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

Vine, Nataliya Le; Butler, Adrian P.; McIntyre, Neil; Jackson, C. R.

doi:10.5194/hess-20-143-2016

Cited by 32 publications

(24 citation statements)

References 56 publications

(86 reference statements)

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“…The current JULES model relies on the more typical free drainage assumption. Le Vine, Butler, McIntyre, and Jackson (2016) made the first attempt to couple a groundwater model with JULES in a chalk groundwater dominated catchment. In particular, they coupled the ZOOMQ3D groundwater model (Jackson, 2001) with JULES to simulate the Kennet catchment, a tributary of the Thames River.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, we can calculate the position of the water table based on the pressure head obtained with the soil moisture estimate in the last soil layer of the soil domain. Our approach is different from the approach of Le Vine et al (2016), since we apply a dynamic groundwater model that interacts with JULES in real time and allows for two‐way interaction between aquifer and soil domain. We will use a more complex 3‐D hydrological model as a benchmark in a set of synthetic experiments.…”

Section: Introductionmentioning

confidence: 99%

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Towards the representation of groundwater in the Joint UK Land Environment Simulator

Batelis

Rahman

Kollet

et al. 2020

Hydrological Processes

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Groundwater is an important component of the hydrological cycle with significant interactions with soil hydrological processes. Recent studies have demonstrated that incorporating groundwater hydrology in land surface models (LSMs) considerably improves the prediction of the partitioning of water components (e.g., runoff and evapotranspiration) at the land surface. However, the Joint UK Land Environment Simulator (JULES), an LSM developed in the United Kingdom, does not yet have an explicit representation of groundwater. We propose an implementation of a simplified groundwater flow boundary parameterization (JULES‐GFB), which replaces the original free drainage assumption in the default model (JULES‐FD). We tested the two approaches under a controlled environment for various soil types using two synthetic experiments: (1) single‐column and (2) tilted‐V catchment, using a three‐dimensional (3‐D) hydrological model (ParFlow) as a benchmark for JULES’ performance. In addition, we applied our new JULES‐GFB model to a regional domain in the UK, where groundwater is the key element for runoff generation. In the single‐column infiltration experiment, JULES‐GFB showed improved soil moisture dynamics in comparison with JULES‐FD, for almost all soil types (except coarse soils) under a variety of initial water table depths. In the tilted‐V catchment experiment, JULES‐GFB successfully represented the dynamics and the magnitude of saturated and unsaturated storage against the benchmark. The lateral water flow produced by JULES‐GFB was about 50% of what was produced by the benchmark, while JULES‐FD completely ignores this process. In the regional domain application, the Kling‐Gupta efficiency (KGE) for the total runoff simulation showed an average improvement from 0.25 for JULES‐FD to 0.75 for JULES‐GFB. The mean bias of actual evapotranspiration relative to the Global Land Evaporation Amsterdam Model (GLEAM) product was improved from −0.22 to −0.01 mm day−1. Our new JULES‐GFB implementation provides an opportunity to better understand the interactions between the subsurface and land surface processes that are dominated by groundwater hydrology.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Batelis

Rahman

Kollet

et al. 2020

Hydrological Processes

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“…5). A potential approach to extending the uncertainty analysis would be a Monte Carlo based global sensitivity analysis, as well as exploring some of the structural 20 uncertainties such as the single porosity, evaporation model and boundary condition assumptions (Le Vine et al, 2016).…”

Section: Discussion 20mentioning

confidence: 99%

Reliability of meteorological drought indices for predicting soil moisture droughts

