What if Saudi Arabia’s water crisis had a buried solution? Scientists explore hidden riverbeds beneath the desert that may offer a new hope for the future.

The Arabian Peninsula is one of the driest regions on Earth. Saudi Arabia, at its heart, experiences an average temperature of 35°C and receives no more than 150mm of rainfall each year. Unlike many other nations, it lacks surface water resources such as lakes and rivers. The country relies on desalination and non-renewable fossil water to meet its growing demand. However, recent discoveries suggest that hidden ancient rivers may exist beneath the desert, holding untapped water reserves that could transform the region’s future.

Unseen valleys beneath the desert

Satellite imagery has revealed unusual patterns across Saudi Arabia’s landscape. Some of these formations resemble valley systems but remain invisible on the surface. Researchers have long speculated about their origins and significance. Dr Mashael Bent Mohammed Al Saud, a geomorphologist and hydrologist who uses space technologies , sought to uncover the truth behind these hidden features. By using advanced satellite imaging and field studies, she identified what appear to be ancient water channels buried beneath layers of sand and rock.

These formations, known as paleodrainages, were once flowing rivers and streams. Over time, shifting sands and erosion concealed them, leaving behind traces that can only be detected through modern technology. The discovery has sparked renewed interest in Saudi Arabia’s geological history and its potential implications for water conservation.

Further studies of these paleodrainages indicate that they are not merely relics of the past. Some of them could still serve as pathways for groundwater movement, making them critical to the country’s long-term water security. Identifying these channels has also raised questions about their historical significance, as ancient civilizations may have thrived along their banks when water was more abundant.

The power of satellite technology

Dr Al Saud’s research relied on multiple satellite datasets to analyse the landscape. Optical satellite images captured terrain details, while radar imaging penetrated the surface to reveal hidden structures. The study involved data from sources such as NASA, the National Geospatial-Intelligence Agency, and the Japanese Aerospace Exploration Agency. Different imaging techniques played a crucial role in mapping these buried rivers. Digital elevation models from the Shuttle Radar Topography Mission (SRTM) helped delineate drainage patterns. Radar images from the Advanced Land Observing Satellite (ALOS) identified subtle surface changes linked to ancient waterways. Meanwhile, thermal imaging from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) detected temperature variations that hinted at moisture beneath the ground.

These technologies allowed scientists to create detailed maps of paleodrainages, some stretching hundreds of kilometres across the desert Figure 1. Field surveys confirmed that these channels contained layers of alluvial deposits such as pebbles and cobbles, indicating they once carried significant water flows Figure 2.

Beyond scientific discovery, the integration of satellite technology into water resource management marks a turning point. Remote sensing enables a more efficient exploration of groundwater sources, reducing the reliance on expensive and time-consuming traditional surveys. As technology advances, future studies could refine the accuracy of these methods and unlock further details about underground reservoirs.

Different types of hidden river systems

In their research, scientists have identified four main types of ancient river systems buried beneath the desert. Some resemble deltas where rivers once emptied into large bodies of water. Others appear unusual in shape, showing signs of natural changes over time. Some of these ancient rivers ended in vast, dried-up lakes, while others changed course due to shifts in the landscape.

These hidden river systems share certain characteristics. They are made up of materials that allow water to move through them easily. Many are located just a few metres beneath the surface, making it easier to access any trapped water. Their gentle slopes meant water flowed slowly, preventing rapid loss due to evaporation. The size and shape of these paleodrainages can now be accurately measured using satellite technology, helping scientists study them more effectively.

Tracing the history of Saudi Arabia’s lost rivers

The existence of ancient rivers in the Arabian Peninsula is not a new theory. Historical studies and geological evidence suggest that the region once experienced a wetter climate. Some researchers attribute the formation of these paleodrainages to a Holocene deluge around 12,000 years ago, while others believe they date back to the Mid-Late Quaternary period, between 160,000 and 12,000 years ago.

Dr Al Saud’s work builds on previous studies but introduces a new approach by combining satellite analysis with field research. Her findings offer a more comprehensive understanding of these hidden water systems and their potential role in Saudi Arabia’s past and future. These findings also raise intriguing questions about early human migration. Scientists have theorized that ancient populations may have followed these river pathways as they moved across the Arabian Peninsula. The presence of water would have made survival possible in what is now an arid environment, offering clues about the connections between climate change and human adaptation.

Could these rivers still hold water?

One of the most intriguing aspects of this discovery is the possibility that some of these buried channels still contain water. Paleodrainages are composed of highly porous materials, allowing them to retain moisture. If groundwater remains trapped within these formations, they could serve as valuable reservoirs.

Dr Al Saud’s research suggests that some of these ancient rivers may still function as groundwater conduits. Their gentle slopes and slow water flow would have minimised loss through evaporation, preserving water beneath the surface. This raises the possibility of tapping into these hidden aquifers for future water supply projects.

Additionally, paleodrainages could be used in artificial groundwater recharge efforts. By directing excess water into these natural channels, Saudi Arabia could enhance its groundwater reserves and improve water security in arid regions.

Geophysical surveys and exploratory drilling could provide further insights into the quality and quantity of the water stored within these formations. If these reservoirs are found to be viable, they could complement existing desalination efforts and provide an alternative water source that is both sustainable and cost-effective.

Implications for water resource management

The discovery of Saudi Arabia’s invisible rivers could transform the country’s approach to water management. As demand for freshwater continues to rise, exploring alternative sources becomes increasingly important. If further studies confirm the presence of usable groundwater in these paleodrainages, it could provide a more sustainable solution for agriculture, industry, and urban development.

Beyond water conservation, these findings also offer insights into geological processes that have shaped the region. Understanding how and where these ancient rivers formed could help predict other hidden resources and improve land-use planning.

One potential application of this discovery is in desert agriculture. With careful planning, buried water reserves could be used to develop sustainable farming systems in regions previously deemed unsuitable for cultivation. This could support food security initiatives and reduce the country’s reliance on imported agricultural products.

What lies ahead?

The identification of paleodrainages is just the beginning. More research is needed to determine how much water, if any, remains within these ancient channels. Advanced geophysical surveys and drilling could provide clearer answers about their potential as groundwater sources.

This discovery challenges traditional assumptions about Saudi Arabia’s water scarcity. If these hidden rivers can be harnessed, they may offer a lifeline for future generations. Could the key to solving Saudi Arabia’s water crisis be buried beneath the very sands that define its landscape? Only time and further exploration will tell.

As scientific advancements continue to uncover the secrets of the Earth’s past, the study of these ancient rivers presents a unique opportunity. Their potential impact extends beyond Saudi Arabia, offering lessons that could benefit other arid regions facing similar challenges. The quest to secure sustainable water resources is an ongoing one, and every new discovery brings hope for a more water-secure future.