Desalination Hopscotch transports clean water to an aquifer near you. Aquifers provide resiliency against scarcity in times of drought.
Waters of the Gulf of Mexico border the south of Texas. Desalination of seawater from the gulf is used to augment the supply of clean water that is available to users in Texas. Linking an underground system of aquifers allows the augmented supply of water to be distributed to inland users.
Known methods of desalination, drilling, pumping, treatment, transport, and injection are used in a number of "hopscotch" steps that bring clean water from one aquifer to the next. Water quantity and quality are maintained or improved in each aquifer that is involved in the operation.
This proposal represents a break in thinking about transport of water following desalination of seawater. Instead of laying a long pipeline from a desalination plant near a coastline to a drought-stricken inland location, a "virtual pipeline" uses a chain of aquifers that each in turn makes clean water available to the next further-inland aquifer.
In an example presented here, the City of San Antonio, Texas, enjoys an augmented supply of clean water from a nearby aquifer. That clean water does not come directly from a desalination plant. Rather, it comes from a series of exchanges of water between aquifers. Those exchanges are initially enabled by using desalination to augment the water supply in the Gulf Coast Aquifer.
A similar series of exchanges could be used to ensure locations in Egypt against water scarcity if its supply of water from the Nile River were to become curtailed by a newly constructed dam in Ethiopia.
Using aquifers to distribute clean water is cost-effective and environmentally responsible. It avoids environmentally destructive effects from constructing long pipelines to distribute desalinated water from coastlines to inland areas.
What actions do you propose?
Note: Readers are kindly asked in this section to leave their preconceptions behind. Desalination Hopscotch is a radical new departure from conventional thinking about water management. A cross-aquifer systems approach to sharing desalination resources creates resilience to water scarcity in a revolutionary way.
Below is our concept of how, in general, a Desalination Hopscotch operation will be managed:
- Water from desalination of ocean water is delivered to Aquifer A 365 days per year. Adding desalinated water from the ocean to Aquifer A will improve the general quality of water that is found in Aquifer A.
- Using pumping, transport and insertion operations, Aquifer B receives water extracted from Aquifer A. That operation will be carried out during wet seasons – times of the year when extraction of water from Aquifer A for the benefit of Aquifer B will in no way compromise the continuous availability of clean water to users of Aquifer A.
- Users of Aquifer A are compensated for water extracted from Aquifer A and inserted in Aquifer B. The compensation is that desalinated water from the ocean is inserted into Aquifer A. Operations of desalination, transport, and insertion are paid for by users of the water that is extracted from Aquifer A and inserted in Aquifer B.
- Users of water from Aquifer B can use previously stored water from Aquifer B whenever it is needed. That increases the resilience of the system of water supply that operates for users of Aquifer B.
Need for surface transport is non-existent if Aquifer B, seen from above, overlaps Aquifer A but is located at a different elevation underground. Need for surface transport is minimal if the two aquifers are close.
In the above scenario:
- Users of water from Aquifer A are benefactors of overall improvement in the quality of their water. The volume of water available to them stays constant, assuming water extracted for treatment, transport, and injection into Aquifer B is equal in volume to what has been supplied to Aquifer A by the desalination plant.
- Users of water from Aquifer B benefit from having an augmented supply of water that comes from Aquifer A. The volume of the supply is equal to the volume of seawater that was desalinated and injected into Aquifer A. The quality of the water injected into Aquifer B is equal to or better than the quality level agreed upon by the interested parties.
In essence, two separate aquifer systems are joined into a larger system in a manner that allows users of both aquifers to benefit from a new source of water that comes by way of desalinating ocean water. Aquifer B users pay to enhance the availability and quality of water in the larger system. Without in any way making Aquifer A users more vulnerable to water scarcity, water levels in Aquifer B can be maintained at levels where users of Aquifer B will enjoy greater resilience against water scarcity during times of drought.
It is easy to imagine an only slightly more complicated scenario where users of a third aquifer (Aquifer C) benefit from an injection of water from Aquifer B. Theoretically, the number of "hopscotch" events – pumping, transporting, and injecting – could extend from one seacoast to another.
In an example of Desalination Hopscotch proposed for Texas (as described in detail below), operations in Texas produce a virtual pipeline of water from the Gulf of Mexico to San Antonio. The feasibility of the operation depends on Gulf Coast Aquifer users accepting as adequate (a) compensation that would be offered by San Antonio in the form of desalinated water and (b) assurances by San Antonio that the Hopscotch operation would be managed in a way that no water scarcity would be created for Gulf Coast Aquifer users because of the Hopscotch operation.
