “National Water Stress” rankings. Among others, 25 countries are facing extremely high water stress including Saudi Arabia, India, South Africa, Belgium and Greece etc. Living at high water stress affects people’s lives, jobs, food and energy security.
While water is vital for crops, livestock, producing electricity, maintaining human health and maintaining the world’s climate, the economies are now curious about better clean water management, population growth, economic development and climate change.
In recent studies, researchers have addressed rapid groundwater level decline globally of more than 0.5 meters (20 inches) per year across the world, including the United States. It has accelerated over the past four decades, highlighting an urgent need for more effective steps to address groundwater depletion. The situation seems alarming but with the right management, every country can prevent water stress from turning into water crisis.
Reason for Decreased Average Rainfall in United States
Climate change is causing more extreme weathers to occur in future leading to a slow increase in the average annual rainfall in US. The recent strong bouts of droughts have impacted the North American region, especially in 2020 when the annual average precipitation fell by 12.8% while 2021 brought upon a slight recovery of rain, growing 0.1%.
Similarly, 2022 was another dry season for the United States region, with average precipitation rates declining 6.4%. But 2023, however, represented a more noticeable boost in precipitation numbers with it going up 3.6% in the year.
The droughts still has noticeable impact on certain parts of the United States and factors like the warmer temperatures are adding pressure for drought levels with the passage of time.
Methods of Rainwater Harvesting
Rainwater harvesting can increase groundwater levels besides other natural processes like lakes, rivers, open water ponds, small and large dams etc. As the rainwater is directed to recharge wells, percolation tanks, shallow wells, dug wells, or infiltration basins, it allows water to seep into the ground, replenishing aquifers.
 |
| Percolation Tank |
Percolation tanks, dug wells and infiltration basins are actually artificial reservoirs constructed across a stream, suppressing a land area with adequate permeability which not only facilitates surface water run-off, but allows it to percolate within the permeable land. A good option is to build these facilities near the residential and irrigation areas.
As the water seeps beneath the ground level it not only help increase baseflow to nearby streams but also removes pollutants from stormwater through natural process. Additionally it adds up the desired minerals from soil like Sodium, Calcium, Magnesium, Potassium, Chloride etc.
Selecting Best Place for Percolation Tanks
Here the selection of the soil for construction of such facilities is extremely important because it is the most important factor in locating infiltration basins. Also, the design of these reservoirs may vary considerably, depending on local design requirements, site constraints or preferences of the designer or community.
Apart from the design, soils should be significantly permeable to ensure that the basin can infiltrate stormwater quite quickly. Soils that infiltrate too rapidly do not provide sufficient treatment and create potential for groundwater contamination. Scientifically, the infiltration rate ranges between 0.5 and 3 inches per hour.
In addition, the soils should have no greater than 20 percent clay content and less than 40 percent silt/clay content for better infiltration. Designers should confirm the infiltration rate and textural class of the soil in the field with approved testing methods and soil surveys before executing their projects.
Besides reducing the volume and pressure of stormwater, infiltration basins also reduce the amount of pollutants that are discharged directly to surface waters. Additionally, by channeling stormwater to underlying soils, infiltration basins use the soil as a filter, which can be an effective removal mechanism for pollutants like sediment, phosphorus and metals in the soil.
Moreover, these artificial reservoirs are not suitable in karst region having natural sinkholes and caves due to the potential for sinkhole formation or groundwater contamination because the soil conditions here are associated with soluble rock types such as limestone, marble, and gypsum.
 |
| Karst Area with natural sinkholes |
Secondly the areas which are not compacted or have poor infiltrating soils, typically limit their use in urban environments. They are also not suitable for areas with a high groundwater table or where groundwater contamination is a concern.
Additionally, there are arrangements of modern technologies of microfiltration treatment of the waste water in United States. The world's largest wastewater recycling facility of Groundwater Replenishment System is in the Orange County Water District in Fountain Valley, California.
This high-tech water purification project has the capacity to produce up to 130 million gallons of high-quality water every day, enough to meet the daily needs of nearly one million residents in north and central Orange County, California.
 |
| Groundwater Replenishment System is in the Orange County Water District in Fountain Valley, California |
Maintenance of the Artificial Reservoirs
Regular maintenance is critical to the successful operation of infiltration basins and percolation tanks preventing sedimentation that could clog and lead to their failure. Infiltration basins are not generally benefitting, particularly if they clog. If an infiltration basin is clogged and takes more than 3 days to drain, the basin could become a source for mosquitoes causing further health risks.
The Social Aspect of Water Conservation
Apart from the above practices, encouraging water-saving practices like implementing smart irrigation systems and practices or opting for waterless landscaping, changing domestic habits, and promoting water conservation awareness campaigns can significantly reduce water consumption. This can even be done by introducing awareness programs in students in schools, colleges and universities
Studies have been presented that a breakdown of total household water usage shows that 20 percent is spent in the shower while another 25 percent goes to flushing toilets every day. Another bulk user of water are golf courses.
Conclusion
While natural processes are essential for maintaining groundwater levels, rainwater harvesting can effectively supplement these processes and increase groundwater recharge rates, especially in areas facing water scarcity or declining groundwater levels. Implementing rainwater harvesting systems can be a proactive measure to enhance water sustainability and resilience against drought.
The governments and private sector organizations are urged to develop a strategy to tackle the issues now, before it’s too late.
Comments
Post a Comment