water Case Report Megacity Wastewater Poured into A Nearby Basin: Looking for Sustainable Scenarios in A Case Study Silvia Chamizo-Checa 1,2, Elena Otazo-Sánchez 2,* , Alberto Gordillo-Martínez 2, Juan Suárez-Sánchez 1,César González-Ramírez 2 and Hipólito Muñoz-Nava 1 1 Facultad de Agrobiología, Universidad Autónoma de Tlaxcala, Autopista Tlaxcala-San Martin Texmelucan km 10.5, CP 90120 Tlaxcala, Mexico, Mexico;
[email protected] (S.C.-C.);
[email protected] (J.S.-S.);
[email protected] (H.M.-N.) 2 Area Académica de Química, Universidad Autónoma del Estado de Hidalgo, Carretera Pachuca-Tulancingo km. 4.5, Mineral de la Reforma, CP 42184 Pachuca, Hidalgo, Mexico;
[email protected] (A.G.-M.);
[email protected] (C.G.-R.) * Correspondence:
[email protected]; Tel.: +52-7717172000 (ext. 2208) Received: 17 January 2020; Accepted: 11 March 2020; Published: 14 March 2020 Abstract: Megacity sewage creates socioeconomic dependence related to water availability in nearby areas, especially in countries with hydric stress. The present article studies the past, current, and future water balance progression of realistic scenarios from 2005 to 2050 in the Mezquital Valley, the receptor of Mexico City untreated sewage since 1886, allowing for agriculture irrigation under unsustainable conditions. The Water Evaluation and Planning System (WEAP) was used to estimate water demand and supply, and validation was performed by comparing results with outflow data from the Tula River. Simulated scenarios were (1st) steady-state based on inertial growth rates (2nd) transient scenario concerning the influence of forecasted climate change perturbations in surface water and hydric stress for 2050; and (3rd) the previous scenario appending scheduled actions, such as 36% reduction in imported wastewater and the startup of a massive Wastewater Treatment Plant, allowing for drip and sprinkler irrigation from the year 2030.