Proposal to Improve Water Quality Based on the Calibration ofthe Streeter-Phelps Model for DO and BOD in the Lurin River, Peru

Grimaldo C.L.C.; Fernandez L.R.; Quispe J.B.A. · Proceedings of the IAHR World Congress (2022) · DOI: 10.3850/iahr-39wc2521716x20221482

Resumen

The Lurin River crosses the districts of Cieneguilla, Pachacamac and Lurin; discharging its waters to the Pacific Ocean, supplying waterto the inhabitants ofthe surrounding areas, it also maintains agricultural, livestock and irrigation areas for human consumption. For the present work, in 20 km of the lower part of the river, 13 sampling points were distributed (8 in the river and 4 in effluents), obtaining the dissolved oxygen and the biochemical oxygen demand, the hydrodynamic characteristics, the water balance considering the demands of the catchments of irrigators, the contribution of the Tinajas creek, the contribution of springs and filtrations of the channel, during the period from February to August 2019. The digital elevation model was gotten from collected images from a system of remotely piloted aircraft-RPAS, the topography and satellite images ofthe study area, which allowed the simulation ofthe hydrodynamic characteristics of the river with the HEC-RAS program. The Streeter-Phelps water quality model was calibrated with the help ofthe Excel-solver optimization algorithm, in order to obtain the calibration ofthe parameters 6ki, 6k2, a, b, c, ki, k2 and k3 with values of (X±S ): 1.19±0.23, 1.02±0.18, 0.87±0.25, 0.85±0.28, 2.53±1.58 0.33±0.89, 12 0.66 ± 0.85 and 0.44 ±2.43, respectively, in addition to a "good" to "very good" performance for the Nash and RSR indices with a Pearson's R of 0.9, significant for a T-test. student with an a of 5%. During the dry season, the presence of diffuse contamination in the districts of Pachacamac and leaks due to recharge of the aquifer to the river were evidenced. Three scenarios were simulated: (i) optimization ofthe San Bartolo WWTP, (ii) passage ofthe irrigation channel from open to closed from La Capilla, and (iii) implementation ofthe Pachacamac WWTP; being the optimization ofthe San Bartolo WWTP and the implementation of a Pachacamac WWTP, the most viable alternative for the river to meet the water quality standards, as well as the threshold flow.

Instituciones: Universidad Nacional Agraria La Molina