http://www.adv-geosci.net/Advances in Geosciences Latest Articlesenhttp://www.adv-geosci.net/29/119/2011/<b><i>Preface</i> Towards practical applications in ensemble hydro-meteorological forecasting</b><br /><br />Advances in Geosciences, 29, 119-121, 2011<br /><br />Author(s): Y. He, F. Pappenberger, J. Thielen-del Pozo, A. Weerts, M.-H. Ramos, and M. Bruen<br /><br />No abstract available.Mon, 05 Sep 2011 00:00:00 +0200http://www.adv-geosci.net/30/39/2011/<b>Crop evapotranspiration estimation using remote sensing and the existing network of meteorological stations in Cyprus</b><br /><br />Advances in Geosciences, 30, 39-44, 2011<br /><br />Author(s): G. Papadavid, D. Hadjimitsis, S. Michaelides, and A. Nisantzi<br /><br />Cyprus is frequently confronted with severe droughts and the need for accurate and systematic data on crop evapotranspiration (ETc) is essential for decision making, regarding water irrigation management and scheduling. The aim of this paper is to highlight how data from meteorological stations in Cyprus can be used for monitoring and determining the country's irrigation demands. This paper shows how daily ETc can be estimated using FAO Penman-Monteith method adapted to satellite data and auxiliary meteorological parameters. This method is widely used in many countries for estimating crop evapotranspiration using auxiliary meteorological data (maximum and minimum temperatures, relative humidity, wind speed) as inputs. Two case studies were selected in order to determine evapotranspiration using meteorological and low resolution satellite data (MODIS – TERRA) and to compare it with the results of the reference method (FAO-56) which estimates the reference evapotranspiration (ETo) by using only meteorological data. The first approach corresponds to the FAO Penman-Monteith method adapted for using both meteorological and remotely sensed data. Furthermore, main automatic meteorological stations in Cyprus were mapped using Geographical Information System (GIS). All the agricultural areas of the island were categorized according to the nearest meteorological station which is considered as "representative" of the area. Thiessen polygons methodology was used for this purpose. The intended goal was to illustrate what can happen to a crop, in terms of water requirements, if meteorological data are retrieved from other than the representative stations. The use of inaccurate data can result in low yields or excessive irrigation which both lead to profit reduction. The results have shown that if inappropriate meteorological data are utilized, then deviations from correct ETc might be obtained, leading to water losses or crop water stress.Mon, 09 May 2011 00:00:00 +0200http://www.adv-geosci.net/30/31/2011/<b>Smart management and irrigation demand monitoring in Cyprus, using remote sensing and water resources simulation and optimization</b><br /><br />Advances in Geosciences, 30, 31-37, 2011<br /><br />Author(s): G. Papadavid, D. Hadjimitsis, K. Fedra, and S. Michaelides<br /><br />This paper presents a research project which integrates technological tools for developing a complete system for monitoring and determining irrigation demand on a systematic basis in Cyprus. Such tools are multi-spectral remotely sensed data dynamic water budget simulation and optimization, crop evapotranspiration (ETc) models and micro-sensor technology. The main aim is to estimate ETc in Cyprus and, furthermore, to undertake the required measures for an effective irrigation water management in the future. Evapotranspiration is difficult to determine since it combines various meteorological and field parameters while in literature quite many different models for estimating ETc are put forward. The proposed wireless sensor network acts as a monitoring tool for providing measurements of the necessary parameters: meteorological, climatic data and other auxiliary parameters required by the irrigation model in order to determine the irrigation demand. <br><br> Reflectance is determined directly from satellite images. Finally, using the WaterWare irrigation software, irrigation scheduling is planned for the area of interest in Paphos, Cyprus. This area is located at almost sea level and is characterized by mild micro-climate. The results of the paper refer to year 2009 and show the daily water requirements of the specific crop in study.Mon, 09 May 2011 00:00:00 +0200http://www.adv-geosci.net/30/23/2011/<b>Estimation of spatio-temporal distribution of precipitable water using MODIS and AVHRR data: a case study for Cyprus</b><br /><br />Advances in Geosciences, 30, 23-29, 2011<br /><br />Author(s): D. Hadjimitsis, Z. Mitraka, I. Gazani, A. Retalis, N. Chrysoulakis, and S. Michaelides<br /><br />In this paper, the atmospheric precipitable water (PW) over the area of Cyprus was estimated by means of Advanced Very High Resolution Radiometer (AVHRR) thermal channels brightness temperature difference (<i>&Delta;T</i>). The AVHRR derived <i>&Delta;T</i> was calculated in a grid of 5 × 5 km cells; the corresponding PW value in each grid cell was extracted from Moderate Resolution Imaging Spectroradiometer (MODIS) Level 2 product (near-infrared algorithm). Once the PW – <i>&Delta;T</i> relationship coefficients corresponding to the area of Cyprus were calculated, the relationship was applied to AVHRR data for one month period. Radiosonde derived PW values, as well as MODIS independent PW values were used to validate the estimations and a good agreement