scholarly journals How does initial soil moisture influence the hydrological response? A case study from southern France

2018 ◽  
Vol 22 (12) ◽  
pp. 6127-6146 ◽  
Author(s):  
Magdalena Uber ◽  
Jean-Pierre Vandervaere ◽  
Isabella Zin ◽  
Isabelle Braud ◽  
Maik Heistermann ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Hydrological Response ◽  
Hydrograph Separation ◽  
Catchment Scale ◽  
Southern France ◽  
Initial Soil Moisture ◽  
Wide Range ◽  
Initial Soil ◽  
Rain Events ◽  
The Impact

Abstract. The Cévennes–Vivarais region in southern France is prone to heavy rainfall that can lead to flash floods which are one of the most hazardous natural risks in Europe. The results of numerous studies show that besides rainfall and physical catchment characteristics the catchment's initial soil moisture also impacts the hydrological response to rain events. The aim of this paper is to analyze the relationship between catchment mean initial soil moisture θ̃ini and the hydrological response that is quantified using the event-based runoff coefficient ϕev in the two nested catchments of the Gazel (3.4 km2) and the Claduègne (43 km2). Thus, the objectives are twofold: (1) obtaining meaningful estimates of soil moisture at catchment scale from a dense network of in situ measurements and (2) using this estimate of θ̃ini to analyze its relation with ϕev calculated for many runoff events. A sampling setup including 45 permanently installed frequency domain reflectancy probes that continuously measure soil moisture at three depths is applied. Additionally, on-alert surface measurements at ≈10 locations in each one of 11 plots are conducted. Thus, catchment mean soil moisture can be confidently assessed with a standard error of the mean of ≤1.7 vol % over a wide range of soil moisture conditions. The ϕev is calculated from high-resolution discharge and precipitation data for several rain events with a cumulative precipitation Pcum ranging from less than 5 mm to more than 80 mm. Because of the high uncertainty of ϕev associated with the hydrograph separation method, ϕev is calculated with several methods, including graphical methods, digital filters and a tracer-based method. The results indicate that the hydrological response depends on θ̃ini: during dry conditions ϕev is consistently below 0.1, even for events with high and intense precipitation. Above a threshold of θ̃ini=34 vol % ϕev can reach values up to 0.99 but there is a high scatter. Some variability can be explained with a weak correlation of ϕev with Pcum and rain intensity, but a considerable part of the variability remains unexplained. It is concluded that threshold-based methods can be helpful to prevent overestimation of the hydrological response during dry catchment conditions. The impact of soil moisture on the hydrological response during wet catchment conditions, however, is still insufficiently understood and cannot be generalized based on the present results.

scholarly journals How does initial soil moisture influence the hydrological response? A case study from southern France

2018 ◽  
Author(s):  
Magdalena Uber ◽  
Jean-Pierre Vandervaere ◽  
Isabella Zin ◽  
Isabelle Braud ◽  
Maik Heistermann ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Moisture ◽  
Spatial And Temporal Variability ◽  
Hydrological Response ◽  
Southern France ◽  
Initial Soil Moisture ◽  
Wide Range ◽  
Initial Soil ◽  
Rain Events ◽  
The Impact

Abstract. The Cévennes-Vivarais region in southern France is prone to high intensity and long lasting rainfalls that can lead to flash floods which are one of the most hazardous natural risks in Europe. The results of numerous studies show that besides rainfall depth and intensity and catchment characteristics such as topography, geology, land use and hydraulic routing, the catchment's initial soil moisture also impacts the hydrological response to rain events. The aim of this paper is to analyze the relationship between catchment mean initial soil moisture θ~ini and the hydrological response that is quantified using the event-based runoff coefficient ϕev in the two nested catchments of the Gazel (3.4 km2) and the Claduègne (43 km2). To this end, two research questions are addressed: (1) How heterogeneous are soil moisture patterns in space and time and do they correlate with land use? (2) How does soil moisture at the event onset affect the hydrological response? The estimation of soil moisture at catchment scale is hindered by high spatial and temporal variability. A sampling setup including 45 permanently installed frequency domain reflectancy probes that continuously measure volumetric soil moisture at three depths is applied. Additionally, on-alert measurements of soil moisture in the topsoil at ≈ 10 locations in each one of 11 plots are conducted. Thus, catchment mean soil moisture can be confidently assessed with a standard error of the mean of ≤ 1.7 vol% over a wide range of soil moisture conditions. ϕev is calculated from high-resolution discharge and precipitation data for several rain events with a cumulative precipitation Pcum ranging from less than 5 mm to more than 80 mm. Because of the high uncertainty of ϕev associated to the hydrograph separation method, ϕev is calculated with several methods, including graphical methods, digital filters and a tracer based method. The results indicate that the hydrological response depends on θ~ini : the seasonal as well as the within-event discharge dynamics follow that of soil moisture. During dry conditions ϕev is consistently close to zero, even for events with high and intense precipitation. Above a threshold of θ~ini = 34 vol% ϕev can reach values up to 0.99 but there is a high scatter. Some variability can be explained with a weak correlation of ϕev with Pcum and rain intensity, but a considerable part of the variability remains unexplained. It is concluded that threshold-based methods can be helpful to prevent overestimation of the hydrological response during dry catchment conditions. The impact of soil moisture on the hydrological response during wet catchment conditions, however, is still insufficiently understood and cannot be generalized based on the present results.