Resiliency in the face of water scarcity can be improved for the users of any or all the intermediary aquifers by adjusting the output levels of the Desalination Plant to meet their water demands beyond the needs of the users of the final aquifer in the Hopscotch operation.
Several professional hydrologists were consulted regarding these proposed actions: (a) Dr. Christiane Runyan from the US, (b) Dr. Delton Chen from Australia, and (c) a third professional hydrologist who remains anonymous because of a restriction in his employment contract. We were encouraged to be given feedback from all three hydrologists that the Desalination Hopscotch approach to increasing resilience against water scarcity was a strategy that could work. However, that positive feedback was accompanied by certain provisos about what would need to be done to plan and carry out a Desalination Hopscotch operation in any specific setting.
Specific provisos included the following:
- Modeling of groundwater locations and flow would need to show that sustainable levels of water would be available from a "donating" aquifer across seasons and years. Some data collection, done at newly drilled wells, would likely need to be conducted if complete and contemporaneous modeling data were not already available from existing records.
- Stakeholders would need to be involved at every level and stage of planning. Significant resistance would be expected if stakeholders became concerned that their access to clean and sufficient quantities of water might become compromised. Careful groundwork could, however, show to stakeholders how adding desalinated water to aquifers would improve the quality and reliability of their water supply.
Quoting Dr. Chen: "Your idea is conceptually sound in my opinion, but the costs and CO2 emissions are key in my mind, and I agree that this kind of issue is about stakeholder engagement. Groundwater aquifers are often misunderstood by the public -- they're mostly porous sedimentary rock, and not like underwater rivers -- and people tend to be rather selfish with water and groundwater."
Regarding CO2 emissions, we would like to point out that some desalination methods can be energy intensive. If the energy source were fossil fuels, then the concern about CO2 emissions would be valid. However, whenever we recommend the use of desalination to augment water resources, we also recommend using renewable energy resources to power that desalination.
Who will take these actions?
We will advocate for desalination plans that can help provide solutions to water scarcity in ways that are environmentally responsible. Such plans will be welcomed by public water officials in drought-stricken areas where pumping and transport of groundwater (a) becomes overly expensive, (b) is not feasible as a long-term solution because aquifers will not recharge fast enough, or (c) is resisted by environmentalists and concerned citizens. See Figure 1 where a sign protests pumping of groundwater 142 miles from Texas’ Burleson County to San Antonio.
Figure 1 - Sign Protesting Groundwater Pumping and Transport Plan
Implementing the Desalination Hopscotch Plan by public water officials will:
- Help owners of water rights maintain their ability to exercise their rights in spite of climate change causing reductions in recharge rates for aquifers;
- Mitigate negative environmental effects that would be caused by falling aquifer levels;
- Augment availability of water in a cost-effective way that also protects water quality; and
- Make seawater desalination part of water conservation planning that emphasizes responsible use, reuse, and recycling.
If public water officials in the US were to adopt a Hopscotch plan to add desalinated water to their systems of water distribution, certain regulatory standards would be required by the Environmental Protection Agency (EPA) for Underground Injection Control (UIC) of Aquifer Recharge (AR) and Aquifer Storage and Recovery (ASR) wells. AR and ASR well owners or operators must submit basic well information to either the EPA or the state. The well is typically authorized if (a) the owner or operator submits the well information and (b) the well injection does not endanger a USDW (underground source of drinking water). 
Additional regulations adopted by states for AR and ASR wells vary. State-specific AR and ASR regulations do not supersede federal regulations that prohibit USDW endangerment.
Where will these actions be taken?
The above scenario can be realized to benefit water users in many places around the world. A specific example is the state of Texas in the United States of America where:
- The desalination plant is in the area of the Gulf of Mexico where seawaters touch upon shores of South Texas;
- Aquifer A is the Gulf Coast Aquifer;
- Aquifer B is the Carrizo-Wilcox Aquifer; and
- Aquifer C is the Edwards Aquifer, which is tapped by water users in San Antonio
Figure 2 - Major Texas Aquifers
Thus, the following hopscotch steps would take place:
Step 1: Seawater would undergo desalination at a location near where waters of the Gulf of Mexico touch the Texas coast. See Figure 2 showing Texas, part of the Gulf, and aquifers in Texas. A coastal part of Texas and a possible site “D” for a desalination plant is shown in Figure 3, where other salient locations are zeroed in upon and described in subsequent steps.
Figure 3 - The Desalination Hopscotch
Step 2: Desalinated water from Step 1 would be injected into the Gulf Coast Aquifer at location “GCI”, very near “D,” thereby augmenting and improving the aquifer’s water.
