HYDRO-CLIMATIC PROCESSES AND HAZARDS

Climate displays an often unrecognized order in both time and space. What may appear as a random sequence of precipitation at a point or within a watershed is actually the local expression of a broad integrated system of weather processes that are active on scales of 100's to 1000's of kilometers. Only when climate forcings and hydrologic responses are considered from a regional perspective does the order become evident. Covariation of precipitation, temperature, and other atmospheric conditions, which often only is evident from regional spatial scales, is an important determinant of hydrologic response. Recognition of these patterns and covariations provides a sound basis for national, regional, and local hydrologic analysis, resource management, and hazard assessment/mitigation.

Temporal climate variations result from a wide range of physical, chemical, and biological processes, including chaotic or near-chaotic fluid dynamics, complex radiative and moist-thermodynamic processes, tropical-extratropical interactions, ocean-air interactions, and the responses of terrestrial ecosystems to atmospheric forcings. Understanding the Nation's hydroclimate, water resources, and water-related hazards requires improved understanding and integration of these processes and interactions into interpretations and procedures. Despite the almost overwhelming complexity of these processes, the fields of statistical and dynamic climatology currently are providing many examples of how climate processes can be interpreted, modeled, and predicted by using physically and statistically based models. The climate system offers numerous possibilities for improving the understanding of hydrologic and water-resources systems, and opportunities for converting improvements in climatological understanding into improvements in hydrologic prediction.

An integral part of the U.S. Geological Survey's mission to appraise the Nation's water resources and provide hydrologic information for managing them must be the extraction of as much order and predictability from the Nation's hydroclimate as possible. The primary objectives of this project are to identify (1) climatologically induced relations within the Nation's hydrologic and water resource system, (2) recurring hydroclimatological patterns and climatologically imposed limits on hydrologic and water resource systems, (3) conditions leading to climatological extremes and resultant hydrologic hazards, and (4) regional and global climatic precursors of hydrologic events and hazards. Products of this project contribute directly to more accurate appraisals and management of the Nation's water resources and water-related hazards.