scholarly journals Investigating the impact of initial soil moisture conditions on total infiltration by using an adapted double-ring infiltrometer

2016 ◽  
pp. 1-17 ◽  
Author(s):  
Romed Ruggenthaler ◽  
Gertraud Meißl ◽  
Clemens Geitner ◽  
Georg Leitinger ◽  
Nikolaus Endstrasser ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Double Ring ◽  
Initial Soil Moisture ◽  
Initial Soil ◽  
Moisture Conditions ◽  
The Impact

Impact of Initial Soil Moisture Anomalies on Subsequent Precipitation over North America in the Coupled Land–Atmosphere Model CAM3–CLM3

2007 ◽  
Vol 8 (3) ◽  
pp. 513-533 ◽  
Author(s):  
Yeonjoo Kim ◽  
Guiling Wang
Keyword(s):  
Soil Moisture ◽  
North America ◽  
Continental Scale ◽  
Model Version ◽  
Initial Soil Moisture ◽  
Spatial Coverage ◽  
Initial Soil ◽  
Atmosphere Model ◽  
Shallow Soils ◽  
The Impact

Abstract To investigate the impact of anomalous soil moisture conditions on subsequent precipitation over North America, a series of numerical experiments is performed using a modified version of the Community Atmosphere Model version 3 and the Community Land Model version 3 (CAM3–CLM3). First, the mechanisms underlying the impact of spring and summer soil moisture on subsequent precipitation are examined based on simulations starting on 1 April and 1 June, respectively. How the response of precipitation to initial soil moisture anomalies depends on the characteristics of such anomalies, including the timing, magnitude, spatial coverage, and vertical depth, is then investigated. There are five main findings. First, the impact of spring soil moisture anomalies is not evident until early summer although their impact on the large-scale circulation results in slight changes in precipitation during spring. Second, precipitation increases with initial soil moisture almost linearly within a certain range of soil moisture. Beyond this range, precipitation is less responsive. Third, during the first month following the onset of summer soil moisture anomalies, the precipitation response to wet anomalies is larger in magnitude than that to dry anomalies. However, the resulting wet anomalies in precipitation quickly dissipate within a month or so, while the resulting dry anomalies in precipitation remain at a considerable magnitude for a longer period. Consistently, wet spring anomalies are likely to be ameliorated before summer, and thus have a smaller impact (in magnitude) on summer precipitation than dry spring anomalies. Fourth, soil moisture anomalies of smaller spatial coverage lead to precipitation anomalies that are smaller and less persistent, compared to anomalies at the continental scale. Finally, anomalies in shallow soil can persist long enough to influence the subsequent precipitation at the seasonal time scale. Dry anomalies in deep soils last much longer than those in shallow soils.

Event runoff calibration with LISEM in a recently burned Mediterranean forest catchment.

2020 ◽  
Author(s):  
Diana Vieira ◽  
Marta Basso ◽  
João Nunes ◽  
Jacob Keizer ◽  
Jantiene Baartman
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Field Data ◽  
Soil Moisture Content ◽  
Model Performance ◽  
Hydrological Response ◽  
Runoff Generation ◽  
Catchment Scale ◽  
Initial Soil ◽  
Total Discharge

