HS2.2.2

Being a proxy for water stress monitoring and as a key element of sustainable water management, evaporation helps to assess the vulnerability of Mediterranean ecosystems to droughts. Estimation of annual basin-scale evaporation rate can be done using cost-effective isotope mass balances approaches that exploit the integrative nature of the river isotopic signal.

In Mediterranean regions, the marked climatic seasonality and uneven precipitation distribution complicates the use of isotope mass balances to obtain basin-scale estimation of average evaporation rates. For example, a mass balance approach carried out on the Tavignanu River watershed in Corsica (France), showed unrealistic evaporation rate estimates of 10% for 2017-2018 and 1% for 2018-2019. These results suggest that not only does evaporation alter the seasonal isotopic composition in the river, but that there is a complex variability of the dominant water reservoirs contributing to the streamflow. Therefore, we propose a modified mass balance approach that includes monthly contribution of the different water sources to the river discharge. This allows the discrimination of isotopic variation occurring by evaporation from that originating by mixing processes. By applying this modified approach, we estimated evaporation rates on the Tavignanu River watershed that were in good agreement with results obtained by hydrological modelling: 40% for 2017-2018 and 46% for 2018-2019, respectively.

The proposed approach can be used to determine evaporation rates in river basins in other semi-arid climates where estimating evaporation is of major concern for water management. More generally, these results should encourage investigations of details in water source contributions to river flow prior to conducing isotope mass balance evaporation estimates. Consequences are expected in several research fields where the portioning of evapotranspiration into components is of interest, including hydrology (e.g. water budget estimations), ecology (e.g. carbon budget estimations) and climatology.

How to cite: Mattei, A., Huneau, F., Garel, E., Santoni, S., and Vystavna, Y.: Basin-scale evaporation rate estimation based on isotopic approach: adaptation to the Mediterranean conditions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2869, https://doi.org/10.5194/egusphere-egu21-2869, 2021.

The time a molecule of rain takes to reach the stream is normally substantially longer than the time for discharge to respond to rainfall. This difference arises because hydraulic potentials propagate through landscapes much faster than water itself does; in other words, the celerity of wave propagation is faster than the velocity of water flow. Although these concepts are well established, most catchment studies are restricted to the calculation of the celerity or response time from hydrometric information. However, to understand the storage, release, and transport of water, as well as identify flow paths through the catchment, one needs to estimate both response and travel times, requiring both hydrometric and tracer data.

We analyzed hydrometric and tracer data from two contrasting sites, the pre-Alpine Erlenbach catchment in Switzerland and the Upper Hafren catchment at Plynlimon in Wales. For both sites, hydrometric data and sub-daily isotopic tracer time series are available, enabling the calculation of response times as well as travel time distributions and new water fractions. To gain a deeper understanding of the functioning of the two catchments, we quantified these metrics and distributions for different ranges of antecedent wetness and precipitation intensity. Generally, wetter catchment conditions and higher precipitation intensities yielded faster runoff responses and shorter travel times.  Contrasts between travel and response time distributions under varying catchment conditions also facilitated more nuanced insights into catchment functioning and the effects of catchment wetness and precipitation intensity on water storage and release.

How to cite: Knapp, J. L. A., Berghuijs, W. R., von Freyberg, J., and Kirchner, J. W.: Impact of antecedent wetness and precipitation intensity on catchment travel and response times, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10301, https://doi.org/10.5194/egusphere-egu21-10301, 2021.

Exploring the isotopic composition of precipitation and streamflow in small catchments and the event and pre-event components of precipitation events using two-component isotopic hydrograph separation may better explain the overall catchment behaviour, more specifically the sources of water origin. This study’s main objective is to investigate the origin of water for different streamflow gauges in a small agricultural catchment, which represent different runoff generation mechanisms. The analysis will be performed in the Hydrological Open Air Laboratory (HOAL) in Austria, a 66 ha experimental catchment dominated by agricultural land use (Blöschl et al., 2016). One of the main specialities of this research catchment is that several tributaries of the catchment representing different runoff generation mechanisms are gauged, such as tile drainage flow or saturation excess runoff from erosion gullies. Two-component isotopic hydrograph separation (for both ¹⁸O and ²H) will be conducted for five streamflow gauges (catchment inlet and outlet, two erosion gullies and a tile drainage system) for multiple events in the period 2013-2018. The results will be linked and interpreted using additional observations such as time-lapse images of overland flow, electric conductivity measurements, groundwater level changes, evapotranspiration measurements, etc. The aim is to explain and discuss the processes of rainfall-runoff generation in small agricultural catchments.