was noted.Mon, 09 May 2011 00:00:00 +0200http://www.adv-geosci.net/30/17/2011/<b>Long-term changes in rainfall and tropical cyclone activity over South and Southeast Asia</b><br /><br />Advances in Geosciences, 30, 17-22, 2011<br /><br />Author(s): H. G. Takahashi<br /><br />Long-term changes in rainfall and associated tropical cyclone (TC) activity in transition seasons between the wet and dry seasons in South and Southeast Asia, namely boreal spring and fall, were examined, using gridded rainfall, TC tracks, and reanalysis datasets, the focus of discussion being the long-term changes in coastal regions. It was found that long-term changes in rainfall during the transition seasons in South and Southeast Asia were closely associated with those in TC activity over the north Indian Ocean and South China Sea. Rainfall in May increased in the last 40 years over and around Myanmar, which indicates an earlier monsoon onset over the western Indochina Peninsula. Rainfall over and around northern Vietnam also increased in the last 40 years during October, which is known as the monsoon retreat period. These increases were associated with the long-term changes in TC activity. Furthermore, although linear trends have been previously suggested, monotonically increasing or decreasing trends in these long-term changes were not found over the last 60 years.Mon, 09 May 2011 00:00:00 +0200http://www.adv-geosci.net/30/11/2011/<b>Local patterns and trends of the Standard Precipitation Index in southern Portugal (1940&ndash;1999)</b><br /><br />Advances in Geosciences, 30, 11-16, 2011<br /><br />Author(s): A. C. Costa<br /><br />This paper analyzes the yearly changes in precipitation from 1940 to 1999 on local and regional scales over the southern region of continental Portugal, which has large areas threatened by desertification. The Standard Precipitation Index (SPI) time series with the 12-month time scale is calculated for 43 meteorological stations. A geostatistical approach is used to evaluate the temporal dynamics of the spatial patterns of precipitation. The spatial homogeneity of the SPI is evaluated for each decade. Afterwards, a geostatistical simulation algorithm (direct sequential simulation) is used to produce 100 equiprobable maps of the SPI for each year. This gridded data set (6000 maps with 800 m × 800 m grid cells) is then used to produce yearly scenarios of the SPI from 1940 to 1999, and uncertainty evaluations of the produced scenarios. The linear trend of SPI values over the sixty years period is calculated at each grid cell of the scenarios' maps using a nonparametric estimator. Wilcoxon-Mann-Whitney one-sided tests are used to compare the local median of the SPI in 1940/1969 with its median in 1970/1999. Results show that moderate drought conditions occur frequently over the study region, except in the northwest coast. Severe drought frequency patterns are found in areas of the centre and southeast regions. A significant trend towards drying occurs in the centre region and in the northeast. Considering the amount of water consumption and irrigation already required in some municipalities, water shortage due to drought is a viable threat in most of the Alentejo region if those local trends persist.Mon, 09 May 2011 00:00:00 +0200http://www.adv-geosci.net/30/3/2011/<b>Drop size distribution comparisons between Parsivel and 2-D video disdrometers</b><br /><br />Advances in Geosciences, 30, 3-9, 2011<br /><br />Author(s): M. Thurai, W. A. Petersen, A. Tokay, C. Schultz, and P. Gatlin<br /><br />Measurements from a 2-D video disdrometer (2DVD) have been used for drop size distribution (DSD) comparisons with co-located Parsivel measurements in Huntsville, Alabama. The comparisons were made in terms of the mass-weighted mean diameter, <i>D</i>_m, the standard deviation of the mass-spectrum, <i>&sigma;</i>_m, and the rainfall rate, <i>R</i>, all based on 1-min DSD from the two instruments. Time series comparisons show close agreement in all three parameters for cases where <i>R</i> was less than 20 mm h⁻¹. In four cases, discrepancies in all three parameters were seen for "heavy" events, with the Parsivel showing higher <i>D</i>_m, <i>&sigma;</i>_m and <i>R</i>, when <i>R</i> reached high values (particularly above 30 mm h⁻¹). Possible causes for the discrepancies include the presence of a small percentage of non-fully melted hydrometers, with higher than expected fall velocity and with very different axis ratios as compared with rain, indicating small hail or ice pellets or graupel. We also present here Parsivel-to-Parsivel comparisons as well as comparisons between two 2DVD instruments, namely a low-profile unit and the latest generation, "compact unit" which was installed at the same site in November 2009. The comparisons are included to assess the variability between the same types of instrument. Correlation coefficients and the fractional standard errors are compared.Mon, 09 May 2011 00:00:00 +0200http://www.adv-geosci.net/30/1/2011/<b>Preface ''Precipitation: Measurement, Climatology, Remote Sensing, and Modeling (EGU 2010)''</b><br /><br />Advances in Geosciences, 30, 1-2, 2011<br /><br />Author(s): S. Michaelides and S. Athanasatos<br /><br />No abstract available.Mon, 09 May 2011 00:00:00 +0200http://www.adv-geosci.net/29/109/2011/<b>Reliability of autoregressive error models as post-processors for probabilistic streamflow forecasts</b><br /><br />Advances in Geosciences, 29, 109-118, 2011<br /><br />Author(s): M. Morawietz, C.