Groundwater recharge decrease with increased vegetation density in the Brazilian cerrado

Abstract

AbstractLarge areas of the Brazilian savanna (cerrado) have been converted into farmland in recent years; however, little attention has been paid to the consequences of this land use and land cover change on groundwater recharge. Here, we assessed groundwater recharge in different physiognomies of the cerrado located in an outcrop area of the Guarani Aquifer System. Water table fluctuations were measured from October 2011 through August 2013, by 58 monitoring wells distributed on four physiognomies of the undisturbed cerrado. We used multiple monitoring wells located in “campo limpo” (cerrado grassland), “campo sujo” (shrub cerrado), “campo cerrado” (open wooded cerrado), and “cerrado sensu stricto” (wooded cerrado), cover types. Recharge rates were computed for each well using the water table fluctuation method. The measured precipitation for hydrological years 2011–2012 and 2012–2013 were 1247 and 1194 mm, respectively. We found values of average annual recharge of 363 ± 87 mm, 354 ± 85 mm, 324 ± 78 mm, and 315 ± 76 mm for “campo limpo,” “campo sujo,” “campo cerrado,” and “cerrado sensu stricto,” respectively. Our results suggest that recharge tends to decrease with the increase in the density of vegetation (grassland to woodland). These results indicate that water table depth may have an influence on the cerrado physiognomies or vice versa. Furthermore, replacement of undisturbed dense cerrado with croplands will likely alter recharge dynamics. Therefore, sound management of land use and land cover is needed to ensure future groundwater quantity and quality.