Mathematical Hydrology and Vulnerability Science: the come-back of a systems approach for Sustainability

Abstract:

The engineering roots of hydrology served society well in solving problems of flood control, prediction under limited observations, river basin management, water availability and distribution, and water allocation at the intersection of the natural and built environment. Scientific hydrology over the past two decades has advanced the physical understanding of hydrologic and related processes and their complex interactions and has generalized ideas and frameworks of estimation and prediction. Equipped with the engineering and scientific aspects of a field, hydrologist are in the best possible position to address new challenges related to sustainability of water quantity and quality under increasing stresses of climate and human perturbations while protecting ecosystem services and economic development. The first line of defense in studying a complex system for sustainability (ability to maintain the system integrity and functionality under perturbations) is to identify its vulnerable spots (places, times, processes that are more susceptible to change). A reductionist approach to such an endeavor is limited. Studying the system in parts with the most sophisticated distributed highly parameterized physically-based models and under non-stationarity might not provide insight into the emergent behavior at larger scales and longer times, exactly what is needed for identifying vulnerabilities that would inform policy and management for a sustainable future. We will present some ideas on a revised systems-approach to vulnerability science in hydro-geomorphologic systems under change via two examples. One example is a dynamic connectivity river network approach for predicting hotspots of geomorphic change in a Midwestern US river basin which is undergoing land-use and hydrologic changes. The other example relates to a new vulnerability assessment framework for delta systems undergoing change where network connectivity and delivery of fluxes dictates local places and actions that would most drastically affect the system as a whole.