Environmental Considerations in the Bahá’í Gardens
From the earliest days, the Bahá’í gardens in Haifa and ‘Akko have been managed in an environmentally-conscious way, with particular emphasis on the conservation of water. For example, the recycling of green waste into mulch and compost dates back to the 1950s, as does the practice of turning under large areas of lawn in the early summer and letting them lie fallow without water until the arrival of the winter rains, when they are reseeded.
During the planning for the construction of the terraced gardens on Mount Carmel in the 1980s, extensive research was conducted and discussions were held with the Water Commission, Mekorot and some of the best Israeli consultants and academics in the fields of horticulture, irrigation and water resource management. The conclusions were fully implemented in the detailed planning of the garden plantings as well as the infrastructure systems so that the project would be based on sound ecological principles and incorporate the most advanced technology. Since completion of this project, we have been updating our practices and extending the use of advanced technology to other parts of the gardens.
The Bahá’í gardens in both Haifa and ‘Akko are designed according to a hierarchical principle involving intensive treatment of relatively small areas at the heart of the site, where a colorful effect is achieved with small but strategically placed beds of seasonal flowers, complimented with eye-catching cactus gardens. The intensively treated areas are surrounded by informal plantings featuring drought-tolerant species such as echium, rosemary and oleander, as well as yucca, almond, olive, cypress and pine trees. Once established, these plantings require minimal maintenance and very little water. They, in turn, blend into areas which are kept in a natural state to host populations of birds, insects and animals that will help maintain the ecological balance of the site.
Every year, more than 75% of the lawn in the ‘Akko gardens is turned under in the summer months. In years of severe water shortage, some of these areas are covered with mulch and left unplanted all year to achieve additional water savings. Likewise, large areas of the Haifa gardens are covered with rye grass in the winter and dried out during the summer. Since the sloping surfaces of the gardens in Haifa must be planted year-round to prevent erosion, extensive use is made of ivy and other ground-covers that require less water than lawn.
The irrigation systems installed in the Bahá’í gardens are considered among the most advanced in the world. At the hub of the system is a computer that operates hundreds of valves to direct water through a complex network of polyethylene tubing so that each type of plant receives the amount it needs at the right time, according to the atmospheric conditions. To achieve this, the irrigation scheduler uses meteorological data from a special weather forecast issued by the Technion to project the evapo-transpiration rate, a major indicator of the amount of water that will be needed by the vegetation.
Most of the water is delivered directly to the plant roots at night using drippers and sprinklers, and the occasional overhead irrigation that must be done in daylight to ensure the absorption of fertilizers and other agro-chemicals is scheduled in the early morning when evaporation is minimal. The computer immediately detects any leakage or other anomaly, and the irrigation team performs frequent checks on the equipment to make sure that any problems are identified and resolved without delay. In addition, there is a constant process of review of the irrigation programming and water delivery systems, including investigation and testing of new technology, new kinds of equipment and new approaches aimed at improving the efficiency of the system. To reduce the strain on potable water, the Bahá’í gardens make extensive use of brackish and/or polluted water pumped from licensed wells on the property, which is then treated to meet the requirements of the gardens.
A central design feature of the terraced gardens on Mount Carmel is the flowing water that seems to accompany the visitor at all times, delighting both the eye and the ear. These effects are achieved without waste, because the fountains and streams running beside the stairs are fed from a single closed system circulating within each terrace unit. The amount of water added to the system each day to offset evaporation for the whole site is less than the daily consumption of an average person.