Baseflow separation methods in snowfed rivers in Mediterranean catchments: a process-oriented assessment for hydrograph analysis

Water storage availability of semiarid regions is closely linked to the snow reservoir and its changes. The change of hydrological regime in mountain rivers is strongly affected by the snowpack&#8217;s dynamics, which plays a crucial role during spring and/or summer season in Mediterranean areas, becoming one of the major water sources to streamflow. This influence can be analyzed from different approaches; however, due to the concurrence of different processes, whose interaction and propagation undoubtedly affect runoff and baseflow generation, a process-oriented approach is required for further understanding the ultimate reasons behind the observed changes. Hence, the partitioning of river flow into baseflow, subsurface flown, and runoff, is a key step in hydrograph analysis and for better understanding snowfed rivers and how climate variability can influence their regime.This work presents an assessment of different baseflow separation methods in mountain rivers of semiarid areas in the framework of a process-oriented approach for identifying the major sources/sinks of water. The study area comprises the headwaters of the different basins in the Sierra Nevada area, in southern Spain, within an altitudinal range of 1000-3479 m a.s.l., high slopes, and different facing. For this, a 20-yr series of daily flow in a gauged point in the Guadalfeo River that drains the southwestern area of Sierra Nevada is analyzed. Five standard baseflow separation methods, together with the simulation by the physically-based hydrological model WiMMed, which includes the module SNOWMED developed from an energy-water balance approach and validated in the study site, were selected and their results compared. Discussion on the effects of the final baseflow series on the descriptors of the direct-runoff hydrograph (daily time step) series is also included, considering snowmelt- and rainfall-driven events, and their combination.The results not only provide a better understanding of baseflow separation in snowfed rivers in semiarid regions, but also assess hydrograph analysis in a process-oriented approach.&#160;&#160;

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Streamflow event classification in snowfed rivers in Mediterranean catchments: a process-oriented assessment

10.5194/egusphere-egu21-15739 ◽

2021 ◽

Author(s):

Pedro Torralbo ◽

Rafael Pimentel ◽

Javier Aparicio ◽

Javier Herrero ◽

Cristina Aguilar ◽

...

Keyword(s):

Sierra Nevada ◽

Catchment Area ◽

River Flow ◽

Meteorological Data ◽

Water Fluxes ◽

Runoff Generation ◽

Mountain Rivers ◽

Process Oriented ◽

The Impact ◽

Oriented Approach

Streamflow in Mediterranean Mountain Areas is highly linked to the storage capacity of snowpacks and its seasonal dynamics, these becoming the only water source,during long periods, particularly during dryer seasons such as spring or summer. This fact makes that to have a better understanding of the significant drivers of change in the hydrological regimen in many mountain rivers requires a process-oriented approach&#160; to assess the different interacting effects and their propagation from atmospheric conditions to runoff and baseflow generation in these areas. Snow dynamics has a direct and major impact on the partitioning of river flow into baseflow, subsurface flow, and runoff. Moreover, the snowpack is extremely affected by the partitioning of precipitation and water outflows (i.e., rainfall vs snowfall and snowmelt vs evaposublimation) that largely modify the riverflow regime with a stronge nonlinearity of their interactions.This work presents the characterization of streamflow events in mountain rivers of semiarid areas based on a process-oriented approach from the identification of the major sources/sinks of water in the snow-dominated headwaters of different basins in the Sierra Nevada area, in southern Spain, within an altitudinal range of 1000-3479 m a.s.l. For this, two&#160; catchments with available time series of streamflow are analyzed together with meteorological data and the simulation of water fluxes from the snowpack by the physically-based model SNOWMED, validated and operational in this area (www.uco.es/dfh/snowmed). First, the Cadiar River catchment (area of 0.19 km2 and mean elevation of 2034 m, 20-yr daily flow series), which is highly dominated by snow,was chosen as a representative catchment with direct dominant impacts on streamflow from snow-related water fluxes. Secondly, the contributing catchment area upstream the &#211;rgive gauge station, in the Guadalfeo River(area of 1058 km2 and mean elevation of 1418.5 m, 28-yr daily flow series), which includes the previous case, was analized to assess the snow impacts propagation and lamination by other runoff generation conditions downstream the snow-dominated areas..&#160;&#160;The resulting streamflow-event series i) shows the variability of the flooding and recession periods in this area on both the seasonal and annual scales due to the variability of the snow regime upstream, and ii) constitutes a key database to assess the impact of climate trends on these rivers and understand how future climate may condition the availability of water during the dry season in the downstream areas. The results not only expand this comprehension of how snowpack-streamflow interacts in semiarid regions, but also provide us with an assessment on predictable events within a short and seasonal forecasting local framework, that can be applied to other Mediterranean mountain rivers after local analyses.

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A process-oriented approach to mantle geochemistry

Chemical Geology ◽

10.1016/j.chemgeo.2021.120350 ◽

2021 ◽

pp. 120350

Author(s):

Andreas Stracke

Keyword(s):

Mantle Geochemistry ◽

Process Oriented ◽

Oriented Approach

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Toward a Robust Canopy Hydrology Scheme with Precipitation Subgrid Variability

Journal of Hydrometeorology ◽

10.1175/jhm585.1 ◽

2007 ◽

Vol 8 (3) ◽

pp. 439-446 ◽

Cited By ~ 13

Author(s):

Dagang Wang ◽

Guiling Wang

Keyword(s):

Land Surface ◽

Surface Characteristics ◽

Hydrological Processes ◽

Canopy Interception ◽

Time Step ◽

Covered Area ◽

Surface Models ◽

Physically Based ◽

Interception Loss ◽

The Impact

Abstract Representation of the canopy hydrological processes has been challenging in land surface modeling due to the subgrid heterogeneity in both precipitation and surface characteristics. The Shuttleworth dynamic–statistical method is widely used to represent the impact of the precipitation subgrid variability on canopy hydrological processes but shows unwanted sensitivity to temporal resolution when implemented into land surface models. This paper presents a canopy hydrology scheme that is robust at different temporal resolutions. This scheme is devised by applying two physically based treatments to the Shuttleworth scheme: 1) the canopy hydrological processes within the rain-covered area are treated separately from those within the nonrain area, and the scheme tracks the relative rain location between adjacent time steps; and 2) within the rain-covered area, the canopy interception is so determined as to sustain the potential evaporation from the wetted canopy or is equal to precipitation, whichever is less, to maintain somewhat wet canopy during any rainy time step. When applied to the Amazon region, the new scheme establishes interception loss ratios of 0.3 at a 10-min time step and 0.23 at a 2-h time step. Compared to interception loss ratios of 0.45 and 0.09 at the corresponding time steps established by the original Shuttleworth scheme, the new scheme is much more stable under different temporal resolutions.

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