干旱区生态环境知识资源中心

Water conservation in the urban landscape can and should occur in every region of the United States. However, in communities located in arid regions of the southwestern United States, a higher percentage of the water is used outdoors. In Las Vegas, the residential sector uses approximately 60% of all the water, with approximately 70% of that water used for the irrigation of residential landscapes (Devitt et al., 2008). Many communities including Las Vegas continue to grow at a rapid pace while facing an uncertain future with regards to water resource availability. Water managers must plan for a future where more people exist, less water is available and some of the water available for use is of poorer quality. In light of this, are cities located in arid and semi arid regions sustainable? In particular, are urban landscapes sustainable with regards to water? Gleick et al (1995) defined sustainable water use as "the use of water that supports the ability of human society to endure and flourish into the indefinite future without undermining the integrity of the hydrological cycle or the ecological systems that depend on it". Based on this definition, many communities in the southwest currently find it difficult to achieve water sustainability in the 21st century. Baker et al. (2004) suggested that a "severe drought might be the tipping point that will test the resilience of desert cities". In the purest sense, landscapes are sustainable only if they do not require any additional resources, that they achieve a certain level of self sufficiency. Although this goal can be attained in wetter regions; arid and semi arid regions can only hope to move toward a greater level of water use sustainability. Such landscapes will need to be based on a concept of minimization; minimal landscape area and minimal irrigation, while still trying to provide aesthetic value and environmental function (modulations of water cycle during storm events, water quality, dust retention, etc.). It is therefore appropriate and critical that cities in arid regions implement conservation programs that emphasize significant water use reduction in urban landscapes.