Comment on 'A hydrological model for root zone water storage simulation non a global scale'

Abstract. The soil water stored in the root zone is a critical variable for many applications, as it plays a key role in several hydrological and atmospheric processes. Many studies have been conducted to obtain reliable information on soil water in the root zone layer. However, most of them are mainly focused on the soil moisture within a certain depth rather than the water stored in the entire rooting system. In this work, a hydrological model named the Water And ecosYstem Simulator (WAYS) is developed to simulate the root zone water storage (RZWS) on a global scale. The model is based on a well-validated lumped model and has now been extended to a distribution model. To reflect the natural spatial heterogeneity of the plant rooting system across the world, a key variable that influences RZWS, i.e., root zone storage capacity (RZSC), is integrated into the model. The newly developed model is first evaluated based on runoff and RZWS simulations across 10 major basins. The results show the ability of the model to mimic RZWS dynamics in most of the regions through comparison with proxy data, the normalized difference infrared index (NDII). The model is further evaluated against station observations, including flux tower and gauge data. Despite regional differences, generally good performance is found for both the evaporation and discharge simulations. Compared to existing hydrological models, WAYS's ability to resolve the field-scale spatial heterogeneity of RZSC and simulate RZWS may offer benefits for many applications, e.g., agriculture and land–vegetation–climate interaction investigations. However, the results from this study suggest an additional evaluation of RZWS is required for the regions where the NDII might not be the correct proxy.

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A hydrological model for root zone water storage simulation on a global scale

10.5194/gmd-2019-52 ◽

2019 ◽

Author(s):

Ganquan Mao ◽

Junguo Liu

Keyword(s):

Soil Water ◽

Hydrological Model ◽

Storage Capacity ◽

Root Zone ◽

Water Storage ◽

Global Scale ◽

Distribution Model ◽

Lumped Model ◽

Zone Water ◽

Strong Capacity

Abstract. The soil water stored in the root zone is a critical variable for many applications as it plays key role in several hydrological and atmospheric processes. Many studies have been done to obtain reliable soil water information in the root zone layer. However, most of them are mainly focused on the soil moisture in a certain depth rather than the water stored in the entire rooting system. In this work, a hydrological model is developed to simulate the root zone water storage (RZWS) on a global scale. The model is based on a well validated lumped model and has been extended now to a distribution model. To reflect the natural spatial heterogeneity of the plant rooting system across the world, a key variable that influencing the RZWS, i.e. root zone storage capacity (RZSC), is integrated into the model. The newly developed model is evaluated on runoff and RZWS simulation across ten major basins. The evaluation of runoff indicates the strong capacity of the model for monthly simulation with a good performance on time series and distribution depiction. Results also show the ability of the model for RZWS dynamics mimicing in most of the regions. This model may offer benefits for many applications due to its ability for RZWS simulation. However, attentions need to also be paid for application as the high latitude regions are not investigated by this work due to the incomplete latitudinal coverage of the RZSC. Therefore, the performance of the model in such regions are not justified.

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Comments on 'A hydrological model for root zone water storage simulation on a global scale'

10.5194/gmd-2019-52-sc1 ◽

2019 ◽

Author(s):

William Chris

Keyword(s):

Hydrological Model ◽

Root Zone ◽

Water Storage ◽

Global Scale ◽

Zone Water

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Development of models to predict Pinus radiata productivity throughout New Zealand

Canadian Journal of Forest Research ◽

10.1139/x09-207 ◽

2010 ◽

Vol 40 (3) ◽

pp. 488-499 ◽

Cited By ~ 33

Author(s):

Michael S. Watt ◽

David J. Palmer ◽

Mark O. Kimberley ◽

Barbara K. Höck ◽

Tim W. Payn ◽

...

Keyword(s):

New Zealand ◽

Pinus Radiata ◽

Root Zone ◽

Water Storage ◽

Site Index ◽

Parent Material ◽

Data Set ◽

Final Model ◽

Soil Parent Material ◽

Zone Water

Development of spatial surfaces describing variation in productivity across broad landscapes at a fine resolution would be of considerable use to forest managers as decision support tools to optimize productivity. In New Zealand, the two most widely used indices to quantify productivity of Pinus radiata D. Don are Site Index and 300 Index. Using an extensive national data set comprising a comprehensive set of national extent maps, multiple regression models and spatial surfaces of these indices for P. radiata were constructed. The final models accounted for 64% and 53%, respectively, of the variance in Site Index and 300 Index. For Site Index, variables included in the final model in order of importance were mean annual air temperature, fractional mean annual available root-zone water storage, mean annual windspeed, length and slope factor, categories describing Land Environments of New Zealand (LENZ), and major soil parent material. The variables included in the final model of 300 Index in order of importance included the degree of ground frost during autumn, fractional mean annual available root-zone water storage, categories describing LENZ, vegetation classification, foliar nitrogen, taxonomic soil order, and major soil parent material. These results highlight the utility of thematic spatial layers as driving variables in the development of productivity models.