<p>Wildfires are known to change post-fire hydrological response as a consequence of fire-induced changes such as soil water repellence (SWR). SWR has also been identified as a key factor determining runoff generation at plot and slope scale studies, in which soil moisture content (SMC) has been presented as dependent variable. However, these relationships have not been established at catchment scale yet, mainly due to the inherent difficulties in monitoring post-fire hydrological responses at this scale and in finding relationships between these events with SWR point (time and space) measurements. To fulfil these knowledge gaps, the present study aims to advance the knowledge on post-fire hydrological response by simulating quick flows from a small burned catchment using a physical event-based soil erosion model (OpenLISEM).</p><p>OpenLISEM was applied to simulate sixteen events with two distinct initial soil moisture conditions (dry and wet), in which the model calibration was performed by adjusting Manning’s n and saturated soil moisture content (theta<sub>s</sub>). Considering that manual calibration resulted in distinct Manning’s n for wet and dry conditions, while thetas required an individual calibration for each event, an alternative parameterization of theta<sub>s</sub> was created by means of linear regressions, for all the events together (“overall”), and for wet and dry events separately (“wet” and “dry”). Model performance was evaluated at the outlet, while hillslope predictions were compared with runoff data from micro-plots that were installed at 3 of the hillslopes (Vieira et al., 2018).</p><p>The validation of field data at micro-plot scale revealed several comparability limitations attributed to the time-step of the field data (1- to 2-weekly) in comparison to the duration of the events (170-940 min). Nevertheless, the most striking result from our simulations is the fact that OpenLISEM did not predict overland flow generation at two out of the three locations where it was observed. Our simulations also showed that the forest roads are a source of the runoff generation and their configuration affects catchment connectivity.</p><p>At the outlet level, OpenLISEM achieved a satisfactory (0.50 < NSE ≤ 0.70) and very good (NSE > 0.80) model performance according to Moriasi, et al. (2015), in predicting total discharge (NSE=0.95), peak discharge (NSE=0.68), and the time of the peak (NSE=1.00), for the entire set of events under manual calibration. In addition, simulations in wet conditions achieved higher accuracy in comparison to the dry ones.</p><p>When using the parameterization based on the linear regression calibration, OpenLISEM simulation efficiency dropped, but still to satisfactory and very good (NSE<sub>overall</sub> = 0.58, NSE<sub>combined</sub> =0.86) accuracy levels for total discharge.</p><p>Overall, we conclude that calibrating post-fire hydrological response at catchment scale with the OpenLISEM model, can result in reliable simulations for total flow, peak discharge and timing of the peaks. When considering the parameterization of theta<sub>s</sub> as proxy for repellent and wettable soils, more information than the initial soil moisture is required.</p>

scholarly journals Skill of 2-m Temperature Seasonal Forecasts over Europe in ECMWF and RegCM Models

2012 ◽  
Vol 140 (4) ◽  
pp. 1326-1346 ◽  
Author(s):  
Mirta Patarčić ◽  
Čedo Branković
Keyword(s):  
Soil Moisture ◽  
Systematic Errors ◽  
Regional Model ◽  
Global Model ◽  
Forecast Skill ◽  
Seasonal Forecasts ◽  
Near Surface ◽  
Initial Soil Moisture ◽  
Initial Soil ◽  
The Impact

Various measures of forecast quality are analyzed for 2-m temperature seasonal forecasts over Europe from global and regional model ensembles for winter and summer seasons during the period 1991 to 2001. The 50-km Regional Climate Model (RegCM3) is used to dynamically downscale nine-member ensembles of ECMWF global experimental seasonal forecasts. Three sets of RegCM3 experiments with different soil moisture initializations are performed: the RegCM3 default initial soil moisture, initial soil moisture taken from ECMWF seasonal forecasts, and initial soil moisture obtained from RegCM3 ECMWF interim Re-Analysis (ERA-Interim)-driven integrations (RegCM3 climatology). Both deterministic and probabilistic skill metrics are estimated. The better-resolved spatial scales in near-surface temperature by RegCM3 do not necessarily lead to the improved regional model skill in the regions where systematic errors are large. The impact of initial soil moisture on RegCM3 forecast skill is seen in summer in the southern part of the integration domain. When regional model soil moisture was initialized from ECMWF seasonal forecasts, systematic errors were reduced and deterministic skill was enhanced relative to the other RegCM3 experiments. The Brier skill score for rare cold anomalies in this experiment is comparable to that of the global model, whereas in other experiments it is significantly smaller than in global model. There is no major impact of soil moisture initialization on forecast skill in winter. However, some significant improvements in RegCM3 probabilistic skill scores for positive anomalies in winter are found in the central part of the domain where RegCM3 systematic errors are smaller than in global model.

scholarly journals Improvement of Short-Term Climate Prediction with Indirect Soil Variables Assimilation in China

2018 ◽  
Vol 31 (4) ◽  
pp. 1399-1412 ◽  
Author(s):  
Chenghai Wang ◽  
Zhiqiang Cui
Keyword(s):  
Soil Moisture ◽  
Climate Prediction ◽  
Seasonal Precipitation ◽  
Seasonal Temperature ◽  
Short Term ◽  
Initial Soil Moisture ◽  
Soil Variables ◽  
Initial Soil ◽  
The Impact ◽  
Atmospheric Variables

