Groundwater: out of Sight but not out of Mind
By Aleisha Dennie, Institute of Marine Affairs
If compelled to, what aspect of our lifestyle do you think we can sustain without the input of water? The answer should be clear. Water in its liquid form fuels the lives of humans, animals, and ecosystems at large. Though much of the world’s freshwater is locked within ice caps, a great portion is available to us in the form of groundwater. Groundwater is said to represent 98% of the world’s accessible freshwater (Farrell 2007). With human demands for freshwater reaching an all-time high in recent years, it is no surprise that utilisation of groundwater has become essential to our survival in these present times and that of the foreseeable future. March 22nd was recognized by the United Nations as World Water Day, with particular focus on groundwater (making the invisible visible). Recently, much was said about the importance of groundwater in our local news. The Minister of Public Utilities, the Honourable Marvin Gonzales, spoke to the strides made to ensure water is supplied to the vast majority of the country and the further efforts to be made in due time. To fully appreciate our end goal of clean reliable water supply to all, we must first understand what threatens our supplies. Groundwater reserves are threatened largely by misuse, mismanagement, contamination, and natural climatic factors.
According to the International Groundwater Resource Assessment Centre, groundwater represents an average one third of the water consumed by humans, with the major users being irrigation and industrial processes. Global estimates have revealed that irrigation accounts for 70% of total water withdrawal, with groundwater representing close to 43% of total irrigation water use. This has made groundwater reserves scarce worldwide. Countries with limited surface water supply are more prone to the impacts of groundwater misuse and abuse. In the Indonesian city Jakarta, groundwater extraction was reported to be significantly high and as such resulted in the city’s infrastructure sinking by approximately 12 cm per year in northern areas of the city. However, over-extraction is one way to look at our problem. Simple acts such as indiscriminate use of water in the household and/or for small- and large-scale agriculture, or use of inadequate infrastructure that result in water leaks can over time result in groundwater depletion. These acts further perpetuate over-extraction as efforts are made to meet the needs of the consumer.
Groundwater is also required for the maintenance of surface water in rivers and lakes and even in wetlands. If the groundwater levels are compromised, then these surface waters can have diminished water tables, which affects the entire ecosystem and the livelihoods of those that depend on them. Globally, we are not in a position to carelessly attract more devastation to our environment. This mismanagement of groundwater can be felt not only from an environmental standpoint but a financial one as well. As mentioned before, if water is constantly pumped out of the aquifer (large storage of groundwater) the water table drops, thus more energy is required to pump this water to the surface. This cost can eventually be the consumer’s burden to bear. Water quality can be affected when excessive pumping in coastal areas causes saltwater to move inland into aquifers. This then increases expenditure for desalination.
Anthropogenic sources of pollution
If quality of water entering our aquifers is to be further examined, land-based development or anthropogenic sources are the major contributors of contamination. Increased development in the form of roads, residential and recreational facilities is likely to result in more surface runoff and an overall decrease in aquifer recharge. There is also evidence to suggest that these urban and agricultural developments can enhance concentration of sediments and chemical pollutants such as pesticides and fertilizers that find its way into aquifers (Farrell 2007). It was reported that 60% of China’s groundwater supplies are polluted, mostly due to chemicals in wastewater from industrial processes (Kaiman, 2014). Liquid pollutants from industrial processes in the form of dense Non-aqueous Phase Liquids (NAPLs) have the potential to sink to the bottom of an aquifer and over time continuously contaminate the groundwater. Some familiar NAPLs include petroleum oil, gasoline and diesel fuel.
Climate change along with climate variability is set to become major impactors to groundwater stores in some Caribbean countries, namely those without adequate surface water supply like Barbados. When considering the effect, a changing climate has on water resources, it is important to first understand the hydrological cycle. The hydrological cycle looks at the movement of water between the oceans, surface water and groundwater. Groundwater is primarily influenced by precipitation, surface run-off and evapotranspiration (water loss from evaporation from soil surface and transpiration from leaves), making climate variability a concern for groundwater storage. It is expected that rising global temperatures and irregular rainfall patterns would increase the demand for water for domestic, agriculture and industrial use. Preliminary climate change trajectory reports for the Caribbean have indicated that rainfall intensity should increase (with negligible increases in overall annual precipitation) resulting in more surface runoff and less infiltration into aquifers. This is to be accompanied by prolonged dry seasons (Farrell 2007).
Luckily in some Middle Eastern countries there is a silver lining! Given the influence climate change has on unconfined groundwater aquifers that lie close enough to the earth’s surface, the confined old or ancient groundwater aquifers may be considered a saving grace. These sources are located deeper below the surface and due to changes in geology have been closed off from recharging sources. They are less susceptible to climate variation and land-based pollution, thus can be used as a last resort if water needs supersede the supply (Farrell 2007). However, because these ancient groundwater supplies have been recorded outside of the Caribbean, the Caribbean islands with limited surface water can experience greater hardships in a world tainted by climate change. There is a need for continuous management of current unconfined groundwater supplies within our region.
How do we manage and protect groundwater aquifers?
A multitude of disciplines are employed to manage our groundwater reserves. Remote Sensing and Geographic Information Systems (GIS) applications are able to determine the rate and direction of groundwater flow through groundwater modeling. The information from these techniques allows for estimations to be made in terms of aquifer recharge and volume, evapotranspiration loss as well as domestic, agricultural and industrial water use (Schmoll, 2006). Chemist and/or geologists routinely employ the use of various meters and tests, aimed at establishing the presence of particular chemicals in addition to monitoring key parameters such as electrical conductivity and pH. When the need arises, bioremediation and chemical remediation techniques are utilized thereafter to make this water useable to the public (Schmoll, 2006).
Ultimately, change that would make a difference lies in the hands of the policymakers. Admirably, some Caribbean islands have begun using strategies that appear to incorporate key components of integrated water resources management. In 2005, the Government of Trinidad and Tobago finalised the Integrated Water Management Policy to allow for management of water and land resources to facilitate maximum economic activity and social welfare with little impact to the key supplying ecosystems. Barbados, St Lucia, and Jamaica are also amongst the Caribbean islands with such policies in place. Policymakers in these countries and elsewhere are being encouraged to conduct assessments of present and future demands by sector, assessments and repair or replacement of existing infrastructure, and risk assessments of natural events that may have an impact on the groundwater supply. Continuous research is also necessary to ensure development of new technologies. This would allow for the optimisation of the already established distribution systems and potential decreases in operation costs, whilst maintaining the same standard of service (Farrell 2007). Above all, rationalisation and updating of legislation are most integral to sustained change.
But what about us, “the everyday consumer”? Both in Trinidad and Tobago, we have a responsibility to manage our water use as well. Especially if you reside in a country that utilises groundwater as their primary source of water supply. We must try to incorporate the following simple habits in our lifestyle, turning off your tap whilst brushing your teeth or shaving, plugging your sink or using a wash basin while washing dishes by hand, fixing your leaky taps, using water saving shower heads or taking shorter showers. Additionally, the grey water draining from your sinks, washing machines and bathtubs can be used for outdoor cleaning purposes and where applicable to water plants. Though the efforts of our policymakers hold a substantial weight in groundwater management, it is our sustainable practices that give us the ultimate fighting chance.