So Much Data and So Few Ways to Use It: The Era of Data Rich Hydrology

Abstract:

Until late in the 20^th century hydrology, and many other Earth Sciences, developed in a limited data environment. For the most part, researchers and practitioners availed themselves of data of very low resolution in time and space. In hydrology, that meant point observations of fluxes like precipitation and evaporation and state variables like soil moisture, temperature and topography. Those observations were rarely hourly, sometimes daily and more commonly weekly and monthly. That situation forced hydrologists to rely on significant data extrapolation and on conceptual mathematical models designed to capture broad system behavior. That situation began changing rapidly at the end of the 20^th century. In the 1990’s the United States (NASA) started implementing the Earth Observing System, some two dozen satellites have or continue to observe Earth and its environment at unimaginable resolution in time and space. In year 2000 the Shuttle Radar Topography Mission mapped the world at resolutions of 30 meters or less. That was a watershed moment for hydrology, it was no longer necessary to conceptualize and deal with lumped aggregated representations of basins. All of a sudden, and to this day, we have more data than we know how to use properly. This richness comes with challenges. The data is unwieldy, its errors structures are different, old models are of little guidance and new representations to match data availability are required. The tools needed to handle the data are different: the “big data” analysis era is with us. This paper explores that evolution in data and its use in hydrology. It will illustrate the challenges using analysis of precipitation, soil moisture, and topography, among others. The message is that the wealth of data now leads our understanding and to exploit that newly found information properly we cannot rely strictly on statistical/analytical procedures but must fall back on our understanding of hydrology/meteorology. In that sense, not much has changed.