The Pros and Cons on Groundwater in Indonesia
There are many sources of water in this world. The earth is mainly covered with around 71% water (USGS, 2019), but only 0.5% of that amount can be used for drinking and sanitation as the rest is mostly saltwater (Bureau of Reclamation California-Great Basin, 2020). Resources of our clean water include surface water, and groundwater, which is discussed in detail in this essay.
According to the Undang-Undang Nomor 7 Tahun 2004, groundwater is defined as water that exists in rock layers below the soil surface (the saturated layer) as shown in Figure 1. The groundwater's main source is rain which moves underground and fills the cracks in the fractured rocks. On top of the saturated layer, there is the unsaturated layer which consists of the soil zone. (Gramedia, n.d.)
In Indonesia groundwater is used in many sectors, such as irrigation, sanitation, and electricity (the Gombong Selatan region utilize the groundwater circulation for power plant). 80% of drinking water is also provided by groundwater. The reason that people were still using groundwater in many sectors is that they're easy to get, high quality, and can be used directly. (Biro Komunikasi Publik Kementerian PUPR, 2003; Gramedia, n.d.)
Despite the important role and the advantages of groundwater, the availability of groundwater is limited, only a part of the groundwater stored in the subsurface can be recovered. Groundwater is neither completely non-renewable sources like petroleum nor renewable sources like solar energy, but the rate for groundwater recovery is smaller than the usage. In Indonesia with the increasing of population and the invasion of the sea water cause the decreasing in the groundwater availability. (Alley et al., 1999; Biro Komunikasi Publik Kementerian PUPR, 2003).
Besides, the development of groundwater is taking many years and the effect on the environment of pumping groundwater to the surfaces. The effect of the continuously pumping groundwater is a decline in ground-water levels, and a change to the pumping well of groundwater that was moving slowly distant from area discharge (Alley et al., 1999). This may lead to be one of the contributors in the recent buzz on why Jakarta may be a sunken city by 2050.
With those conditions, the development a sustainable system for groundwater is needed. The sustainability of groundwater itself is defined as the development and the use of groundwater to fulfil current and future needs without damaging the environment and socioeconomic issues. For example, the program from the US government for ground-water sustainability is called safety yield, ground-water mining, and an overdraft. (Alley et al., 1999)
Safety yield is a term to quantify groundwater development such as the correlation of pumping effect to water-level declines, reduced streamflow, and degradation of water quality (Alley et al., 1999). The numerical study on the impact of water pumping on the quality of groundwater. The main principle is using Darcy's Law about continuity and the conservation of mass.
The second term, groundwater mining usually refers to a prolonged and progressive decrease in the amount of water stored in a ground-water system (Alley et al., 1999). For example, In Jakarta, the decrease of the groundwater surface is about 7.5-35 cm/year. These phenomena also happen in another part of the world, in south-eastern Spain, the cumulative groundwater reserve depletion is about 15 km3. In Gran Canaria and Tenerife Islands, it is about 2 km3. The current rate of depletion is 0.3 to 0.4 km3/year. (Beritagar.id, 2019; Custodio et al., 2017). In Jakarta, due to 32% people are still using groundwater would increase the risk of the sinking of Jakarta. In addition, the quality of groundwater would be affected if overusing it. (BPS,2018; The conversation, 2022). The numerical study on the impact of water pumping on the quality of groundwater.
Overdraft refers to withdrawals of groundwater from a source, which is considered to be excessive and categorized as overdevelopment. Thus, overdraft may refer to ground-water mining that is considered excessive as well as to other unwanted effects of groundwater withdrawals (Alley et al., 1999). The study was performed in the groundwater system of the Ganges– Meghna–Brahmaputra (GMB) delta in Southeast Asia, showing that overdraft can be impacting in the quality of water and the distribution of unwanted contamination (Chatterjee & Chowdhury, 2020).
The Indonesian government also attempted to develop sustainability of groundwater, such as increasing the infiltration wells. Besides, the government has made regulations, Undang Undang Pengairan No 15 ayat 1 regulates the violation usage of ground water and the punishment are maximum 2 years in prison with a fine of 5 million IDR. Additionally, The Government has given a budget for the reservoir development in Depok. The community is hoped to be contributed by building the infiltration well and using the water wisely. (Biro Komunikasi Publik Kementerian PUPR, 2003).
To close, groundwater is an important resource which can benefit people economically to have proper access to clean water. However, collaborations between sectors must exist in order to ensure its sustainability and avoid overuse. The concerns on groundwater sustainability has also reached an international scope. UNESCO attempts to create the ground water sustainability by organizing a summit that will be held in & December 2022 in Paris with topic Groundwater: making the invisible visible. The summit will unify the statements from all major groundwater-related events into one, comprehensive groundwater message for the UN 2023 Water Conference (UNESCO,2022).
By: Shafira Nur Adiningsih
References:
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