Surface and groundwater dynamics in the sedimentary plains of the Western Pampas (Argentina)

Abstract

Sedimentary plains with extremely flat topography, such as the Pampas in Argentina, often display flooding-drought cycles. Changes in water table depth and surface water coverage affect natural and cultivated vegetation, wildlife, and people. Here, we describe groundwater dynamics and water-body expansion in a 10-year flooding cycle in the valuable agricultural lands of Western Pampas. We analysed water-table depth, surface water coverage, and rainfall from 1996 to 2005 covering ¾28 000 km 2 . We characterized the dynamics of water storage based on groundwater observations and remote sensing estimates of the coverage (LANDSAT) and elevation (ENVISAT) of water bodies as well as water storage anomalies captured by the gravity recovery and climate experiment (GRACE). Surface water coverage fluctuated from 3 to 28% and groundwater levels displayed a ¾2Ð5 m change. Regional water storage raised by ¾800 mm with 63% of this water accretion accounted by groundwater. Ground and surface water dynamics were closely coupled but this link differed between lowlands and highlands and depending on whether the system was at the gaining or retraction stage. This asymmetrical behaviour was likely caused by shifts in regional connectivity. Regional surface C groundwater storage compared well with water storage anomalies obtained from GRACE, suggesting that this tool may represent a methodological shortcut to estimate water storage changes. The tight connection between ground and surface water, and the relatively slow process of cumulative water accretion and coalescence of water bodies that precedes flood events offer the opportunity of developing warning systems that could help land managers to adapt to climate changes.

Trade‐offs in water and carbon ecosystem services with land‐use changes in grasslands

“…, Kim and Jackson ); (3) woody encroachment in clay soils leads to lose–lose from loss of soil organic carbon (this study); and (4) rain‐fed cultivation in humid flood‐prone areas leads to lose–lose from increased flooding risks (Aragón et al. ).…”

“…Specifically, high recharge rates in the humid Pampas of Argentina can induce groundwater flooding due to shallow water tables and a lack of surface drainage features (Aragón et al. ). At the wettest end of our study gradient (>1000 mm rainfall), land‐use changes that gain carbon but lose water, such as woody encroachment, might represent win–win situations by contributing to flood mitigation (Fig.…”

Recent La Plata basin drought conditions observed by satellite gravimetry

“…Limited groundwater level data are available in a small area in the southern La Plata basin (see Figure 2a). In this area, the topography is extremely flat and surface water and shallow groundwater are strongly interconnected [ Aragon et al , 2010]. Groundwater storage changes were compared with GRACE and GLDAS TWS estimates in the area delineated by the red box in Figure 2a.…”

Patterns and drivers for wetland connections in the Prairie Pothole Region, United States

“…These findings are particularly relevant to floodplains, permafrost landscapes and formerly glaciated landscapes that often exhibit low topographic gradients, low rates of infiltration, and low stream density. Runoff events in these landscapes rarely satisfy the threshold surface storage volume so that excess surface water (precipitation inputs exceeding soil infiltration and evapotranspiration) tends to accumulate instead of leaving the watershed as stream discharge (Hamilton et al 2004;Yao et al 2007;Aragón et al 2011;Kuppel et al 2015), leading to wetland consolidation and surfacewater connections.…”