-Y. Xu, and L. Gottschalk<br /><br />In this study, the reliability of different versions of autoregressive error models as post-processors for probabilistic streamflow forecasts is evaluated. Rank histograms and reliability indices are used as performance measures. An algorithm for the construction of confidence intervals to indicate ranges of reliable forecasts within the rank histograms is presented. To analyse differences in performance of the post-processors, scatter plots of the standardized residuals of the error models are generated to assess the homoscedacity of the residuals with respect to streamflow. A problem of distorted impressions may appear when such plots are generated with a regular x-scale. The problem is analysed with both synthetic and real data, and a rank scaled x-axis is proposed to remedy the problem. The results of the study reveal large differences in the reliability of the post-processors. Versions with empirical distribution functions are clearly superior to those with standard normal distribution, but for validations with independent data their rank histograms still lie outside of the confidence bands for reliable forecasts.Wed, 27 Apr 2011 00:00:00 +0200http://www.adv-geosci.net/29/103/2011/<b>Precipitation forecasting through an analog sorting technique: a comparative study</b><br /><br />Advances in Geosciences, 29, 103-107, 2011<br /><br />Author(s): A. Ben Daoud, E. Sauquet, M. Lang, G. Bontron, and C. Obled<br /><br />This study aims at comparing two quantitative precipitation forecasting techniques based on the meteorological analogy concept. Method A considers first a selection of analogous situations at synoptic scale. Second a subset of the most similar situations in terms of hygrometry is extracted. Method B extends method A by two innovative ways, which are restricting the search for analogues with temperature information instead of the common season criterion, and exploiting the information about vertical motion considering vertical velocity. Forecasts are evaluated in a perfect prognosis context and in operational conditions as well, by mean of verification measures (Continuous Ranked Probability Skill Score and scores computed from contingency tables). Results of the case study in France show that: (1) there is an increase in forecast skill when temperature and vertical velocity are included in the procedure, (2) it is possible to anticipate rainfall events up to one week ahead and (3) the introduction of new variables such as vertical velocity may be useless beyond few days ahead if the forecast of the weather model is not reliable.Tue, 05 Apr 2011 00:00:00 +0200http://www.adv-geosci.net/27/149/2011/<b>Coupled forest growth-hydrology modelling as an instrument for the assessment of effects of forest management on hydrology in forested catchments</b><br /><br />Advances in Geosciences, 27, 149-154, 2011<br /><br />Author(s): J. Sutmöller, S. Hentschel, J. Hansen, and H. Meesenburg<br /><br />The type and intensity of forest management directly influences regional catchment hydrology. Future forest management must optimise the effects of its practices to achieve sustainable management. With scenario analysis of forestry practices, the effects of different forest utilisation strategies on the hydrology of forested catchments can be temporally and spatially quantified. <br><br> The approach adopted in this study necessitated the development of an interactive system for the spatially distributed modelling of hydrology in relation to forest stand development. Consequently, a forest growth model was used to simulate stand development assuming various forest management activities. Selected simulated forest growth parameters were entered into the hydrological model to simulate water fluxes under different conditions of forest structure. The approach enables the spatially differentiated quantification of changes in the water regime (e.g. increased evapotranspiration). <br><br> The results of hydrological simulations in the study area, the Oker catchment (northern Harz Mountains), show that forests contribute to the protection of water systems because they have a balancing effect on the hydrological regime. As scenario simulations also suggest, however, forestry practices can also lead to substantial changes in water budgets of forested catchments. The preservation of the hydrological services of forests requires a sustainable and long-term forest conversion on the basis of current management directives for near natural silviculture. Management strategies on basis of moderate harvesting regimes are preferred because of their limited impact on the water budget.Wed, 09 Mar 2011 00:00:00 +0100http://www.adv-geosci.net/29/95/2011/<b>Verification and comparison of probabilistic precipitation forecasts using the TIGGE data in the upriver of Huaihe Basin</b><br /><br />Advances in Geosciences, 29, 95-102, 2011<br /><br />Author(s): L.-N. Zhao, F.-Y. Tian, H. Wu, D. Qi, J.