Many have heard that over half of the human population lives in urban areas, and this concentration of people is projected to increase. What does this mean to water resources managers who have limited resources and growing demands?
14 of the globes’ largest 20 cities are currently in drought or facing water scarcity. Yet we are not the first to deal with resource constraints, our civilizations have a rich history of managing and mis-managing water. In fact, much of known human history has been characterized by the rise and fall of societies due to periods of rapid urbanization followed by water and food shortages. For example, the great Indus Valley Civilizations, located in present-day Pakistan and India, as early as 2,600 BCE, was marked by intricate sewers, water storage facilities, and public baths. Yet it was this urban population density combined with drought and floods that led to their demise. Similarly, the Akkad civilization in Iraq, dating back to the 3rd millennium BCE thrived along the banks of the Tigris and the Euphrates rivers which supported a lavish lifestyle. However, the blossoming of this civilization was short-lived due to a drought, while improper irrigatoin methods led to a progressive salinization of the soil. Yet another example is the well documented drought that sent Ancient Egypt spiraling into a dark age which lasted for over 1,000 years before it was able to thrive once again. Affluence and abundance today is not a guarantee of long term prosperity, especially as population increases and demand for freshwater access escalates.
Today’s water managers are wise to understand the relationships between urban humanity and water, both historically and globally. These lessons from ancient civilizations are being repeated with remarkable frequency today. In 2015, Sao Paulo, a city of millions of people, and rich with natural resources, has run out of water; Beijing has less water supply capacity per capita than Kuwait City; Mexico City has so overexploited its groundwater that the entire city has sunk several feet, leaving millions without access to water. New Orleans lived with the obvious threat of flood risk, without understanding how to deal with it; and it is yet to be seen if California has learned lessons from the recent threats from drought. Had these modern societies been more aware of human history and water resource management, they may have better avoided the devastating economic impacts, sudden life changes, ecological losses and the billions of recovery dollars.
As Earth’s population grows and concentrates into dense mega-urban centers, our infrastructure will need new tools for management, a new urgency to manage it well, and a new burden on society to understand their relationship with fresh water resources. Fortunately there are incredible tools at our disposal:
- Technology: meter technology, GIS, Computer Models, communications, etc
- Lessons learned: from past and current scenarios, local and global perspectives, and
- Ability to share knowledge: information technology, professional societies
For example, today we can leverage smart meter technology with Advanced Metering Infrastructure (AMI) to tell our customers if they have a leak, or to understand when and where water is used. From this information, we can customize programs to shift behavior by customer type. Given proper goals, informed by our past management lessons, we can greatly influence water conservation and shift water’s energy demand. Today, water utilities can elect to monitor source water to know if the quality has changed – long before it enters treatment processes. (Unfortunately, Toledo did not leverage this technology, and despite knowing this threat was real and despite being on the shores of 20% of Earth’s surface fresh water, in 2014 Toledo had a water ban for fear of poisoning from algal blooms).
With these trends and abilities comes an increased responsibility to use the tools and knowledge at our disposal, and to educate our residents about the need to invest and support actionable foresight. Fortunately, examples of societies and their leaders who understand this dynamic have implemented the appropriate changes. A few examples include:
- Wichita Falls, TX. With the threat of drought and a long term vision, Wichita Falls chose to upgrade their wastewater treatment to make it suitable for plumbing directly into their potable water works. This is a complete recycling of domestic waste water which closes the loop and dramatically increases their resilience to drought and declining groundwater resources. It took an educated citizen body, in collaboration with careful planning, proper engineering, policy, and environmental science to make this progressive investment.
While Wichita Falls is an example of Direct Potable Reuse (DPR), there are many examples of Indirect Potable Reuse (IPR), where wastewater effluent passes through an environmental buffer (such as a reservoir or aquifer) prior to entering the potable water treatment works. A few examples of IPR include:
- Orange County Water District, CA. Opened in 2008, the $480 million dollar waste water facility produces 85 million gallons a day of high quality water. About half is injected to the aquifer to prevent saltwater intrusion (protecting the aquifer) the other half to percolation fields supplying the local water demands.
- San Diego Water Repurification Project, CA. In 2007, San Diego has piloted the use of indirect reuse of water by discharging reclaimed water into the San Vicente Reservoir, which serves their primary purification facility. The pilot has led the way for a 15 MGD expansion, which in will have lower energy costs than desalination, and has seen a rise in public support from 24% to 73% since the pilot was planned.
- El Paso, TX. In 1986 an average of 4.4 MGD of wastewater effluent from the Fred Harvey Water Reclamation Plant began flowing into the Hueco Bolson aquifer, supplying about 50% of El Paso’s water supply. More recently, El Paso has utilized reclaimed waste water from several facilities as part of a growing purple pipe network, supplying over 6,000 acre-feet per year for El Paso Water Utility.
- Tampa Water Resource Recovery Project, FL. In 1987-1989 Tampa Bay invested in advanced treatment of the Howard F. Cullen WWTP to discharge into a potable water reservoir to close the loop in defense against drought.
These utilities are a few of the reasons why we should all be hopeful, that we do not end up the way of past civilizations. They are creating the future state that we will all share within our growing urban centers. Urbanization is here to stay, we must all take the challenge seriously to apply the smartest technology and actively manage our way to a better future.