Laser vision : lidar as a transformative tool to advance critical zone science

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hydrology and Earth System Sciences 19 (2015): 2881-2897, doi:10.5194/hess-19-2881-2015.Observation and quantification of the Earth's surface is undergoing a revolutionary change due to the increased spatial resolution and extent afforded by light detection and ranging (lidar) technology. As a consequence, lidar-derived information has led to fundamental discoveries within the individual disciplines of geomorphology, hydrology, and ecology. These disciplines form the cornerstones of critical zone (CZ) science, where researchers study how interactions among the geosphere, hydrosphere, and biosphere shape and maintain the "zone of life", which extends from the top of unweathered bedrock to the top of the vegetation canopy. Fundamental to CZ science is the development of transdisciplinary theories and tools that transcend disciplines and inform other's work, capture new levels of complexity, and create new intellectual outcomes and spaces. Researchers are just beginning to use lidar data sets to answer synergistic, transdisciplinary questions in CZ science, such as how CZ processes co-evolve over long timescales and interact over shorter timescales to create thresholds, shifts in states and fluxes of water, energy, and carbon. The objective of this review is to elucidate the transformative potential of lidar for CZ science to simultaneously allow for quantification of topographic, vegetative, and hydrological processes. A review of 147 peer-reviewed lidar studies highlights a lack of lidar applications for CZ studies as 38 % of the studies were focused in geomorphology, 18 % in hydrology, 32 % in ecology, and the remaining 12 % had an interdisciplinary focus. A handful of exemplar transdisciplinary studies demonstrate lidar data sets that are well-integrated with other observations can lead to fundamental advances in CZ science, such as identification of feedbacks between hydrological and ecological processes over hillslope scales and the synergistic co-evolution of landscape-scale CZ structure due to interactions amongst carbon, energy, and water cycles. We propose that using lidar to its full potential will require numerous advances, including new and more powerful open-source processing tools, exploiting new lidar acquisition technologies, and improved integration with physically based models and complementary in situ and remote-sensing observations. We provide a 5-year vision that advocates for the expanded use of lidar data sets and highlights subsequent potential to advance the state of CZ science.The workshop forming the impetus for this paper was funded by the National Science Foundation (EAR 1406031). Additional funding for the workshop and planning was provided to S. W. Lyon by the Swedish Foundation for International Cooperation in Research and Higher Education (STINT grant no. 2013-5261). A. A. Harpold was supported by an NSF fellowship (EAR 1144894)

Corrigendum to "Laser vision: lidar as a transformative tool to advance critical zone science" published in Hydrol. Earth Syst. Sci., 19, 2881–2897, 2015

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hydrology and Earth System Sciences 19 (2015): 2943, doi:10.5194/hess-19-2943-2015

Identifying environmental controls on the shoreline of a natural river delta

River deltas form where sediment-laden water debouches into a basin. The spatial delineation of a delta is nontrivial and yet is fundamental to systematically evaluating fluxes across its surface. Here we study shoreline dynamics of the Wax Lake Delta (WLD), a naturally developing delta, downstream of the Atchafalaya River, USA. We demonstrate the ability to extract hydrodynamic and morphodynamic shorelines from time series of satellite imagery and topography data, respectively. The hydrodynamic shoreline corresponds to the traditional dry-wet interface, whereas we introduce the concept of a morphodynamic shoreline demarcating the topset-foreset transition of a delta to quantitatively express the degree of inundation of a delta plain. These shorelines enable us to assess environmental controls on inundation of the WLD delta plain, noting the abundance of satellite imagery, whereas time series of bathymetric data from delta plains are scarce. From the analysis of NOAA and U.S. Geological Survey environmental data, we identify the effects of river discharge, tides, wind, and vegetation on shoreline position. In particular, using Delft3D simulations and a simplified momentum balance, we highlight the nonuniform and nonlinear effect of wind on delta plain inundation. Our analyses reveal that wind, riverine discharge, and tides significantly contribute to inundation of the WLD, and hence, incorporating their interaction is essential to the accurate modeling of hydrodynamics and ecodynamics of the WLD delta plain, as well as to the dynamic shape of delta plains in general