-Y. Di, and Z. Wang<br /><br />The precipitation forecasts of three ensemble prediction systems (EPS) and two multi-model ensemble prediction systems (MM EPS) were assessed by comparing with observations from 19 rain gauge stations located in the <i>Dapoling-Wangjiaba</i> sub-catchment of Huaihe Basin for the period from 1 July to 6 August 2008. The sample Probabilistic Distribution Functions (PDF) of gamma distribution, the Relative Operating Characteristic (ROC) diagrams, the percentile precipitation and a heavy rainfall event are analyzed to evaluate the performances of the single and multi-model ensemble prediction system (EPS). <br></br> The three EPS were from the China Meteorological Administration (CMA); the United States National Centre for Environment Predictions (NCEP); and the European Centre for Medium-Range Weather Forecasts (ECMWF), all were obtained from the TIGGE-CMA archiving centre (THORPEX Interactive Grand Global Ensemble, TIGGE). The MM EPS were created using the equal weighting method for every ensemble member over the test area, the first ( MM-1) consisted of all three EPS, the second (MM-2) consisted of the ECMWF and NCEP EPS. <br></br> The results demonstrate the level of correspondence between deterioration in predictive skill and extended lead time. Compared with observations and with a lead time of one day, ECMWF performs a little better than other centre's. With over five days in advance, all the three EPS and the two MM EPS don't give reliable probabilistic precipitation forecasts. Both MM EPS can outperform CMA and NCEP for most of the forecasted days, but still perform a little worse than ECMWF. Though variation of daily percentile precipitation and ROC areas show MM-2 outperforms MM-1, gamma distribution indicates much similar performances for all 10-day forecast, and neither is superior to ECMWF.Fri, 04 Mar 2011 00:00:00 +0100http://www.adv-geosci.net/29/85/2011/<b>A comparison between ensemble and deterministic hydrological forecasts in an operational context</b><br /><br />Advances in Geosciences, 29, 85-94, 2011<br /><br />Author(s): M.-A. Boucher, F. Anctil, L. Perreault, and D. Tremblay<br /><br />Ensemble forecasts can greatly benefit water resources management as they provide useful information regarding the uncertainty of the situation at hand. However, weather forecasting systems are evolving and the cost for reanalysis and reforecasts is prohibitive. Consequently, series of ensemble weather forecasts from a particular version of the forecasting system are often short. In this case study, we consider a hydrological event that took place in 2003 on the Gatineau watershed in Canada and caused management difficulties in a hydropower production context. The weather ensemble forecasting system in place at that time is now obsolete, but we show that with minimal post-processing of the forecasts, it is still beneficial to exploit ensemble rather than deterministic forecasts, even if the latter emerge from a more advanced meteorological model and possess superior spatial resolution.Thu, 03 Mar 2011 00:00:00 +0100http://www.adv-geosci.net/29/77/2011/<b>The use of MOGREPS ensemble rainfall forecasts in operational flood forecasting systems across England and Wales</b><br /><br />Advances in Geosciences, 29, 77-84, 2011<br /><br />Author(s): J. Schellekens, A. H. Weerts, R. J. Moore, C. E. Pierce, and S. Hildon<br /><br />Operational flood forecasting systems share a fundamental challenge: forecast uncertainty which needs to be considered when making a flood warning decision. One way of representing this uncertainty is through employing an ensemble approach. This paper presents research funded by the Environment Agency in which ensemble rainfall forecasts are utilised and tested for operational use. The form of ensemble rainfall forecast used is the Met Office short-range product called MOGREPS. It is tested for operational use within the Environment Agency's National Flood Forecasting System (NFFS) for England and Wales. Currently, the NFFS uses deterministic forecasts only. The operational configuration of the NFFS for Thames Region is extended to trial the use of the new ensemble rainfall forecasts in support of probabilistic flood forecasting. Evaluation includes considering issues of model performance, configuration (how to fit the ensemble forecasts within the current configurations), data volumes, run times and options for displaying probabilistic forecasts. Although ensemble rainfall forecasts available from MOGREPS are not extensive enough to fully verify product performance, it is concluded that their use within current Environment Agency regional flood forecasting systems can provide better information to the forecaster than use of the deterministic forecasts alone. Of note are the small number of false alarms of river flow exceedance generated when using MOGREPS as input and that small flow events are also forecasted rather well, notwithstanding the rather coarse resolution of the MOGREPS grid (24 km) compared to the studied catchments. In addition, it is concluded that, with careful configuration in NFFS, MOGREPS can be used in existing systems without a significant increase in system load.Tue, 01 Mar 2011 00:00:00 +0100http://www.adv-geosci.net/29/69/2011/<b>Flash flood detection through a multi-stage probabilistic warning system for heavy precipitation events</b><br /><br />Advances in Geosciences, 29, 69-75, 2011<br /><br />Author(s): L. Alfieri, D. Velasco, and J. Thielen<br /><br />The deadly combination of short to no warning lead times and the vulnerability of urbanized areas makes flash flood events extremely dangerous for the modern society. This paper contributes to flash flood early warning by proposing a multi-stage warning system for heavy precipitation events based on threshold exceedances within a probabilistic framework. It makes use of meteorological products at different resolutions, namely, numerical weather predictions (NWP), radar-NWP blending, and radar