Sedimentation velocities in pluvial waters of Cd. Juárez, Chihuahua, México

  • Angelina Domínguez-Chicas Departamento de Ingeniería Civil y Ambiental, Instituto de Ingeniería y Tecnología, Universidad Autónoma de Cd. Juárez, Av. del Charro 450 Nte, 32310 Cd. Juárez, Chih., México.
  • Thomas K retzschmar Departamento de Ingeniería Civil y Ambiental, Instituto de Ingeniería y Tecnología, Universidad Autónoma de Cd. Juárez, Av. del Charro 450 Nte, 32310 Cd. Juárez, Chih., México. Dirección actual: Departamento de Geología, División de Ciencias de la Tierra, Centro de Investigación Científica y de Enseñanza Superior de Ensenada CICESE, Carretera Tijuana–Ensenada Km.107, 22760 Ensenada, B.C., México.
  • Francisco Núñez-Sánchez Instituto Municipal de Investigación y Planeación (IMIP) de Ciudad Juárez, Av. B. Franklin 4185, Circuito Pronaf, 32310 Cd. Juárez, Chih., México.
Keywords: runoff, sedimentation, suspended solids, pluvial water, Cd. Juárez, Mexico.

Abstract

The use of storm water presents a wide range of benefits to achieve a sustainable management of the resource. The accumulation of water during sporadic rain events in zones with arid climates for its subsequent recovery and utilization is not usual in Latin America. In other regions with similar climatic conditions, for example Australia and the Southwest of the United States, the storm water runoff of urban areas is frequently recovered for use. Nevertheless, storm water is considered a possible contaminantion source for subterranean and superficial water bodies. Depending on the urbanization of the area, the surface water runoff presents site specific characteristics. Nevertheless, the major contaminant in the runoff consists in particulate material. Giving a well sufficient retention time, 80– 85% of the particulate material will be able to settle. Giving the hydraulic characteristics of common retention structures, the occurring sedimentation process is of Type I, where the sedimentation velocity depends on the diameter y density of the particle. Due to the variable size and density of particles in storm waters, the mean sedimentation velocity can only be estimated if the size distributions of the particles is known. The data regarding suspended particles and its removal suggest that the sedimentation velocities are directly proportional to the level of urbanization of the studied sites. Additionally, it is shown that a lesser content of suspended solids and higher sedimentation velocities correlate with the increase in urbanization. This could indicate that the particles in urbanized areas present a higher density, which could cause partial precipitation in the case of low turbulences in the runoff. The sedimentation velocities based on time steps (g/m3/min) indicate high sedimentation rates at the beginning for the samples taken in Cd. Juárez following a significant decrease at 32 and 128 minutes for the sites PEMEX and MORELIA, respectively. In the other sites, the measured precipitation velocities are low, which indicates the presence of particles of low density, which have to be treated with an agent to initiate the precipitation of the suspended solids.

Published
2018-05-14
Section
Regular Papers