Evolving flood patterns in a Mediterranean region (1301–2012) and climatic factors – the case of Catalonia
Summary: Catastrophic floods (the most severe ones) in Catalonia from 1301 do not show any statistical trend, while extraordinary floods (moderate ones) have increased since 1850 due to a marked increase in developed land and population in small coastal basins.
The most significant flood-rich periods occurred with a strong negative NAO phase.
Solar activity has some impact on changes in catastrophic floods: flood-rich periods in autumn generally occurred during periods of increased solar activity.
Using high-resolution phosphorus data to investigate mitigation measures in headwater river catchments
Summary: High-resolution phosphorus and flow data were used to gauge the effects of diffuse (soil P) and point source (septic tank system) mitigation measures in two flashy headwater river catchments. Over 4 years the data indicated an overall increase in P concentration in defined high flow ranges and low flow P concentration showed little change. The work indicates fractured responses to catchment management advice and mitigation which were also affected by variations in seasonal hydrometeorology.
Using measured soil water contents to estimate evapotranspiration and root water uptake profiles – a comparative study
Summary: This paper is the result of a numerical study to test the application of water balance methods for estimating evapotranspiration and water extraction profiles based on measured soil water content data. The advantage of the tested methods is that they do not rely on a priori information of any root distribution parameters. Our research shows the potential of water balance methods for derivation of water extraction profiles, but their application may be challenging in realistic conditions.
ERA-Interim/Land: a global land surface reanalysis data set
Summary: ERA-Interim/Land is a global land surface reanalysis covering the period 1979–2010. It describes the evolution of soil moisture, soil temperature and snowpack. ERA-Interim/Land includes a number of parameterization improvements in the land surface scheme with respect to the original ERA-Interim and a precipitation bias correction based on GPCP. A selection of verification results show the added value in representing the terrestrial water cycle and its main land surface storages and fluxes.
G. Balsamo, C. Albergel, A. Beljaars, S. Boussetta, E. Brun, H. Cloke, D. Dee, E. Dutra, J. Muñoz-Sabater, F. Pappenberger, P. de Rosnay, T. Stockdale, and F. Vitart Hydrol. Earth Syst. Sci., 19, 389-407, 2015 AbstractFinal Revised Paper (PDF, 2244 KB)Discussion Paper (HESSD)
21 Jan 2015
Climate and hydrological variability: the catchment filtering role
Summary: Does climate variability necessarily imply hydrological variability? This paper analyses the catchment filtering role by analytically deriving the annual maximum peak flow frequency distribution based on realistic hypotheses about the rainfall process and the rainfall-runoff transformation. Depending on changes in the annual number of rainfall events, the catchment filtering role is particularly significant. Results also largely depend on the return period considered.
Assessment of precipitation and temperature data from CMIP3 global climate models for hydrologic simulation
Summary: Here we assess GCM performance from a hydrologic perspective. We identify five better performing CMIP3 GCMs that reproduce grid-scale climatological statistics of observed precipitation and temperature over global land regions for future hydrologic simulation. GCM performance in reproducing observed mean and standard deviation of annual precipitation, mean annual temperature and mean monthly precipitation and temperature was assessed and ranked, and five better performing GCMs were identified.
Satellite radar altimetry for monitoring small rivers and lakes in Indonesia
Summary: This paper investigates the possibility of monitoring small water bodies through Envisat altimetry observation. A novel approach is introduced to identify qualified and non-qualified altimetry measurements by assessing the waveform shapes for each returned radar signal. This research indicates that small lakes (extent < 100 km2) and medium-sized rivers (e.g., 200--800 m in width) can be successfully monitored by satellite altimetry.
What made the June 2013 flood in Germany an exceptional event? A hydro-meteorological evaluation
Summary: Extreme antecedent precipitation, increased initial hydraulic load in the river network and strong but not extraordinary event precipitation were key drivers for the flood in June 2013 in Germany. Our results are based on extreme value statistics and aggregated severity indices which we evaluated for a set of 74 historic large-scale floods. This flood database and the methodological framework enable the rapid assessment of future floods using precipitation and discharge observations.
The skill of seasonal ensemble low-flow forecasts in the Moselle River for three different hydrological models
Summary: This paper investigates the skill of 90-day low-flow forecasts using three models. From the results, it appears that all models are prone to over-predict runoff during low-flow periods using ensemble seasonal meteorological forcing. The largest range for 90-day low-flow forecasts is found for the GR4J model. Overall, the uncertainty from ensemble P forecasts has a larger effect on seasonal low-flow forecasts than the uncertainty from ensemble PET forecasts and initial model conditions.
Development of a large-sample watershed-scale hydrometeorological data set for the contiguous USA: data set characteristics and assessment of regional variability in hydrologic model performance
Summary: The focus of this paper is to (1) present a community data set of daily forcing and hydrologic response data for 671 unimpaired basins across the contiguous United States that spans a very wide range of hydroclimatic conditions, and (2) provide a calibrated model performance benchmark using a common conceptual snow and hydrologic modeling system. This benchmark provides a reference level of model performance across a very large basin sample and highlights regional variations in performance.
A. J. Newman, M. P. Clark, K. Sampson, A. Wood, L. E. Hay, A. Bock, R. J. Viger, D. Blodgett, L. Brekke, J. R. Arnold, T. Hopson, and Q. Duan Hydrol. Earth Syst. Sci., 19, 209-223, 2015 AbstractFinal Revised Paper (PDF, 4407 KB)Discussion Paper (HESSD)
14 Jan 2015
Monitoring of riparian vegetation response to flood disturbances using terrestrial photography
Summary: We use a high-resolution ground-based camera system with near-infrared sensitivity to quantify the response of riparian vegetation in an Alpine river to floods with the use of vegetation indices. The vegetation showed both damage and enhancement within 1 week following floods, with a selective impact determined by pre-flood vegetation vigour, morphological setting and intensity of flood forcing. The tested vegetation indices differed in the direction of predicted change in the range 0.7-35.8%.