HS10.1

Agroforestry systems (AFSs) are associated with many benefits such as augmented soil fertility or enhanced biodiversity. However, in water-limited areas the competition over water resources between trees and crops can reduce the productivity of the crop component. We want to share some of our results gained from in-depth analyses of time series (October 2019 to March 2020) and campaign (September 2019) data of soil moisture and matric potential in a South African AFS.

Soil water content was measured in a soil profile at two locations within an AFS plot: alongside a windbreak consisting of Italian Alders (Alnus cordata) and amongst the crop i.e. within blackberry rows. Matric potential time series are only available at the windbreak soil profile. Surficial soil samples taken along transects perpendicular to the windbreak were analysed for physical properties (e.g. texture, water retention curve).

Based on extracted water retention curves and matric potential time series, we found no evidence for plant water limitation during the measurement period (summer months) within the field site. Estimated root water uptake indicated that the trees take water from a greater range of depths, including deeper layers, than the blackberry plants. We observed divergent hydrological behaviour of the soil at the two locations during precipitation events, potentially resulting from dissimilar storage capacities and runoff formation potentials. Furthermore, the matric potential revealed hydrological information on plant water usage that was not as obvious from the soil moisture data.

How to cite: Hoffmeister, S., Hassler, S. K., Kestel, F., Maier, R., and Zehe, E.: Combining field survey and time series data to learn about plant water usage in a South African agroforestry system, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4009, https://doi.org/10.5194/egusphere-egu22-4009, 2022.

Observing ecohydrological processes of indigenous, drought-tolerant trees in arid and semi-arid regions is of profound importance for assessing the suitability of plant species for future climate conditions. The objective of this study is to quantify transpiration and soil moisture of pine (Pinus brutia) and cypress (Cupressus sempervirens) trees. The study site is located in Athalassa Forest Park, in Cyprus. The site has a surface area of 10 ha with an average slope of 4%. Average annual rainfall is 315 mm with a mean daily minimum temperature of 5° C during January and a mean daily maximum temperature of 37° C during August. The site was converted in 2011 from rainfed agriculture to a mixed forest by planting seedlings of different tree and shrub species.

Six P. brutia and six C. sempervirens trees were randomly selected for sap flow monitoring with sensors (heat ratio method) attached to the tree trunks. Forty-five soil moisture sensors were installed under the canopy, the edge of canopy and areas with no tree canopy at depths of 10 cm, 30 cm and 50 cm. Data from November 2020 to December 2021 indicated that mean total transpiration per tree was higher for C. sempervirens (≅2.2 m³) than for P. brutia (≅1.3 m³). Total rainfall during these 14 months was 339 mm. Higher transpiration of cypress trees was also reflected in the soil moisture, as canopy area soil moisture contents were generally lower for cypress than for pine for the depths of 10 and 50 cm. After rain maximum soil moisture values were similar for cypress and pine at the depth of 30 cm but the reduction of soil moisture over time was quicker for cypress. 

This research has received support from the Water JPI (Joint Call 2018) FLUXMED Project, funded through the Cyprus Research and Innovation Foundation.

How to cite: Djuma, H., Bruggeman, A., Eliades, M., Zoumides, C., Siakou, M., and Fasakhondi, M.: Water use of drought-tolerant coniferous trees (Pinus brutia and Cupressus sempervirens) in a semi-arid environment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9647, https://doi.org/10.5194/egusphere-egu22-9647, 2022.

