River hydrology is the study of the dynamic volumes of water within fluvial channels. Each river has a unique hydrologic signature—an outcome of the complex interactions between climate and the surrounding landscape, the geology and geomorphology, and the longitudinal, lateral, and vertical connections between the aquatic and terrestrial interface. Hydrology shapes channel and floodplain morphologies and organizes the physiochemical characteristics of lotic habitats in which riverine organisms are adapted. As such, hydrology is considered the master variable of river ecosystem organization; however, the interactions between discharge and other abiotic properties that shape riverine ecological communities are complex and poses challenges for river managers. To cope with such complexity, many hydrologic statistics were developed to summarize river discharge into meaningful metrics for setting water policy standards and understanding fundamental linkages between hydrology and ecology. Although the field of statistical hydrology was aimed at reducing complexity, hundreds of hydrologic statics are now available to summarize discharge, and this has created its own paradox for researchers and river managers. Further research continues to identify the most important statistics to consolidate complexity and understand hydrologic variation.

• River Discharge Measurements
• Reservoir Sediment Monitoring