scholarly journals Identifying Flow Pathways for Phosphorus Transport Using Observed Event Forensics and the CRAFT (Catchment Runoff Attenuation Flux Tool)

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1081 ◽  
Author(s):  
Russell Adams ◽  
Paul Quinn ◽  
Nick Barber ◽  
Sean Burke
Keyword(s):  
Overland Flow ◽  
Forensic Analysis ◽  
Frequency Resolution ◽  
Storm Event ◽  
Hydrograph Separation ◽  
Near Surface ◽  
Headwater Catchments ◽  
Additional Tool ◽  
Flow Pathways ◽  
Catchment Runoff

Identifying key flow pathways is critical in order to understand the transport of Phosphorus (P) from agricultural headwater catchments. High frequency/resolution datasets from two such catchments in Northwest England enabled individual events to be examined to identify the flow (Q) and Total P (TP) and Total Reactive P (TRP) dynamics (forensics). Detailed analysis of multiple flow and water quality parameters is referred to here as the event forensics. Are there more flow pathways than just surface runoff (dominated by overland flow) and baseflow (mainly groundwater) contributing at the outlet of these catchments? If so, hydrograph separation alone will not be sufficient. This forensic analysis gives a classification of four storm event response types. Three classes are based on the balance of old and new water giving enrichment and dilution of TRP pattern in the subsurface flow. A fourth type was observed where a plume of nutrient is lost to the channel when there is no observed flow. Modelling is also essential when used in combination with the event forensics as this additional tool can identify distinct flow pathways in a robust form. A case study will apply the Catchment Runoff Attenuation Flux Tool (CRAFT) to two contrasting small headwater catchments in Northwest England, which formed part of the Demonstration Test Catchments (DTC) Programme. The model will use data collected during a series of events observed in the two catchments between the period 2012 and 2014. It has the ability to simulate fast near surface (that can represent flow in the upper soil horizons and field drains) and event subsurface soil flow, plus slower groundwater discharge. The model can capture P enrichment, dilution and the role that displacement of “old” P rich water has during events by mixing these flows. CRAFT captures the dominant flow and P fluxes as seen in the forensic analysis and can create outputs including smart export coefficients (based on flow pathways) that can be conveyed to policy makers to better underpin decision making.

scholarly journals Use of deuterium to understand runoff generation in a headwater catchment containing a dambo

1998 ◽  
Vol 2 (1) ◽  
pp. 65-76 ◽  
Author(s):  
M. P. McCartney ◽  
C. Neal ◽  
M. Neal
Keyword(s):  
Overland Flow ◽  
Hydrological Cycle ◽  
Hydrograph Separation ◽  
Runoff Generation ◽  
Rainfall Characteristics ◽  
Headwater Catchments ◽  
Antecedent Conditions ◽  
Storm Flow ◽  
Total Proportion ◽  
Made In

Abstract. Dambos, seasonally saturated wetlands, are widespread in headwater catchments in southern Africa and play an important role in the regional hydrological cycle. However, the processes influencing runoff from these catchments are poorly understood. This paper reports an isotopic investigation of runoff-generating mechanisms within a Zimbabwean catchment containing a dambo. Hydrograph separation using deuterium reveals that, once the dambo is saturated, up to 70% of total storm flow can be considered "new" water (i.e. derived directly from rainfall generating the runoff event). However, both the total proportion and the instantaneous maximum amount of "new" water in hydrographs are sensitive to rainfall characteristics and antecedent conditions. These results are (1) compatible with observations made in catchments in temperate climates when wetlands are present, and contrast with results obtained when wetlands are absent and (2) consistent with saturation overland flow, generated in saturated regions of the dambo, being the major storm runoff mechanism. To reconcile these observations with past perceptions that dambos attenuate flood flows, a dual role for dambos in storm flow production is postulated.

Controls on streamwater age in a saturation overland flow-dominated catchment

2021 ◽  
Author(s):  
Dana Lapides ◽  
David Dralle ◽  
Daniella Rempe ◽  
William Dietrich ◽  
W. Jesse Hahm
Keyword(s):  
Overland Flow ◽  
Return Flow ◽  
Field Observations ◽  
Hydrograph Separation ◽  
Storm Events ◽  
Runoff Generation ◽  
Water Age ◽  
Flow Pathways ◽  
Generation Mechanisms ◽  
California Coast Ranges

