Analyzing the Effects of Variability of Precipitation on the Performance of Enhanced Infiltration Systems in Harris County, TX

Abstract

Managed aquifer recharge strategies such as enhanced infiltration systems aim to mitigate floods and enhance urban water supply by capturing water during wet periods. Precipitation variability plays an important role in the infiltration process, and in the Texas Gulf Coast is highly influenced by hurricanes and El Niño Southern Oscillation. In this study, we analyzed how the variability of precipitation events rate and frequency affect the performance of enhanced infiltration structures using data from a pilot study carried out in Harris County, TX.

The precipitation variability was addressed by doing a Monte Carlo simulation. A stochastic analysis of precipitation events was performed to find distributions that could describe the rate and frequency of precipitation events for different seasonality. From these distributions 100 timeseries were created and used as input in a model developed in HYDRUS 2D using the physical characteristics of the study site.

Our results indicate that there is precipitation variability in the region because of hurricane season and El Niño Southern Oscillation. The higher variability of the rate and frequency of precipitation events during the strongest subdivisions of the El Niño and the La Niña phases. The analysis demonstrates that the statistical methods used to describe the precipitation were not adequate to model the precipitation patterns at the site of study. Moreover, our results suggest that higher average depth of precipitation events achieve a lower ratio of cumulative infiltration over total rainfall, and longer time between precipitation events lead to a higher ratio of cumulative infiltration over total rainfall.