Halwatura

McIntyre

Lechner

et al. 2016

Preprint

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Abstract. Meteorological drought indices based on precipitation and/or evaporation are commonly used to detect the presence, severity and duration of soil moisture droughts. However, it is debatable whether droughts can be adequately characterised using only precipitation and/evaporation, or whether more physical based methods using soil water deficits and pressures is necessary. To address this question, the performances of two commonly used meteorological drought indices, the Standard Precipitation Index (SPI) and the Reconnaissance Drought Index (RDI), are evaluated against soil moisture 10 droughts identified using a physically based soil water model. Our analysis is based on three sites in Eastern Australia, each representing specific soil-climate conditions. Drought duration and severity were estimated using SPI and RDI and soil water pressure data were simulated with Hydrus-1D. The performance of the two drought indices was measured in terms of their correlation with simulated monthly minimum soil water pressures, and their ability to estimate the frequency with which the simulated pressure drops below threshold values. 15There was a significant correlation between the two drought indices (SPI and RDI) and the monthly minimum soil water pressure. Failure rate (FR) and false alarm rate (FAR) of drought indices detect soil moisture drought reasonably well (FR and FAR is <50%) for both drought indices (SPI and RDI) and soil depths (5cm and 30 cm) (except Melbourne). Overall SPI performs better (except shallow soils in Bourke) than RDI. However an uncertainty of the FR and FAR in the soil water retention curve is always higher than the uncertainties of drought indices. The complexity and the uncertainty in the model 20 encourage to use the simple drought indices, however the model provide physically relevant soil water pressure values which are species specific for plants.

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“…In general, surface runoff production is very limited over the regions of the catchment where chalk outcrops. The flow regime shows a distinct characteristic of slow response to groundwater held within the chalk aquifer (Le Vine et al, 2016). According to Ireson and Butler (2013), the unsaturated zone of chalk shows slow drainage over summer and bypass flow during wet periods in this catchment.…”

Section: Study Areamentioning

confidence: 99%

“…A linear reservoir was included in the TOPMODELbased runoff formulation of the CLSM to account for the contribution of chalk aquifers to river discharge. Le Vine et al (2016) applied the Joint UK Land Environment Simulator (JULES; Best et al, 2011) over the Kennet catchment in southern England to evaluate the hydrological limitations of land surface models. In that study, two intersecting Brooks and Corey curves were proposed, which allowed a dual-curve soil moisture retention representation for the two distinct flow domains of chalk (i.e.…”

Section: Introductionmentioning

confidence: 99%

Towards a simple representation of chalk hydrology in land surface modelling

Rahman

Rosolem

2017

Hydrol. Earth Syst. Sci.

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Abstract. Modelling and monitoring of hydrological processes in the unsaturated zone of chalk, a porous medium with fractures, is important to optimize water resource assessment and management practices in the United Kingdom (UK). However, incorporating the processes governing water movement through a chalk unsaturated zone in a numerical model is complicated mainly due to the fractured nature of chalk that creates high-velocity preferential flow paths in the subsurface. In general, flow through a chalk unsaturated zone is simulated using the dual-porosity concept, which often involves calibration of a relatively large number of model parameters, potentially undermining applications to large regions. In this study, a simplified parameterization, namely the Bulk Conductivity (BC) model, is proposed for simulating hydrology in a chalk unsaturated zone. This new parameterization introduces only two additional parameters (namely the macroporosity factor and the soil wetness threshold parameter for fracture flow activation) and uses the saturated hydraulic conductivity from the chalk matrix. The BC model is implemented in the Joint UK Land Environment Simulator (JULES) and applied to a study area encompassing the Kennet catchment in the southern UK. This parameterization is further calibrated at the point scale using soil moisture profile observations. The performance of the calibrated BC model in JULES is assessed and compared against the performance of both the default JULES parameterization and the uncalibrated version of the BC model implemented in JULES. Finally, the model performance at the catchment scale is evaluated against independent data sets (e.g. runoff and latent heat flux). The results demonstrate that the inclusion of the BC model in JULES improves simulated land surface mass and energy fluxes over the chalk-dominated Kennet catchment. Therefore, the simple approach described in this study may be used to incorporate the flow processes through a chalk unsaturated zone in large-scale land surface modelling applications.

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

Cited by 32 publications

References 56 publications

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Towards the representation of groundwater in the Joint UK Land Environment Simulator

Reliability of meteorological drought indices for predicting soil moisture droughts

Towards a simple representation of chalk hydrology in land surface modelling

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