Citation:

OConnor, T. Total Water Management: A Watershed Based Approach - slides. Presented at 2013 International Low Impact Development Symposium, St Paul, MN, August 18 - 21, 2013.

Impact/Purpose:

Decision support tools such as WEAP and other system simulation models can be useful in analyzing whether TWM produces net benefits by examining water resources in a more interconnected and integrated manner. Each application of TWM needs to be evaluated based on local water resources challenges and unique baseline conditions. A final report of the Los Angeles case study was completed by CDM (now CDM Smith) and published (Report EPA/600/R-12/551). This report is available from the EPA website for downloading. The presentation will summarize the approach used and results of the report.

Description:

ABSTRACT In this urbanizing world, municipal water managers need to develop planning and management frameworks to meet challenges such as limiting fresh water supplies, degrading receiving waters, increasing regulatory requirements, flooding, aging infrastructure, rising utility (energy) costs, shifting populations, and changing climate. The traditional paradigm for water resources and infrastructure management - characterized as once-pass-through use of resources, supply-side solutions to growth, end-of-pipe solutions to wastewater and runoff, and single-purpose projects - is no longer adequate to meet the rapidly evolving challenges of water management. Total Water Management (TWM) is an interconnected approach that reduces fresh water demands, increases water reclamation, changes stormwater management into water assets development through integration of low impact development (LID) strategies, matches water quality to end user needs and achieves environmental goals through multi-purpose, multi-benefit infrastructure. TWM represents a new paradigm for urban water systems. Traditional urban water management separates the municipality’s water resources into distinct classes of potable water, wastewater, and urban runoff, while TWM approaches water as a resource undergoing a continual cycle which can be managed in a fully integrated manner. A case study for the TWM modeling approach is presented demonstrating cost savings and decrease water usage based on data from the City of Los Angeles, California. A systems model was developed based on Water Evaluation and Planning (WEAP) software (Stockholm Environment Institute), an object oriented platform in which water schematics are created using a drop and drag approach. WEAP allows users to build customized models of water systems, which can include water supply, distribution, treatment, reclamation, and disposal infrastructure. WEAP performs mass balances throughout the systems, allocating water based on user-defined demand priorities and supply preferences. Reservior and groundwater storage are tracked over time, and indoor and outdoor water demands can be split to account for conservation and irrigation with reclaimed water, respectively. The software can simulate supply reliability, total lifecycle costs, water quality of receiving waters, and additional environmental indicators.

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