As population becomes larger the demand for water soars, including water needed for domestic, industrial and municipal uses (Mogelgaard 2011). One example of that, is India, where on 20 June 2019 the city of Chennai almost run out of water. Satellite images show the extent of the water shortage in the city (figure 1). While people are queuing up to get water from water trucks that transfer water to the city, the greatest struggle is taking place in the city’s municipal buildings and businesses. Hospitals are facing the threat of not having enough water to treat patients and to clean equipment, and businesses are forced to shut down and wait until the crisis is over.
Humanity is challenged by severe climate change phenomena with detrimental consequences. So, what can space, and technology do to tackle water shortage of the urban canopy layer? On May 2018 a satellite mission by the name GRACE-FO was scheduled for launch. The mission is the continuation of a NASA experiment for Gravity Recovery and Climate Experiment (GRACE), where the satellite is set to follow the movement of water on Earth, by detecting the differences in gravity. It functions like this: Two satellites that are moving at a fixed distance between one another and collect data on the gravitational changes due to variations of the Earth’s mass. When water bodies on Earth change, then Earth’s mass changes as well, causing the two satellites to move at a different distance than the predetermined one. The point of the orbit, where the distance between the satellites is altered, is giving information of the location of the change. These variations of gravity can be used to detect water shortage on Earth. Furthermore, the data can then be translated to identify water sources and help implement mitigation strategies for water scarcity.
In ARUP’s Cities Alive Water for People Report it is indicated that “One in four large cities are already facing water stress, and demand for water is only projected to increase”. Considering that climate change will continue to affect water resources on Earth, it is expected that this number will increase in the next years, more specifically, by 55% by 2050 (ARUP 2018). This showcases a strong need for using satellite data to not only predict water shortage, but to organise an efficient system in cases of emergency. Urban water infrastructure should adapt to the future conditions to sustain quality of life in cities. Space technology is a viable solution to that.
Good news is that droughts can be predicted using data from GRACE, the predecessor of GRACE-FO. The National Drought Mitigation Centre (NDMC) in Lincoln translated GRACE and other data (including in-situ data) into an interactive map for the U.S. Drought Monitor maps (figure 3), which has now become one of the country’s most important tools to track droughts (GRACE-FO Will Help Monitor Droughts 2018). These maps are renewed weekly, which gives municipalities the opportunity to plan for an upcoming water shortage. Frequently changing weather conditions require that we develop technology to provide us with accurate drought warnings.
Climate change is causing temperatures to rise. What happens in cases of extreme temperatures where reservoirs lose their water capacity rapidly, especially of those reservoirs filled with potable water? Could real-time data processing give us more accurate predictions of water quality and shortage?
In order to answer this question, we will use the work by Ms. Nima Pahlevan as an example for water quality measurements. Ms. Pahlevan is a scientist at NASA, who uses real time data to generate water pollution alerts to water managers (Voiland 2018). She does this by using satellite technology, including the different sensors, to collect data on water bodies to identify their level of chlorophyll or coloured dissolved organic matter. These variables can be used as an indicator for water quality. Water quality is linked to water scarcity, because a lack of water means a lack of potable water.
Similar to Mrs. Pahlevan’s real time approach, the initiative for a European Gravity Service for Improved Emergency Management (EGSIEM) has established three different prototype services using GRACE-FO data to generate early warning systems. One of their prototypes is for a near real-time service that provides dedicated gravity field information with a maximum latency of five days (Jäggi 2019). The EGSIEM prototype showcases that early warning systems are applicable to GRACE and GRACE-FO data. These (near) real-time approaches to data handling help municipalities, because they allow stakeholders to react quickly to possible problems with fresh drinking water.
What happened in India is a warning to what climate change can provoke and space applications can help induce issues such as droughts. Water is a critical resource. We have formed our civilization according to water supply and if the amount of water resources changes, then that could cause severe ramification to the way we live our lives.