The climate change strongly influences the hydrological cycle mainly due to redistribution of precipitation and changes in its seasonal patterns, resulting in longer dry periods and more intense heavy rainfall events. As precipitation is the main input for rainfall interception, throughfall and stemflow, we can expect the climate change to influence also these processes. In our study plot in Ljubljana, Slovenia, covering a small urban park with two separate groups of trees (Pinus nigra Arnold and Betula pendula Roth.), we have been performing throughfall, stemflow and rainfall measurements since January 2014. In that period, we have captured various rainfall events and the measurements are available for different periods. Among them we have also covered an especially wet (2014) and a dry (2015) year. According to the long term yearly rainfall amount, equal to 1355 mm, the total rainfall amount delivered during the year 2014 was much higher (1841 mm) and in the year 2015 considerably lower (1106 mm), which characterize those years as a wet and a dry one. For each year we have analysed the influence of meteorological conditions (e.g. rainfall amount, duration, intensity, air temperature, vapour pressure deficit, size and velocity of raindrops) on rainfall interception, throughfall and stemflow under each tree species using the boosted regression trees and random forest approach. Similar influences of the variables were recognized by both models. Comparison of the obtained results with previous analysis (e.g. Zabret et al., 2018, doi: 10.1016/j.jhydrol.2018.01.025; Zabret and Šraj, 2021, doi: 10.3389/ffgc.2021.663100) showed that the indicated influential variables for wet and dry year are to some extent similar to the variables, indicated as influential in leafless and leafed period. For example, the rainfall duration was recognized as one of the most influencing variables on rainfall interception during the wet year 2014, which was previously observed also for the leafless period. Additionally, rainfall intensity had significant influence on rainfall partitioning by birch tree during the dryer year 2015 as well as in the leafed period.

How to cite: Zabret, K. and Šraj, M.: Rainfall partitioning respond for a wet and dry year conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3400, https://doi.org/10.5194/egusphere-egu22-3400, 2022.

The partitioning of bulk precipitation (PR) in forest ecosystems and its chemical composition depends on both meteorological factors, such as precipitation amount and intensity, evaporation rate, and wind speed, and stand structural factors, such as stand density, canopy structure, bark texture, and spatiotemporal distribution and density of foliage. We analysed fluxes of water and element contained therein of a mature European beech (Fagus sylvatica L.) forest stand on sandy soils in northeastern Germany. We applied a radially symmetrical setup within a stem distance gradient to measure stand precipitation (SP) with its components of throughfall (TF) and stemflow (SF), as well as to measure soil moisture, the chemical composition of the soil solution, the soil chemistry, and the fine root distribution. The chemical analysis of the constituents covered the macroelements (Ca, Mg, K, Na, Al, Fe, Mn, Si, S, P), the cations and anions NH₄⁺, NO₃^-, Cl^-, SO₄^2-, and a few heavy metals (Cu, Pb, Zn). With an average PR of 620 mm a^-1, the partitioning resulted in 79% TF, 6% SF, and 15% canopy evaporation. TF volume increased with distance to stem during summer, but decreased during winter. Clear spatial gradients with increasing concentrations from PR, to different classes of TF as the distance from the trunk decreased, to SF were observed for nearly all elements. The contact of precipitation with leaves and the canopy structures alters the chemical composition of TF and SF by transferring elements from dry deposition or leaching of intracellular materials from the canopy and leads to the input of larger amounts of macroelements and heavy metals with the SP into the soil. Spatial patterns of canopy structures thus affect the spatial variation of TF and its constituents, which also affects the spatial distribution of roots and, at least in phases, the chemical composition of the topsoil solution.

How to cite: Jochheim, H., Lüttschwager, D., and Riek, W.: Stem distance as an explanatory variable for the spatial distribution and chemical conditions of stand precipitation and soil solution under beech (Fagus sylvatica L.) trees, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3780, https://doi.org/10.5194/egusphere-egu22-3780, 2022.

Vegetation induces spatial heterogeneity in water entering the soil as it partitions precipitation into net precipitation components. Net precipitation patterns have potential to influence spatial variation of percolation and soil water content, including hotspots of soil bypass flow. As a result, the canopy layer can be an important driver for changing soil moisture response to rainfall. In forest and shrub ecosystems the effect of canopy induced heterogeneity in water input on soil water dynamics has already been investigated, but rarely in grassland ecosystems, where the canopy is commonly characterized as homogeneous and uniform layer. However, observations in short vegetation points at a relation between canopy layer and soil moisture variability, indicating that short vegetation can also introduce heterogeneity and influence soil water dynamics. Yet, these observations are mostly confined to evapotranspiration, and no investigation has been extended for understanding the effect of spatially variable vegetation and net precipitation patterns on soil wetting patterns. Therefore, in this study, we investigated soil moisture response to rainfall in a grassland in temperate climate. Further, we explored the effect of wind speed, gross precipitation, throughfall patterns, vegetation height and antecedent soil moisture status on soil moistening after rainfall.

