Synoptic dendroclimatology: a process-based approach for linking tree-ring information to atmospheric circulation over the Pacific and western North America [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Synoptic dendroclimatology uses dated tree rings to study and reconstruct climate from the viewpoint of the climate's weather components and their relationship to atmospheric circulation. This approach defines a connection between large-scale circulation and ring-width variation at local sites using correlation fields, composite maps, indexing, and other circulation-based methodologies

emerging perspectives for flood risk assessment and management

Flood estimation and flood management have traditionally been the domain of hydrologists, water resources engineers and statisticians, and disciplinary approaches abound. Dominant views have been shaped; one example is the catchment perspective: floods are formed and influenced by the interaction of local, catchment-specific characteristics, such as meteorology, topography and geology. These traditional views have been beneficial, but they have a narrow framing. In this paper we contrast traditional views with broader perspectives that are emerging from an improved understanding of the climatic context of floods. We come to the following conclusions: (1) extending the traditional system boundaries (local catchment, recent decades, hydrological/hydraulic processes) opens up exciting possibilities for better understanding and improved tools for flood risk assessment and management. (2) Statistical approaches in flood estimation need to be complemented by the search for the causal mechanisms and dominant processes in the atmosphere, catchment and river system that leave their fingerprints on flood characteristics. (3) Natural climate variability leads to time-varying flood characteristics, and this variation may be partially quantifiable and predictable, with the perspective of dynamic, climate-informed flood risk management. (4) Efforts are needed to fully account for factors that contribute to changes in all three risk components (hazard, exposure, vulnerability) and to better understand the interactions between society and floods. (5) Given the global scale and societal importance, we call for the organization of an international multidisciplinary collaboration and data-sharing initiative to further understand the links between climate and flooding and to advance flood research

Floods and climate: emerging perspectives for flood risk assessment and management

Flood estimation and flood management have traditionally been the domain of hydrologists, water resources engineers and statisticians, and disciplinary approaches abound. Dominant views have been shaped; one example is the catchment perspective: floods are formed and influenced by the interaction of local, catchment-specific characteristics, such as meteorology, topography and geology. These traditional views have been beneficial, but they have a narrow framing. In this paper we contrast traditional views with broader perspectives that are emerging from an improved understanding of the climatic context of floods. We come to the following conclusions: (1) extending the traditional system boundaries (local catchment, recent decades, hydrological/hydraulic processes) opens up exciting possibilities for better understanding and improved tools for flood risk assessment and management. (2) Statistical approaches in flood estimation need to be complemented by the search for the causal mechanisms and dominant processes in the atmosphere, catchment and river system that leave their fingerprints on flood characteristics. (3) Natural climate variability leads to time-varying flood characteristics, and this variation may be partially quantifiable and predictable, with the perspective of dynamic, climate-informed flood risk management. (4) Efforts are needed to fully account for factors that contribute to changes in all three risk components (hazard, exposure, vulnerability) and to better understand the interactions between society and floods. (5) Given the global scale and societal importance, we call for the organization of an international multidisciplinary collaboration and data-sharing initiative to further understand the links between climate and flooding and to advance flood research

Hydroclimatology of flow events in the Gila River basin, central and southern Arizona

Traditional flood-frequency techniques are based on the assumption that the observed flood record represents a sample that has been drawn from a single climatically homogeneous population of floods. A hydroclimatic approach was used to evaluate this assumption by identifying the circulation patterns and atmospheric flood-generating mechanisms which control the temporal and spatial variability of flooding. Mean monthly discharges and instantaneous peak flows of the partial duration series were analyzed for thirty gaging stations in the climatically sensitive, semiarid, Gila River basin for the period 1950 to 1980. Correlation fields and composite maps were constructed to define the relationship between 700 mb height circulation anomalies and mean monthly streamflow. Individual flood events were linked to climate by analyzing daily synoptic weather maps and classifying each flood event into one of eight hydroclimatic categories on the basis of the atmospheric mechanisms which generated each flow. The analysis demonstrated that floods and anomalously high streamflow in the Gila River basin originate from a variety of atmospheric processes which vary spatially, seasonally, and from year-to-year. The mechanisms most important for generating floods included winter fronts, cutoff lows, tropical storms, snowmelt, and widespread and localized summer monsoon-related circulation patterns. When flood discharges were grouped into hydroclimatically homogeneous categories, histogram plots of their frequency distributions exhibited means and variances that differed from those of the overall frequency distribution of the entire flood series. The means of the discharges generated by frontal precipitation and tropical storms tended to plot above the mean of the overall series, while the means of floods generated by snowmelt tended to plot below the overall mean. Flood estimates computed from a series containing mixed distributions were not the same as flood estimates computed from climatically homogeneous subsets of the same series. These results have implications for traditional flood-frequency analysis and other stochastic methods of analyzing hydrologic time series. The hydroclimatically-defined subgroups in the flood series of the Gila River basin indicate that nonhomogeneity and nonstationarity can be imparted to a hydrologic time series by differing atmospheric mechanisms alone.hydrology collectio

A review of flood records from tree rings

Palaeohydrology is now recognized as a valuable approach to characterize the hazards posed by flooding. Tree rings have emerged as an important source of evidence for paleohydrological studies, and, since the 1960s, have been used to document the occurrence of past floods. In this progress report we outline the major contributions of tree-ring records to flood research. By reviewing the key advances in this field, documenting different research trajectories, and highlighting recent developments, we make an argument in favor of more extensive use of tree rings in flood analyses. We show how tree-ring data have been applied to risk assessment and outline how the widespread distribution of flood-affected trees can be used to improve the understanding of flood processes. In addition, we outline new approaches and future perspectives for the inclusion of woody vegetation in hazard assessments, and end with new thematic perspectives

Tracking precipitation patterns across a western U.S. metropolitan area using volunteer observers: RainLog

The southwestern United States experiences extreme hydroclimatic variability, including intense but localized monsoon thunderstorms, tropical storms, and winter storms, resulting in complex and variable patterns of precipitation over space and time. Official gauges associated with long‐term monitoring networks are sparsely distributed throughout the region and are unable to capture the spatial complexity and variability of these precipitation patterns. The RainLog program, a volunteer precipitation monitoring program, was started in southern Arizona in 2005 to leverage enthusiasm among non‐scientists around weather, water, and climate to address the gaps in official monitoring networks. An examination of the portion of the dataset that spans the Tucson metropolitan area illustrates the opportunities and challenges in using volunteer data to track precipitation. We compare near‐complete records to an official observation to highlight how the broader RainLog network supports characterizing hydroclimatic variability over the period of record. We also examine several case study events drawn from metrics of network variability that represent different forms of hydroclimatic extremes. We find that in most cases the RainLog network captures a range of precipitation values that were notably different than the single value recorded at the official observing site, adding substantial value in recording and reconstructing past extreme precipitation events. This work highlights how volunteer citizen science precipitation monitoring networks can provide critical data for tracking precipitation variability and changes, although are only one complementary piece of coherent, long‐term hydroclimatic monitoring.Climate Program OfficeOpen access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]