UniFHy v0.1: A community framework for the terrestrial water cycle in Python

Abstract. Land surface, hydrological, and groundwater modelling communities all have expertise in simulating the hydrological processes at play in the land system, but these communities have largely remained distinct with limited collaboration between disciplines. In order to address key societal questions regarding the future availability of water resources and the intensity of extreme events such as floods and droughts in a changing climate, these communities must build on the strengths of one another. The development of a common modelling infrastructure, a framework, can contribute to stimulating cross-fertilisation between them. By allowing (parts of) their existing models to be coupled together, improved land system models can be built to better understand and simulate the terrestrial hydrological cycle. This paper presents a Python implementation of such a framework named the Unified Framework for Hydrology (unifhy). The framework aims to provide the technical infrastructure required to couple models, taking into account the specific needs of a land system model. Its conceptual design and technical capabilities are outlined first, before its usage and useful characteristics are demonstrated through case studies. The limitations of the current framework and necessary future developments are finally presented as a road map for later versions and/or other implementations of the framework.

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Evaluation of Global Water Resources Reanalysis Products in the Upper Blue Nile River Basin

Journal of Hydrometeorology ◽

10.1175/jhm-d-19-0233.1 ◽

2020 ◽

Vol 21 (5) ◽

pp. 935-952 ◽

Cited By ~ 2

Author(s):

Marika Koukoula ◽

Efthymios I. Nikolopoulos ◽

Zoi Dokou ◽

Emmanouil N. Anagnostou

Keyword(s):

Water Resources ◽

Land Surface ◽

Hydrological Cycle ◽

Water Cycle ◽

Spatial Scales ◽

Meteorological Forcing ◽

Blue Nile ◽

Blue Nile Basin ◽

Terrestrial Water

AbstractWater resources reanalysis (WRR) can be used as a numerical tool to advance our understanding of hydrological processes where in situ observations are limited. However, WRR products are associated with uncertainty that needs to be quantified to improve usability of such products in water resources applications. In this study, we evaluate estimates of water cycle components from 18 state-of-the-art WRR datasets derived from different land surface/hydrological models, meteorological forcing, and precipitation datasets. The evaluation was conducted at three spatial scales in the upper Blue Nile basin in Ethiopia. Precipitation, streamflow, evapotranspiration (ET), and terrestrial water storage (TWS) were evaluated against in situ daily precipitation and streamflow measurements, remote sensing–derived ET, and the NASA Gravity Recovery and Climate Experiment (GRACE) product, respectively. Our results highlight the current strengths and limitations of the available WRR datasets in analyzing the hydrological cycle and dynamics of the study basins, showing an overall underestimation of ET and TWS and overestimation of streamflow. While calibration improves streamflow simulation, it results in a relatively poorer performance in terms of ET. In addition, we show that the differences in the schemes used in the various land surface models resulted in significant differences in the estimation of the water cycle components from the respective WRR products, while we noted small differences among the products related to precipitation forcing. We did not identify a single product that consistently outperformed others; however, we found that there are specific WRR products that provided accurate representation of a single component of the water cycle (e.g., only runoff) in the area.

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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.

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Intercomparison of terrestrial water budgets in EURO-CORDEX and TSMP evaluation runs

10.5194/egusphere-egu2020-5745 ◽

2020 ◽

Author(s):

Mohamed Eltahan ◽

Klaus Goergen ◽

Carina Furusho-Percot ◽

Stefan Kollet

Keyword(s):

