Assessing Infrastructure Decisions to Manage Water Resources in the Valle de México

9 p.International audienceGroundwater supplies nearly seventy percent of the regional water supply in Mexico City. Past groundwater extraction in the central city caused subsidence of up to 40 feet in some areas. Today, while pumping in the center city has ceased, groundwater supplies come from areas surrounding Mexico City, which are themselves experiencing effects of groundwater exploitation. Managing groundwater resources to preserve aquifer quality and quantity in the Mexico City Basin must incorporate a variety of strategies, such as promoting infiltration, altering extraction rates, managing demand, and developing wastewater treatment and reuse options. Further, aquifer management decisions have both long-term and short-term planning components. This paper describes a framework for characterizing infrastructure decisions to meet both long-term planning needs and short-term requirements. Long-term decisions include capital-intensive options such as construction of infiltration basins and wastewater treatment facilities, while short-term actions manage demands based on unexpected hydrologic and use parameters. Both short-term and long-term decisions have inherent uncertainty. Such a framework can be used to assess groundwater management and water supply options in Mexico City given infrastructure decisions, water demand forecasts, climate variability, and urban sustainability initiatives. The framework informs planning and management models for the basin

Adapting Urban Water Systems to Manage Scarcity in the 21st Century: The Case of Los Angeles.

Acute water shortages for large metropolitan regions are likely to become more frequent as climate changes impact historic precipitation levels and urban population grows. California and Los Angeles County have just experienced a severe four year drought followed by a year of high precipitation, and likely drought conditions again in Southern California. We show how the embedded preferences for distant sources, and their local manifestations, have created and/or exacerbated fluctuations in local water availability and suboptimal management. As a socio technical system, water management in the Los Angeles metropolitan region has created a kind of scarcity lock-in in years of low rainfall. We come to this through a decade of coupled research examining landscapes and water use, the development of the complex institutional water management infrastructure, hydrology and a systems network model. Such integrated research is a model for other regions to unpack and understand the actual water resources of a metropolitan region, how it is managed and potential ability to become more water self reliant if the institutions collaborate and manage the resource both parsimoniously, but also in an integrated and conjunctive manner. The Los Angeles County metropolitan region, we find, could transition to a nearly water self sufficient system

Groundwater exchange pools in Los Angeles: An innovative example of adaptive management

Across California, Groundwater Sustainability Agencies (GSAs) are devising plans to reduce long-term overdraft. As part of the 2014 Sustainable Groundwater Management Act, GSAs will submit plans in 2020-2022, which detail strategies to bring groundwater use into balance by 2040. Planning processes must assemble stakeholders and estimate sustainable yields of groundwater, quantify existing pumping, describe future options to limit overdraft, and identify funding. GSAs are actively searching for ways to stretch limited supplies and sustainably use the underground storage space created by decades of overdraft, drawing on lessons of previous regional agreements

Stormwater Governance and Future Cities

Urban stormwater infrastructure traditionally promoted conveyance. Cities are increasingly designing stormwater infrastructure that integrates both conveyance and infiltration in hybrid systems to achieve public health, safety, environmental, and social goals. In addition, cities face decisions about distribution of responsibilities for stormwater management and maintenance between institutions and landowners. Hybrid governance structures combine centralized and distributed management to facilitate planning, operations, funding, and maintenance. Effective governance in any management approach will require changes in the expertise of stormwater agencies. Recognizing the distinction between hybrid infrastructure and hybrid governance is important in long-term planning decisions for construction and management of stormwater systems. A framework is presented that relates the level and type of existing stormwater infrastructure with available capital, institutional development, and predominant citizen contributions. Cities with extensive existing infrastructure are increasingly integrating distributed, “green” approaches that promote infiltration, and must improve institutional expertise for governance decisions. For cities with little existing infrastructure, landowner management often dominates, especially when municipalities cannot keep pace with rapid growth. In between, rapidly industrializing cities are positioned to use growing capital resources to fund both conveyance and infiltration measures based on current design principles. For all cities, local management innovations, including decisions regarding public engagement, will be critical in shaping future urban stormwater systems

Systems analysis of metropolitan-scale reuse with effects on water supply resilience and water quality

Water reuse with Advanced Water Treatment (AWT) is increasingly appealing for urban areas seeking water supply reliability. In cities facing water scarcity, how can large-scale reuse support reliability and how do reuse operations affect water quality, energy use, and water conservation? This paper presents a systems analysis of metropolitan-scale water reuse and its effects on water supply and quality. For the case study of Los Angeles County, California, USA, hydroeconomic modeling is used to evaluate reuse as a contributor to water supply given urban water conservation, drought-induced water scarcity, and costs and benefits for supply and demand. Results indicate that AWT can be a viable source of supply especially when coupled with conservation. Across modeled scenarios, reuse provides as much as 30% of regional supplies. New water reuse with AWT becomes viable when imported water availability is 50% or less of historic values. Existing indirect potable reuse operations in the county remain important. Systemwide energy intensity of operations increases with greater reuse in the absence of water conservation. Modeled influent flow rates to wastewater treatment plants resemble historical values, but extreme flow events could pose risks. The paper offers a holistic framework to evaluate water reuse as a component of urban water management.</p

Artes: An Integrated Model of Water Supply in L.A. County

Artes is a model of water management in metropolitan Los Angeles. It was developed to investigate the potential for maximizing local water supplies and reducing imports across Los Angeles and its hundreds of water agencies. Model results have helped assess the implications of local water supply on urban water systems reliability, stormwater capture and water reuse, groundwater management, environmental flows, economics, and urban landscapes (trees and plants). The model is a product of the California Center for Sustainable Communities at UCLA and was developed through a collaborative research network spanning UCLA, the University of Utah, and Colorado School of Mines. The project was funded through the National Science Foundation's Water, Sustainability, and Climate program.

Artes: An Integrated Model of Water Supply in L.A. County

Artes is a model of water management in metropolitan Los Angeles. It was developed to investigate the potential for maximizing local water supplies and reducing imports across Los Angeles and its hundreds of water agencies. Model results have helped assess the implications of local water supply on urban water systems reliability, stormwater capture and water reuse, groundwater management, environmental flows, economics, and urban landscapes (trees and plants). The model is a product of the California Center for Sustainable Communities at UCLA and was developed through a collaborative research network spanning UCLA, the University of Utah, and Colorado School of Mines. The project was funded through the National Science Foundation's Water, Sustainability, and Climate program.

Fragmented Flows: Water Supply in Los Angeles County.

In the Los Angeles metropolitan region, nearly 100 public and private entities are formally involved in the management and distribution of potable water-a legacy rooted in fragmented urban growth in the area and late 19th century convictions about local control of services. Yet, while policy debates focus on new forms of infrastructure, restructured pricing mechanisms, and other technical fixes, the complex institutional architecture of the present system has received little attention. In this paper, we trace the development of this system, describe its interconnections and disjunctures, and demonstrate the invisibility of water infrastructure in LA in multiple ways-through mapping, statistical analysis, and historical texts. Perverse blessings of past water abundance led to a complex, but less than resilient, system with users accustomed to cheap, easily accessible water. We describe the lack of transparency and accountability in the current system, as well as its shortcomings in building needed new infrastructure and instituting new water rate structures. Adapting to increasing water scarcity and likely droughts must include addressing the architecture of water management