nowcasting. The system is composed by two main modules. First, a European Precipitation Index based on a simulated Climatology (EPIC) and probabilistic weather forecasts is calculated to pinpoint catchments at risk of upcoming heavy precipitation. Then, a Probabilistic Flash Flood Guidance System (PFFGS) is activated at the regional scale and uses more accurate input data to reduce the estimation uncertainty. <br></br> The system is tested for a high flow event occurred in Catalonia (Spain) in November 2008 and results from the different meteorological input data are compared and discussed. The strength of coupling the two systems is shown in its ability to detect areas potentially at risk of severe meteorological conditions and then monitoring the evolution by providing more accurate information with higher spatial-temporal resolution as the event approaches.Tue, 01 Mar 2011 00:00:00 +0100http://www.adv-geosci.net/29/61/2011/<b>Coupling ensemble weather predictions based on TIGGE database with Grid-Xinanjiang model for flood forecast</b><br /><br />Advances in Geosciences, 29, 61-67, 2011<br /><br />Author(s): H.-J. Bao, L.-N. Zhao, Y. He, Z.-J. Li, F. Wetterhall, H. L. Cloke, F. Pappenberger, and D. Manful<br /><br />The incorporation of numerical weather predictions (NWP) into a flood forecasting system can increase forecast lead times from a few hours to a few days. A single NWP forecast from a single forecast centre, however, is insufficient as it involves considerable non-predictable uncertainties and lead to a high number of false alarms. The availability of global ensemble numerical weather prediction systems through the THORPEX Interactive Grand Global Ensemble' (TIGGE) offers a new opportunity for flood forecast. The Grid-Xinanjiang distributed hydrological model, which is based on the Xinanjiang model theory and the topographical information of each grid cell extracted from the Digital Elevation Model (DEM), is coupled with ensemble weather predictions based on the TIGGE database (CMC, CMA, ECWMF, UKMO, NCEP) for flood forecast. This paper presents a case study using the coupled flood forecasting model on the Xixian catchment (a drainage area of 8826 km²) located in Henan province, China. A probabilistic discharge is provided as the end product of flood forecast. Results show that the association of the Grid-Xinanjiang model and the TIGGE database gives a promising tool for an early warning of flood events several days ahead.Mon, 28 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/29/51/2011/<b>A hydrologic post-processor for ensemble streamflow predictions</b><br /><br />Advances in Geosciences, 29, 51-59, 2011<br /><br />Author(s): L. Zhao, Q. Duan, J. Schaake, A. Ye, and J. Xia<br /><br />This paper evaluates the performance of a statistical post-processor for imperfect hydrologic model forecasts. Assuming that the meteorological forecasts are well-calibrated, we employ a "General Linear Model (GLM)" to post-process simulations produced by a hydrologic model. For a particular forecast date, the observations and simulations from an "analysis window" and hydrologic model forecasts for a "forecast window", the GLM Post-Processor (GLMPP) is used to produce an ensemble of predictions of the streamflow observations that will occur during the "forecast window". The objectives of the GLMPP are to: (1) preserve any skill in the original hydrologic ensemble forecast; (2) correct systematic model biases; (3) retain the equal-likelihood assumption for the ensemble; (4) preserve temporal scale dependency relationships in streamflow hydrographs and the uncertainty in the predictions; and, (5) produce reliable ensemble predictions. <br></br> Observed and simulated daily streamflow data from the Second Workshop on Model Parameter Estimation Experiment (MOPEX) are used to test how well these objectives are met when the GLMPP is applied to ensemble hydrologic forecasts driven by well calibrated meteorological forecasts. A 39-year hydrologic dataset from the French Broad basin is split into calibration and verification periods. The results show that the GLMPP built using data from the calibration period removes the mean bias when applied to hydrologic model simulations from both the calibration and verification periods. Probability distributions of the post-processed model simulations are shown to be closer to the climatological probability distributions of observed streamflow than the distributions of the unadjusted simulated flows. A number of experiments with different GLMPP configurations were also conducted to examine the effects of different configurations for forecast and analysis window lengths on the robustness of the results.Mon, 28 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/29/43/2011/<b>Multi-model data fusion as a tool for PUB: example in a Swedish mesoscale catchment</b><br /><br />Advances in Geosciences, 29, 43-50, 2011<br /><br />Author(s): J.-F. Exbrayat, N. R. Viney, J. Seibert, H.