Land Surface ◽

Water Budget ◽

Climate Models ◽

Water Cycle ◽

Weather Prediction ◽

Regional Climate ◽

Shallow Groundwater ◽

Surface Model ◽

Frequency Distributions ◽

Terrestrial Water

Water is one of Earth&#8217;s most important geo-ecosystem components. Here we present an evaluation of water cycle components using 12 EURO-CORDEX Regional Climate Models (RCMs) and the Terrestrial Systems Modeling Platform (TSMP) from ERA-Interim driven evaluation runs. Unlike the other RCMs, TSMP provides an integrated representation of the terrestrial water cycle by coupling the numerical weather prediction model COSMO, the land surface model CLM and the surface-subsurface hydrological model ParFlow, which simulates shallow groundwater states and fluxes. The study analyses precipitation (P), evapotranspiration (E), runoff (R), and terrestrial water storage (TWS=P-E-R) at a 0.11degree spatial resolution (about 12km) on EUR-11 CORDEX grid from 1996 to 2008. As reference datasets, we use ERA5 reanalysis to represent the complete terrestrial water budget, as well as the E-OBS, GLEAM and E-Run datasets for precipitation, evapotranspiration and runoff, respectively. The terrestrial water budget is investigated for twenty catchments over Europe (Guadalquivir, Guadiana, Tagus, Douro, Ebro, Garonne, Rhone, Po, Seine, Rhine, Loire, Maas, Weser, Elbe, Oder, Vistuala, Danube, Dniester, Dnieper, and Neman). Annual cycles, seasonal variations, empirical frequency distributions, spatial distributions for the water cycle components and budgets over the catchments are assessed. The analysis demonstrates the capability of the RCMs and TSMP to reproduce the overall characteristics of the water cycle over the EURO-CORDEX domain, which is a prerequisite if, e.g., climate change projections with the CORDEX RCMs or TSMP are to be used for vulnerability, impacts, and adaptation studies.

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Impacts of Snow Darkening by Light-absorbing aerosols on the Water Cycle over the Western Eurasia and East Asia

10.5194/egusphere-egu2020-6556 ◽

2020 ◽

Author(s):

Jeong Sang ◽

Maeng-Ki Kim ◽

William K. M. Lau ◽

Kyu-Myong Kim

Keyword(s):

Land Surface ◽

Moisture Transport ◽

Hydrological Cycle ◽

Water Cycle ◽

Initial Conditions ◽

East Asian ◽

Development Program ◽

Eurasian Continent ◽

Absorbing Aerosols ◽

Western Eurasia

In this paper, we have investigated the snow darkening effects by light-absorbing aerosols on the regional changes of the water cycle over the Eurasian continent using the NASA GEOS-5 Model with aerosol tracers and a state-of-the-art snow darkening module, the Goddard SnoW Impurity Module (GOSWIM) for the land surface. Two sets of ten-member ensemble experiments for 10-years were carried out forced by prescribed sea surface temperature (2002-2011) with different atmospheric initial conditions, with and without SDE, respectively. Results show that SDE can exert a significant regional influence in partitioning the contributions of evaporative and advective processes on the hydrological cycle, during spring and summer season. Over western Eurasia, SDE-induced rainfall increase during early spring can be largely explained by the increased evaporation from snowmelt. Rainfall, however, decreases in early summer due to the reduced evaporation as well as moisture divergence and atmospheric subsidence associated with the development of an anomalous mid- to upper tropospheric anticyclonic circulation. On the other hand, in the East Asian monsoon region, moisture advection from adjacent ocean is a main contributor to rainfall increase in the melting season. Warmer land-surface caused by earlier snowmelt and subsequent drying further increases moisture transport and convergence significantly enhancing rainfall over the region. This findings suggest that the SDE may play an important role in leading to hotter and drier summer over western Eurasia, through coupled land-atmosphere interaction, while enhancing East Asian summer monsoonal precipitation via enhanced land-ocean thermal contrast and moisture transport due to SDE-induced warmer Eurasian continent.&#160;This work was supported by the Korea Meteorological Administration Research and Development Program under grant KMI2018-03410.

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The AmazonWater Cycle: Perspectives fromWater Budget Closure and Ocean Salinity

Journal of Climate ◽

10.1175/jcli-d-20-0309.1 ◽

2020 ◽

pp. 1-44

Author(s):

J. E. Jack Reeves Eyre ◽

Xubin Zeng

Keyword(s):

