Statistical Characterization of Environmental Hot Spots and Hot Moments
and Applications in Groundwater Hydrology
Abstract
Environmental hot spots and hot moments (HSHMs) represent rare locations
and events that exert disproportionate influence over the environment.
While several mechanistic models have been used to characterize HSHMs
behavior at specific sites, a critical missing component of research on
HSHMs has been the development of clear, conventional statistical
models. In this paper, we introduced a novel stochastic framework for
analyzing HSHMs and the uncertainties. This framework can easily
incorporate heterogeneous features in the spatiotemporal domain and can
offer inexpensive solutions for testing future scenarios. The proposed
approach utilizes indicator random variables (RVs) to construct a
statistical model for HSHMs. The HSHMs indicator RVs are comprised of
spatial and temporal components, which can be used to represent the
unique characteristics of HSHMs. We identified three categories of HSHMs
and demonstrated how our statistical framework are adjusted for each
category. The three categories are (1) HSHMs defined only by spatial
(static) components, (2) HSHMs defined by both spatial and temporal
(dynamic) components, and (3) HSHMs defined by multiple dynamic
components. The representation of an HSHM through its spatial and
temporal components allows researchers to relate the HSHM’s uncertainty
to the uncertainty of its components. We illustrated the proposed
statistical framework through several HSHM case studies covering a
variety of surface, subsurface, and coupled systems.