Reference:

Blöschl, G., et al. (2016). The Hydrological Open Air Laboratory (HOAL) in Petzenkirchen: A hypothesis‐driven observatory. Hydrol. Earth Syst. Sci., 20(1), 227–255. doi: 10.5194/hess‐20‐227‐2016.

How to cite: Széles, B., Parajka, J., Holko, L., Wyhlidal, S., Schott, K., Stumpp, C., Hogan, P., Pavlin, L., Strauss, P., and Blöschl, G.: Isotopic hydrograph separation in a small agricultural catchment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6209, https://doi.org/10.5194/egusphere-egu21-6209, 2021.

Hydrologists continue to be challenged in accurately predicting spatial variation in storage, runoff, and other hydrological processes in both natural and disturbed landscapes. Lakes and wetlands are important hydrologic stores in Precambrian shield watersheds. Identifying how they affect streamflow, independently and/or collectively is a challenge. Tracer-aided hydrologic modeling coupled with field-based stable isotope surveys offer a potentially powerful approach to investigation of mesoscale streamflow generation processes because the influence of evaporative enrichment generates a distinct signature of the surface water endmember, and continuous and distributed simulated streamflow can be tested against field observations under a range of flow conditions. The main objectives of this research are to investigate the influence of lakes and wetlands on streamflow generation by developing application of the tracer-aided hydrologic model isoWATFLOOD for the ~ 15275 km² Sturgeon - Lake Nipissing - French River (SNF) basin located on the Precambrian Shield in Northeastern Ontario, Canada. Monthly surveys of δ¹⁸O and δ²H in river flow were collected between 2013 to 2019 (weekly to monthly) across eight sub-catchments, with supporting observations of volumes and stable isotopes in snowcores, snowmelt, precipitation and groundwater. Application of the hydrologic model isoWATFLOOD to the SNF Basin is developed for the first time, allowing for simulation of discharge and stable isotopes in streamflow and soil moisture across multiple sub-catchments. In model building, consideration of differences in quaternary geology, landcover, and sub catchment locations are considered.  Landcover ranges from the boreal forests to impervious urban areas, while dominated by temperate forest, with some coverage of agriculture/disturbed impacted systems; several major sub-catchments having hydropower regulations. Previous statistical analysis has highlighted the importance of wetlands, lakes, and quaternary geology as influential on differences in hydrologic and isotope response in SNF watershed, as a result, model building is considering different landcover types as lakes and wetlands. Six different Landover are considered for generating Group Response Units (GRUs). The model is calibrated using discharge and stable water isotope.  IsoWATFLOOD can represent variation in streamflow generation across the study area. Identifying the different impacts of lakes and wetlands on streamflow generation processes in study area by applying isoWATFLOOD for the SNF watershed will be the main achievement of this study.

How to cite: Tafvizi, A., James, A., Stadnyk, T., Yao, H., and Ramcharan, C.: Investigation of Lake and Wetlands Influence on Streamflow in Mesoscale Precambrian Shield Watersheds Using IsoWATFLOOD, A Tracer-Aided Hydrologic Model, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5907, https://doi.org/10.5194/egusphere-egu21-5907, 2021.

