Landscape Ecohydrology

 We aim to understand the ecohydrological functioning of catchments at different spatio-temporal scales, i.e. how and how long is water stored and released in landscapes. For this, we link landscapes and riverscapes by understanding the physical processes that generate stream flow, and the way these processes influence the hydrochemistry and ecohydrology of landscapes and streams. One of our main tools is the use of stable isotope tracers as "fingerprints" of waters to quantify internal processes of water storage, transmission and release, and ecohydrological fluxes monitored across spatio-temporal scales. We integrate our extensive environmental data into ecohydrological models (the group developed the tracer-aided model EcH2O-iso) to parameterise ecohydrological fluxes and interactions in a physically-based way. This allows the effects of vegetation on water use, and the direct effects of climate and landuse change on water flow paths and availability to be quantitatively assessed.

Tracer-aided models use coupled isotope-hydrology water tracking to simulate stable isotope ratios and their transformation from precipitation to stream flow through fluxes in vegetation canopies, rooting zones, deeper soils and groundwater aquifers. These approaches also allow us to estimate ages of water. One goal is to investigate soil-vegetation-atmosphere-water dynamics through tracers and tracer-aided modelling to quantify the heterogeneity in spatio-temporal patterns of "green" (evaporation and transpiration) and "blue" (groundwater recharge and runoff) water fluxes and to identify how plant water use will affect and possibly alter signals of potential climate change. We also use other tracer-aided models developed by the group (e.g. STARR). 

Currently, we work at the following main experimental sites: (i) The Demnitzer MillCreek catchment in the East of Brandenburg, Germany, which has soil and vegetation conditions representative of the drought-sensitive parts of NE Germany and central Europe and where stream intermittence is a big issue; in 2023 it was selected as a one of the Global Network of Ecohydrology Demonstration Sites by the UNESCO-IHP ECOHYDROLOGY PROGRAMME. (ii) the urban area of Berlin, where we also conduct extensive monitoring of atmosphere-soil-vegetation-stream flow interactions is also conducted in the city of Berlin to understand these processes in urban settings and thus, support decision-making for sustainable urban development; (iii) the floodplains of the National Park Lower Oder Valley to understand dynamics in floodplain-river connectivity; (iv) The Sophienfliess near Buckow, Maerkische Schweiz, where we aim to understand hydrological, water quality and water isotope dynamics in a steep headwater catchment in Brandenburg, affected by beaver activities; (v) the Girnock Burn catchment in NE Scotland, which is characteristic for northern climates with deep organic soils. Finally, we use local processed-based insights from different geographical environments from international inter-catchment comparisons to synthesise a more holistic understanding of hydrological and ecological function.

Our research delivers new scientific understanding for assessing how different land use affects "green" and "blue" water partitioning, providing a crucial basis for evaluating how water storage and flux dynamics can be mediated by land management strategies to build ecohydrological resilience and to protect water resources against future climate change.

Within Department 1, Ecohydrology & Biogeochemistry, our team addresses the three departmental core areas of research: Landscape-waterscape interactions; ecohydrology and biogeochemistry of urban and disturbed systems; and abiotic-biotic coupling.

Here some examples of our current projects:
(i) Studies in rural landscapes of Brandenburg:

Modelling the spatio-temporal patterns of hydrological and water quality processes at catchment-scale (Wu et al., 2022, Disentangling the influence of landscape characteristics, hydroclimatic variability and land management on surface water NO3 ‐N dynamics: spatially distributed modelling over 30 years in a lowland mixed land use catchment. Water Resources Research) and wetland-scale (Wu et al., 2022, Tracer-aided identification of hydrological and biogeochemical controls on in-stream water quality in a riparian wetland. Water Research) to assess the role of climate, land use, vegetation, topography and other local drivers; evaluating the uncertainty in calibration process of distributed hydrological models (Wu et al., 2022, Identifying Dominant Processes in Time and Space: Time-varying Spatial Sensitivity Analysis for a Grid-based Nitrate Model. Water Resources Research) (Songjun Wu)

Using tracer-aided ecohydrological models to assess the long-term drought effects on landscape water storage and the impacts of alternative landuse strategies on optimizing water availability in drought sensitive catchments (Dr. Shuxin Luo). Luo et al., 2024, Long-term drought effects on landscape water storage and resilience under contrasting landuses. Journal of Hydrology. This project, which aims to address the emerging challenges and devise strategies for coordinated action in the Berlin-Brandenburg model region, receives its funding from the Einstein Research Unit Climate and Water under Change (CliWaC).

Investigating inter-annual variation in water quality in an intermittent stream under drought conditions and high-resolution water quality dynamics of riparian wetlands in nutrient-rich lowland catchments (PhD Famin Wang).

Understanding groundwater-surface water dynamics in a mixed land use, lowland catchment through integrating water stable isotopes, hydrochemistry, geophysical and modelling approaches Ying et al., 2024, Developing a conceptual model of groundwater – surface water interactions in a drought sensitive lowland catchment using multi-proxy data. Journal of Hydrology (PhD Zhengtao Ying).

