Dr. Sa’d Abdel-Halim Shannak
Floods are typically associated with regions that experience heavy rainfall or are home to dense forests and/or coastal areas. However, the Gulf Cooperation Council (GCC) states, known for their arid climates and minimal rainfall, are becoming increasingly vulnerable to flooding due to rapid urbanization, inadequate drainage infrastructure, and the impacts of climate change leading to intense, unpredictable rainfall and rising sea levels. Additionally, the natural topography, soil composition, and poor water management practices further exacerbate the risk of floods in these traditionally arid regions.
According to the National Oceanic and Atmospheric Association, floods are essentially the overflow of water into areas that are not normally wet, such as from water lines to land, that occur when water levels in rivers, streams, or ditches rise due to excessive rainfall. These events can last for days or weeks. By contrast, flash floods are triggered by heavy or excessive rainfall within a short period, typically less than six hours. They may also result from the failure of dams or levees, sudden water release from debris or ice jams, or even in the absence of rainfall. Countries like Oman and the United Arab Emirates, which have desert conditions and typically receive only around 100-300 mm of rainfall per year, are perfect examples of regions with low annual precipitation. In Saudi Arabia and Qatar, heavy rains are extremely rare, but when they do occur they are usually intense and short-lived. Regions with this weather pattern are more likely to be affected by flash floods.
To diminish the damage caused by floods in arid regions, we need to pay close attention to specific conditions in these areas and be better prepared for flood events. Traditionally, flood management encompasses two key approaches: structural schemes and the non-structural options. The former consists of architectural solutions like floodwalls, seawalls, floodgates and levees. Typically erected along rivers and coastal areas, these structures serve to contain water overflow and prevent flooding beyond the riverbanks. They also play a vital role in the protection of important structures by catching overflow water and creating a higher-level setting area above the floodwaters. This in turn cuts down the adverse effects of floods on bordering neighborhoods or towns.
Non-structural methods are additional solutions used alongside structural measures in flood risk management. Land-use planning, for example, includes procedures for limiting construction in flood-prone areas. Floodplains and wetlands are preserved by governments thereby protecting natural capital, future housing estates, and mitigating flood risk. Early warning systems are also essential features of flash flood mitigation, providing timely alerts and effective response plans. These systems are lifesavers for people who live in flooded areas and encourage affected populations to be prepared for emergency situations. Technology and real-time data are used during emergency events in order to facilitate evacuation and allocation of resources in a timely manner.
Natural systems should nevertheless be brought back to normal states after flooding by long-term and sustainable mechanisms. In this respect, traditional solutions tend to come with a large carbon footprint because of the materials and energy-consuming construction processes they use. Conversely, non-structural measures minimize damage by moving people and property away from high-risk areas, making them an increasingly appealing option.
To this end, Hamad Bin Khalifa University’s (HBKU) Qatar Environment and Energy Research (QEERI) continues to explore unique flood management strategies that will help prevent problems caused by precipitation in arid climates. These include the adoption of green infrastructure (GI) such as bio-retention basins, permeable pavements, and green roofs to counter intense flooding. Otherwise known as rain gardens, bio-retention basins are shallow, landscaped depressions designed to capture and treat stormwater runoff. By mimicking natural hydrological processes, these basins temporarily hold and allow water to infiltrate into the ground, reducing the volume and rate of runoff, thus mitigating the risk of overwhelming stormwater systems during heavy rainfall events.
Other promising options include permeable pavements made from materials like porous asphalt, pervious concrete, and interlocking pavers. These allow rainwater to pass through them directly infiltrating the ground. Doing so reduces surface runoff, lowers peak flow rates, and helps recharge groundwater thereby decreasing the likelihood of urban flooding and reducing the burden on stormwater infrastructure. Similarly, green roofs covered with vegetation and a growing medium, absorb and retain rainwater reducing runoff during storms. The vegetation and soil layers slow down the flow of water, allowing more to evaporate or be used by plants, lowering the volume of water entering stormwater systems and peak discharge rates.
Research by QEERI scientists supports the efficacy of these methods, showing that combining bio-retention and permeable pavements results in the greatest reductions in peak discharges for all recurrence intervals (2-year, 10-year, 25-year, and 100-year) equivalents to (3.5, 6.1, 7.6, and 10) inches of rainfall respectively. Findings further indicate that permeable pavements alone had the least percentage of reductions for all recurrence intervals whereas all green infrastructure practices demonstrated a 100% reduction in bankfull flows for the 2-year recurrence intervals. These results underscore the significant potential of integrated green infrastructure systems in effectively managing stormwater and mitigating flood risks in urban areas.
By mimicking natural environmental processes, urban flooding volumes and speeds are significantly reduced, while green areas and water quality are increased through enhanced infiltration into groundwater reservoirs. Through the integration of green infrastructure, intelligent land use planning, and the latest technology, QEERI is committed to creating cities that are safe from floods, capable of coping with the effects of global warming, and promoting sustainable development within the GCC and beyond.
Dr. Sa’d Abdel-Halim Shannak is a scientist at Hamad Bin Khalifa University’s (HBKU) Qatar Environment and Energy Research Institute (QEERI).