High nutrient concentrations despite mitigation measures and reduced inputs are a common problem in anthropogenically impacted catchments. To investigate how water and solutes of different ages are mixed and released from catchment storage to the stream, catchment-scale models based on water transit time from StorAge Selection functions (SAS) are a promising tool. Tracking fluxes of environmental tracers, such as stable water isotopes, allows to calibrate and validate these models. However, this requires collection of water samples with an adequate temporal and spatial resolution, while sampling in catchments at the management scale is often limited by the high costs of the instruments, maintenance and chemical analysis. Therefore, temporal and spatial interpolation techniques are needed. This study demonstrates how to deal with sparse tracer data in space and time, and evaluates if these data are valuable to constrain the subsurface mixing dynamics and transit time with SAS modelling. We simulated water isotope data in diverse sub-basins of the Bode catchment (Germany) and calibrated the SAS function parameters against the measured streamflow isotope data. We tested four different combinations of spatial and temporal interpolation of the measured precipitation isotope data. In terms of temporal interpolation, monthly oxygen isotopes in precipitation (δ¹⁸O_P) collected between 2012 and 2015 were converted to a daily time step with a step function and sinusoidal interpolation. In terms of spatial interpolation, the model was tested with raw values of δ¹⁸O_P collected at a specific sampling point and with δ¹⁸O_P interpolated using kriging to gain the spatial pattern of precipitation. The effect of the spatial and temporal interpolation techniques on the modeled SAS functions was analyzed using different parameterizations of the SAS function (i.e., power law time-invariant, power law time-variant and beta law). The results show how tracer input data with different distribution in time and space affect the SAS parameterization and water transit time. Moreover, they reveal preference of the sub-basins to mobilize either younger or older water, which has implications on how water flows through a catchment and on the fate of solutes.

How to cite: Borriero, A., Lutz, S., Kumar, R., Nguyen, T., Attinger, S., and Fleckenstein, J.: Investigating the value of regional water isotope data on transit time and SAS modelling, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11174, https://doi.org/10.5194/egusphere-egu21-11174, 2021.

Stable isotope analysis of hydrogen and oxygen is one of the important methods used to model the hydrological cycle. Oxygen and hydrogen isotopic investigation of river water, its tributaries, and groundwater of its catchment from the Satluj basin was undertaken to estimate the contributions of the main sources comprising discharge during major periods throughout a hydrologic year.

Estimation of the snow/glaciers melt contribution is also very important for tracing the sources and processes regulating the flow from the provenance and reservoirs in the context of global warming, for estimating flood flow, and for other water resource development activities in large parts of the Indian subcontinent. Water samples were collected during the non-monsoon season at increasing altitudes. In this work, in addition to stable isotopes, we also assessed the water quality using various physicochemical parameters and geochemistry of the water.

From isotopic analyses of river water samples, the mean value of the δ¹⁸O was found to be ~ -13‰, and the mean value of δD was found to be~ -85‰. For the samples from Satluj tributaries, the mean value of the δ¹⁸O was ~ -11‰, and the mean value of δD was ~ -69‰. A mean value of -8.4‰, was found based on the δ¹⁸O measurements of the groundwater samples, while the average δD value was found to be ~ -55‰.

For the mainstream and tributary, LWL, y = 8.2604x +20.208, and range of d-excess (>10‰) and y = 8.2079x + 22.182 and d-excess > 10‰ indicates a system recharged by sources of recycled moisture derived from continental sources in addition to monsoonal climates. For the groundwater data, the slope is 6.7, and d-excess ranges from 7‰ to 17‰. These observations are suggestive of the monsoonal source of Indian Ocean precipitation that has experienced significant evaporation during the non-monsoon season.

Our new data clearly shows that the surface water whether mainstream, tributary, and groundwater isotopes are homogenized from regional trends in precipitation, modified by evaporation, and are thus greatly influenced by latitude, elevation, and patterns of climate.

How to cite: Jahan, A., Khan, M. U., Rai, N., Maurya, A. S., and Kumar, S.: Stable isotope geochemistry of Oxygen and Hydrogen: A case study of the Satluj River Basin, India , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2375, https://doi.org/10.5194/egusphere-egu21-2375, 2021.

We have used stable isotopes of oxygen and hydrogen (δ¹⁸O and δD) which are important tracers for understanding various hydrological processes, to assess the spatial and temporal variability due to dual moisture sources in the Upper Jhelum River Basin (UJRB) of the north-western Himalayan region. The HYSPLIT back trajectory analysis shows large variability in spatial moisture transport pathways over the region during Southwest monsoon (SWM) and is mainly restricted to the Mediterranean Sea during Western disturbances (WDs). The isotopic composition of precipitation is significantly controlled by temperature and Relative Humidity during precipitation events from WDs; however, this control is found to be weak during the SWM.

