2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Water Cycle Dynamics in a Changing Environment Advancing Hydrologic Science through Synthesis to organize and employ synthesis activities to produce transformational outcomes that will be utilized to improve the predictability of water cycle dynamics in a changing Earth environment. Objective Hydromorphology: Human-Nature Interactions #1. Interactions between hydrosphere and biosphere processes #2. Interactions of landscape processes within intensively managed watersheds Evolution, structure and function of hydrologic subsystems in hillslopes Stochastic transport in heterogeneous media Research Themes Principal Investigators: Murugesu Sivapalan, Praveen Kumar, Bruce Rhoads, Don Wuebbles

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Unprecedented Types, Rates, Scales, and Magnitudes of Change

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Limits to predictability Prediction means making probabilistic statements about future system states given the current and past observed states and our understanding of how nature works. The four classical limits to predictability are (NRC WSTB, 2002): Type I – uncertainty in the characterization of initial states Type II – uncertainty in the characterization of the dynamics at the interfaces Type III – uncertainty in the characterization of model parameters Type IV – uncertainty or inadequacy of characterization of critical processes, process interactions and feedbacks

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Working Hypotheses: Patterns Patterns help us to reduce the complexity through reduced dimensionality, and thus help to improve predictions Patterns (both observed and so far unobserved) are emergent properties arising out of complex interactions and feedbacks between a multitude of processes. Study of patterns (how to describe them, why they emerge, their impact on the overall response) yields new insights and lead to increased understanding. Study of observed patterns (why they emerge) may give insights into unobservable or as yet unobserved patterns, and help to make improved predictions

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Theme #1: Interactions between hydrosphere and biosphere processes Water balance partitioning at the catchment scale Peter Troch, Ciaran Harman and Sally Thompson

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA The Horton Index Precip “Fast” runoff “Slow” runoff ET Wetting Annual Evapotranspiration Annual Wetting HI = Proportion of available water that is vaporized

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Horton Index vs. Humidity Index Between catchments Troch et al., 2009 (HP) Between years Pattern that intrigues….. Humidity Index = Annual Precipitation Annual Potential Evaporation

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Horton, 1933 (AGU) V : Growing-season vaporization (E+T) W : Growing-season wetting (P-S) “The natural vegetation of a region tends to develop to such an extent that it can utilize the largest possible proportion of the available soil moisture supplied by infiltration” (Horton, 1933, p.455) Pattern that intrigues…..

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA MOPEX catchments

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Models of landscapes as nonlinear filters Penman Monteith Model RnVPDLAIUPT E max E T Interception Model PPT Runoff Drainage Infiltration Multiple Wetting Front Model Root Water Uptake Model

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA FLUXNET sites

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Hypothesis ? ? ?

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Theme #2: Interactions of landscape processes within intensively managed watersheds Sediment and Contaminant Dynamics Across Scales Nandita Basu, Ciaran Harman, Sally Thompson

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Patterns that intrigue….. Nitrate load-discharge relationships across Mississippi Sediment load-discharge relationships

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Filtering of solute variability across scales: Study sites Mississippi Basin Little Vermilion Single Tile Drain

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Landscape and Network Filtering of Sediment Transport: Study Sites Goodwin Creek, Mississippi Rio Isabena, Spain

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Hypothesis: Landscapes act as cascading,coupled filters Filtering of variable inputs by landscape structure and biogeochemical processes produces PATTERNS, as water and solutes cascade across spatial and temporal scales Observed “patterns” are windows into this filtering

2009 Hydrologic Synthesis Reverse Site Visit – Arlington VA Summary Summer institute: grassroots type organization – team based, egalitarian, targeted and yet free to explore alternative ideas or approaches, trail blazing Data based: recognize/extract patterns from data Patterns needing a multitude of perspectives from different disciplines to explain or interpret Interpretation of patterns using parsimonious models: a top-down approach What are the minimum processes needed to describe strong physical, chemical and biological coupling over a wide range of spatial and temporal scales? How do complex highly heterogeneous physical, chemical and biological systems respond to changes in forcing behavior and system structure? Comparative hydrology: develop generalizable insights through comparisons and classification Modeling of landscapes as nonlinear hierarchical filters – potentially transformative approach