Urban water : harvesting rainwater at household level to improve the current water metabolism in Cuenca, Ecuador

Abstract

With a global population about 7 billion people and their continued growth are pressuring global natural resources, in freshwater matter this pressure is altering both the river flows; timing season of water flows; and spatial patterns in order to meet human demands both in urban as rural areas. However, water stress in urban areas are increasing and expectations by 2050 are grim with a global urban development by 70 percent moreover urbanization rate expected by 2030 in Latin America is 80 percent, thus the water concerns because of high average water consumption 220 lpd, and water leakage by 29 percent in the third largest city of Ecuador Cuenca have motivated to perform this analysis. The analysis is based on a metabolic perspective in order to determine anomalies in the urban water cycle at household level for then apply one of the tools of stormwater management in short term such as harvesting rainwater to find how feasible can be this system both individually as communally in Cuenca urban area based on criteria of rainfall, roof surface, roof material, water average consumption, and costs; in order to generate social, economic, and environmental benefits. Moreover, give recommendations and strategies in mid and long term to get an Integrated Urban Water Management (IUWM) model that allow ensuring the enough natural resources, environmental health, and economic sustainability for current and future demands. The main problems in the urban water cycle are in a outdated urban water management because of water leakage in the delivery network and unsuitable water pricing as well as bad consumers habits; these are affecting economically the water enterprise; nonetheless these problems are not putting in risk freshwater resources, and infrastructure capacity to meet future demands but the implementation of harvesting rainwater systems both individual as community can allow water savings by 18 percent at household level, and by 11 percent in whole water production process at city level. Moreover, the implementation can generate 750.000 job positions both direct as indirect. Finally, the risk of floods can be mitigated due to, roughly 2.88 million m3 of runoff rainwater a year are not released on rivers. To conclude, economic losses are avoiding that this money can be used to improve and maintain the current infrastructures, and development socio-technical projects in order to get a more suitable water metabolism. In other hand, encourage a harvesting culture at household level is a good strategy in short term but its feasibility is related directly to five drivers of which four can be handled such as roof surface area, roof material, domestic water consumption, and costs; in order to get most efficient systems. Finally, there are more tools and strategies to get sustainable goals in short mid and long term through an Integrated Urban Water Management model, in order to urban dwellers can move from simply consumers to a status of suppliers and managers of resources.