Stable isotope signatures of precipitation are found to show a well-defined altitudinal effect (δ¹⁸O=0.19‰/100m) and a negative correlation with ambient temperature (R² = 0.65, p<0.01 for WDs & R²=0.48, p>0.1 for SWM). Mixing various tributary waters with different isotopic compositions leads to variability in the Jhelum River’s (JR) isotopic composition along its course. The observed spatial variability of δ¹⁸O and d-excess results from the exchange processes between groundwater and surface water. The higher depletion of precipitation during WDs leads to depletion of surface and groundwater and produces enrichment due to the evaporative loss of heavier isotopes due to drier weather conditions during SWM. Evaporation signals are more prominent in shallow groundwater (SGW) and lake water, indicating SGW being discharged in the proximity of lake water bodies. The isotopic values in the upper reaches are observed to be depleted, potentially due to inputs from melting glaciers and snow. In the middle, it reaches slightly enriched, likely due to shifts in groundwater and rainfall inputs. In the downstream, due to increased residence time and flat topography, the isotopic composition is relatively enriched, potentially related to the evaporative losses of heavier isotopes. The d-excess values in UJRB are found to vary between 11‰ to 20‰ with an average value of ~17‰, which is relatively higher than the long-term average observed for the Indian summer monsoon (~8‰), and Upper Indus in the Ladakh region (11.7‰) but almost similar to observed for Lower Indus (18‰).

The contribution of moisture from each source (WDs and SWM) are estimated using a two-component mixing model. The moisture source contribution over UJRB via WDs is 75%(±20) from the Mediterranean Sea and 20%(±10) from SWM. WDs contribution over UJRB is higher than in the Trans-Himalayan region in the Ladakh (Indian sector in the east) but smaller in Lower Indus Basin (Pakistan sector in the west). Hence, the influence of moisture of WDs decreases from west to east along the Himalayan region. This work based on stable isotope geochemistry of oxygen and hydrogen highlights the effects of meteorological and physiographic controls on the moisture dynamics and contributes to explain the spatial and temporal variability of hydrologic processes in the region.

How to cite: Dar, T., Rai, N., and Kumar, S.: Implications for water cycle dynamics in the Upper Jhelum River Basin of North-Western Himalayas based on hydrogen and oxygen isotope signatures of precipitation, surface water, and groundwater, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1077, https://doi.org/10.5194/egusphere-egu21-1077, 2021.

The forest stand can significantly affect the snow deposition and consequently the runoff during the melt period. This study focuses on water and element fluxes from snowpack in two Czech boreal headwater lake catchments with different forest stands (mature vs. regenerating after bark beetle tree dieback) using isotopic and hydrochemical tools. Sampling and analysis of the surface water, precipitation and snowpack throughout one  hydrological year enabled us to estimate the isotopic balance and chemical snowpack evolution, but also the snowmelt contribution in lakes inlets and outlets.

Isotopic signatures of the snowpack were seasonal, with δ²H amplitudes of -25‰ in the mature and -17‰ in the regenerating forest catchments. The mature forest had a ~1 month longer duration of snow cover and higher concentration of solutes in the precipitation and snowpack. In both catchments, heavier isotopes (¹⁸O and ²H) preferentially left the snowpack, which was saturated with rainwater. This resulted in the final spring snowmelt being enriched with lighter isotopes (¹⁶O and ¹H). Ions were also eluted from the snowpack during rain-on-snow events and partial snow melting throughout the winter, causing fluxes of diluted water at the end of the snowmelt. Our results demonstrate the hydrological and hydrochemical variability of the snowpack, which in the future may even increase with rising temperatures and changes of precipitation patterns.

How to cite: Juras, R., Vystavna, Y., Paule-Mercado, M. C., Schmidt, S. I., Kopacek, J., Hejzlar, J., and Huneau, F.: Effects of snowmelt on the runoff dynamics in two catchments with different forest stands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15057, https://doi.org/10.5194/egusphere-egu21-15057, 2021.

Rising concentrations of dissolved organic carbon (DOC) in inland waters are observed and investigated intensely in the last decades. The development of adaptive measures requires the forecasting of DOC-exports from catchments. Since DOC is exported from river catchments along hydrological pathways it is evident that the investigation of runoff generation, retention and travel times along flow paths are important to quantify DOC-loads and to develop a forecast model.