The grassland site (0.045 ha) is in Thuringia, Germany as a part of Hainich CZE and it is mown 2-3 times in a year. The field observation setup composed of closely paired (within 1.5 m in distance) net precipitation and soil water content measurements at 18 locations. Next to the field measurements in 2019 (April-August), we employed linear mixed effects model to untangle the role of canopy layer on soil moistening patterns from other abiotic factors. Also, we calculated spatially average water balance to trace soil storage recharge over the growing season.

We found that the increase in soil water storage was remarkably lower than water input regardless of foliage cover. Also, the water balance showed that topsoil (0-17.5 cm) stored less and less precipitation compared to the deeper part (17.5-37.5 cm) through the growing season despite the increasingly drier soil conditions, probably because of non-equilibrium fast flow. The mixed-effects model revealed that spatial variation of grass height is a significant driver for soil wetting patterns together with the average antecedent soil moisture status and precipitation. Soil wetting was suppressed at locations with taller grass, especially under drier antecedent soil moisture conditions. However, the effect of throughfall patterns was obscured probably due to the prevalence of preferential flow. Our results suggest that drier conditions and grassland stemflow might reinforce and expedite preferential flow. The results confirmed that spatially varied grassland canopy together with soil moisture status alters soil moisture wetting patterns and indicates a strong influence of preferential flow on soil water patterns.

How to cite: Demir, G., Michalzik, B., Filipzik, J., Metzger, J., and Hildebrandt, A.: Spatially heterogeneous grassland wetting patterns are controlled by canopy processes and antecedent soil moisture, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8691, https://doi.org/10.5194/egusphere-egu22-8691, 2022.

The most common rainfall interception models (Rutter, Gash and Liu) require the knowledge of two canopy-related parameters, the canopy storage capacity (S) and the canopy cover fraction (c). Even though canopy cover changes over time, these parameters are treated as constants in most rainfall interception studies. The aim of this study is to evaluate the performance of these three interception models with the use of time-variable S and c with meteorological and throughfall data from a semi-arid Pinus brutia forest (Cyprus). Leaf area index (LAI) were acquired from the Copernicus global land service (https://land.copernicus.eu/global/products/lai). These data were interpolated with a cubic spline function to obtain a daily time series. Daily S and c values were expressed as one-parameter linear (S) and exponential (c) functions of the daily LAI values The model results with the variable S and c were compared with the model calibration and validation results obtained with constant S and c values. The interception losses computed with the three models ranged between 18 and 20% of the total rainfall. 
All three models showed high performance for both calibration and validation periods with Kling–Gupta Efficiency (KGE) above 0.90. However, the constant S and c models show equifinality, meaning that a range of combinations of the input parameters S and c will result in the same interception loss. The Gash model with the variable S and c resulted in higher KGE (0.968) and lower percent bias (0.8%) than the Gash model with constant S and c (0.956 KGE and 1.5% percent bias), during the calibration period. Rutter and Liu models with the variable S and c resulted in lower bias (-6 mm and -11 mm) than the models with constant S and c (17 mm and 27 mm). The models were all capable of capturing the inherently variable interception process. However, ground-based LAI data are needed to validate the satellite-based data. 
This research has received funding from the European Union's Horizon 2020 Research and Innovation programme, under Grant Agreement 641739 (BINGO Project) and from the Research and Innovation Foundation of Cyprus, through the Water Joint Programming Initiative (FLUXMED project).

How to cite: Eliades, M., Bruggeman, A., and Djuma, H.: Performance of three rainfall interception models with variable canopy cover fraction (c) and canopy storage capacity (S), from satellite-based leaf area index (LAI) data., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11021, https://doi.org/10.5194/egusphere-egu22-11021, 2022.

Understanding how plants react to different light treatments is of increasing importance to assess the potential of modern agricultural technologies such as agrivoltaics and hydroponics, which are considered as promising methods to optimize crop productivity and water use without the need to increase land consumption. Here, we extend a well-established model of plant photosynthesis and transpiration to explicitly take into account the spectra of incident light and photosynthetically action radiation (PAR) curves (i.e., absorptance and quantum yield). The proposed model reasonably reproduces the response of various C3 plant types treated with different light spectra in controlled laboratory conditions. A sensitivity analysis to the most important abiotic forcing variables (irradiance, air temperature, humidity and CO₂ concentration) suggests that the blue part of the light spectrum is the less efficient in terms of carbon assimilation and water use and could be effectively filtered out to produce solar energy. However, the plant response to different light treatments seems to be species-specific; therefore, accurate and updated PAR curves are needed to assess which crops are more suited to be grown in controlled agricultural systems.

