By G. Allison Hedges, ASLA
Abu Dhabi Urban Planning Council (UPC)
Estidama Pearl Qualified Professional (PQP) for Villas, Buildings and Communities
Living in a desert means that we all need to conserve water regardless of which time of the year it is. For landscape professionals one of the best ways to integrate this into our work is through careful selection of plant materials to promote water usage at sustainable levels.
The Abu Dhabi Urban Planning Council (UPC) has been proactive in compiling a comprehensive list of plants that minimize water consumption. The Public Realm Design Manual (PRDM) identifies trees, palms, shrubs, groundcovers, ornamental grasses, succulents, perennials and climber plant materials.
Plants are designated into many different categories; whether they can handle extreme sun, those that require wind shelter, or shelter from afternoon sun, or require partial or full shade. If they are locally occurring, or native, saline and drought tolerant. Other plants that are not locally occurring are also listed due to their regional adaptability.
Plants are further designated according to their irrigation classification or water demand. Water demands are classified as having a: low, medium-low, medium, high to wetland irrigation demand.
The plant list also notes plant hazards to consider such as those having thorns, or those that are sources of pollen leading to allergies or that are poisonous.
In addition, plants are also classified according to the location in which they would most likely thrive. Inland Suitability plants are those that thrive in an inland urban location or a desert location. Waterfront Suitability plants are those that thrive in urban and non-urban waterfront locations.
The UPC defines the Public Realm as all exterior places and linkages. These may be streets, pedestrian walkways, bikeways, bridges, plazas, nodes, squares, transportation hubs, gateway parks, waterfronts, natural features, view corridors, landmarks and building interfaces. The four categories for best suited locations are: parks, streetscapes, waterfronts and public places.
Another great resource found in the Abu Dhabi Public Realm Design Manual (PRDM) is the Irrigation Guide. This is located in Appendix C from pages 211-216.
Irrigation water is no longer as freely available in the Emirates as it was when the UAE was less developed. Although the Abu Dhabi PRDM primarily focuses on the Emirate of Abu Dhabi (which also includes Al Ain and the Western Region) its application to all seven Emirates should be employed. All Emirates face the same water supply needs as they pursue development resulting from increased population in the region.
Soil composition is critical to enhancing moisture retention. Use of natural mineral based and polymer free soil moisture retention additives, such as clay or similar, can help establish a soil capable of holding sufficient moisture. These natural mineral additives can therefore hold moisture and sustain the plant so that irrigation occurs as infrequently asevery three days during the summer and every 7 to 10 days during the winter. Therefore, the irrigation frequency of the plant material decreases due to the moisture held by the soil’s composition.
Irrigation technologies should also be incorporated into the landscape plan to monitor water usage. Water meters can manage water delivery rates and monitor potential leaks in the system. This is actually a minimum requirement to attain a “One Pearl” rating for any proposed landscape plan.
The Abu Dhabi Urban Planning Council (UPC) rates the design and construction of buildings, communities and villas according to their compliance with the “Estidama” (Arabic for sustainability) Pearl Rating System (PRS). A “One Pearl” rating is the minimum requirement and is mandatory; however, any additional approved sustainable features incorporated into the plan can increase the Pearl rating of the building adding to its merit. The highest rated plan is a “Five Pearl” rated design.
As we continue water saving strategies, one that should be incorporated into the design is a maintenance schedule whereby 100% of landscape green waste is recycled onsite. Onsite recycling encourages water retention, soil regeneration, and nutrient recycling, which inhibits soil heating. Incorporating naturalized plant materials into the design and minimizing pruning will lower the rate of green waste production and salt deposition in the soil.
Landscape architects and city planners must incorporate plant material in their designs that require less frequent irrigation. Designer’s careful plant selection and grouping of similar plant materials can also contribute to less frequent irrigation.
The following is a short list of plants listed by their “Common Name” that require less frequent irrigation and should be incorporated into a sustainable planting design. Additional plants can be found on the Abu Dhabi PRDM site as previously mentioned.
Ground Covers and Ornamental Grasses
Succulents and Perennials
Crimson or African Fountain Grass
Garden Trumpet Vine
Queen Sago Palm
King Sago Palm
Texas Ranger or Texas Sage
Swamp River or Spider Lily
Senegal Date Palm
Red Dwarf Poinciana
Red or Purple Fountain Grass
Egyptian Star Cluster
California Fan Palm
Rose of Sharon
Bird of Paradise
Frangipani or Temple Tree
Alexander Fan Palm