-G. Frede, and L. Breuer<br /><br />Post-processing the output of different rainfall-runoff models allows one to pool strengths of each model to produce more reliable predictions. As a new approach in the frame of the "Prediction in Ungauged Basins" initiative, this study investigates the geographical transferability of different parameter sets and data-fusion methods which were applied to 5 different rainfall-runoff models for a low-land catchment in Central Sweden. After usual calibration, we adopted a proxy-basin validation approach between two similar but non-nested sub-catchments in order to simulate ungauged conditions. <br></br> Many model combinations outperformed the best single model predictions with improvements of efficiencies from 0.70 for the best single model predictions to 0.77 for the best ensemble predictions. However no "best" data-fusion method could be determined as similar performances were obtained with different merging schemes. In general, poorer model performance, i.e. lower efficiency, was less likely to occur for ensembles which included more individual models.Mon, 28 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/29/33/2011/<b>Can a multi-model approach improve hydrological ensemble forecasting? A study on 29 French catchments using 16 hydrological model structures</b><br /><br />Advances in Geosciences, 29, 33-42, 2011<br /><br />Author(s): J. A. Velázquez, F. Anctil, M. H. Ramos, and C. Perrin<br /><br />An operational hydrological ensemble forecasting system based on a meteorological ensemble prediction system (M-EPS) coupled with a hydrological model searches to capture the uncertainties associated with the meteorological prediction to better predict river flows. However, the structure of the hydrological model is also an important source of uncertainty that has to be taken into account. This study aims at evaluating and comparing the performance and the reliability of different types of hydrological ensemble prediction systems (H-EPS), when ensemble weather forecasts are combined with a multi-model approach. The study is based on 29 catchments in France and 16 lumped hydrological model structures, driven by the weather forecasts from the European centre for medium-range weather forecasts (ECMWF). Results show that the ensemble predictions produced by a combination of several hydrological model structures and meteorological ensembles have higher skill and reliability than ensemble predictions given either by one single hydrological model fed by weather ensemble predictions or by several hydrological models and a deterministic meteorological forecast.Mon, 28 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/29/27/2011/<b>Forecast convergence score: a forecaster's approach to analysing hydro-meteorological forecast systems</b><br /><br />Advances in Geosciences, 29, 27-32, 2011<br /><br />Author(s): F. Pappenberger, K. Bogner, F. Wetterhall, Y. He, H. L. Cloke, and J. Thielen<br /><br />In this paper the properties of a hydro-meteorological forecasting system for forecasting river flows have been analysed using a probabilistic forecast convergence score (FCS). The focus on fixed event forecasts provides a forecaster's approach to system behaviour and adds an important perspective to the suite of forecast verification tools commonly used in this field. A low FCS indicates a more consistent forecast. It can be demonstrated that the FCS annual maximum decreases over the last 10 years. With lead time, the FCS of the ensemble forecast decreases whereas the control and high resolution forecast increase. The FCS is influenced by the lead time, threshold and catchment size and location. It indicates that one should use seasonality based decision rules to issue flood warnings.Fri, 25 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/29/21/2011/<b>Effects of temporal resolution of input precipitation on the performance of hydrological forecasting</b><br /><br />Advances in Geosciences, 29, 21-25, 2011<br /><br />Author(s): F. Wetterhall, Y. He, H. Cloke, and F. Pappenberger<br /><br />Flood prediction systems rely on good quality precipitation input data and forecasts to drive hydrological models. Most precipitation data comes from daily stations with a good spatial coverage. However, some flood events occur on sub-daily time scales and flood prediction systems could benefit from using models calibrated on the same time scale. This study compares precipitation data aggregated from hourly stations (HP) and data disaggregated from daily stations (DP) with 6-hourly forecasts from ECMWF over the time period 1 October 2006–31 December 2009. The HP and DP data sets were then used to calibrate two hydrological models, LISFLOOD-RR and HBV, and the latter was used in a flood case study. The HP scored better than the DP when evaluated against the forecast for lead times up to 4 days. However, this was not translated in the same way to the hydrological modelling, where the models gave similar scores for simulated runoff with the two datasets. The flood forecasting study showed that both datasets gave similar hit rates whereas the HP data set gave much smaller false alarm rates (FAR). This indicates that using sub-daily precipitation in the calibration and initiation of hydrological models can improve flood forecasting.Fri, 25 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/29/13/2011/<b>A staggered approach to flash flood forecasting – case study in the Cévennes region</b><br /><br />Advances in Geosciences, 29, 13-20, 2011<br /><br />Author(s): L. Alfieri, P. J. Smith, J. Thielen-del Pozo, and K. J. Beven<br /><br />A staggered approach to flash flood forecasting is developed within the IMPRINTS project (FP7-ENV-2008-1-226555). Instead of a single solution system, a chain of different models and input data is being proposed that act in sequence and provide decision makers with information of increasing accuracy in localization and magnitude as the events approach. The first system in the chain is