Sediment flow paths and associated organic carbon dynamics across a Mediterranean catchment
Summary: This study follows organic carbon from soils along sediment flow paths at catchment scale to analyse the evolution of OC pools. Selectivity of particles during detachment and transport, and protection of OC during transport and deposition are key for the concentration and quality of OC at depositional settings and for the terrestrial carbon sink. OC can also be increased by ecological processes and by replacement in eroded areas, converting catchments into relevant sinks for C budget.
C. Boix-Fayos, E. Nadeu, J. M. Quiñonero, M. Martínez-Mena, M. Almagro, and J. de Vente Hydrol. Earth Syst. Sci., 19, 1209-1223, doi:10.5194/hess-19-1209-2015, 2015 AbstractFinal Revised Paper (PDF, 3930 KB)Discussion Paper (HESSD)
03 Mar 2015
Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land uses
Summary: Several methods for measuring unsaturated soil characteristics have been tested on sandy soil in northeastern Thailand, with different land uses. Each method shows significantly different parameters, regardless of land use. Nevertheless, when used for annual water balance modeling with HYDRUS1D, no noticeable differences for the various sets of parameters appeared. Any of these measurement method could be employed. Therefore, we recommended using the cheapest and easiest (i.e., Beerkan) method.
S. Siltecho, C. Hammecker, V. Sriboonlue, C. Clermont-Dauphin, V. Trelo-ges, A. C. D. Antonino, and R. Angulo-Jaramillo Hydrol. Earth Syst. Sci., 19, 1193-1207, doi:10.5194/hess-19-1193-2015, 2015 AbstractFinal Revised Paper (PDF, 2665 KB)Supplement (59 KB)Discussion Paper (HESSD)
03 Mar 2015
Explaining and forecasting interannual variability in the flow of the Nile River
Summary: This paper explains the different natural modes of interannual variability in the flow of the Nile River and also presents a new index based on the sea surface temperature (SST) over the southern Indian Ocean to forecast the flow of the Nile River. It also presents a new hybrid forecasting algorithm that can be used to predict the Nile flow based on indices of the SST in the eastern Pacific and southern Indian oceans.
Technical Note: Higher-order statistical moments and a procedure that detects potentially anomalous years as two alternative methods describing alterations in continuous environmental data
Summary: We present tools to assess shifts in the distributional properties of continuous environmental variables and to identify potentially anomalous years. We demonstrate the utility of these tools using stream temperature as an illustrative example. We were able to examine seasonal and annual responses to climate and other human-related influences. These tools will be useful to characterize how regimes of continuous phenomena have changed in the past, or may respond in the future.
Sampling frequency trade-offs in the assessment of mean transit times of tropical montane catchment waters under semi-steady-state conditions
Summary: Stream, soil and precipitation waters were collected in a tropical montane cloud forest catchment for 2 years and analyzed for stable water isotopes in order to infer transit time distribution functions and mean transit times for semi-steady-state conditions. Samples were aggregated to diverse sampling resolutions for checking the sensitivity of sampling frequency on lumped-model predictions. Results provide valuable information for the planning of future fieldwork in similar catchments.
E. Timbe, D. Windhorst, R. Celleri, L. Timbe, P. Crespo, H.-G. Frede, J. Feyen, and L. Breuer Hydrol. Earth Syst. Sci., 19, 1153-1168, doi:10.5194/hess-19-1153-2015, 2015 AbstractFinal Revised Paper (PDF, 4061 KB)Discussion Paper (HESSD)
02 Mar 2015
Polarimetric radar observations during an orographic rain event
Quantitative high-resolution observations of soil water dynamics in a complicated architecture using time-lapse ground-penetrating radar
Summary: In this study, we analyze a set of high-resolution, surface-based, 2-D ground-penetrating radar (GPR) observations of artificially induced subsurface water dynamics. In particular, we place close scrutiny on the evolution of the capillary fringe in a highly dynamic regime with surface-based time-lapse GPR. We thoroughly explain all observed phenomena based on theoretical soil physical considerations and numerical simulations of both subsurface water flow and the expected GPR response.
