A Mathematical View of Water Table Fluctuations in a Shallow Aquifer in Brazil

Abstract

Detailed monitoring of the groundwater table can provide important data about both short- and long-term aquifer processes, including information useful for estimating recharge and facilitating groundwater modeling and remediation efforts. In this paper, we presents results of 4 years (2002 to 2005) of monitoring groundwater water levels in the Rio Claro Aquifer using observation wells drilled at the Rio Claro campus of São Paulo State University in Brazil. The data were used to follow natural periodic fluctuations in the water table, specifically those resulting from earth tides and seasonal recharge cycles. Statistical analyses included methods of time-series analysis using Fourier analysis, cross-correlation, and R/S analysis. Relationships could be established between rainfall and well recovery, as well as the persistence and degree of autocorrelation of the water table variations. We further used numerical solutions of the Richards equation to obtain estimates of the recharge rate and seasonable groundwater fluctuations. Seasonable soil moisture transit times through the vadose zone obtained with the numerical solution were very close to those obtained with the cross-correlation analysis. We also employed a little-used deep drainage boundary condition to obtain estimates of seasonable water table fluctuations, which were found to be consistent with observed transient groundwater levels during the period of study.

Effect of temporal averaging of meteorological data on predictions of groundwater recharge

“…In this study we evaluated the different temporal scaling effects on groundwater recharge using the HYDRUS 1-D software package of Šimůnek et al (2013, 2016), which has been previously used in several other recharge studies (e.g., Assefa and Woodbury, 2013;Jiménez-Martinez et al, 2009;Leterme et al, 2012;Neto et al, 2016). Simulations were carried out for a 2-m deep unsaturated soil profile subject to transient meteorological conditions involving precipitation, evaporation and possible runoff.…”

Recent Developments and Applications of the HYDRUS Computer Software Packages

“…An important advantage of the HYDRUS models is that they are not limited to any particular spatial or temporal scale. HYDRUS‐1D has been applied to scales involving very short laboratory soil columns, soil profiles of one to several meters deep (e.g., Ramos et al, 2011, 2012; Neto et al, 2016), as well as to soil profiles several hundred meters deep (Scanlon et al, 2003). HYDRUS (2D/3D) has been used similarly for transport domains ranging from <1 m wide to transects of several tens or hundreds of meters wide and for both laboratory (e.g., Rühle et al, 2013, 2015) and field‐scale applications (e.g., Yakirevitch et al, 2010; Pachepsky et al, 2014).…”

Avaliação numérica da eficiência da remediação de plumas de nitrato a partir de pulsos de injeção de etanol

“…A área de estudo para a realização das simulações foi o Campus da UNESP de Rio Claro (Figura 1), onde anteriormente foi conduzida a caracterização hidrogeológica conduzida por diversos trabalhos, incluindo Oliva et al (2005), Oliva (2006), Neto et al (2016) e Gonçalves & Chang (2018 Em razão da disponibilidade de oxigênio no aquífero, inicialmente o etanol é degradado por biodegradação aeróbica (Equação 1), tendo em vista que esta representa a reação termodinamicamente mais favorável.…”