Water Vapor ◽

Land Surface ◽

Water Cycle ◽

Water Storage ◽

River Mouth ◽

Small Subset ◽

Terrestrial Water Storage ◽

Crucial Component ◽

Ocean Salinity ◽

Terrestrial Water

AbstractGlobal and regional water cycle includes precipitation, water vapor divergence, and change of column water vapor in the atmosphere, and land surface evapotranspiration, terrestrial water storage change, and river discharge which is linked to ocean salinity near the river mouth. The water cycle is a crucial component of the Earth system, and numerous studies have addressed its individual components (e.g., precipitation). Here we assess, for the first time, if remote sensing and reanalysis datasets can accurately and self consistently portray the Amazon water cycle. This is further assisted with satellite ocean salinity measurements near the mouth of the Amazon River. The widely-used practice of taking the mean of an ensemble of datasets to represent water cycle components (e.g., precipitation) can produce large biases in water cycle closure. Closure is achieved with only a small subset of data combinations (e.g., ERA5 reanalysis precipitation and evapotranspiration plus GRACE satellite terrestrial water storage), which rules out the lower precipitation and higher evapotranspiration estimates, providing valuable constraints on assessments of precipitation, evapotranspiration and their ratio. The common approach of using the Óbidos stream gauge (located hundreds of kilometres from the river mouth) multiplied by a constant (1.25) to represent the entire Amazon discharge is found to misrepresent the seasonal cycle, and this can affect the apparent influence of Amazon discharge on tropical Atlantic salinity.

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Creation of the WATCH Forcing Data and Its Use to Assess Global and Regional Reference Crop Evaporation over Land during the Twentieth Century

Journal of Hydrometeorology ◽

10.1175/2011jhm1369.1 ◽

2011 ◽

Vol 12 (5) ◽

pp. 823-848 ◽

Cited By ~ 596

Author(s):

G. P. Weedon ◽

S. Gomes ◽

P. Viterbo ◽

W. J. Shuttleworth ◽

E. Blyth ◽

...

Keyword(s):

Twentieth Century ◽

Land Surface ◽

Water Cycle ◽

Potential Evapotranspiration ◽

Reanalysis Data ◽

Meteorological Forcing ◽

Global Average ◽

Murray Darling Basin ◽

Terrestrial Water ◽

Reference Crop

Abstract The Water and Global Change (WATCH) project evaluation of the terrestrial water cycle involves using land surface models and general hydrological models to assess hydrologically important variables including evaporation, soil moisture, and runoff. Such models require meteorological forcing data, and this paper describes the creation of the WATCH Forcing Data for 1958–2001 based on the 40-yr ECMWF Re-Analysis (ERA-40) and for 1901–57 based on reordered reanalysis data. It also discusses and analyses model-independent estimates of reference crop evaporation. Global average annual cumulative reference crop evaporation was selected as a widely adopted measure of potential evapotranspiration. It exhibits no significant trend from 1979 to 2001 although there are significant long-term increases in global average vapor pressure deficit and concurrent significant decreases in global average net radiation and wind speed. The near-constant global average of annual reference crop evaporation in the late twentieth century masks significant decreases in some regions (e.g., the Murray–Darling basin) with significant increases in others.

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Diagnosing hydrological limitations of a Land Surface Model: application of JULES to a deep-groundwater chalk basin

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-7541-2015 ◽

2015 ◽

Vol 12 (8) ◽

pp. 7541-7582

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 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 utilised to improve the model's hydrology: (a) observations, (b) information about expected response from regionalised 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.

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A worldwide analysis of trends in water-balance evapotranspiration

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-10-5739-2013 ◽

2013 ◽

Vol 10 (5) ◽

pp. 5739-5765 ◽

Cited By ~ 3

Author(s):

A. M. Ukkola ◽

I. C. Prentice

Keyword(s):

Water Balance ◽

Interannual Variability ◽

Land Surface ◽

Time Series Data ◽

Hydrological Cycle ◽

Atmospheric Co2 ◽

Series Data ◽

Additional Control ◽

Terrestrial Water ◽

Strong Control

Abstract. Climate change is expected to alter the global hydrological cycle, with inevitable consequences for freshwater availability to people and ecosystems. But the attribution of recent trends in the terrestrial water balance remains disputed. This study attempts to account statistically for both trends and interannual variability in water-balance evapotranspiration (ET), estimated from the annual observed streamflow in 109 river basins during "water years" 1961–1999 and two gridded precipitation datasets. The basins were chosen based on the availability of streamflow time-series data in the Dai et al. (2009) synthesis. They were divided into water-limited "dry" and energy-limited "wet" basins following the Budyko framework. We investigated the potential roles of precipitation, aerosol-corrected solar radiation, land-use change, wind speed, air temperature, and atmospheric CO2. Both trends and variability in ET show strong control by precipitation. There is some additional control of ET trends by vegetation processes, but little evidence for control by other factors. Interannual variability in ET was overwhelmingly dominated by precipitation, which accounted on average for 52–54% of the variation in wet basins (ranging from 0 to 99%) and 84–85% in dry basins (ranging from 13 to 100%). Precipitation accounted for 39–42% of ET trends in wet basins and 69–79% in dry basins. Cropland expansion increased ET in dry basins. Net atmospheric CO2 effects on transpiration, estimated using the Land-surface Processes and eXchanges (LPX) model, did not contribute to observed trends in ET because declining stomatal conductance was counteracted by slightly but significantly increasing foliage cover.