Short-term climate prediction based on a regional climate dynamical model heavily depends on atmospheric forcing and initial soil moisture state. In this study, the Weather Research and Forecasting (WRF) Model with different nudging schemes is used for approximate 2-yr simulations for investigating the importance of soil variables in seasonal temperature and precipitation simulations. The results show that the improvement of seasonal climate simulation (precipitation and air temperature) is more evident in the experiment of assimilating both soil and atmospheric variables than that in the experiments of assimilating atmospheric variables only. Further investigation of the impact of indirectly assimilating soil moisture on precipitation prediction with an indirect soil nudging (ISN) scheme shows that the precipitation reproducibility in summer is better than that in winter, and the effect of ISN is particularly prominent in the region where seasonal precipitation exceeds 200 mm. Moreover, statistical results also illustrate that initial soil moisture plays a crucial role in seasonal precipitation forecasts because of its slowly evolving nature, and its effect is more distinct in semiarid and semihumid regions than in arid and humid regions. The effects of indirectly assimilating soil moisture on precipitation can last two and three months in semiarid and semihumid areas, respectively.

scholarly journals A Numerical Sensitivity Study on the Impact of Soil Moisture on Convection-Related Parameters and Convective Precipitation over Complex Terrain

2011 ◽  
Vol 68 (12) ◽  
pp. 2971-2987 ◽  
Author(s):  
Christian Barthlott ◽  
Norbert Kalthoff
Keyword(s):  
Soil Moisture ◽  
Complex Terrain ◽  
Weather Prediction ◽  
Sensitivity Study ◽  
Convective Precipitation ◽  
Small Scale ◽  
Near Surface ◽  
Initial Soil Moisture ◽  
Initial Soil ◽  
The Impact

Abstract The impact of soil moisture on convection-related parameters and convective precipitation over complex terrain is studied by numerical experiments using the nonhydrostatic Consortium for Small-Scale Modeling (COSMO) model. For 1 day of the Convective and Orographically Induced Precipitation Study (COPS) conducted during summer 2007 in southwestern Germany and eastern France, initial soil moisture is varied from −50% to +50% of the reference run in steps of 5%. As synoptic-scale forcing is weak on the day under investigation, the triggering of convection is mainly due to soil–atmosphere interactions and boundary layer processes. Whereas a systematic relationship to soil moisture exists for a number of variables (e.g., latent and sensible fluxes at the ground, near-surface temperature, and humidity), a systematic increase of 24-h accumulated precipitation with increasing initial soil moisture is only present in the simulations that are drier than the reference run. The time evolution of convective precipitation can be divided into two regimes with different conditions to initiate and foster convection. Furthermore, the impact of soil moisture is different for the initiation and modification of convective precipitation. The results demonstrate the high sensitivity of numerical weather prediction to initial soil moisture fields.

scholarly journals Impact of Soil Moisture Anomalies on Summer Rainfall over East Asia: A Regional Climate Model Study

2007 ◽  
Vol 20 (23) ◽  
pp. 5732-5743 ◽  
Author(s):  
Jung-Eun Kim ◽  
Song-You Hong
Keyword(s):  
Soil Moisture ◽  
East Asia ◽  
Large Scale ◽  
Climate Model ◽  
Regional Climate ◽  
Summer Rainfall ◽  
Department Of Energy ◽  
Initial Soil Moisture ◽  
Initial Soil ◽  
The Impact

Abstract Numerous modeling studies have shown that soil moisture anomalies in later spring have a significant effect on the summer rainfall anomalies in North America. On the other hand, the role of soil moisture in forming monsoonal precipitation in East Asia has not been identified. This study attempts to clarify the importance of soil moisture on the summer rainfall in late spring in East Asia. The National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) is utilized for 3-month (June–August) simulations in 1998 (above-normal precipitation year) and 1997 (below-normal precipitation year). Initial and boundary conditions are derived from the NCEP–Department of Energy (DOE) reanalysis. The control run uses the initial soil moisture from the reanalysis, whereas it is set as a saturation and wilting point for “wet” and “dry” experiments, respectively. The impact of soil moisture anomalies on the simulated summer rainfall in East Asia is not significant. The change in precipitation between the wet and dry experiments is about 10%. A conflict between the local feedback of soil moisture and a change in large-scale circulations associated with the summertime monsoonal circulation in East Asia can be attributed as a reason for this anomaly. It is found that enhanced (suppressed) evaporation from the soil to the atmosphere in wet (dry) initial soil moisture reduces (increases) the land–sea contrast between East Asia and the Pacific Ocean, leading to a weakened sensitivity of the monsoonal circulations to the initial soil moisture. It can be concluded that the impact of the initial soil moisture is significant on the dynamic circulation in East Asia.

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