Department Surface Waters - Research and Management
Habitat dynamics: from concept to toolbox
River habitats are dynamic. When discharge changes, habitat availability, persistence, hydraulic stress and connectivity also change within a river reach. These dynamics matter at the patch scale. The concept of patch-scale habitat dynamics captures how aquatic organisms experience changing conditions in their immediate surroundings, such as current velocity, drying, refugia availability and habitat shifts.
Here, we present a general approach to quantify discharge-driven patch-scale habitat dynamics in rivers. We link discharge time-series with hydraulic simulations and habitat classifications to reconstruct habitat time-series. The approach was initially developed for hydropeaking rivers, i.e., rivers experiencing rapid, hydropower-induced discharge fluctuations that repeatedly alter habitat conditions within patches. However, the underlying framework can also be transferred to other river systems and management questions, such as residual flows, flood disturbance and environmental flows. It adds a dynamic layer to existing habitat-quality assessments.
HaDy_MZB (Habitat Dynamics MacroZooBenthos) is an open-source Python toolbox that operationalizes the patch-scale habitat dynamics approach for benthic macroinvertebrates. Four metrics describe habitat probability, habitat shifts, drift risk and desiccation risk. Together, these metrics identify stable versus dynamic zones and areas with potential ecological bottlenecks. The work supports process-based impact assessment and restoration in rivers.
 | Dr. Nico Bätz |
 | Dr. Christine Weber group leader +41 58 765 2214 send email |
Funding
Developed within Eawag research on hydropeaking mitigation and river restoration, with support from Swiss Federal Office for the Environment FOEN.
Collaboration
- Eawag, Surface Waters – Research and Management
- UR RiverLy, INRAE, Centre de Lyon-Villeurbanne
- VAW, Laboratory of Hydraulics, Hydrology and Glaciology, ETH
- KIT, Institute for Water and Environment, Karlsruhe Institute for Technology
- EPFL, Hydraulic Constructions Platform
- Several practice partners
Patch-scale habitat dynamics: concept and metrics
Why habitat dynamics matter
Traditional habitat assessments often focus on habitat availability under selected discharges. Examples include mean discharge, base discharge, peak discharge or specific flood discharges. However, ecological impacts are not only determined by how much habitat is available at one moment in time. They also depend on how habitat conditions change, how long suitable habitats persist, where hydraulic stressors concentrate, and whether refugia remain available and connected.
A patch-scale perspective helps to capture these processes. Discharge changes do not affect all parts of a river reach equally. Some patches may dry, experience high current velocities or lose habitat suitability. Others may remain relatively stable and function as refugia. This spatial variability is important because organisms interact with their environment at the scale of local habitat patches. Their response also depends on traits such as mobility, life stage and sensitivity to hydraulic stress.
Habitat dynamics are relevant for different types of flow alteration. Natural floods can disturb habitats but also create heterogeneity and maintain connectivity. Hydropeaking can repeatedly alter water depth, current velocity and habitat conditions within short time periods. Residual-flow regimes can reduce disturbance, renewal and connectivity. In all cases, the question is how flow regime and river morphology interact to shape habitat availability, persistence, refugia availability and potential ecological bottlenecks.
Patch-scale metrics
The original patch-scale habitat dynamics framework uses three complementary metrics to quantify discharge-driven habitat dynamics:
- M1 – Habitat probability
Quantifies the time-integrated availability of habitat conditions within each patch. - M2 – Habitat shifts within patches
Quantifies how often habitat conditions change within a fixed patch. - M3 – Spatial shifts of habitats
Quantifies how far habitat types move through space over time.
Together, these metrics help identify where habitat dynamics are highest, where suitable habitats persist, and where ecological bottlenecks may occur. They also help compare hydrological or morphological scenarios.
For benthic macroinvertebrates, the HaDy_MZB toolbox adapts this framework to quantify habitat persistence, drift risk and desiccation risk. These additional indicators focus on organisms with limited mobility and high sensitivity to hydraulic stress and drying.
