Impact of Urban Growth and High Residential Irrigation on Streamflow and Groundwater Levels in a Peri‐Urban Semiarid Catchment

Abstract

The impact of urbanization on groundwater is not simple to understand, as it depends on a variety of factors such as climate, hydrogeology, water management practices, and infrastructure. In semiarid landscapes, the urbanization processes can involve high water consumptions and irrigation increases, which in turn may contribute to groundwater recharge. We assessed the hydrological impacts of urbanization and irrigation rates in an Andean peri‐urban catchment located in Chile, in a semiarid climate. For this purpose, we built and validated a coupled surface–groundwater model that allows the verification of a strong stream–aquifer interaction in areas with shallow groundwater, higher than some sewers and portions of the stream. Moreover, we also identified a significant local recharge associated with pipe leaks and inefficient urban irrigation. From the evaluation of different future scenarios, we found a sustainable water conservation scenario will decrease the current groundwater levels, while the median flow reduces from 408 to 389 L/s, and the low flow (Q95%) from 43 to 22L/s. Overall, our results show the relevance of integrating the modeling of surface and subsurface water resources at different spatial and temporal scales, when assessing the effect of urban development and the suitability of urban water practices.

Daily and seasonal variation of the surface temperature lapse rate and 0°C isotherm height in the western subtropical Andes

“…The basin hosts Santiago, the Chilean capital, with more than seven million inhabitants in the metropolitan area (approximately 40% of the nation's population) (INE, 2018). During past decades, the city has grown towards the Andes foothills (Romero et al, 1999;Pávez et al, 2010;Sanzana et al, 2019), where more than 30 sub-catchments are drained by ravines and gullies forming alluvial fans, posing an increasing risk to population (Lara et al, 2018). These ravines are in the western slope of Andes mountains, known as "Pre-Cordillera," where the highest altitude (3,250 m ASL) is the San Ramón hill in the Quebrada de Ramón catchment (Sepúlveda and Padilla, 2008).…”

Using LiDAR to assess transitions in riparian vegetation structure along a rural‐to‐urban land use gradient in western North America

“…However, in the middle reach, we found no relationship between HAR and canopy height, and greater HAR was associated with lower density and cover here. The typical complexity of groundwater–surface water interactions in urban systems (Garcia‐Fresca & Sharp, 2005; Hardison, O'Driscoll, DeLoatch, Howard, & Brinson, 2009; Sanzana et al, 2019; Tubau, Vázquez‐Suñé, Carrera, Valhondo, & Criollo, 2017) makes it difficult to draw conclusions about the causal effects of HAR in this more urbanized reach, flowing partly through the University Campus. It is surprising that HAR was a relatively weak predictor of vegetation structure overall (affecting canopy height in the upper canyon, cover and density in the middle reach and not affecting any of our vegetation metrics in the lower reach), although the patterns we observed were consistent with water supply as a dominant influence on larger trees in the upper section of the stream.…”

“…However, in the middle reach, we found no relationship between HAR and canopy height, and greater HAR was associated with lower density and cover here. The typical complexity of groundwater-surface water interactions in urban systems (Garcia-Fresca & Sharp, 2005;Hardison, O'Driscoll, DeLoatch, Howard, & Brinson, 2009;Sanzana et al, 2019;Tubau, Vázquez-Suñé, Carrera, Valhondo, & Criollo, 2017) It is tempting to assume that urbanization is typically paired with the removal of vegetation and thus systematically leads to a decline in vegetation. Even though this narrative that riparian forests decline through urbanization has long dominated the literature, in recent decades, authors have found evidence for canopy expansion along many urban streams in (semi)arid regions (Grossinger, Striplen, Askevold, Brewster, & Beller, 2007;Solins, Thorne, & Cadenasso, 2018;Villarreal, Drake, Marsh, & Mccoy, 2012;White & Greer, 2006 In terms of community composition, there is a consensus that increases in nonnative species occur along gradients of urbanization around the globe across multiple taxa (McKinney, 2006).…”

Crossing the rural–urban boundary in hydrological modelling: How do conceptual rainfall–runoff models handle the specificities of urbanized catchments?

“…On one hand, the BFI could be higher in some urbanized catchments owing to water treatment facility releases during the dry period (Oudin et al, 2018), reduction in vegetation cover, or leakage in high-pressure potable water systems (Göbel et al, 2004;Lancia, Zheng, Yi, Lerner, & Andrews, 2019). On the other hand, BFI could be lower in some urbanized catchments in which groundwater pumping is intensive and the river-groundwater connection is cut by sealing the riverbanks (Braud et al, 2013;Brun & Band, 2000;Sanzana et al, 2019;Zektser & Everett, 2004). These two possible changes are observed in our catchment set, but for the majority, BFI decreased.…”