developed by adapting methodologies of the European Flood Alert System (EFAS) to forecast flash floods and has the potential to provide early indication for probability of flash floods at the European scale. The last system in the chain is an adaptation of the data based mechanistic model (DBM) to probabilistic numerical weather predictions (NWP) and observed rainfall, with the capability to forecast river levels up to 12 h ahead. The potential of both systems to provide complementary information is illustrated for a flash flood event occurred on 2 November 2008 in the Cévennes region in France. Results show that the uncertainty in meteorological forecasts largely affects the outcomes. However, at an early stage, uncertain results are still valuable to decision makers, as they raise preparedness towards prompt actions to be taken.Fri, 25 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/29/1/2011/<b>Hydrological ensemble forecasting at ungauged basins: using neighbour catchments for model setup and updating</b><br /><br />Advances in Geosciences, 29, 1-11, 2011<br /><br />Author(s): A. Randrianasolo, M. H. Ramos, and V. Andréassian<br /><br />In flow forecasting, additionally to the need of long time series of historic discharges for model setup and calibration, hydrological models also need real-time discharge data for the updating of the initial conditions at the time of the forecasts. The need of data challenges operational flow forecasting at ungauged or poorly gauged sites. This study evaluates the performance of different choices of parameter sets and discharge updates to run a flow forecasting model at ungauged sites, based on information from neighbour catchments. A cross-validation approach is applied on a set of 211 catchments in France and a 17-month forecasting period is used to calculate skill scores and evaluate the quality of the forecasts. A reference situation, where local information is available, is compared to alternative situations, which include scenarios where no local data is available at all and scenarios where local data started to be collected at the beginning of the forecasting period. To cope with uncertainties from rainfall forecasts, the model is driven by ensemble weather forecasts from the PEARP-Météo-France ensemble prediction system. The results show that neighbour catchments can contribute to provide forecasts of good quality at ungauged sites, especially with the transfer of parameter sets for model simulation. The added value of local data for the operational updating of the hydrological ensemble forecasts is highlighted.Fri, 25 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/26/149/2011/<b>Lessons learnt from the snow emergency management of winter season 2008–2009 in Piemonte</b><br /><br />Advances in Geosciences, 26, 149-153, 2011<br /><br />Author(s): R. Pelosini, S. Bovo, and M. Cordola<br /><br />The winter season 2008–2009 has been characterized by heavy snowfalls over the western Alps. The snowfalls have been exceptional because of their earliness, persistence, intensity and territorial spread. The impact on the regional environment and territory has been relevant, also from the economical point of view, as well as the effort of the people involved in the forecasting, prevention and fighting actions. The environmental induced effects have been shown until late spring. Several snowfall events affected also the plains and the main towns, causing social impacts. The purpose of this work is to describe the overall effects of the anomalous snowfalls and the emergency response by the local government and institutions to face the hazard scenario and mitigate the risk for people, properties and environment. Arpa Piemonte (Regional Agency for Environmental Protection) gave the technical support to the snow emergency management borrowing the expertise acquired during the heavy hydrological events occurred in the Piemonte region and contributing to minimize losses. A short list of recommendations came out from the experience, as well as the technical tools and products, all highlighting the emergency preparedness relevance.Wed, 16 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/26/145/2011/<b>A multivariate regional test for detection of trends in extreme rainfall: the case of extreme daily rainfall in the French Mediterranean area</b><br /><br />Advances in Geosciences, 26, 145-148, 2011<br /><br />Author(s): L. Neppel, N. Pujol, and R. Sabatier<br /><br />In this paper we present a multivariate regional test we developed for the detection of trends in extreme rainfall, which takes into account the spatial dependence between rainfall measurements with copula functions. The test is based on four steps. It was applied to a set of 92 series of Annual Daily Maxima (ADM) rainfall in the French Mediterranean area, sampled during the 1949–2004 observation period. The results show a low significant trend, concerning mainly the mountains area in the west part of the French Mediterranean region. The position's parameters of the ADM rainfall probability distribution functions present a low but significant increasing trend of about 5% to 10%, the same increase as that observed in ADM rainfall quantiles in the last 56 years. Further work is needed to understand if this significative trend is related to the global climate change or to the natural variability of Mediterranean climate.Tue, 08 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/26/139/2011/<b>Regional analysis of runoff