Scientific basis
Concept
- Bätz, N., Judes, C. & Weber, C. (2023). Nervous habitat patches: the effect of hydropeaking on habitat dynamics. River Research and Applications, 39(3), 349-363.
Metrics
- Bätz, N., Judes, C., Vanzo, D., Lamouroux, N., Capra, H., Baumgartner, J., Berger, B. & Weber, C. (2025). Patch-scale habitat dynamics: three metrics to assess ecological impacts of frequent hydropeaking. Journal of Ecohydraulics, 10(1), 79-106.
Empirical study
- Friese N, Mathers KL, Weber C, Tonolla D, Bätz N. (2025). Habitat-Specific Response of Macroinvertebrate Drift to Flow Pulses: Implications for Hydropeaking Management. Freshwater Biology 70, no. 10: e70103.
Practice-oriented articles
- Bätz, N., Hayes, D. S., Lecrivain, A., Greimel, F., Auhser, A., Vanzo, D. & Weber, C. (2026). Restless rivers: impacts of frequent hydropeaking on habitat dynamics. AQUA - Water Infrastructure, Ecosystems and Society. 2026; jws2026126.
- Bätz, N., Hayes, D. S., Lecrivain, A., Greimel, F., Auhser, A., Vanzo, D. & Weber, C. 2026). Nervöse Fliessgewässer: Auswirkungen der Schwall-Sunk-Frequenz auf die Lebensraumdynamik. Hydrosuisse Journal, 118(2), 35-43.
- Bätz, N., Hayes, D. S., Lecrivain, A., Greimel, F., Auhser, A., Vanzo, D. & Weber, C. (2026). Rivières agitées: Effets de la fréquence des éclusées sur la dynamique des habitats. Hydrosuisse Journal, 118(2), 35-43
HaDy_MZB: from concept to open-source toolbox
A practical toolbox
HaDy_MZB (Habitat Dynamics MacroZooBenthos) is an open-source Python toolbox. It translates the patch-scale habitat dynamics concept into a practical workflow for research and practice.
The toolbox links discharge time-series with precomputed hydraulic or habitat data for selected discharges. It then reconstructs habitat time-series at the patch scale. Based on these time-series, it calculates habitat probability (M1 above) and within-patch habitat shifts (M2 above). It complements these with drift-risk and desiccation-risk metrics.
HaDy_MZB was developed with a focus on benthic macroinvertebrates in hydropeaking-affected rivers. In this context, it helps quantify how frequent discharge pulses affect habitat persistence, drift risk and desiccation risk. The workflow can also be adapted to other organisms and life stages with limited mobility or sensitivity to changing hydraulic conditions. Examples include fish eggs, fish larvae and riparian vegetation.
What HaDy_MZB can be used for
- HaDy_MZB is particularly suited for analyzing discharge-driven habitat dynamics using hydraulic simulations and discharge time-series. Applications include:
- assessment of hydropeaking impacts
- analysis of managed environmental flow releases and natural or managed high-discharge events
- comparison of natural, regulated and mitigation flow regime scenarios
- analysis of repeated discharge pulses and their effects on habitat persistence
- evaluation of morphological complexity and its influence on habitat dynamics
- identification of patches exposed to drift or desiccation risk
- assessment of stable and dynamic habitat conditions for organisms with limited mobility
- spatially explicit support for river restoration and hydropeaking mitigation planning.
The toolbox does not replace hydrodynamic modelling, morphodynamic modelling or ecological expert judgement. Instead, it provides a reproducible workflow for translating hydraulic simulations, habitat classifications and discharge time-series into interpretable patch-scale habitat dynamics metrics.
For questions concerning flood refugia, river restoration or habitat variation across discharge intensities, HaDy_MZB can complement other spatial indicators. Examples include habitat-heterogeneity indices, refugia availability and thresholds for critical hydraulic conditions.
Scientific basis
Lecrivain A., De Cesare G., Weber C. & Bätz N (2026). Macroinvertebrate habitat dynamics under frequent hydropower-induced discharge fluctuations: patch-scale metrics to quantify effects of hydropeaking and morphological complexity. Environmental Management.