THINKING ABOUT LANDSCAPE ARCHITECTURE
gain, and revitalizes disused or derelict sites. Plants host myriad pollinator species associated with their flowers and play a central role in the growth of a multitude of plants and crops. Plants are a source of delight and sense of well-being for humans. The presence of plants either as a natural or constructed landscape is a contributory factor to property values and to the overall quality of life and health of communities. The physical and visual presence of plants is now known to improve and speed up the healing process of patients recovering in hospitals.3
Managing Storm Water The term green infrastructure discussed earlier refers to systems and practices designed by landscape architects and other professionals such as civil engineers that mimic natural processes. One example is the design for handling storm water so as to retain surface water in rain gardens or retention ponds, allowing time for the water to infiltrate the soil and to return the water to the atmosphere either through evaporation or by plants. The designed retention systems hold storm water on the site where it can later be used for irrigation and other purposes (fire control, for example). Green infrastructure systems are appropriate for a wide range of landscape project types in place of, or in addition to, the traditional stormwater management infrastructure. A landscape architect can employ any one or a combination of the following elements from the green infrastructure tool kit in designing a storm-water management plan: s Bio-swales are vegetated, shallow, slightly sloping, landscaped depressions designed to capture and to treat storm-water runoff as it moves through a select palette of plants across the topography and downstream (see Figure 10.2). Bio-swales are typically sized to accommodate the volume of the water from a prescribed storm event. The initial runoff collected is also known as the “first flush.” The swales are designed to allow sediment and pollutants to settle out prior to recharging the ground water. The plant species used, in addition to achieving some other functional or aesthetic goals, are selected to absorb targeted pollutants and hold loose sediment in place. s Rain gardens are designed to capture, temporarily hold, and allow storm water to infiltrate the soils of a property. They are created with plants in combination with a depressed ground form designed to be an attractive addition to a property, in addition to managing storm water, often in combination with other storm-water management systems (Figure 10.3). Detained water has time to percolate into the soil and to provide moisture for the rain garden plants. In some cases the rain garden itself is designed to slope—in the way Figure 10.2 Bio-swale along a city street, City of Burbank, that a swale slopes—carrying excess water farther California, Department of Water and Power, by Ahbé Landscape downstream to a larger-capacity retention area. Architects. 194