To gain comprehensive insights in runoff formation and DOC export in a small forested catchment in the Bavarian Forest National Park we apply a nested multi-tracer approach, combining experimental and analytical methods with the aim to develop a hydrological forecast model which is able to reproduce the dominant mobilization- and export processes of DOC in forested mountain catchments. The use of multiple tracers combines different approaches to determine source areas, flow paths and retention times of runoff water in catchments. Stable isotopes (d2H, d18O) are suitable as natural tracers to estimate contributions from precipitation to stream discharge. With the additional use of geochemical tracers (e.g. DOC, SiO2) contributions from groundwater and the organic and mineral soil horizons can be estimated. Combined with a nested approach these analyses can be conducted on different spatial scales, enabling the development of scalable prognostic models of runoff formation in catchments.

To complement the limited information from historic data sets we instrumented two hill transects to observe lateral contributions from hill slopes and to investigate potential preferential flow paths. Water samples from stream-, soil-, ground- and precipitation water were collected during two flood events and analysed for stable isotopes and chemical compositions. To support the nested approach, the sampling sites were chosen at strategical sites within the catchment, including the instrumented hill transects and the stream network from the creek to the catchment outlet.

Preliminary results of stable isotope analysis show, that after dry periods nearly no event water seems to contribute to runoff formation, whereas after wet periods the proportions can be up to 40 %. A strongly delayed reaction of the groundwater was observed which suggests that deep groundwater is not contributing to stream flow, but a possible mobilization of pre-event water in the riparian zone was observed as a response to precipitation events.

A likely major source of DOC is in the organic soil horizons due to storage and degradation of organic material. This is supported by higher DOC-concentrations in the soil water from these horizons. In how far residence times, precipitation intensities and flow paths activation from different source areas influence concentration peaks of DOC in the stream will be analysed in the next steps.

The results of the recent field campaign help to identify the dominant processes of runoff generation and DOC mobilization on different temporal and spatial scales and for different antecedent system states. The data and insights gained from the field campaign will be used to develop and calibrate process models for hypothesis testing and further analyses to eventually develop a forecast model for DOC mobilization.

How to cite: Rommel, L. and Wöhling, T.: Hydrological analysis of runoff generation in a forested mountain catchment using a nested multi-tracer approach, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11112, https://doi.org/10.5194/egusphere-egu21-11112, 2021.

The island of Tenerife (Canary Islands, Spain) relies on basalt-hosted aquifers to provide 90% of water for agriculture and human consumption. The island is characterised by a low-permeability core, overlain by permeable materials which are cut by impermeable dykes. The effect is a compartmentalised aquifer, which is exploited sequentially as each “pocket” of water is exhausted. The island is home to ~1 million people (with an additional 5 million visiting tourists per year), and although rain/snowfall can be heavy in winter storms, it is unpredictable from year to year, and rapid surface water run off occurs due to the steep geography. While net recharge into the upper zones of the Tenerife aquifer have been quantified (around 2 months between intense rainfall and water table fluctuations), water must then follow a tortuous path to recharge lower zones and aquifer “pockets”. Water recharge to the coastal aquifers is also interrupted and extracted during its journey. Human and agricultural pressure is highest near the coast, and has led to intensive exploitation of existing wells and horizontal galleries. In response to the intensification of water extraction and slow recharge rates, marine intrusions into the coastal aquifers of Tenerife have occurred, traditionally recorded by rising chloride levels and resulting in well/gallery closures as well as increased pressure on other extraction sites. However, in a volcanic ocean island setting, natural processes can mimic the appearance of salinisation in a coastal aquifer. Management of aquifer resources require careful consideration of seawater incursions vs. volcanic degassing contributions vs. ocean island rainfall. Full hydrochemical breakdown of 43 coastal aquifer extraction sites reveal seawater intrusion is affecting the western coastal aquifer, with the agreement of multiple parameters. The strontium isotopic signature of well samples was also measured, because it is not subject to the biological or physical fractionation processes of other isotopic systems, thereby forming distinct reservoirs for groundwater (⁸⁷Sr/⁸⁶Sr of host rock), and seawater. ⁸⁷Sr/⁸⁶Sr signatures suggest the northern coastal aquifers are also subject to seawater incursions. This parameter may be a more sensitive indicator than chlorides and conductivity markers for salinisation, especially in an ocean island environment where coastal aquifers are subject to intensive land use practices, seawater spray, and affected by diffuse volcanic degassing.

