Impact of irrigation on groundwater

Source: https://www.urbanet.info/world-urban-population/

The world's population is currently growing at an unprecedented rate. According to forecasts, it can exceed 9.5 billion by 2050. Supplying a growing population brings new challenges to agriculture. As the amount of cultivable areas are limited, we must enhance crop yield to have enough food.

But how is it all related to groundwater? To understand the answer, we have to know that about 85% of the population lives in arid areas, where irrigation is the key to grow plants. Nowadays, 43% of all water used for irrigation comes from groundwater resources. Due to climate change and the vulnerability of surface waters, this ratio is expected to increase.

Source: https://www.digital-water.city/solution/early-warning-system-for-safe-reuse-of-treated-wastewater-for-agricultural-irrigation/

However, if we are not careful enough, intensive agricultural activity and, as part of this, irrigation can be dangerous to the environment. The most evident problem may be the depletion of aquifers. It’s especially true for arid and semi-arid areas (e.g.: desert areas of North Africa) where precipitation cannot replace the pumped irrigation water. The high temperature leads to strong evaporation which is also not fortunate. Currently, 10% of global grain production (about 150 million tonnes per year) is irrigated from non-renewable resources. A less obvious, but significant problem is that groundwater production also contributes to the global sea level rise with 3.3 mm / year, as some of the irrigation water enters the sea through rivers. We can also mention the exaggerated use of pesticides and fertilizers which lead to groundwater pollution and the accumulation of salt.

The use of Managed Aquifer Recharge (MAR systems) can be a good alternative, both in terms of quantity and quality. This technology is based on planned and purposeful resupply of the aquifers with high-quality water (e.g.: surface water, rainwater). This way we can preserve the original groundwater level, which is favorable not only for agriculture but for nature and ecosystems as well. In addition, it is important to know the chemical composition of the water used for irrigation in order to use the water accordingly. For example, in the case of a high nitrate content, it is advisable to reduce the amount of fertilizer used. Precision irrigation technologies, such as the drip irrigation (read more about it in our earlier post), could also be a solution.