Evaluating the storage-flux-isotope-water age spatio-temporal interactions and partitioning of “blue” (groundwater and surface water) and “green” (evapotranspiration) water in the Demnitzer Mill Creek catchment using the physically based- tracer-aided ecohydrological model, EcH2O-iso (Dr. Aaron Smith) e.g. Smith et al., 2022; Critical zone response times and water age relationships under variable catchment wetness states: insights using a tracer-aided ecohydrological model. Water Resources Research; Smith et al., 2021, Quantifying the effects of land use and model scale on water partitioning and water ages using tracer-aided ecohydrological models. Hydrology and Earth System Science. (HESS); Kleine et al., 2021, Modelling ecohydrological feedbacks in forest and grassland plots under a prolonged drought anomaly in central Europe 2018-2020. Hydrological Processes.

Using stable water isotopes and ecohydrological monitoring to investigate the interlinkages between the soil-plant-atmosphere continuum as well as the effects of specific land use types (forest, agriculture, and grassland) on the ecohydrological fluxes of the Demnitzer Mill Creek catchment (PhD Jessica Landgraf); e.g. Landgraf et al. (2022) Using stable water isotopes to understand ecohydrological partitioning under contrasting land uses in a drought-sensitive rural, lowland catchment. Hydrological Processes.

 Investigations of the Spree river: Large scale synoptic surveys using water stable isotopes (PhD Ke Chen) Chen at al., 2023, Synoptic water isotope surveys to understand the hydrology of large intensively managed catchments. Journal of Hydrology; and Nitrate Liu et al., 2023, Quantifying changes and trends of NO3 concentrations and concentration-discharge relationships in complex large, heavily managed river systems. Journal of Hydrology, (Dr Ji Liu) to understand the hydrology and concentration-discharge relationships of a large intensively managed catchment.

 (ii) Research in urban ecosystems of Berlin:

Using stable water isotopes and environmental DNA to investigate the interlinkages between microbial community patterns and hydrology as well as other biotic and abiotic factors in urban streams, to assess the resilience and functioning of urban blue-green infrastructure and improve planning and restoration of nature-based solutions in cities: BiNatUr – Bringing Nature Back (Dr. Maria Warter). Warter et al., 2024, Environmental DNA, hydrochemistry and stable water isotopes as integrative tracers of urban ecohydrology. Water Research.

Using in-situ measurements of isotopes in plant xylem and atmospheric vapour and synoptic sampling to investigate high-resolution ecohydrological process dynamics at the urban soil-plant-atmosphere interface (PhD Ann-Marie Ring; who is part of the Graduate school Urban Water Interfaces UWI) Ring et al., 2024 Assessing the impact of drought on water cycling in urban trees via in-situ isotopic monitoring of plant xylem water. Journal of Hydrology; and temporal high-resolution in-situ measurements of moisture, energy balance, and tracers with the tracer-aided ecohydrological model, EcH2O-iso, we explore the complex mixing and transit times and interactions of vegetation and soil water (Dr. Aaron Smith); e.g. Smith et al. (2022) Modelling temporal variability of in-situ soil water and vegetation isotopes reveals ecohydrological couplings in a willow plot. Biogeosciences.

Within the Graduate school Urban Water Interfaces UWI we also apply tracer-aided ecohydrological modelling to investigate the impact of ongoing urbanisation on the components of the water balance in urban and peri-urban catchments, to intercompare and assess nonßlinearities in their long-term responses over periods including dry and wet years (Dr. Gregorio López Moreira) López Moreira Mazacotte et al., 2024, Integrated monitoring and modeling to disentangle the complex spatio-temporal dynamics of urbanized streams under drought stress. Environmental Monitoring and Assessment.

Using measurements of soil moisture as well as stable isotopes in both soil and xylem water with the tracer-aided ecohydrologcial model EcH2O-iso, we explore the differences in water partitioning between urban trees and grassland. This research can for example help inform policy makers optimize the use of urban green spaces combating urban heat or to promote groundwater recharge e.g. Gillefalk M, et al. (2021) Quantifying the effects of urban green space on water partitioning and ages using an isotope-based ecohydrological model. Hydrology and Earth System Sciences (HESS).

With the aid of stable water isotopes and hydrochemistry as natural "fingerprints" of water we aim to understand how water is transported through the urban environment in terms of water sources, pathways and ages to disentangle the effects of urbanization on the water balance (PhDs Lena-Marie Kuhlemann, Christian Marx). E.g. Kuhlemann et al. (2022) The imprint of hydroclimate, urbanization and catchment connectivity on the stable isotope dynamics of a large river in Berlin, Germany. Journal of Hydrology. Marx et al.  (2022) Spatial variations in soil-plant interactions in contrasting urban green spaces: preliminary insights from water stable isotopes. Journal of Hydrology.

(iii) Research in the floodplains of the Oder river

Quantifying connectivity dynamics between a large river, the Oder, and its floodplain using stable water isotopes, water quality and remote sensing approaches Zheng et al., 2024 Quantifying intra- and inter-annual dynamics of river-floodplain connectivity and wetland inundation with remote sensing and wavelet analysis. Hydrological Processes (PhD Hanwu Zheng).

Field observatory Demnitz Millcreek >