thresholds behaviour in Southern Italy based on theoretically derived distributions</b><br /><br />Advances in Geosciences, 26, 139-144, 2011<br /><br />Author(s): M. Fiorentino, A. Gioia, V. Iacobellis, and S. Manfreda<br /><br />The analysis of runoff thresholds and, more in general, the identification of main mechanisms of runoff generation controlling the flood frequency distribution is investigated, by means of theoretically derived flood frequency distributions, in the framework of regional analysis. Two nested theoretically-derived distributions are fitted to annual maximum flood series recorded in several basins of Southern Italy. Results are exploited in order to investigate heterogeneities and homogeneities and to obtain useful information for improving the available methods for regional analysis of flood frequency.Tue, 01 Feb 2011 00:00:00 +0100http://www.adv-geosci.net/26/133/2011/<b>Performance of multi-model AEMET-SREPS precipitation probabilistic forecasts over Mediterranean area</b><br /><br />Advances in Geosciences, 26, 133-138, 2011<br /><br />Author(s): A. Callado, C. Santos, P. Escribà, D. Santos-Muñoz, J. Simarro, and J. A. García-Moya<br /><br />Spanish Meteorological Agency (AEMET) runs a daily experimental multi-model Short-Range Ensemble Prediction System (AEMET-SREPS). The role of the system horizontal resolution (0.25 degrees) on the performance of 24-h precipitation probabilistic forecasts, and its relation with mesoscale events, are assessed comparing the performance over the Mediterranean area and over an European Atlantic area. Gridded high resolution rain observations and standard verification measures have been used at different precipitation thresholds, while studying the dependency on seasons for a one year period (May 2007 to June 2008). As a general result, performance over the Mediterranean area is higher than over the Atlantic one, albeit some relative loss of skill is found in autumn, when mesoscale convective organization is assumed to play a more important role. So it is suggested that AEMET-SREPS system precipitation predictability over the Mediterranean in autumn could be expected to improve if the horizontal and vertical resolution is increased in order to take into account the effect of meso-beta scale, especially important for convective organization.Fri, 21 Jan 2011 00:00:00 +0100http://www.adv-geosci.net/26/125/2011/<b>CORSiCA: a Mediterranean atmospheric and oceanographic observatory in Corsica within the framework of HyMeX and ChArMEx</b><br /><br />Advances in Geosciences, 26, 125-131, 2011<br /><br />Author(s): D. Lambert, M. Mallet, V. Ducrocq, F. Dulac, F. Gheusi, and N. Kalthoff<br /><br />CORSiCA (Corsican Observatory for Research and Studies on Climate and Atmosphere-ocean environment) is a project for a multi-site instrumented platform located in Corsica. It is dedicated to oceanographic and atmospheric studies in the framework of the Mediterranean projects HyMeX (Hydrological cycle in the Mediterranean Experiment) and ChArMEx (Chemistry-Aerosol Mediterranean Experiment). The observatory will provide the international scientific community with facilities for setting up a multiparametric observation platform in a region with little instrumentation at present. HyMeX and ChArMEx objectives and actions in Corsica are presented.Fri, 14 Jan 2011 00:00:00 +0100http://www.adv-geosci.net/27/145/2010/<b>Modelling of long term nitrogen retention in surface waters</b><br /><br />Advances in Geosciences, 27, 145-148, 2010<br /><br />Author(s): S. Halbfaß, M. Gebel, and S. Bürger<br /><br />In order to derive measures to reduce nutrient loadings into waters in Saxony, we calculated nitrogen inputs with the model STOFFBILANZ on the regional scale. Thereby we have to compare our modelling results to measured loadings at the river basin outlets, considering long term nutrient retention in surface waters. The most important mechanism of nitrogen retention is the denitrification in the contact zone of water and sediment, being controlled by hydraulic and micro-biological processes. Retention capacity is derived on the basis of the nutrient spiralling concept, using water residence time (hydraulic aspect) and time-specific N-uptake by microorganisms (biological aspect). Short time related processes of mobilization and immobilization are neglected, because they are of minor importance for the derivation of measures on the regional scale.Thu, 09 Dec 2010 00:00:00 +0100http://www.adv-geosci.net/27/139/2010/<b>Modelling of nitrogen turnover and leaching in Saxony</b><br /><br />Advances in Geosciences, 27, 139-144, 2010<br /><br />Author(s): M. Gebel, S. Halbfaß, S. Bürger, H. Friese, and S. Naumann<br /><br />From 2005 to 2009 we modelled the input of nitrogen and phosphorus in waters in the area of the Federal State of Saxony (Germany). The model results are an important component in elucidating the present situation of nutrient loads in groundwater and surface water as well as its future development. The present contribution focuses on the modelling of diffuse nitrogen leaching on arable land. Processes of mobilization and immobilization of nitrogen are included in the modelling. They will be estimated as induced by the respective types of fruit, management practices and local conditions. Source areas can be derived using the relationship of nitrogen sources (mobilization, deposition) and sinks (immobilization, denitrification) on the regional scale.Thu, 09 Dec 2010 00:00:00 +0100