1
1
Toward Multiscale
Hydrologic Remote
Sensing for Creating
Integrated Hydrologic
Observatories
Ni-Bin Chang and Yang Hong
1.1 INTRODUCTION
The global water cycle is driven by a multiplicity of complex processes and interactions between and within the Earth’s atmosphere, lands, oceans, and biological
systems over a wide range of space and time scales. Horizontally, the water cycle
ranges from hill slopes and headwater streams, through river basins and regional
aquifers, to the whole continent and the globe. Timewise, it involves the dynamic
temporal variation of processes and responses ranging from minutes to hourly, daily,
seasonal, and interannual swings of water fluxes and storages, to rare and episodic
events. As the time and space scales change, new levels of complexity and interactions are introduced, and such multiscale nonlinearity can hardly be explained by
simply upscaling or downscaling the data. Historically, hydrologic science has long
relied on a spectrum of observations from the laboratory as well as field plots to
test various hydrologic theories. Traditional responses to hydrologic variability focus
on the statistical analysis of the regional hydrologic cycle with stationary assumptions. Many factors conspire against traditional hydrologic processes across space
and time scales due to rapidly declining water resources and the nonstationarity of
climate variations. Over the last two decades, our society has experienced global
climate change, economic development and globalization, increased frequency of
natural hazards, rapid urbanization, and population growth along with migration
CONTENTS
1.1 Introduction ...................................................................................................... 1
1.2 Current Challenges ...........................................................................................2
1.3 Featured Areas ................................................................................................. 3
References ................................................................................................................. 5
1
Toward Multiscale
Hydrologic Remote
Sensing for Creating
Integrated Hydrologic
Observatories
Ni-Bin Chang and Yang Hong
1.1 INTRODUCTION
The global water cycle is driven by a multiplicity of complex processes and interactions between and within the Earth’s atmosphere, lands, oceans, and biological
systems over a wide range of space and time scales. Horizontally, the water cycle
ranges from hill slopes and headwater streams, through river basins and regional
aquifers, to the whole continent and the globe. Timewise, it involves the dynamic
temporal variation of processes and responses ranging from minutes to hourly, daily,
seasonal, and interannual swings of water fluxes and storages, to rare and episodic
events. As the time and space scales change, new levels of complexity and interactions are introduced, and such multiscale nonlinearity can hardly be explained by
simply upscaling or downscaling the data. Historically, hydrologic science has long
relied on a spectrum of observations from the laboratory as well as field plots to
test various hydrologic theories. Traditional responses to hydrologic variability focus
on the statistical analysis of the regional hydrologic cycle with stationary assumptions. Many factors conspire against traditional hydrologic processes across space
and time scales due to rapidly declining water resources and the nonstationarity of
climate variations. Over the last two decades, our society has experienced global
climate change, economic development and globalization, increased frequency of
natural hazards, rapid urbanization, and population growth along with migration
CONTENTS
1.1 Introduction ...................................................................................................... 1
1.2 Current Challenges ...........................................................................................2
1.3 Featured Areas ................................................................................................. 3
References ................................................................................................................. 5