Author(s): R. Rene Autrique; C. Eduardo Rodal

Linked Author(s):

Keywords: Urbanization; Sustainability; Potable water; Aqueducts; Aquifers

Abstract: Urbanization, or the concentration of population in cities, is an irreversible social and economic fact. At different levels and with different growth rates, it exists in all continents, in developed and developing countries. In Latin America, for example, the urban population is close to 75%. Urban growth and its potable water demand normally exceed, in large cities, the annual recharge of the local aquifer, usually the first source of water supply, requiring aqueducts to transfer water from non urbanized neighboring basins, creating water conflicts between urban and rural populations. These water conflicts should be handled taking into consideration present and future agricultural and urban water requirements, promoting its efficient use, its equitable access, and preserving its sources, in quantity and quality. They should be dealt in a multidisciplinary way, from its economic and technical feasibilities to its social aspects, with the participation of all social and institutional actors, to reach long term agreements. It is presented, from the technical discipline, a general model for grand vision planning to determine, for typical cities from 1 to 20 million inhabitants, the scale of its local aquifer mining and depletion, deducting from the urban withdrawal the annual aquifer recharge. Along with the evaluation of time available before total aquifer exhaustion, increasing water withdrawal costs are compared to the typical costs of building aqueducts from neighboring basins. The general model, comprising a city model, a recharge model, an aquifer model, a wellfield model, an aqueduct model and a distribution network model, is developed and presented in graphs showing city population, occupied territory, population density, annual per capita water provision, recharge areas, precipitation (from 500 to 1500 mm), recharge area/urban area ratio, recharge/precipitation ratio, local aquifer characteristics, and the potential sources for the importation of water, with distances and topographic profiles for the required aqueducts. Real cities can be plotted in these general graphs, showing patterns and tendencies. It is applied to three Mexican cities with 1, 4 and 20 million inhabitants. The model is based in the statistics for large cities published by international organizations, defining model cities by its population, territory and population density; in the estimation methods of aquifer recharge reported in the groundwater literature, and in aqueduct models previously developed and published by the authors. Through distribution network models, the effects of urbanization in the water networks are discussed, and the ways of attaining more efficient and resilient networks. It is concluded that large cities require importation of water through aqueducts, in amounts depending of its specific hydrological and geohydrological condition, with its consequent water conflicts, to be solved under the principle: “same for all, for ever”.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022947

Year: 2022