Step 3: Further inland, a location “GCP” is shown, where water from the Gulf Coast Aquifer is removed by pumping from the aquifer and transported toward the Carrizo-Wilcox Aquifer by pipeline “P1.”
Step 4: At location “CWI” water is injected into the Carrizo-Wilcox Aquifer. Prior to injection, the water is treated as necessary so that it is as pure or purer than the water already in the Carrizo-Wilcox Aquifer.
Step 5: At location “CWP” water is pumped from the Carrizo-Wilcox Aquifer to be transported by pipeline “P2” to the Edwards Aquifer.
Step 6: At location “EI” water is injected into the Edwards Aquifer. Prior to injection, the water is treated as necessary so that it is as pure or purer than the water already in the Edwards aquifer.
Step 7: At location “S” water is pumped from the Edwards Aquifer for use by consumers in San Antonio.
What are other key benefits?
Applying Desalination Hopscotch could determine the difference between war and peace in various parts of the world. For example, war is threatened between (a) Egypt, which depends on water flowing in the Nile River, and (b) Ethiopia, which is building a dam to contain the Nile River far upstream from Egypt . An alternative to war would be for Egypt to offset any loss of Nile River water by tapping an unlimited supply of desalinated water from the Mediterranean Ocean and the Red Sea. Desalinated water from those sources could be injected into the nearby and very extensive Karstified Carbonate and Nubian Sandstone aquifers. Virtually all of Egypt could be supplied with an abundance of water from those aquifers or by a single hopscotch step from those aquifers to other aquifers in Egypt. See Figure 4.
Figure 4 - Egypt Aquifers
What are the proposal’s costs?
The San Antonio water utility, San Antonio Water System (SAWS), is planning to pump and transport water from Burleson County to San Antonio (Bexar County) through a pipeline project—the Vista Ridge Water Supply Project. The contract between SAWS and the Vista Ridge Consortium, the project contractor, will bring San Antonio up to 50,000 acre-feet (1 ac-ft = 1,233 m3) of water per year for 30 years with the possibility of extending water delivery beyond the end of the 30-year period.
Here is what it will cost SAWS to get 1 ac-ft of water through the Vista Ridge Water Supply Project :
Here is what it will cost SAWS to get 1 ac-ft of water through the Desalination Hopscotch Plan [3,4,5]:
This cost comparison does not include the cost of externalities that result from the negative environmental impact of installing and operating a pipeline along a 142-mile path to transport water from Burleson County to San Antonio.
So, the Desalination Hopscotch Plan would result in 30% savings for SAWS ($1,616 vs. $2,307 per ac-ft). These savings would be much greater if the externalities were taken into account. In addition, the Desalination Hopscotch Plan will augment the existing water resources in Texas. By doing so, it will help to improve the resilience of Texas in the face of anticipated frequent and severe droughts.
Phase 1 – Information Collection
The authors of this proposal will travel to meet and interview a number of public water officials in Texas during the month of June 2017. The Desalination Hopscotch Plan will be modified, based on input from those officials, representatives from environmental groups (e.g., the Sierra Club), and other concerned citizens.
Phase 2 – Advocacy
Based on information and advice collected during Phase 1, a detailed proposal will be prepared during the following few months and distributed to water officials, elected officials, media representatives, environmental groups, and concerned citizens.
Phase 3 – Implementation
If the Desalination Hopscotch Plan is accepted by officials for implementation, the authors will be available for consultations. Successful implementation in Texas could lead to later efforts to implement similar plans in places like Egypt.
- US Environmental Protection Agency. Aquifer Recharge and Aquifer Storage and Recovery. Retrieved from the Internet February 9, 2017, at https://www.epa.gov/uic/aquifer-recharge-and-aquifer-storage-and-recovery
- W. Hussein, Water wars intensify between Egypt, Ethiopia. (Cairo, March 3, 2016). Retrieved from the Internet February 9, 2017, at http://www.al-monitor.com/pulse/originals/2016/03/egypt-ethiopia-renaissance-dam-water-storage-nile-dispute.html#
- R. Puente, Vista Ridge Water Supply Contract. Board of Trustees Briefing. San Antonio Water System, 2014.
- AWWA, Desalination of Seawater – Manual of Water Supply Practices M61. American Water Works Association, 2011.
- C. Job, Groundwater Economics. Taylor and Francis Group, 2010.
- Texas Water Development Board. Bech Bruun, Kathleen Jackson, Peter Lake, and Jeff Walker, Texas Aquifers Study. Groundwater Quantity, Quality, Flow, and Contributions to Surface Water, December 31, 2016. Retrieved from the Internet, February 9, 2017, at www.twdb.texas.gov/groundwater/docs/studies/TexasAquifersStudy_2016.pdf