Abstract
Waterbodies (natural lakes and reservoirs) are a critical part of a watershed’s ecological and hydrological balance, and in many cases dictate the downstream river flows either through natural attenuation or through managed controls. Investigating waterbody dynamics relies primarily on understanding their morphology and geophysical characteristics that are primarily defined by bathymetry. Bathymetric conditions define stage-storage relationships and circulation/transport processes in waterbodies. Yet many studies oversimplify these mechanisms due to unavailability of the bathymetric data. We developed a novel GLObal Bathymetric (GLOBathy) dataset of 1.4+ million waterbodies to align with the well-established global dataset, HydroLAKES. GLOBathy uses a GIS-based framework to generate bathymetric maps based on the waterbody maximum depth estimates and HydroLAKES geometric/geophysical attributes of the waterbodies. The maximum depth estimates are validated at 1,503 waterbodies, making use of several observed data sources. We also provide estimations for head-Area-Volume (h-A-V) relationships of the HydroLAKES waterbodies, driven from the bathymetric maps of the GLOBathy dataset. The h-A-V relationships provide essential information for water balance and hydrological studies of global waterbody systems.
Highlights
Background & SummaryThe majority of Earth’s accessible fresh surface water is stored in more than 100 million lakes and reservoirs, which serve as vital resources for an exhaustive list of critical ecosystem functions and human and animal habitats[1]
Changes in storage volume and/or the timing due to climate variability, human activity, etc., can lead to disruptions of natural physiologic processes and affect water quality and quantity. Such changes and their negative consequences have been observed in waterbodies around the world, for which a scientific consensus on the climatological and hydrological drivers behind these associated changes in water storage is still evolving[2,3]
Advancements in computing, Geographic Information Systems (GIS), remote sensing (RS), airborne LiDAR, and optical imaging have increased accessibility and fidelity of waterbody geometry parameters[6,7,8], reducing the reliance on limited ground-based observations. These technologies have led to advancements in estimates of time-varying waterbody parameters such as surface area, volume, and discharges[5,9,10,11] and RS-based data services provide daily estimates of changes in global waterbody surface levels such as Cooley et al.’s analysis of water levels in global waterbodies[12], Global Reservoirs and Lakes Monitor (G-REALM; https://ipad.fas.usda.gov/cropexplorer/global_reservoir/), and Database for Hydrological Time Series of Inland Waters (DAHITI; https:// dahiti.dgfi.tum.de/en/), inferred from relevant information offered by a suite of satellites, e.g., ICESat-2, Jason-2, and TOPEX-POSEIDON
Summary
The majority of Earth’s accessible fresh surface water is stored in more than 100 million lakes and reservoirs (hereafter waterbodies), which serve as vital resources for an exhaustive list of critical ecosystem functions and human and animal habitats[1]. These datasets provide valuable information for basic hydrologic and limnological modeling applications, they lack the bathymetric information needed to accurately and/or realistically depict geophysical conditions in the global inland waterbody systems and support long-term modeling of physical and biogeochemical processes and water balance simulations at an adequate spatial resolution. GLOBathy is the first dataset to provide reliable estimates of maximum depth, bathymetry, and h-A-V relationships on such a scale and at high resolution, relevant to a wide range of hydrological, environmental, biological, limnological, and coastal applications
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