In physically-based land surface models, the parameters can all be prescribed a priori but calibration can be used to enhance the realism of the simulations in well instrumented domains. In such a ...case, the transferability of calibrated parameters under non-stationary conditions needs to be addressed, especially in the context of climate change. To this end, we used the Catchment Land Surface Model (CLSM) in the Upper Durance watershed located in the French Alps, which experienced a significant increase in temperature over the last century. The CLSM is forced by a 50-year meteorological dataset of good quality. Four parameters of the CLSM (one related to snow processes and three to soil properties) are calibrated against discharge observations with a multi-objective algorithm. First, the robustness of the CLSM parameterizations is tested by the Differential Split Sample Test (DSST). The simulations show good performances over a wide range of retrospective climatic conditions, except when the parameters are calibrated over a period with a large contribution of snowmelt to annual mean discharge. Then, the use of a climate change scenario reveals that the parameterizations of soil moisture processes in the CLSM are responsible for an increasing dispersion among simulations when facing dry and warm conditions. However, the differences between the simulated changes of river discharge remain very small. This work shows that calibration conveys some uncertainties, but they are moderate in the studied case, and pertain to the most conceptual parameterizations of this physically-based model.
Given the contradictory results from recent studies, this paper compares classical regionalization schemes of catchment model parameters over the wide range of hydroclimates found in France. To ...ensure the generality of the conclusions, we used two lumped rainfall-runoff models applied to daily data over a large set of 913 French catchments. Three types of approaches were considered: regionalization using regression, regionalization based on spatial proximity and regionalization based on physical similarity. This comparison shows that in France, where a dense network of gauging stations is available, spatial proximity provides the best regionalization solution. The regression approach is the least satisfactory, with results very close to those obtained using one median parameter set for the whole country. The physical similarity approach is intermediary. However, the results obtained with these three methods lag far behind those obtained by full model calibration. Our results also show that some improvement could be made by combining spatial proximity and physical similarity, and that there is still considerable room for progress in the field of ungaged catchment modeling.
1 This paper examines the possible solutions that may allow a rainfall-runoff model to cope with the existence of unknown intercatchment groundwater flows over a given catchment. On the basis of a ...large catchment set we compare four versions of the GR4J and the SMAR rainfall-runoff models that differ in the way they use one of their parameters to adjust catchment-scale water balance. We show that from both the hydrological likelihood and the modeling efficiency point of view it is preferable to explicitly represent intercatchment groundwater transfers. The surrogate corrective solutions tested in this paper (correcting or scaling factors applied to the climatic input data or to the catchment area) that are sometimes used in practice could be used on the sole grounds of streamflow simulation efficiency, but we show that they should be avoided since they may lead to obviously unrealistic corrections and consequently yield a similarly unrealistic distribution between evaporation streamflow and underground fluxes.
This paper described the geothermal water of Kerguelen and its active geothermal system. We reconstruct the meteoric origin, and the hydrothermal processes from chemical and isotopic data of rain ...water and thermal water. Interpretations indicate series of reactions from 6 up to 260 °C and few hundred meters below the surface.
Display omitted
•O, H stable isotopes data with Local Meteoric Water Line.•Dominant meteoric charge with snow melted.•Hydrochemical modeling of geothermal areas.•Schematic block diagram of water-rock interaction.
This study is the first synthesis of chemical composition and stable isotopes values for the Kerguelen archipelago waters. The stable isotope values for rainfall and river waters in the Kerguelen archipelago allow a calculation of the Local Meteoric Water Line (δD rainfall = 8.43 x δ18O rainfall + 11) and a summer runoff line (δD river drainage = 7.45 x δ18O river drainage + 6). Surface waters with low- ion concentrations, chlorine facies and stable isotope values infiltrate through fractures and lava flows recharging deeper groundwaters. Thermal groundwater with low- (7 to 50 °C) and high- (50 to 100 °C) temperatures emerges in different localities in the volcanic archipelago. The low-temperature thermal waters might represent a mixture of high-temperature water with rainfall, thermal gradient changes or shallower infiltration compared to that for high-temperature thermal waters. The Rallier du Baty and Val Travers areas contain geothermal fluids with high-temperature springs, fumaroles and a large water flow. In the Rallier du Baty, the major ion chemistry and O, H, C and S stable isotope ratio of low (7 to 50 °C) temperature spring waters in Rallier du Baty area demonstrate a geothermal-system recharged by meteoric water (δD H2O liquid = 7.0 x δ18O H2O liquid + 0.5) rather than sea water. The chemical and isotopic compositions of elevated temperature spring waters (50 to 100 °C) have a long and complex history of meteoric water interacting with cooling magmas (δD H2O liquid = 1.78 x δ18O H2O liquid – 23). Surficial precipitation of aragonite, kaolinite, pyrite, native sulfur attest to a long livied geothermal system. A temperature of the geothermal reservoir has been estimated between 193 and 259 °C by cation geothermometry. The combination of minerals observed, major ion composition of water with thermodynamic modeling and stable isotope data suggest a geothermal system with a series of water/rock interactions from 50 to 250 °C. The conductive cooling of rising of H2O−CO2-rich fluids have produced a H2O−CO2 phase separation with the precipitation of secondary minerals.
The Touvre spring is the only outlet of a large karstic system, the La Rochefoucauld karst, located in the West of France. This system is particularly interesting from a modeler's point of view, for ...it allows to investigate how karstic losses and gains can be accounted for within a rainfall-runoff model. Indeed, this spring is fed by the losses of three rivers, which are themselves gaged after recharging the karstic aquifer: this setting is exceptional in that simulations of surface catchment losses (estimated by the GR4J rainfall-runoff model) can be compared with measurements of spring discharge at the outlet of the karstic system. It provides an opportunity to test the estimates of “catchment leakages”, which are often suspected but seldom measurable, against observations. We show here that the conceptualization of surface losses in the GR4J rainfall-runoff model yields simulated leakage volumes that are consistent with the spring flow volumes and that, provided a routing store is added to GR4J to account for the specific retarding behavior of the karstic aquifer, an integrated model can be proposed to represent the behavior of the whole system adequately. The Touvre case study shows that a parsimonious, empirical rainfall-runoff representation of a karstic system is possible. It also provides an independent corroboration for the conceptualization of surface catchment leakages proposed in the GR4J rainfall-runoff model.
PDF