How to cite: Camporese, M. and Abou Najm, M.: Modeling the response of plant gas exchanges to different light and PAR curves spectra, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2243, https://doi.org/10.5194/egusphere-egu22-2243, 2022.

Evapotranspiration (ET) is a key parameter in the water exchange of atmosphere, plant and soil and was studied on many different scales. In urban environments, the estimation of evaporation is particularly difficult, as it is effected by complex patterns of shading, which varies on a very small scale as a function of street canyon layout and orientation. Moreover, shading varies not only in space but also in time due to the seasonal orientation and altitude of the sun. Therefore, for a correct ET assessment, the diurnal variations as well as the annual variations of shading must be taken into account. For this purpose, radiation is divided into direct and diffuse radiation; in case of complete shading only the diffuse radiation was used for ET estimation, reducing the direct radiation to zero. The diffuse radiation is further influenced by the amount of visible sky in a street canyon as a function of street widths, which can be derived using the sky view factor.
To reduce the uncertainty of ET estimation in the built environment, a process-based model was developed with an hourly resolution that takes into account the particularly heterogeneous spatial variability of urban surfaces. To assess the impact of shading on ET, six different shadow scenarios as well as two typical urban soil sealing scenarios for a wide and a narrow street canyon were analysed regarding differences and similarities of radiation and resulting actual and potential ET of a street tree as well as soil water dynamics.
The model scenarios showed that ET is highly influenced by shading. Furthermore, shadow scenarios affect actual ET (ETA) differently during the vegetation period: whereas in April the ETA is higher for fully exposed sites, this changes by June when less exposed sites periodically have higher ETA rates. This difference is directly connected to alteration of soil moisture dynamics, for a fully sun exposed site a soil moisture of 10 Vol% is already reached by June. For a shaded site the decrease to 10 Vol% takes two months longer.

In conclusion, the results highlight that it is essential to include the effects of shading in the quantification of vertical water fluxes in urban environments. Moreover, this new model approach will help to identify water shortage periods and critical locations for street trees.

How to cite: Tams, L., Paton, E. N., and Kluge, B.: Sitting in the dark- The impact of shading on evapotranspiration in complex urban landscapes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2943, https://doi.org/10.5194/egusphere-egu22-2943, 2022.

Tillage practices are known to affect soil water retention, plant available water and, consequently, crop production. Therefore, adjusted and sustainable tillage practices may contribute to an efficient use of limited available water resources. Impacts of tillage can be determined by assessing soil hydraulic properties and crop characteristics. In this study, three tillage practices were investigated with respect to soil water distribution and crop development, with a specific focus on determining actual evapotranspiration (ET) and crop transpiration (T). T/ET ratios should give additional information on soil water availability and crop water use. The practices included conventional tillage, reduced tillage (no plow), and no-tillage and were investigated on a long-term rainfed field experiment with soybean (glycine max l. merr) planting. The long-term experimental field is located in Raasdorf in the agricultural region Marchfeld east of Vienna, Austria (48°14’ N, 16°35’ E; 156 m elevation a.s.l., average annual precipitation of approx. 497 mm). The field is separated in experimental plots of 960 or 1,440 m². The measurements comprised automated monitoring of weather and soil water by means of a telemetric sensor network as well as manual monitoring of crop development. ET and its components were determined using an isotope-based water balance technique. ET rates were determined at the conventional experimental plot based on a water balance and verified with scintillometer measurements on a nearby field of 11.5 ha. In the researched vegetation period with limited water availability, the conservative tillage practices showed better water storage, water use, and crop yields compared to the conventional practice. The weekly T/ET ratios progressed according to the canopy development, which was affected by the tillage-induced soil conditions. In this context, delayed plant development – specifically at the no-till plots – led to extended green cover and productive water use during the late season, where a large part of the precipitation has fallen. The tillage-induced difference of wetness at soil surface, however, did not have a substantial effect on T/ET; even soil evaporation was similar at all plots. Furthermore, the ratios showed the beneficial effect of mulch protection regarding unproductive losses by evaporation, in particular during the initial periods of crop emergence and development. Thus, the assessment of T/ET ratios improved the insights in impacts of management practices and showed potential to promote the efficient use of the available water resources.

