CHORALE 1.4 Interdisciplinarity

Interdisciplinarity in CHORALE is operational rather than additive: the contributing disciplines will not operate in isolated development streams brought together at the end, but will interact throughout model development to jointly formulate, constrain and evaluate process representations at their scientific interfaces. Hydrology, ecosystem modelling, Earth Observation and climate modelling often describe different aspects or scales of the same coupled land-system processes using different concepts, assumptions and observational constraints. CHORALE will explicitly identify these interfaces (T4.1), evaluate them jointly in the common offline process testbed (T4.2) and record their transferability across models in the Development and Transferability Matrix (T4.4), using information emerging from one disciplinary perspective to challenge, refine and complement representations developed in another. Vegetation access to subsurface water provides a concrete example. Hydrology can infer an integrated climate- and water-balance-based constraint on vegetation-accessible root-zone storage, including the effects of past hydroclimatic deficits and assumptions on vegetation drought memory (T2.2), while ecosystem modelling provides mechanistic representations of how plants distribute roots vertically and adjust their access to soil water (T3.4). Bringing these perspectives together allows CHORALE to assess whether mechanistic rooting strategies are consistent with independently inferred storage requirements, whether the two approaches provide complementary or mutually constraining information, and how their combination needs to be adapted across different model architectures. Neither disciplinary perspective alone suffices: hydrology does not resolve the rooting strategy, and ecosystem modelling does not constrain the total storage the hydroclimate requires. The same methodological logic will be applied to other cross-disciplinary interfaces (Figure 1.2), including groundwater–vegetation water access (T2.3×T3.4), hydrological thresholds–physiological water stress (T2.2×T3.2), irrigation water availability–plant and crop water demand (T2.4×T3.2), and hydrological memory–ecosystem stress and recovery (T2.2×T3.3). Interdisciplinarity therefore becomes a mechanism for generating new process understanding and reducing structural uncertainty, rather than simply a characteristic of consortium composition.

The integration of Social Sciences and Humanities (SSH) is not a core research requirement of this topic, whose scope is centred on Earth system science and climate-process understanding within the remit of IPCC Working Group I. Accordingly, CHORALE’s scientific advances in structural hydrology, scale-aware parameterisations, Water-Energy-Carbon interactions, benchmarking and coordinated multi-model experimentation are grounded primarily in the physical and environmental sciences. SSH-related expertise contributes where CHORALE’s scientific results are translated into assessment-relevant evidence, climate services and decision-support knowledge. Through WP7-9, and in particular the science-to-policy interface (T7.2/T8.2/T9.2), the project will engage with scientific assessment communities, climate-service providers, water and risk-management authorities and policy actors to identify information needs, support the uptake of project results and develop science-to-policy knowledge products. SSH perspectives are particularly relevant to the interpretation and communication of the irrigation-sustainability and regreening experiments, whose implications depend on socio-economic scenarios and constraints, implementation feasibility, trade-offs and potential unintended consequences. These questions are addressed in the three policy roundtables of T7.2/T8.2/T9.2, two of which are timed to inform the selection of the production future experiments (MS5.1, MS5.2). These activities draw on consortium expertise in climate policy, socio-economic impact and climate-risk assessment, and stakeholder engagement (WEMC, CYI, VUB), and in science communication and knowledge brokerage (WEMC, CYI), complemented by Advisory Board expertise in science-policy interfaces, climate-risk assessment and water governance and economics (Table 3.3).