Today, poor water quality remains the world’s biggest health risk and still threatens developed countries and is projected to remain a problem even in 2050. Significant improvements have taken place over the last 40 years in respect to source point pollution (i.e. known sources of water pollution like factories discharging into streams); however, non-point source pollution has remained steady, or gotten worse in many developed countries. Non-point source pollution is when rain or snowmelt runoff collect pollutants (i.e. toxic chemicals, trash, disease-carrying organisms, and large amounts of nutrients) prior to draining into rivers, lakes, and oceans. While some of the richest countries in the world have progressively approached river water quality, nutrient pollution still exceeds critical loads in most of their rivers (i.e. European Union, United States, New Zealand)
Water pollution comes from a wide variety of both highly and sparsely populated areas, active and in-active industries, and even the occasional accidents. While it is impossible to list all the sources and problems of water quality, we discuss the largest known contributors that have yet to be tackled.
There are several challenges and hurdles, but all can be boiled down to lack of knowledge, money, and action. The sad truth is that researchers, practitioners, and environmentalist have the knowledge, and governments, businesses, and certain individuals have the money, but too often the action is missing.
"Pollution is nothing but the resources we are not harvesting. We allow them to disperse because we've been ignorant of their value" Buckminster Fuller.
To reduce water pollution, we need to educate the public, integrate new technologies, and incorporate both public and private parties. From agriculture to cities great and small and from river basins to coastlines, solutions are needed now. There are several exciting technologies and applications that have emerged over the last decade and right now. Below, we focus on agriculture and cities.
Agriculture around the world is on the brink of a technology and efficiency revolution due to Precision Agriculture. There are many sensors and technologies available, from batteries powering intelligent irrigation systems to Unmanned Aircraft Systems (or UAS, or drones).
Drones are particularly exciting as they offer several benefits:
- water quality mapping for non-point source pollution,
- targeted herbicide, pesticide, and fertilizer
- surface water runoff (i.e. where is water wasted)
- soil moisture analysis (i.e. areas needing more/less water)
- crop health/stress
- plant counting
- maturity analysis
- yield forecasting
- elevation monitoring to identify erosion and subsidence
All of these are available from various sensors (standard RGB camera, near-infrared camera, red-edge camera, multispectral camera, thermal infrared camera) that are already available in various agriculture drones and approved to fly in most countries. These systems, software, and data storage are already available in user-friendly interfaces. Several companies offer these services for as low as $4 usd/acre (depending on acreage), which includes data collection, processing, and tidy results. In addition to affordable data, these systems typically save farmers money due to using less materials and gaining greater crop yields. Currently, there are few case studies available that share statistics about precision agriculture; however, some results have shown that nitrogen levels were reduced by 10-15% to 30% (saving $18/acre), and irrigation reduced by 25% (saving 44 euro/acre), without impacts to yield.
Irrigation sensors and new methods are also exciting. Center-pivots are widely used for irrigation as they are simple and durable compared to other irrigation methods and can efficiently use 90% of the water. New developments in 'sensitive center pivots' are now being outfitted with various sensors to provide analysis of soil moisture. For example, Susan O'shaughnessy has been using infrared sensors and system software to determine the amount of irrigation needed for the specific field and crop. Not only are these systems allowing irrigation to become even more efficient, but it also helps save energy and time in water management.
Drip system irrigation is also widely utilized in farming as it can limit the amount of water being evaporated and deliver nutrients directly to the plants root systems. However, these systems may save in water, they utilize energy due to pumps, pressure regulators, and cost a lot to install and upkeep. A new innovative approach is to go back to the idea of flood irrigation; however, utilizing soil-moisture sensors and smart irrigation gates to limit the water to the critical amount required. This is actively being researched by the University of Southern Queensland and Rubicon Water, in a method they call high-performance surface irrigation, and are trying to prove that this could be as efficient as drip irrigation.
Simply, urban landscapes need to reduce the amount of water runoff. To reduce runoff, cities need to increase the surfaces' ability to absorb the water where it lands, which reduce the transport of pollutants to the waterways. This solution comes in the form of green infrastructure, green roof tops, rain gardens, conservation buffers, and permeable surfaces. Not only can these technologies reduce pollution, but they can help prevent urban flooding, help recharge the ground water, and in many cases they are cheaper than alternatives environmental solutions (e.g. gray water, storm water filtration plants). All the technologies for these exist and have been proven effective, they just need large scale adoption and adequate how-to-guides to ensure optimal efficiency (e.g. many rain garden manuals miss the point that top soil alone does not filter pollutants well).
In addition to infiltrating the runoff, cities should make better use of the water. By many estimates, the world only reuses 1% of it's water. However, recent technologies and reuse programs have successfully utilized wastewater for street cleaning, irrigation, fire-fighting, industrial processing, and the restoration of wetlands to name a few. Since these applications do not require the water to be drinking quality (i.e. potable water), the treatment process is simplified and uses less energy. In many situations, this offers considerable savings in both available water and cost.
- Good, J.F. (2010). Rain Gardens: Top Soil Alone is NOT Adequate to Remove Pollution.
- Colaizzi, P., O'shaughnessy, S., & Evett, S. (2015). Center Pivot Mounted Infrared Sensors: Retrieval of ET and Interface with Satellite Systems.