Total Hydrology Planning: Using Water to Drive Community
BUILDING DIALOGUE
Total hydrology planning is a methodology we developed to identify and utilize all water resources on a project site. This customized, holistic, insightful approach maps all water as a basis for site design, maximizing and manipulating all on and off-site water flow for beneficial use. We apply appropriate technologies, analysis, management, and design, in response to the pervasive water supply issues that plague the West and other areas. This radical approach is the basis for our design.
Craig Karn, ASLA, ULI, NAHB
Principal and Founder, Consilium Design
Water, civilization and the growth of cities. Throughout history, cities and civilizations have risen and fallen because of water. Since ancient times people have depended on and harnessed water to survive, build their cities and grow their civilizations. The examples abound from Angkor Wat, 12th century BC; Jordan, 6th century BC; and Maya, 20th century BC to the early 16th century.
Innovative water strategies have been a part of American history as well. Thomas Jefferson used rainwater capture to irrigate crops and gardens at his hilltop estate at Monticello. Here in Colorado, Gen. William Jackson Palmer, founder of the Fountain Colony, later to be named Colorado Springs, established the El Paso Ditch Co., the first in the territory. They constructed over 60 miles of irrigation canals and runnels along major streets to create a shady urban tree lined streetscape.
What is total hydrology planning? Strategies to bring a site’s water supply and demand as close to balance as possible. When the relationship between climatic conditions and site-specific dynamics are well understood, projects can be designed with resiliency to storm events and drought.
Planning and design. New efficiencies in traditional water infrastructure can be accomplished through innovative land planning at the beginning of the development process. Reducing the development footprint of neighborhoods and communities reduces the linear foot runs of water, sanitary sewer and the developed flows, scaling down stormwater management systems, as well as the amount of irrigated landscape. More efficient patterns and connectivity of streets allows for more frequent internal looping of the system to better balance water pressure, reduce line sizes and phasing of construction.
More efficient, compact lot sizes reduce the amount of landscape to be irrigated. Other site design techniques that reduce water needs include clustering homes around common “front yards” for gathering and play, only using turf for small outdoor living areas if at all and using synthetic turf for outdoor play spaces.
The native landscape. The most water-efficient, sustainable landscape for any land is the predevelopment, native landscape. Preserving the native landscape and restoring disturbed areas to a native or naturalized condition should be a priority. Compact, low-impact design allows for the preservation of larger, consolidated landscape areas that are easier to protect and preserve during construction. Native/naturalized landscapes are easier to reestablish in disturbed areas without the need for permanent irrigation. Only use irrigated turf grasses for active use landscapes like sports fields, event and entertainment spaces and play areas. Managing stormwater at its source, where it meets the ground can eliminate or reduce the size and complexity of the structured storm system. Bioswales and bioremediation basins improve stormwater quality and reduce the need for supplemental irrigation.
Rainwater harvesting. Rainwater harvesting can reduce potable water demand in the landscape by 30% or more. There are several techniques that can be applied at the home, neighborhood and community level. Rooftop rainwater harvesting that may or may not include storage systems, depending on jurisdictional limitations on stormwater retention. Impervious surface rainwater should be directed as sheet flows from streets, parking lots, patios and walks to adjacent landscape areas whenever possible. If sheet flow is impractical, frequent curb cuts that direct rainwater to the adjacent landscape before it enters a structured drainage system is effective. Using level spreading devises to disperse water at the outfall of storm lines will reduce erosion and encourage infiltration. Many non-native and naturalizing trees and shrubs will benefit from and perform well with slightly more water than direct rainfall provides, reducing the need for structured irrigation systems.
Reclaimed water. Reclaimed, nonpotable water can be an effective alternative to using potable water in the landscape. There are drawbacks: It requires constructing a duplicate conveyance system, source may be too far away to be cost-effective, nonpotable water can elevate levels of salts and other minerals and impact the health and lifespan of plant materials. It is often not desired for use in active play areas and public spaces, depending on the quality of the water.
Changing the culture of water. We don’t have a water scarcity problem as much as we have a water management problem. For total hydrology to be successful, we need to engage the public and build understanding and acceptance of new ideas and approaches to how everyone values and uses water. Water providers and other organizations that manage and regulate the distribution and use of water need to change codes and policies to allow for new, innovative practices to be implemented.
Published in the June 2020 issue of Building Dialogue.
