Organization of complexity in water limited ecohydrology

Abstract

Water limited ecohydrological systems (WLES), with their broad extent, large stores of global terrestrial carbon, potential for large instantaneous fluxes of carbon and water, sensitivity to environmental changes, and likely global expansion, are particularly important ecohydrological systems. Strong nonlinear responses to environmental variability characterize WLES, and the resulting complexity of system dynamics has challenged research focussed on general understanding and site specific predictions. To address this challenge our synthesis brings together current views of complexity from ecological and hydrological sciences to look towards a framework for understanding ecohydrological systems (in particular WLES) as complex adaptive systems (CAS). This synthesis suggests that WLES have many properties similar to CAS. In addition to exhibiting feedbacks, thresholds, and hysteresis, the functioning of WLES is strongly affected by self-organization of both vertical and horizontal structure across multiple scales. As a CAS, key variables for understanding WLES dynamics are related to their potential for adaptation, resistance to variability, and resilience to state changes. Several essential components of CAS, including potential for adaptation and rapid changes between states, pose challenges for modelling and generating predictions of WLES. Model evaluation and predictable quantities may need to focus more directly on temporal or spatial variance in contrast to mean state values for success at understanding system-level characteristics. How coupled climate and vegetation changes will alter available soil, surface and groundwater supplies, and overall biogeochemistry will reflect how self-organizational ecohydrological processes differentially partition precipitation and overall net metabolic functioning.

Drought in a human-modified world: reframing drought definitions, understanding, and analysis approaches

“…The field of ecohydrology has evolved in the last 15 years to a quantitative understanding of the interrelated dynamics of plants and water (e.g. Hannah et al, 2007;Asbjornsen et al, 2011;Jenerette et al, 2012). The importance of including vegetation feedback in future drought modelling was, for example, highlighted by Prudhomme et al (2014).…”

Biogeochemical hotspots: Role of small water bodies in landscape nutrient processing

“…On the other hand, studies quantifying the behavior of systems at larger scales such as watersheds or even continents will encounter issues of expensive computational simulations because of model complexity [Beven, 2000;Beven and Freer, 2001]. In the case of larger scales, the first-order rate constant approach is often considered sufficient to describe the behavior of water bodies as many processes may be averaged spatially or temporally -thus organization from complexity may emerge so that dominant behaviours may be quantified at these scales with simple rate constants [Turcotte, 2007;Jenerette et al, 2012;Sivakumar and Singh, 2012;Bras, 2015]. The scope of this thesis more closely aligns with the second category and thus the CSTR and PFR models were explored.…”

Modeling Acequia Irrigation Systems Using System Dynamics: Model Development, Evaluation, and Sensitivity Analyses to Investigate Effects of Socio-Economic and Biophysical Feedbacks

“…This effort is unique in that it seeks to link social, economic, hydrologic and ecologic dynamics to study natural and social stressors on CNH systems. System Dynamics (SD) was adopted for the modeling platform as it is particularly designed for multidisciplinary systems that express organized complexity [22,23] and evolve over time (for full methodological considerations, see [24]). This approach has been used in other water related research projects [25][26][27][28][29][30] and is valuable for engaging stakeholders and enhancing communication and management of the problem issue at hand [31][32][33][34].…”