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Water Cycle Extremes in the GRACE and GRACE-FO Data Record

10.5194/gstm2020-35 ◽

2020 ◽

Author(s):

Matthew Rodell ◽

Bailing Li

Keyword(s):

Land Surface ◽

Water Mass ◽

Water Cycle ◽

Land Surface Model ◽

Surface Model ◽

Drought Event ◽

Terrestrial Water Storage ◽

Data Record ◽

Terrestrial Water ◽

Hydrological Droughts

A unique aspect of satellite gravimetry is its ability to quantify changes in all water stored at all depths on and beneath the land surface.&#160; Hence, GRACE and GRACE-FO are well suited for quantifying both hydrological droughts, when terrestrial water storage (TWS) is low, and pluvial events, when TWS is high.&#160; In this study we use GRACE and GRACE-FO data assimilation within a land surface model to fill the 1-year gap between the two missions and to replace other missing data.&#160; We apply a cluster analysis approach to identify the locations and extents of TWS extreme events in resulting data record.&#160; We then rank these events based on their intensity, i.e., the integral of the non-seasonal water mass anomaly over the period of the event. &#160;In this presentation we report on the largest wet and dry events over each continent.&#160; During the period of study, Africa, North America, and Australia each had a wet event with an intensity that exceeded 10,000 km3 * month, although the 2010-2012 event in Australia can largely be attributed to a depressed baseline TWS during the period caused by the millennial drought.&#160; With 30 more years of data it is probable that the intensity of that drought would have been greater than the recovery and wet event during 2010-2012.&#160; As it stands, the biggest drought event was determined to be one occurred in South America during 2015-2016, with an intensity of over 10,000 km3 * month.

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Evaluating Surface Water Cycle Simulated by the Australian Community Land Surface Model (CABLE) across Different Spatial and Temporal Domains

Journal of Hydrometeorology ◽

10.1175/jhm-d-12-0123.1 ◽

2013 ◽

Vol 14 (4) ◽

pp. 1119-1138 ◽

Cited By ~ 20

Author(s):

Huqiang Zhang ◽

Bernard Pak ◽

Ying Ping Wang ◽

Xinyao Zhou ◽

Yongqiang Zhang ◽

...

Keyword(s):

Land Surface ◽

Water Cycle ◽

Land Surface Model ◽

Surface Model ◽

Model Parameters ◽

Global Soil ◽

Australian Community ◽

Forest Regions ◽

Terrestrial Water ◽

Multimodel Ensembles

Abstract The terrestrial water cycle in the Australian Community Atmosphere Biosphere Land Exchange (CABLE) model has been evaluated across a range of temporal and spatial domains. A series of offline experiments were conducted using the forcing data from the second Global Soil Wetness Project (GSWP-2) for the period of 1986–95, but with its default parameter settings. Results were compared against GSWP-2 multimodel ensembles and a range of observationally driven datasets. CABLE-simulated global mean evapotranspiration (ET) and runoff agreed well with the GSWP-2 multimodel climatology and observations, and the spatial variations of ET and runoff across 150 large catchments were well captured. Nevertheless, at regional scales it underestimated ET in the tropics and had some significant runoff errors. The model sensitivity to a number of selected parameters is further examined. Results showed some significant model uncertainty caused by its sensitivity to soil wilting point as well as to the root water uptaking efficiency and canopy water storage parameters. The sensitivity was large in tropical rain forest and midlatitude forest regions, where the uncertainty caused by the model parameters was comparable to a large part of its difference against the GSWP-2 multimodel mean. Furthermore, the discrepancy among the CABLE perturbation experiments caused by its sensitivity to model parameters was equivalent to about 20%–40% of the intermodel difference among the GSWP-2 models, which was primarily caused by different model structure/processes. Although such results are model dependent, they suggest that soil/vegetation parameters could be another source of uncertainty in estimating global surface energy and water budgets.

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