Estimation of Mexico megacity wastewater volumes poured into the Mezquital Valley from 1985 to 2020

The sewer system of Mexico City is very complex and has four drains: the Grand Canal and the Central, West, and East drain, which transport wastewater (from population, industry, services) and rainwater to the Mezquital Valley. However, there are not records of the historical volumes of wastewater received by the Mezquital Valley. Therefore, an estimate was made of the volume of wastewater and rainwater sent the drainage system from four main sources of discharges: population, industries, services, and rivers, for the period 1985-2020, in a five-year period. The average rainfall contributed by the metropolitan areas was 648 +/- 12.49 hm(3). The average estimate of industrial discharges and services reported by the Public Registry of Water Rights (REPDA) was 117 +/- 18.09 hm3 3 and the population increased the discharge of sewage from 582 hm(3) in 1985 to 803 hm(3) in 2020. This study disaggregates the volumes transported by each drain toward the El Salto and El Salado rivers. It is reported for the first time an annual estimate of the historical volume of wastewater that has led to the socioeconomic development of the Mezquital Valley, allowing subsequent work of future scenarios for decision making and disaster prevention.