The paper deals with the hydro-chemical analysis performed in order to reveal processes, sources, paths and timing of the runoff generation in an experimental catchment representative of the hilly, terrigenous and forested watershed in the Mediterranean humid eco-region of southern Italy. The analysis is based on the data recorded at the outlet of the catchment during 2013–2014. A mixing law procedure was applied on discharge (Q) and electrical conductivity (EC) data, by using the Q–EC end members previously collected at selected groundwater, sub-surficial and surficial stations. In this way, we found four bound curves delimiting fields in a Q–EC plot, each with hydro-chemograph value ranges. At annual time scale, the analysis revealed a seasonal behaviour of the hydrological response, different for the wet period, when the aquifer is recharging, and the dry periods, when the aquifer is discharging, despite frequent summer rain showers. At event time scale, the catchment seems to show the behaviour of a typical hydro-geomorphic threshold system. We interpreted this behaviour as due to a progressive addition of water from distinctive components (i.e. deep aquifer, riparian corridor, hillslope and hollow), each with originally different mechanisms of runoff production (i.e. groundwater, groundwater ridging, saturation excess, infiltration excess and soil pipe exfiltration) and response time. During the event, the contributing areas enlarge upward the riparian corridors and the zero-order basins, where the aforementioned components become superposed and the mechanisms interact more and more. We hypothesize that the threshold values between different states of the system are defined by the intersections of the boundary curves on the Q– EC plot. Different patterns in the Q–EC hysteretic cycles are prevalently related to the pre-event soil saturation and groundwater contributions to stormflow and recharge mechanisms. Copyright © 2016 John Wiley & Sons, Ltd.
|Titolo:||Using hydro-chemograph analyses to reveal runoff generation processes in a Mediterranean catchment|
|Data di pubblicazione:||2016|
|Appare nelle tipologie:||1.1.1 Articolo su rivista con DOI|