Assessment of Groundwater Recharge Potential Using Integrated GIS, Remote Sensing, and Magnetotelluric Data in Banda Aceh-Indrapuri, Aceh Besar, Indonesia
This study evaluates groundwater recharge potential in Banda Aceh-Indrapuri, Indonesia, by integrating GIS, remote sensing, and magnetotelluric data to demonstrate a strong negative correlation between recharge indices and subsurface resistivity, thereby establishing a robust framework for regional water management in complex tropical settings.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Water that falls from the sky does not always find its way into the ground. In many places, especially in the humid tropics where rain is abundant, the water runs off the surface, flowing into rivers and oceans before it can soak deep enough to replenish the underground reservoirs that communities rely on. This hidden water, known as groundwater, is a critical resource for drinking and farming, yet understanding where it accumulates and how it moves is difficult. The ground is not a uniform sponge; it is a complex layer cake of rock, soil, and cracks, some of which let water pass easily while others block it completely. To manage this resource safely, scientists need to know which parts of the landscape are best at catching rain and letting it sink down, and which parts are likely to let it run away.
In the Banda Aceh-Indrapuri region of northern Sumatra, Indonesia, researchers faced this exact challenge. The area is a mix of flat coastal plains and rolling inland hills, with a climate that delivers heavy rainfall year-round. Yet, despite the abundance of rain, the ability of the ground to recharge its underground water supplies varies wildly across the landscape. To solve this puzzle, a team of scientists from Universitas Syiah Kuala combined two very different ways of looking at the earth: one that sees the surface from above, and one that listens to the ground from below. They wanted to create a map that shows exactly where the rain is most likely to become groundwater, and then prove that their map was correct by checking what lies beneath the soil.
The team began by building a digital model of the region using satellite images and computer mapping tools. They looked at five specific features of the land that control how water behaves. First, they examined the type of rock and soil, or lithology, because soft, porous rocks like sandstone act like sponges, while hard, solid rocks like volcanic stone often repel water. Next, they analyzed land use, noting that forests and farms allow water to soak in, while cities with concrete and asphalt force water to run off. They also measured the density of cracks and faults in the earth, known as lineaments, which can act as hidden highways for water to travel deep underground. They mapped the density of rivers and streams, reasoning that areas with fewer, slower-moving streams allow more time for water to seep into the ground, whereas a dense network of fast-flowing streams drains water away quickly. Finally, they looked at the slope of the land, as water flows faster down steep hills, giving it less time to infiltrate, while it pools and sinks on gentle slopes.
By layering all these factors together in a computer system, the researchers created a single score for every square kilometer of the study area. This score, which they called a recharge potential index, ranged from 23 to 55. They divided the region into five categories, from poor to very good. The results showed that nearly half of the area, about 47 percent, has good to very good potential for recharging groundwater. These favorable zones are mostly found in the lowland areas where sedimentary rocks meet the flat terrain, and where the land is not too steep. In contrast, the steeper, hilly areas in the south and the heavily built-up urban zones showed much lower potential, meaning the rain there is more likely to run off the surface rather than fill the underground aquifers.
However, a map based only on surface features is just a guess until it is tested against reality. To verify their findings, the scientists turned to a method called magnetotellurics. This technique uses natural electromagnetic signals from the Earth and the sky to measure how easily electricity flows through the ground. Since water-saturated soil and rock conduct electricity much better than dry, solid rock, a low electrical resistance reading usually indicates a zone rich in groundwater. The team set up four stations across the region to take these measurements, probing the ground to a depth of about 300 meters.
When they compared the results, a clear pattern emerged. The places where their surface-based map predicted high recharge potential consistently showed low electrical resistance in the ground below. Conversely, the areas predicted to have poor recharge potential showed high resistance. The relationship was so strong that the two datasets moved in opposite directions with a high degree of consistency. This confirmed that the surface features the team mapped—such as the type of rock, the slope, and the land cover—are reliable indicators of what is happening deep underground. The study suggests that in this complex tropical environment, the surface tells a true story about the hidden water, provided you know how to read it.
The findings offer a practical tool for local authorities and planners. By knowing exactly which areas are best at capturing rain, officials can protect those zones from development that would seal the ground with concrete. They can also identify areas where groundwater is scarce and manage water usage more carefully to avoid running out. This approach, which blends satellite observation with direct underground measurement, provides a robust way to understand water resources in regions where detailed drilling data is often unavailable. It demonstrates that even in a landscape as varied and active as northern Sumatra, the path of the rain can be traced from the clouds to the deep earth, offering a clearer path toward sustainable water management.
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