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GLOBAL ASSESSMENT OF WASTEWATER IRRIGATION: UNDERSTANDING HEALTH RISKS AND CONTRIBUTIONS TO FOOD SECURITY USING AN ENVIRONMENTAL SYSTEMS APPROACH
Impact/Purpose:
Rapid urbanization without concomitant improvements in wastewater treatment infrastructure in developing countries has led to the widespread contamination of surface water sources, which downstream farmers rely on for irrigation. At present, 90 percent of the world’s wastewater receives no treatment before it is discharged to the environment. Paradoxically, these same flows concurrently pose health risks and provide a reliable, nutrient rich water source for peri-urban farmers. The overarching objectives of this research include: (1) quantifying the global extent of de facto reuse of untreated wastewater for irrigation; (2) understanding how the drivers and health risks associated with this practice vary spatially; and (3) characterizing the role of wastewater irrigation in global food security and integrated water resources management strategies.
Description:
This research will quantify the extent of de facto reuse of untreated wastewater at the global scale. Through the integration of multiple existing spatial data sources, this project will produce rigorous analyses assessing the relationship between wastewater irrigation, health, fecal contamination in surface water sources, water resources allocation and urban food security. The inherent flexibility in the spatial models being developed for this project allows for the inclusion of additional modules and higher resolution datasets, as they become available. Examples of additional analyses that could be built onto this existing framework in the future include an assessment of the water quality impacts of different sanitation interventions, nutrient production and reuse potential, changes in wastewater irrigation over time and the role of wastewater in mitigating the impacts of water scarcity.
Potential to Further Environmental/Human Health Protection
Conspicuously absent from the Joint Monitoring Program’s definition of improved sanitation facilities is the provision for treatment of accumulated human waste from “improved” sanitation facilities. Such an approach to sanitation planning disregards the implications of sanitation infrastructure choice on downstream communities, especially farmers reliant on surface water sources for irrigation. By quantifying the extent of irrigation with untreated wastewater at the global scale, this research not only draws attention to the need for integrated wastewater and water resources management but also provides planners and policy makers with rigorous, concrete data on the drivers and health risks of this practice at scale. This research fills these key knowledge gaps through its systemslevel analysis of the extent, drivers and risks of wastewater irrigation across heterogeneous water resources, agricultural, economic, infrastructural and ecological contexts.