<p>Water age and flow pathways should be related; however, it is still generally unclear how integrated catchment runoff generation mechanisms result in streamflow age distributions at the outlet. Here, we combine field observations of runoff generation at the Dry Creek catchment with StorAge Selection (SAS) age models to explore the relationship between streamwater age and runoff pathways. Dry Creek is an intensively monitored catchment in the northern California Coast Ranges with a Mediterranean climate and thin subsurface critical zone. Due to limited storage capacity, runoff response is rapid (~1-2 hours), and total annual streamflow consists predominantly of saturation overland flow, based on field mapping of saturated extents and runoff thresholds. Even though SAS modeling reveals that streamflow is younger at higher wetness states, flow is still typically older than one day and thus older than event water. Because streamflow is mostly overland flow, this means that a significant portion of overland flow must derive from groundwater returning to the surface, consistent with field observations of exfiltrating head gradients, return flow through macropores, and extensive saturation days after storm events. We conclude that even in a landscape with widespread overland flow, runoff pathways may be longer than anticipated, with implications for contaminant delivery and biogeochemical reactions. Our findings have implications for the assumptions built into classic hydrograph separation inferences, namely, that overland flow is not all new water.</p>

scholarly journals Isotopic hydrograph separation in two small mountain catchments during multiple events

2018 ◽  
Vol 44 (2) ◽  
pp. 453 ◽  
Author(s):  
L. Holko ◽  
S. Bičárová ◽  
J. Hlavčo ◽  
M. Danko ◽  
Z. Kostka
Keyword(s):  
Isotopic Composition ◽  
Elevation Gradient ◽  
Rain Gauge ◽  
Windward Side ◽  
Storm Event ◽  
Hydrograph Separation ◽  
Tatra Mountains ◽  
Isotopic Signatures ◽  
Water Fractions ◽  
End Members

Two-component isotopic hydrograph separation (IHS) was developed to determine the event- and pre-event components of a single storm event. Its application for several sucessive events requires repeated determination of isotopic signatures of end-members (precipitation, pre-event component) for each event. The existence of several possible alternative signatures results in differences in calculated contributions of event-/pre- event components. This article addresses the question of how big the differences could be in small mountain catchments with different methods for detemining the end member signatures. We analyzed data on isotopic composition of daily/event precipitation at different elevations in two catchments located in the highest part of the Carpathians in July 2014.The isotopic composition of streamflow sampled every 4-6 hours was analyzed as well. Elevational gradients of δ18O and δ2H in precipitation in the study period were -0.18 ‰ 100 m-1 and -1.1 ‰ 100 m-1, respectively. An elevation gradient in deuterium excess (0.29 ‰ 100 m-1) was also found. Precipitation on the windward side of the mountains was isotopically lighter than expected for a given rain gauge elevation. Five large rainfall-runoff events occurred in the study period in the meso-scale catchment of the Jalovecký creek (Western Tatra Mountains, area 22.2 km2) and in the headwater catchment of the Škaredý creek (High Tatra Mountains, area 1.4 km2). Isotopic hydrograph separation was conducted using eight options for the isotopic signatures of event and pre-event water. The isotopic signature of the event water (rainfall) was alternatively represented by data from high or low elevations. Pre-event water was represented either by the streamflow before the event or by the value taken from the statistics of the long-term data on isotopic composition of the stream. Both isotopes (18O and 2H) were used to calculate event water fractions during peak flows of individual events. Calculated peak flow event water fractions were below 0.2-0.3 for most events. However, the differences in calculated event water fractions for alternative isotopic composition of end-members were significant even if we did not take into account changes in isotopic composition during individual rainfalls. Coefficients of variation for event water fractions calculated for various options varied during individual events from 0.14 to 0.36. It is therefore perhaps better to use a range of possible values instead of a single accurate number to interpret the IHS results. Hydrograph separations based on 18O and 2H provided similar results.

scholarly journals What happens after the catchment caught the storm? Hydrological processes at the small, semi-arid Weatherley catchment, South-Africa

2005 ◽  
Vol 2 ◽  
pp. 237-241 ◽  
Author(s):  
S. Uhlenbrook ◽  
J. Wenninger ◽  
S. Lorentz
Keyword(s):  
South Africa ◽  
Electrical Resistivity ◽  
Soil Moisture ◽  
Experimental Techniques ◽  
Storm Event ◽  
Residence Times ◽  
Hydrological Response ◽  
Flow Paths ◽  
Flow Pathways ◽  
Semi Arid

Abstract. The knowledge of water flow pathways and residence times in a catchment are essential for predicting the hydrological response to a rain storm event. Different experimental techniques are available to study these processes, which are briefly reviewed in this paper. To illustrate this, recent findings from the Weatherley catchment a 1.5 km2 semi-arid headwater in South-Africa, are reported in this paper. Beside classical hydrometric measurements of precipitation and runoff different experimental techniques were applied to explore flow paths (i.e. soil moisture and groundwater measurements, natural tracers, and 2-D electrical resistivity tomographies (ERT)).