A groundwater recharge perspective on locating tree plantations within low-rainfall catchments to limit water resource losses
Summary: This paper examines modern and historical groundwater recharge rates to determine the impacts of reforestation in south-eastern Australia. This study shows that over both the long and short term, groundwater recharge in the study area occurs predominantly in the lower catchment areas. The results of this study show that spatial variations in recharge are important considerations for locating tree plantations, especially when looking to conserve water for downstream users in low rainfall regions.
A conceptual socio-hydrological model of the co-evolution of humans and water: case study of the Tarim River basin, western China
Summary: A simplified conceptual socio-hydrological model based on logistic growth curves is developed for the Tarim River basin in western China and is used to illustrate the explanatory power of a co-evolutionary model. The socio-hydrological system is composed of four sub-systems, i.e., the hydrological, ecological, economic, and social sub-systems. The hydrological equation focusing on water balance is coupled to the evolutionary equations of the other three sub-systems.
Sensitivity of potential evaporation estimates to 100 years of climate variability
Summary: We used the past century’s time series of observed climate, containing non-stationary signals of atmospheric oscillations, global warming, and global dimming/brightening, to quantify possible systematic errors that may be introduced in estimates of potential evaporation and in hydrological modeling studies due to straightforward application of i) the common two-step approach for potential evaporation specifically, and ii) fixed instead of time-variant model parameters in general.
Nitrogen surface water retention in the Baltic Sea drainage basin
Summary: In this study, we used the MESAW statistical model to estimate the surface water N retention. Such large-scale estimates are lacking for the Baltic Sea and there are only a few studies of this globally. Our results show that around 380 000t of N are annually retained in surface waters draining to the Baltic Sea. The total annual riverine load from the 117 basins to the Baltic Sea was estimated at 570 000t of N, yielding a total surface water N retention of around 40%.
P. Stålnacke, A. Pengerud, A. Vassiljev, E. Smedberg, C.-M. Mörth, H. E. Hägg, C. Humborg, and H. E. Andersen Hydrol. Earth Syst. Sci., 19, 981-996, doi:10.5194/hess-19-981-2015, 2015 AbstractFinal Revised Paper (PDF, 1766 KB)Discussion Paper (HESSD)
23 Feb 2015
Development and evaluation of an efficient soil-atmosphere model (FHAVeT) based on the Ross fast solution of the Richards equation for bare soil conditions
Summary: In agricultural management, a good timing in operations is essential to enhance economical and environmental performance. To improve such timing, predictive software is of particular interest. The objective of this study is to assess the accuracy of a physically based model with high efficiency. Compared to a more complex software (TEC) under bare soil conditions, a coupled model shows mostly improved efficiency and balance and a good capacity to predict water content thresholds.
Derivation of a new continuous adjustment function for correcting wind-induced loss of solid precipitation: results of a Norwegian field study
Summary: The article reports on measurements, analysis and results of a Norwegian field study aimed to adjust automatic precipitation measurements for under-catch during windy conditions. An unique data set could be collected, documenting the under-catch of snow at very high wind speeds for the first time. A new continuous adjustment function for precipitation measured by an automated gauge covering all three precipitation types (snow, mixed and rain) was established.
From days to decades: numerical modelling of freshwater lens response to climate change stressors on small low-lying islands
Summary: Freshwater lenses are vulnerable to many climate change stressors that act over varying spatial and temporal scales. This study evaluates the spatial and temporal response of a freshwater lens to short- and long-acting climate stressors using a numerical modeling approach. The results identify critical factors affecting the freshwater lens response for a typical small, low-lying island setting, as well as the effectiveness of remedial options in improving lens recovery.
Climate change impacts on the seasonality and generation processes of floods – projections and uncertainties for catchments with mixed snowmelt/rainfall regimes
Summary: Projected shifts towards more dominant autumn/winter events during a future climate correspond to an increasing relevance of rainfall as a flood generating process in six Norwegian catchments. The relative role of hydrological model parameter uncertainty, compared to other uncertainty sources from our applied ensemble, is highest in those catchments showing the largest shifts in flood seasonality which indicates a lack in parameter robustness under non-stationary hydroclimatological conditions.