Stormwater Management is the process of controlling rainwater runoff that comes primarily from impervious surfaces like parking lots, driveways, and rooftops. In emerging nations, as a result of rising population and urbanization as well as recent signs of climate change, there may not be enough water available to meet the needs of the urban population. Adaptive management, professional collaboration, and public involvement in water planning are required since climate change poses a significant challenge to urban water planning and increases the risk of flooding.

With the intensified rainfall brought on by climate change, rainwater harvesting (RWH) is essential for reducing the consequences of drought and controlling flooding. Modern stormwater management systems are designed not only to prevent flooding but also to remove pollutants, protect waterbodies, capture rainfall to replenish groundwater, and prevent damage to property and wildlife habitat. These Modern Stormwater Management systems are referred to as Low Impact Development (LID) Techniques.

Importance of Stormwater Management in the GCC

More than 20 billion cubic meters of water are needed to fill a massive deficit in the GCC countries. This need is primarily filled by extensive over-drafting of both renewable and non-renewable groundwater resources for the agricultural sector, extensive installation of very expensive desalination plants for the municipal sector, and small-scale reuse of treated wastewater in the agricultural and municipal sectors. 

By 2030, annual water demand is expected to more than double based on the present population growth rates, water resources management strategies, and water consumption patterns.  Due to limited desalination capacity and wastewater reuse, this demand will primarily have to be satisfied by additional groundwater extraction, which will result in loss of aquifer reserves and the deterioration of water quality and salinization of agricultural lands. Predicting this need, the GCC has invested heavily in increasing its groundwater reserves and stormwater management.

Use of Low-Impact Development (LID) Strategies

The region’s infrastructure was not built with increased rainfall in mind, resulting in increased short-term flooding. The implementation of LID Techniques for rainwater harvesting and management serves to cope with the increasing short-duration floods and convert this excess into  an additional source of drinking water.

LID, as a consideration in new projects, can be used to manage stormwater by various control methods, including but not limited to green roofs, vegetated areas, permeable pavements, rain barrels, and infiltration blocks. The main goal of these strategies is the improvement of resilience against the increase of storm-water flows and the risk of flooding, which can be responsible for significant impacts on present and future development. Typically in the real-world, LID designs incorporate more than one type of practice or technique to provide an integrated treatment of runoff from a site.

LID strategies that are implemented to manage stormwater are detailed below

Rain Garden

A rain garden is a type of treatment facility, commonly known as bioretention. The primary pollutant removal mechanisms are filtration by native vegetation through phytoremediation processes that clean water as it passes through the facility. Rain gardens contain layers of organic sandy soil and mulch for vegetation. Low-maintenance plants are recommended for rain gardens based on their suitability to local climate, soil, and moisture conditions without the use of fertilizers and chemicals. Rain gardens are best applied on a relatively small scale. They work well along driveways and in low-lying areas of a property.

Vegetated Roof

Vegetated roofs, also known as green roofs, are an innovative way to reduce impervious surfaces. A vegetated or green roof consists of a lightweight vegetated planting bed that is installed on a new or existing roof. This enables the roof to retain precipitation on and within the planting bed and on the surface of the vegetation. This stored water is later released through evapotranspiration, thereby reducing the volume of runoff from the roof. The exact amount of rainfall storage and runoff reduction will depend upon the depth and porosity of the planting bed and, to a lesser degree, the type and density of vegetation.

Permeable Pavement

Porous pavement is a permeable pavement surface. Porous pavement replaces traditional pavement, allowing parking lot stormwater to infiltrate directly and receive water quality treatment. There are various types of porous surfaces, including porous asphalt, pervious concrete, and grass or permeable pavers. 

Infiltration Trench

An infiltration trench is a rock‐filled trench that receives stormwater runoff. Stormwater runoff passes through some combination of pre-treatment measures, such as a swale and detention basin, and into the trench. Runoff is stored in the void space between the stones and infiltrates through the bottom and into the soil matrix. The primary pollutant removal mechanism of this practice is filtering through the soil. With LID, every landscape or infrastructure, such as roof, parking, sidewalks, and green space, can be designed to be multifunctional, incorporating detention, retention, filtration, or runoff use.

Low Impact Development (LID) Techniques are one of the proven methods to improve water efficiency in semi-arid areas such as the GCC. Rainwater harvesting is a self–sufficient stormwater management system (LID), if designed well, does not require electricity, chemical, or extensive maintenance for its functioning. The water stored can be used for gardening, toilet flushing, and car washing.  Rainwater harvesting via LID techniques can be considered as a sustainable water resource that is easily accessible to everyone. Low Impact Development (LID) techniques can achieve significant cost savings through reduced grading, landscaping, paving, and infrastructure costs. It does however require expert organization, execution, management, and upkeep. Especially to ensure that year around sedimentation does not clog up the infiltration system set up around a project. 

Our Sustainability Team at Alpin Limited provides consultancy services on stormwater management techniques for construction projects and existing infrastructures. Reach out to us at contact@alpinme.com or give us a call at +971-2-234-6198.