Remote Sensing of the Terrestrial Water Cycle

Space-borne observations of terrestrial water storage (TWS) are an essential ingredient for understanding the Earth's global water cycle, its susceptibility to climate change, and for risk assessments of ecosystems, agriculture, and water management. However, the complex distribution of water masses in rivers, lakes, or groundwater basins remains elusive in coarse-resolution gravimetry observations. We combine machine learning, numerical modeling, and satellite altimetry to build and train a downscaling neural network that recovers simulated TWS from synthetic space-borne gravity observations. The neural network is designed to adapt and validate its training progress by considering independent satellite altimetry records. We show that the neural network can accurately derive TWS anomalies in 2019 after being trained over the years 2003 to 2018. Specifically for validated regions in the Amazonas, we highlight that the neural network can outperform the numerical hydrology model used in the network training.https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL089258

Download Full-text

Plants, vital players in the terrestrial water cycle

10.5194/egusphere-egu21-3085 ◽

2021 ◽

Author(s):

Marie-Claire ten Veldhuis ◽

Tom van den Berg ◽

Martine van der Ploeg ◽

Elias Kaiser ◽

Satadal Dutta ◽

...

Keyword(s):

Water Transport ◽

Water Cycle ◽

Turgor Pressure ◽

Water Dynamics ◽

Plant Water ◽

Flow Monitoring ◽

Vital Functions ◽

Main Challenge ◽

Macro Scale ◽

Terrestrial Water

Plant transpiration accounts for about half of all terrestrial evaporation (Jasechko et al., 2013). Plants need water for many vital functions including nutrient uptake, growth, maintenance of cell turgor pressure and leaf cooling. Due to the regulation of water transport by stomata in the leaves, plants lose 97% of the water they take via their roots, to the atmosphere. They can be viewed as transpiration-powered pumps on the interface between the soil and atmosphere.Measuring plant-water dynamics is essential to gain better insight into their role in the terrestrial water cycle and plant productivity. It can be measured at different levels of integration, from the single cell micro-scale to the ecosystem macro-scale, on time scales from minutes to months. In this contribution, we give an overview of state-of-the-art techniques for transpiration measurement and highlight several promising innovations for monitoring plant-water relations. Some of the techniques we will cover include stomata imaging by microscopy, gas exchange for stomatal conductance and transpiration monitoring, thermometry for water stress detection, sap flow monitoring, hyperspectral imaging, ultrasound spectroscopy, accelerometry, scintillometry and satellite-remote sensing.Outlook: To fully assess water transport within the soil-plant-atmosphere continuum, a variety of techniques is required to monitor environmental variables in combination with biological responses at different scales. Yet this is not sufficient: to truly solve for spatial heterogeneity as well as temporal variability, dense network sampling is needed.In PLANTENNA (https://www.4tu.nl/plantenna/en/) a team of electronics, precision and microsystems engineers together with plant and environmental scientists develop and implement innovative (3D-)sensor networks that measure plant and environmental parameters at high resolution and low cost. Our main challenge for in-situ sensor autonomy (&#8220;plug and forget&#8221;) is energy: we want the sensor nodes to be hyper-efficient and rely fully on (miniaturised) energy-harvesting.REFERENCES: Jasechko, S., Sharp, Z. D., Gibson, J. J., Birks, S. J., Yi, Y., & Fawcett, P. J. (2013). Terrestrial water fluxes dominated by transpiration. Nature, 496(7445), 347-350. Plantenna: "Internet of Plants". (n.d.). https://www.4tu.nl/plantenna/en/&#160;

Download Full-text

Role of Lateral Terrestrial Water Flow on the Regional Water Cycle in a Complex Terrain Region: Investigation With a Fully Coupled Model System

Journal of Geophysical Research Atmospheres ◽

10.1029/2018jd029004 ◽

2019 ◽

Vol 124 (2) ◽

pp. 507-529 ◽

Cited By ~ 7

Author(s):