How to cite: Liebhard, G., Klik, A., Neugschwandtner, R. W., and Nolz, R.: Effects of tillage systems on soil water distribution, crop development, and transpiration of soybean., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4406, https://doi.org/10.5194/egusphere-egu22-4406, 2022.

Environmental water is indispensable for promoting and maintaining environmental assets in managed catchments. Water in the Macquarie Catchment is managed by releases from Burrendong Dam, which has played an important role supplying water needs in the Macquarie Valley, and environmental flows to the Ramsar listed Macquarie Marshes. Management decisions tools are necessary to analyze impacts of environmental water at a catchment scale and are critical to preserve ecosystems services under future uncertainties of climate variability and change. Here we implemented WATHNET5, a Network Linear Programming (NLP) tool to analyze effects of environmental water in the Macquarie Catchment. Our semi-distributed model includes storage areas (Dam and wetlands), input flows of the main tributary rivers, irrigation and water consumption demands, routing and conveyance losses. For model setup, rules for operation of the dam were adjusted to current conditions, while tributary rivers, irrigation and water consumption demands were obtained from a hydrological model used by local authorities for the Macquarie River. The ecological outputs of environmental releases were assessed at five locations along the river and following the objectives provided in the Long-Term Water Plan determined by the Environmental Authority (EA). In each of the five locations, our model computed different flows; Base Flows (BF), Small Fresh (SF), Large Fresh (LF) and Overbank flows (OS, OM and OL for small, medium and large respectively), which are associated to different environmental objectives. The EA determined minimum thresholds for each of the flows in terms of timing, duration, frequency and interval between events as indicators of environmental objectives compliance. Our model determines if the different flows met the thresholds and computes the amount for time that the conditions are met during the simulation period. Calibration of the flows over a 30-year period were carried out and the NLP model results were compared with the observations in five gauging station along the catchment. We found that the model adequately represents the flows with Nash–Sutcliffe efficiency coefficients between 0.42 and 0.6. Simulations were carried out for 120 years to analyze the effect of environmental water releases on ecological outcomes compared to natural condition (no dam and irrigation), showing tradeoffs between the different types of flows in different parts of the catchment. Our NLP model can be used as a multi-objective optimization tool to help identify long-term management decisions that can improve system resilience and protect environmental assets under an uncertain future climate.

How to cite: Quijano Baron, J. P., Carlier, R., Rodriguez, J., Saco, P., Sandi, S., Wen, L., and Kuczera, G.: Environmental water assessment at a catchment scale comparing natural and managed conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11009, https://doi.org/10.5194/egusphere-egu22-11009, 2022.

In the context of climate warming, frequent outbreaks of flash droughts are causing serious damage to ecosystems, so there is an urgent need to understand the water stress on ecosystems during flash droughts. High vapor pressure deficit (VPD) and low soil moisture (SM) are regarded as atmospheric and soil water stress on the ecosystem, but their stress mechanisms are different. Their independent influences are difficult to separate during flash droughts that develop fast with a strong land-atmospheric coupling. Therefore, to understand the response mechanism of vegetation gross primary productivity (GPP) to flash droughts, this study uses statistical analysis to decouple the effects of atmospheric and terrestrial water stress on GPP at the site scale and regional scale, respectively. At the site scale, we use the FLUXNET2015 Dataset to decouple the stress of SM and VPD on the GPP during flash droughts, and find that low SM dominants water stress for 55% of the stations, and high VPD dominants water stress for 10%. We further investigate the differences of GPP response to moisture deficit for different ecosystems during different stages of flash droughts. The results show that non-forest ecosystems respond to water stress during the onset stage of flash droughts, while more forests respond during the drought recovery stage. Specifically, for the days that are accompanied by high temperature and intense solar radiation during flash droughts , the water stress dominated by high VPD increase to 41% of the stations. For the regional scale, we use remote sensing data to decouple the effects of water stress over China. Our results show that water stress during flash droughts is dominated by soil moisture deficit over most regions of China, but VPD stress is stronger over northern China than that over southern China.