Overland flow during a storm event strongly affects stream water chemistry and bacterial community structure

2021 ◽  
Vol 84 (1) ◽  
Author(s):  
Huong T. Le ◽  
Thomas Pommier ◽  
Olivier Ribolzi ◽  
Bounsamay Soulileuth ◽  
Sylvain Huon ◽  
...  
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Water Chemistry ◽  
Bacterial Community Structure ◽  
Overland Flow ◽  
Stream Water ◽  
Storm Event ◽  
Stream Water Chemistry

scholarly journals Water flow pathways and the water balance within a head-water catchment containing a dambo: inferences drawn from hydrochemical investigations

1999 ◽  
Vol 3 (4) ◽  
pp. 581-591 ◽  
Author(s):  
M. P. McCartney ◽  
C. Neal
Keyword(s):  
Water Balance ◽  
Stream Water ◽  
Management Strategies ◽  
Dry Season ◽  
Sub Saharan Africa ◽  
Flow Paths ◽  
Headwater Catchments ◽  
Sub Saharan ◽  
Flow Pathways ◽  
Water Catchment

Abstract. Dambos, seasonally saturated wetlands, are widespread in headwater catchments in sub-Saharan Africa. It is widely believed that they play an important role in regional hydrology but, despite research conducted over the last 25 years, their hydrological functions remain poorly understood. To improve conceptualisation of hydrological flow paths and investigate the water balance of a small Zimbabwean catchment containing a single dambo, measurements of alkalinity and chloride in different water types within the catchment have been used as chemical markers. The temporal variation in alkalinity is consistent with the premise that all stream water, including the prolonged dry season recession, is derived predominantly from shallow sources. The proposition that dry season recession flows are maintained by water travelling at depth within the underlying saprolite is not substantiated. There is evidence that a low permeability clay lens, commonly present in many dambos, acts as a barrier for vertical water exchange. However, the highly heterogeneous chemical composition of different waters precludes quantitative hydrograph split-ting using end member mixing analysis. Calculation of the chloride mass-balance confirms that, after rainfall, evaporation is the largest component of the catchment water budget. The study provides improved understanding of the hydrological functioning of dambos. Such understanding is essential for the development and implementation of sustainable management strategies for this landform.

scholarly journals Storm-event flow pathways in lower coastal plain forested watersheds of the southeastern United States

2014 ◽  
Vol 50 (10) ◽  
pp. 8265-8280 ◽  
Author(s):  
Michael P. Griffin ◽  
Timothy J. Callahan ◽  
Vijay M. Vulava ◽  
Thomas M. Williams
Keyword(s):  
United States ◽  
Coastal Plain ◽  
Southeastern United States ◽  
Storm Event ◽  
Forested Watersheds ◽  
Flow Pathways ◽  
Event Flow ◽  
Lower Coastal Plain

scholarly journals Regional-Scale 3D Ground-Motion Simulations of Mw 7 Earthquakes on the Hayward Fault, Northern California Resolving Frequencies 0–10 Hz and Including Site-Response Corrections

2020 ◽  
Vol 110 (6) ◽  
pp. 2862-2881
Author(s):  
Arthur J. Rodgers ◽  
Arben Pitarka ◽  
Ramesh Pankajakshan ◽  
Bjorn Sjögreen ◽  
N. Anders Petersson
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Regional Scale ◽  
Frequency Resolution ◽  
Earthquake Ground Motion ◽  
Northern California ◽  
Soft Soils ◽  
Near Surface ◽  
Ground Motion Simulations ◽  
Scenario Earthquakes

ABSTRACT Large earthquake ground-motion simulations in 3D Earth models provide constraints on site-specific shaking intensities but have suffered from limited frequency resolution and ignored site response in soft soils. We report new regional-scale 3D simulations for moment magnitude 7.0 scenario earthquakes on the Hayward Fault, northern California with SW4. Simulations resolved significantly broader band frequencies (0–10 Hz) than previous studies and represent the highest resolution simulations for any such earthquake to date. Seismic waves were excited by a kinematic rupture following Graves and Pitarka (2016) and obeyed wave propagation in a 3D Earth model with topography from the U.S. Geological Survey (USGS) assuming a minimum shear wavespeed, VSmin, of 500  m/s. We corrected motions for linear and nonlinear site response for the shear wavespeed, VS, from the USGS 3D model, using a recently developed ground-motion model (GMM) for Fourier amplitude spectra (Bayless and Abrahamson, 2018, 2019a). At soft soil locations subjected to strong shaking, the site-corrected intensities reflect the competing effects of linear amplification by low VS material, reduction of stiffness during nonlinear deformation, and damping of high frequencies. Sites with near-surface VS of 500  m/s or greater require no linear site correction but can experience amplitude reduction due to nonlinear response. Averaged over all sites, we obtained reasonable agreement with empirical ergodic median GMMs currently used for seismic hazard and design ground motions (epsilon less than 1), with marked improvement at soft sedimentary sites. At specific locations, the simulated shaking intensities show systematic differences from the GMMs that reveal path and site effects not captured in these ergodic models. Results suggest how next generation regional-scale earthquake simulations can provide higher spatial and frequency resolution while including effects of soft soils that are commonly ignored in scenario earthquake ground-motion simulations.

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