Thomas Rummler ◽

Joel Arnault ◽

David Gochis ◽

Harald Kunstmann

Keyword(s):

Water Flow ◽

Complex Terrain ◽

Water Cycle ◽

Coupled Model ◽

Model System ◽

Terrestrial Water ◽

Fully Coupled ◽

Regional Water

Download Full-text

Diagnosing hydrological limitations of a land surface model: application of JULES to a deep-groundwater chalk basin

Hydrology and Earth System Sciences ◽

10.5194/hess-20-143-2016 ◽

2016 ◽

Vol 20 (1) ◽

pp. 143-159 ◽

Cited By ~ 11

Author(s):

N. Le Vine ◽

A. Butler ◽

N. McIntyre ◽

C. Jackson

Keyword(s):

Land Surface ◽

Expert Knowledge ◽

Water Cycle ◽

Land Surface Model ◽

Surface Model ◽

Deep Groundwater ◽

Resolution Model ◽

Terrestrial Water ◽

Water Redistribution ◽

Types Of Information

Abstract. Land surface models (LSMs) are prospective starting points to develop a global hyper-resolution model of the terrestrial water, energy, and biogeochemical cycles. However, there are some fundamental limitations of LSMs related to how meaningfully hydrological fluxes and stores are represented. A diagnostic approach to model evaluation and improvement is taken here that exploits hydrological expert knowledge to detect LSM inadequacies through consideration of the major behavioural functions of a hydrological system: overall water balance, vertical water redistribution in the unsaturated zone, temporal water redistribution, and spatial water redistribution over the catchment's groundwater and surface-water systems. Three types of information are utilized to improve the model's hydrology: (a) observations, (b) information about expected response from regionalized data, and (c) information from an independent physics-based model. The study considers the JULES (Joint UK Land Environmental Simulator) LSM applied to a deep-groundwater chalk catchment in the UK. The diagnosed hydrological limitations and the proposed ways to address them are indicative of the challenges faced while transitioning to a global high resolution model of the water cycle.

Download Full-text

Inverse streamflow routing

Hydrology and Earth System Sciences ◽

10.5194/hess-17-4577-2013 ◽

2013 ◽

Vol 17 (11) ◽

pp. 4577-4588 ◽

Cited By ~ 18

Author(s):

M. Pan ◽

E. F. Wood

Keyword(s):

Water Budget ◽

Temporal Dynamics ◽

Water Cycle ◽

Ohio River ◽

Temporal Difference ◽

Time And Space ◽

Ohio River Basin ◽

Budget Analysis ◽

Spatially Distributed ◽

Terrestrial Water

Abstract. The process whereby the spatially distributed runoff (generated through saturation/infiltration excesses, subsurface flow, etc.) travels over the hillslope and river network and becomes streamflow is generally referred to as "routing". In short, routing is a runoff-to-streamflow process, and the streamflow in rivers is the response to runoff integrated in both time and space. Here we develop a methodology to invert the routing process, i.e., to derive the spatially distributed runoff from streamflow (e.g., measured at gauge stations) by inverting an arbitrary linear routing model using fixed interval smoothing. We refer to this streamflow-to-runoff process as "inverse routing". Inversion experiments are performed using both synthetically generated and real streamflow measurements over the Ohio River basin. Results show that inverse routing can effectively reproduce the spatial field of runoff and its temporal dynamics from sufficiently dense gauge measurements, and the inversion performance can also be strongly affected by low gauge density and poor data quality. The runoff field is the only component in the terrestrial water budget that cannot be directly measured, and all previous studies used streamflow measurements in its place. Consequently, such studies are limited to scales where the spatial and temporal difference between the two can be ignored. Inverse routing provides a more sophisticated tool than traditional methods to bridge this gap and infer fine-scale (in both time and space) details of runoff from aggregated measurements. Improved handling of this final gap in terrestrial water budget analysis may potentially help us to use space-borne altimetry-based surface water measurements for cross-validating, cross-correcting, and assimilation with other space-borne water cycle observations.

Download Full-text