How to cite: Xi, X. and Yuan, X.: Decoupling terrestrial and atmospheric water stress on ecosystem productivity during flash droughts, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6738, https://doi.org/10.5194/egusphere-egu22-6738, 2022.

A major problem faced by European coastal zones is the lack of understanding for the complex cross-littoral interactions between major anthropogenic activities. This shortcoming results generally in single-sector management of coastal water resources and water-related ecosystem services instead of a multi-sector ecosystem-based management approach. The above problem becomes more pronounced when conflicts arise between all involved ecosystem services.

The study site involves a coastal natural and artificial hydrosystem in the Region of Epirus (NW Greece) that incorporates: (a) irrigation management through a complex network of surface canals; (b) an important water transfer infrastructure; (c) upstream-located hydropower dams that utilise surface water resources; (d) two river basins (Louros and Arachthos) that are hydraulically connected with the underlying aquifer system and discharging into the sea; (e) a karstic aquifer that supports both surface water resources as well as anthropogenic demands (drinking water supply and irrigation); and (f) a sensitive marine ecosystem (Amvrakikos) as final receptor that is highly depended on upstream water quantity and quality.

This research aims to provide an ecosystem service analysis through the identification and characterisation of all involved socio-economic and environmental processes that link land- and sea-based economic and human activities.

How to cite: Pouliaris, C., Kofakis, P., Chrysanthopoulos, E., Myriounis, C., Markantonis, K., Koltsida, E., Pappa, D., Kaliampakos, D., Perdikaki, M., and Kallioras, A.: Conflicting ecosystem services within coastal natural hydrosystems. The case of Louros-Arachthos-Amvrakikos, W. Greece., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12011, https://doi.org/10.5194/egusphere-egu22-12011, 2022.

To ensure sustainable development it is vital to account the stocks and flows of ecosystem services, understand the status quo of these resources and project how resilient or vulnerable they are to future climate and land cover change. In this study, we applied the U.S. Forest Service eco-hydrological model, Water Supply Stress Index (WaSSI), to estimate the monthly spatial dynamics of green & blue water resources and evaluate the ecosystem services (water supply and carbon sequestration) across sixteen German states by land covers and during extreme drought events. The simulated discharge (Q), evapotranspiration (ET) and Gross Primary Productivity (GPP) from upstream watersheds were validated against measurements from gauging stations, eddy covariance (EC) data, and remotely sensed ET and GPP estimates. Our results showed that eleven out of twelve watersheds modeled Q bias and determination coefficient (R²) are within ± 25% and above 0.60, respectively. Similarly, when we compared ET against EC data, ten out of eleven watersheds had R² above 0.60 and seven out of eleven watersheds have Kling-Gupta efficiency above 0.6. The R² between simulated and Moderate Resolution Imaging Spectroradiometer (MODIS) ET was around 0.48 with a gradient of 0.63. The model bias between simulated ET and precipitation minus observed discharge (P-Q _observed) values for all the validated watersheds was within ± 25%. Likewise, modeled GPP was higher than MODIS GPP by 16% and a lower R² (0.37). A comparison to Copernicus GPP (CGLS-GPP) gave a much better R² (0.70) with an overestimation of 7%. Moreover, a land cover specific comparison between simulated GPP and EC observed GPP showed nine out of fourteen watersheds had a model bias within ± 25% and Nash-Sutcliffe efficiency above 0.4, while twelve watersheds had R² above 0.60. Overall, the validation results demonstrate that WaSSI can capture seasonal hydrological and carbon cycles reasonably well. It is estimated that the mean annual ET across Germany is 530 ± 49.5 mm yr^-1, the mean annual water yield is 259 ± 173.5 mm yr^-1, and the mean annual Net Ecosystem Productivity (NEP) is 308.3 ± 78.2 g C m^-2 yr^-1. The annual water yield and carbon sequestration at the German national scale was around 84.86 billion m³ yr^-1 and 106.03 Tg C yr^-1, respectively. We found that Mecklenburg-Vorpommern (-1.91 Tg C/yr) and Thüringen (-0.57 Tg C/yr) were the only two states where anthropogenic CO₂ emissions were less than NEP. Across Germany, cropland and deciduous broadleaf forest are the largest share of water supply and carbon sequestration, respectively.  We found the severe drought events of 2003 and 2018 in Germany caused significant decrease in Q (29.6% & 26.8%), GPP (8.8% & 11.7%), and NEP (18.5% & 24.7%) due to decrease in P (22.7% & 25.5%) and ET (8.7% & 11.7%). In the next step, the potential impacts of different adaptive land cover and climate change scenarios on ecosystem services will be studied.