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New interpretation of the role of water balance in an extended Budyko hypothesis in arid regions

Hydrology and Earth System Sciences ◽

10.5194/hess-20-393-2016 ◽

2016 ◽

Vol 20 (1) ◽

pp. 393-409 ◽

Cited By ~ 37

Author(s):

C. Du ◽

F. Sun ◽

J. Yu ◽

X. Liu ◽

Y. Chen

Keyword(s):

Steady State ◽

Water Balance ◽

Water Supply ◽

Arid Regions ◽

Root Zone ◽

Water Storage ◽

Unsteady State ◽

Monthly Water Balance ◽

Storage Change ◽

Zone Water

Abstract. The Budyko hypothesis (BH) is an effective approach to investigating long-term water balance at large basin scale under steady state. The assumption of steady state prevents applications of the BH to basins, which is unclosed, or with significant variations in root zone water storage, i.e., under unsteady state, such as in extremely arid regions. In this study, we choose the Heihe River basin (HRB) in China, an extremely arid inland basin, as the study area. We firstly use a calibrated and then validated monthly water balance model, i.e., the abcd model, to quantitatively determine annual and monthly variations of water balance for the sub-basins and the whole catchment of the HRB, and find that the roles of root zone water storage change and that of inflow from upper sub-basins in monthly water balance are significant. With the recognition of the inflow water from other regions and the root zone water storage change as additional possible water sources to evapotranspiration in unclosed basins, we further define the equivalent precipitation (Pe) to include local precipitation, inflow water and root zone water storage change as the water supply in the Budyko framework. With the newly defined water supply, the Budyko curve can successfully describe the relationship between the evapotranspiration ratio and the aridity index at both annual and monthly timescales, whilst it fails when only the local precipitation being considered. Adding to that, we develop a new Fu-type Budyko equation with two non-dimensional parameters (ω and λ) based on the deviation of Fu's equation. Over the annual timescale, the new Fu-type Budyko equation developed here has more or less identical performance to Fu's original equation for the sub-basins and the whole catchment. However, over the monthly timescale, due to large seasonality of root zone water storage and inflow water, the new Fu-type Budyko equation generally performs better than Fu's original equation. The new Fu-type Budyko equation (ω and λ) developed here enables one to apply the BH to interpret regional water balance over extremely dry environments under unsteady state (e.g., unclosed basins or sub-annual timescales).

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Subsurface Water Retention Technology Improves Root Zone Water Storage for Corn Production on Coarse-Textured Soils

Vadose Zone Journal ◽

10.2136/vzj2014.11.0166 ◽

2015 ◽

Vol 14 (7) ◽

pp. vzj2014.11.0166 ◽

Cited By ~ 5

Author(s):

Andrey K Guber ◽

Alvin J. M. Smucker ◽

Samrawi Berhanu ◽

James M. L. Miller

Keyword(s):

Water Retention ◽

Root Zone ◽

Water Storage ◽

Subsurface Water ◽

Corn Production ◽

Zone Water

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Plants as sensors: vegetation response to rainfall predicts root-zone water storage capacity in Mediterranean-type climates

Environmental Research Letters ◽

10.1088/1748-9326/abb10b ◽

2020 ◽

Vol 15 (10) ◽

pp. 104074

Author(s):

David N Dralle ◽

W Jesse Hahm ◽

Daniella M Rempe ◽

Nathaniel Karst ◽

Leander D L Anderegg ◽

...

Keyword(s):

Storage Capacity ◽

Root Zone ◽

Water Storage ◽

Vegetation Response ◽

Water Storage Capacity ◽

Zone Water

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Technical note: Accounting for snow in the estimation of root-zone water storage capacity from precipitation and evapotranspiration fluxes

10.5194/hess-2020-602 ◽

2020 ◽

Author(s):

David N. Dralle ◽

W. Jesse Hahm ◽

K. Dana Chadwick ◽

Erica McCormick ◽

Daniella M. Rempe

Keyword(s):