How to cite: Coldwell, B., Cordero, M., Pérez, N. M., Amonte, C., Asensio-Ramos, M., Melián, G., and Padrón, E.: An over-used ocean island coastal aquifer, Tenerife (Spain) – tracing inputs for improved resource management, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15003, https://doi.org/10.5194/egusphere-egu21-15003, 2021.

Bacteriophages are numerous, tremendously diverse and ubiquitous in the environment. Since the 1960s, bacteriophages have been proposed as new tracers to investigate the hydrological processes in addition to conventional tracers (i.e. isotopes, salts, dyes). Their dynamic into water (i.e. surface water, groundwater) have been well studied. However, the soil compartment known for its important microbial activity, have been few characterized in terms of bacteriophage diversity. Hence, in the present study, the objective is to investigate the transport of soil viral population from the soil matrix to the soil water compartment. This mobilization from the soil matrix is mainly driven by the adsorption/desorption mechanisms to which bacteriophages are subjected. Therefore, in order to understand the dynamics of the bacteriophage population, both soil and soil water were sampled from the Weierbach forest, located in the Attert River basin (Grand-Duchy of Luxembourg) at the topsoil level (i.e. 0-20 cm) over a period of one month. Due to a lower abundance of the microbial population in soil water, an enrichment method was carried out to increase the concentration. Subsequently, a shotgun metagenomics analysis was performed on the soil and soil water samples to obtain the DNA sequences, which were then sorted using bioinformatics and statistical analyses, allowing ultimately the identification of the viral populations. The moving of the bacteriophage populations from the soil to the soil water provides information on their transport capacity, in particular by taking into account environmental conditions such as air and soil temperatures, precipitation, soil humidity, soil pH, etc.  

Key words: bacteriophages, soil, water, transport, environmental conditions

How to cite: Florent, P., Cauchie, H.-M., and Ogorzaly, L.: Mobilization of bacteriophages from soil matrix to soil water in the Attert River basin: A case study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12113, https://doi.org/10.5194/egusphere-egu21-12113, 2021.

Forest disturbance resulting from bark beetle infestation is becoming a widespread phenomenon due to climate warming and changing precipitation patterns. Such disturbance could result in alterations of streamflow and stream geochemistry. Our previous study found that these changes developed relatively rapidly after infestation and have long-lasting (decadal-scale) effects. Furthermore, infestation-induced changes in event-scale dynamics of in-stream electric conductivity (EC) – discharge (Q) relations were found to be considerable, impacting even the annual average EC-values. In this study, therefore, all rainfall-induced runoff events occurring during an 11-year period were identified and their distinct EC-Q relations were evaluated. The evaluation was done based on 10-min high-frequency monitoring of Q and EC and in four experimental catchments (~4 km² each; located in the Sumava Mountains, Central Europe), having different forest cover (disturbance) stages. Furthermore, snapshot sampling was carried out to map EC and chemical parameters (N, DOC, etc.) in different hydrological landscape units (riparian area, hillslope, and terrace) and in multiple vertical layers of soil (surface, soil, and groundwater). Results showed that after infestation the EC-Q hysteresis loops at the event-scale shifted from positive to negative relationships, implying changes in the subsurface chemical composition and runoff patterns. Specifically, healthy forest systems required event flows to mobilize substances in the soil and groundwater systems as the groundwater level rose into the relatively conductive, shallow part of the soil profile during an event. Such flush-driven systems were known for their release of large fractions of total annual in-stream substance loads showing a positive EC-Q relationship. By contrast, after infestation-induced tree mortality, the mobilization and downward percolation of nutrients and carbon from litter and decomposing needles may be considerable even during moderate rain and infiltration events. When the system is flooded under event conditions, substance-enriched soil water and groundwater may be mixed with and diluted by low-salinity event water, leading to a negative EC-Q relationship.  This study exemplifies how EC monitoring techniques can be used as an alternative to high-cost geochemical monitoring in quantifying complex rainfall-runoff processes as well as runoff generation processes, allowing for long monitoring periods at high temporal resolution and reasonable costs.

How to cite: Su, Y. and Langhammer, J.: Geochemical transformation of forested catchments following bark beetle infestation: Evidence from EC hysteresis during rainfall-runoff events, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15614, https://doi.org/10.5194/egusphere-egu21-15614, 2021.