How to cite: Pyarali, K., Zhang, L., Liu, N., Sun, G., and Al-Qubati, A.: How water and carbon ecosystem services vary over land covers and extreme weather events across Germany?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1897, https://doi.org/10.5194/egusphere-egu22-1897, 2022.

It is well known that vegetation shows the apparent spatial distribution characteristics in mountainous terrain at fine scales (tens of meters to kilometers). The micrometeorological data, like radiation and temperature, are intensely governed by local topography. The relationship between terrain and the distribution of vegetation, water, energy, and carbon fluxes at fine scales in terrestrial ecosystems is still unclear. This study aims at analyzing the eco-hydrological process at tens of meters scales in a typical humid hilly area, with varying altitudes, slopes, aspects, and soil textures causing the corresponding uneven micrometeorological conditions. We use the radiation and temperature data corrected by the micro-topography data to drive the eco-hydrological model (Ecosystem demography model version 2). Results showed that different regions have different micrometeorological conditions, the distribution of vegetation, water, energy, and carbon fluxes. Furthermore, the topographic heterogeneity, giving rise to the uneven soil texture and micrometeorological conditions, directly or indirectly affects the distribution of vegetation, water, energy, and carbon fluxes. The findings will improve our understanding of the eco-hydrological processes.

How to cite: Li, Y., Zhang, K., and Bardossy, A.: Study on the coupled eco-hydrological processes impacted by fine-scale landscape heterogeneity in a typical humid hilly area, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3856, https://doi.org/10.5194/egusphere-egu22-3856, 2022.

In many poorly drained agricultural regions, humans have introduced expansive networks of subsurface tile drains and straightened headwater streams to improve drainage. These networks serve as a direct link between cropland and larger streams and rivers, but the transport and retention of nutrients like phosphorus (P) in these networks is not well understood. Here we evaluate transport and retention of dissolved P and fine particles (which sorb dissolved P) within an agricultural drainage ditch in the Maumee River Basin in northeastern Ohio, USA. We conducted three constant rate injections of conservative salt (Cl as NaCl), dissolved P (KH₂PO₄), and a fluorescent fine particle (Dayglo AX-11-5 Aurora Pink®) following precipitation events in the spring (May), summer (July), and autumn (December). We model the breakthrough curves using the Continuous Time Random Walk (CTRW) approach to quantify solute and particle transport behavior. Preliminary analysis of Cl breakthrough curves indicates that in-stream velocities were slightly greater in spring (0.079 m/s compared with 0.039 m/s in summer and 0.060 m/s in fall), and conservative solute retention was also greatest in spring, as indicated by residence time behavior (tail power-law slope of -1.73 compared with -1.23 in summer and -1.59 in fall). Preliminary analysis of dissolved P breakthrough curves indicates that the nutrient spiraling length was longer in the spring (4070 m) and decreased in the summer (1560 m). Vegetation stands throughout the stream were denser in the summer and autumn and likely influenced P transport through both physical and biological processes. With the increasing frequency and severity of harmful algal blooms in major waterbodies that receive P from agricultural lands, it is crucial to understand how P moves through highly modified agricultural drainage networks. Tentatively, this study indicates that aquatic vegetation drives biophysical processes in drainage ditches that dictate seasonal nutrient export to larger waterbodies.

How to cite: Field, H. R., Sawyer, A. H., Welch, S. A., Benefiel, R. K., Mathie, D. M., Hood, J. M., Pawlowski, E. D., Karwan, D. L., Kreiling, R. M., Johnson, Z. I., Hanrahan, B. R., and King, K. W.: Phosphorus and Fine Particle Retention in Agricultural Headwater Streams, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10993, https://doi.org/10.5194/egusphere-egu22-10993, 2022.