December 2007, Vol. 19, No.12


To Combat Water Shortages, Utility Offers ‘Cash for Grass’ Incentive

The Water Smart Landscapes program operated by the Southern Nevada Water Authority (SNWA; Las Vegas) provides cash rebates for residents and businesses that replace grass with drought-tolerant landscaping. The program has surpassed more than 18.9 million m³ (5 billion gal) saved annually since its inception in 1999.

More than 24,000 homes and businesses have participated in the program, replacing 8.4 million m² (90 million ft²) of grass. Qualifying residential and commercial customers receive $21.53/m² ($2/ft²) for up to 139 m² (1500 ft²) of grass they replace with water-efficient plants and shrubs, according to an SNWA news release. The authority based its estimated annual savings on a multiyear study.

SNWA is a regional agency that manages water conservation, water quality, and water resources, with member agencies that include the Big Bend Water District (Laughlin); the cities of Las Vegas, North Las Vegas, Henderson, and Boulder City; the Clark County Water Reclamation District; and the Las Vegas Valley Water District.

According to SNWA, Water Smart Landscapes is only one of several campaigns that have enabled Southern Nevada to decrease its water consumption by 68 million m³ (18 billion gal) between 2002 and 2006, despite several years of drought and the addition of about 330,000 new residents and nearly 40 million annual visitors.

“How we grow as a community has a tremendous impact on our water resource needs,” said SNWA General Manager Pat Mulroy. “The so-called ‘Manhattanization’ of Las Vegas, with numerous high-rise condominiums under construction, is the best possible form of development from a water efficiency perspective. Like resorts, these buildings use most of their water indoors, limiting consumptive uses to central air-conditioning systems, community swimming pools, and small patches of landscaping.”

At the same time, single-family homes have improved their water efficiency through Water Smart Landscapes and strict municipal landscaping codes limiting the amount of grass permitted in residential yards. This ultimately reduces each home’s consumptive draw on the community’s water supply, according to SNWA.

Other SNWA conservation programs stress compliance with mandatory watering schedules and implementing water-efficient technologies for businesses. For more information on Water Smart programs, see

Flooded Chinese River Gets Flood Control System

China’s Huaihe River Basin is experiencing its worst flood since 1954. In July, media reports indicated more than half a million people had to flee the flooding area and that at least 100 have died. Moreover, more than US$500 million in economic losses have been incurred, according to a news release from architecture and environmental consulting company EDAW (San Francisco).

In July, EDAW unveiled its framework for the National Flood Control Decision Support System for China, centered on the Huaihe River Basin. The firm submitted the plan in conjunction with engineering and consulting firm Riverside Technologies Inc. (Fort Collins, Colo.) to the Chinese Ministry of Water Resources and the Huaihe River Commission.

EDAW and Riverside worked collaboratively for 8 months to develop a pilot model for flood control along the Huaihe River, a detailed set of functional requirements for a national-scale flood control decision support system, and an implementation and investment plan to make it a reality.

Using technology from the U.S. Army Corps of Engineers Hydrologic Engineering Center in Davis, Calif., the project team designed real-time flood management models specially tailored to the terrain and contexts of the river. The team specifically looked at a 120-km (75-mi) stretch between the Lutaizi Gauging Station and the Bengbu Gates in Anhui province. The model provides management tools that, if implemented, will minimize casualties and economic losses caused by floods, according to the news release.

The project team also analyzed the economic and beneficial impacts of implementing this flood control system on a national scale. The results show that the full implementation of the National Flood Control System will annually reduce numerous casualties and save 6 billion yuan (US$795 million), or 0.03% of China’s gross domestic product. Furthermore, EDAW notes, during the next 25 years, the flood control system would accumulate 69.1 billion yuan (US$9.1 billion) in national savings, far exceeding an initial investment of 580 million yuan (US$72 million).

“The final report we have submitted to the Ministry of Water Resources and the Huaihe River Commission offers a clear and comprehensive land-based solution for China’s massive and persistent flooding challenges,” said Stephane Asselin, regional director of environmental services for EDAW in Asia. “Its successful implementation would mitigate the disastrous effects of massive flooding in China.”