Sierra Nevada ◽

Hydrological Modeling ◽

Storage Capacity ◽

Root Zone ◽

Water Storage ◽

Original Method ◽

Technical Note ◽

Simple Extension ◽

Water Storage Capacity ◽

Zone Water

Abstract. A common parameter in hydrological modeling frameworks is root-zone water storage capacity (SR[L]), which mediates plant-water availability during dry periods and the partitioning of rainfall between runoff and evapotranspiration. Recently, a simple flux-tracking based approach was introduced to estimate the value of SR (Wang-Erlandsson et al., 2016). Here, we build upon this original method, which we argue may overestimate SR in snow-dominated catchments due to snow melt and evaporation processes. We propose a simple extension to the method presented by Wang-Erlandsson et al. (2016), and show that the approach provides a more conservative minimum estimate of SR in snow-dominated watersheds. This SR dataset is available at 1 km resolution for the continental United States, along with the full analysis code, on Google Colaboratory and Earth Engine platforms. We highlight differences between the original and new methods across the rain-snow transition in the Southern Sierra Nevada, California, USA. As climate warms and precipitation increasingly arrives as rain instead of snow, the subsurface may be an increasingly important reservoir for storing plant-available water between wet and dry seasons; improved estimates of SR will therefore better clarify the future role of the subsurface as a storage reservoir that can sustain forests during seasonal dry periods and episodic drought.

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Technical note: Accounting for snow in the estimation of root zone water storage capacity from precipitation and evapotranspiration fluxes

Hydrology and Earth System Sciences ◽

10.5194/hess-25-2861-2021 ◽

2021 ◽

Vol 25 (5) ◽

pp. 2861-2867

Author(s):

David N. Dralle ◽

W. Jesse Hahm ◽

K. Dana Chadwick ◽

Erica McCormick ◽

Daniella M. Rempe

Keyword(s):

Sierra Nevada ◽

Hydrological Modeling ◽

Storage Capacity ◽

Root Zone ◽

Water Storage ◽

Original Method ◽

Technical Note ◽

Simple Extension ◽

Water Storage Capacity ◽

Zone Water

Abstract. A common parameter in hydrological modeling frameworks is root zone water storage capacity (SR[L]), which mediates plant water availability during dry periods as well as the partitioning of rainfall between runoff and evapotranspiration. Recently, a simple flux-tracking-based approach was introduced to estimate the value of SR (Wang-Erlandsson et al., 2016). Here, we build upon this original method, which we argue may overestimate SR in snow-dominated catchments due to snow melt and evaporation processes. We propose a simple extension to the method presented by Wang-Erlandsson et al. (2016) and show that the approach provides a lower estimate of SR in snow-dominated watersheds. This SR dataset is available at a 1 km resolution for the continental USA, along with the full analysis code, on the Google Colab and Earth Engine platforms. We highlight differences between the original and new methods across the rain–snow transition in the Southern Sierra Nevada, California, USA. As climate warms and precipitation increasingly arrives as rain instead of snow, the subsurface may be an increasingly important reservoir for storing plant-available water between wet and dry seasons; therefore, improved estimates of SR will better clarify the future role of the subsurface as a storage reservoir that can sustain forests during seasonal dry periods and episodic drought.

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Stepwise improvement of hydrological models using satellite-based evaporation and total water storage estimations

10.5194/egusphere-egu21-796 ◽

2021 ◽

Author(s):

Markus Hrachowitz ◽

Petra Hulsman ◽

Hubert Savenije

Keyword(s):

Model Calibration ◽

Hydrological Model ◽

Model Development ◽

Water Storage ◽

Spatiotemporal Variability ◽

Model Structure ◽

Hydrological Models ◽

Total Water ◽

Spatiotemporal Model ◽

Multiple Variables

<p>Hydrological models are often calibrated with respect to flow observations at the basin outlet. As a result, flow predictions may seem reliable but this is not necessarily the case for the spatiotemporal variability of system-internal processes, especially in large river basins. Satellite observations contain valuable information not only for poorly gauged basins with limited ground observations and spatiotemporal model calibration, but also for stepwise model development. This study explored the value of satellite observations to improve our understanding of hydrological processes through stepwise model structure adaption and to calibrate models both temporally and spatially. More specifically, satellite-based evaporation and total water storage anomaly observations were used to diagnose model deficiencies and to subsequently improve the hydrological model structure and the selection of feasible parameter sets. A distributed, process based hydrological model was developed for the Luangwa river basin in Zambia and calibrated with respect to discharge as benchmark. This model was modified stepwise by testing five alternative hypotheses related to the process of upwelling groundwater in wetlands, which was assumed to be negligible in the benchmark model, and the spatial discretization of the groundwater reservoir. Each model hypothesis was calibrated with respect to 1) discharge and 2) multiple variables simultaneously including discharge and the spatiotemporal variability in the evaporation and total water storage anomalies. The benchmark model calibrated with respect to discharge reproduced this variable well, as also the basin-averaged evaporation and total water storage anomalies. However, the evaporation in wetland dominated areas and the spatial variability in the evaporation and total water storage anomalies were poorly modelled. The model improved the most when introducing upwelling groundwater flow from a distributed groundwater reservoir and calibrating it with respect to multiple variables simultaneously. This study showed satellite-based evaporation and total water storage anomaly observations provide valuable information for improved understanding of hydrological processes through stepwise model development and spatiotemporal model calibration.</p>

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