The role of flood size and duration on streamflow and riparian groundwater composition in a semi-arid basin

摘要: Summary Floods with differing sizes and durations are likely to impact riparian systems in different hydrologic geochemical ways. Here the of flood size duration was investigated. Flood-driven recharge along predominantly losing reaches Bill Williams River (western Arizona, USA) later reemerges as baseflow downstream gaining reaches, river’s longest reach (Planet Valley) retains releases most recharge. discharge volume flow intermittency Planet Valley is highly dependent upon length time since last major flood. After large floods (e.g. 2004–2005), dominated by flood’s chemical (SO 4 , Cl) isotopic (δ 18 O H2O , δ 2 H 34 S SO4 ) composition for long periods (>4 years), suggesting that largest events result much more a longer persistence floodwater subsurface than after smaller, recent events. The continued dominance 2004–2005 nearly 5 years later—despite three smaller 2007, 2008 2009—highlights long-term impacts have on water composition. Of these events, only (in 2009) caused observable changes both groundwater, thereby threshold exists alter system’s state behavior. dependence winter tendency particular set atmospheric conditions (associated El Nino-Southern Oscillation, or ENSO) cause region’s indicates importance ENSO system, future climate change could drastically properties overall hydrology southwestern rivers.