Assessing land–ocean connectivity via Submarine Groundwater Discharge (SGD) in the Ria Formosa Lagoon (Portugal): combining radon measurements and stable isotope hydrology
Summary: We combine radon and stable isotopes in water to determine total Submarine Groundwater Discharge (SGD) in the Ria Formosa and discriminate its component modes. We show that tidal action filters the entire water volume in the lagoon through local beaches 3.5 times a year, driving an estimated 350 Ton Nitrogen/year into the system. Conversely, fresh groundwater is discharged into the lagoon only occasionally, adding ~61 Ton Nitrogen/year, but is capable of driving new production in the system.
Hydrol. Earth Syst. Sci. Discuss., 12, 12433-12482, doi:10.5194/hessd-12-12433-2015, 2015
Uncertainty contributions to low flow projections in Austria
Summary: Stream flow estimation during low flow conditions is important for estimation of environmental flows, effluent water quality, hydropower operations, etc. However it is not clear how the uncertainties in assumptions used in the projections translate into uncertainty of estimated future low flows.The objective of the study is to explore the relative role of hydrologic model calibration and climate scenarios in the uncertainty of low flow projections in Austria.
Hydrol. Earth Syst. Sci. Discuss., 12, 12395-12431, doi:10.5194/hessd-12-12395-2015, 2015
HESS Opinions: Advocating process modeling and de-emphasizing parameter estimation
Summary: There has been much recent debate regarding the future of the hydrological sciences, and several publications have voiced opinions on this subject. This opinion paper seeks to comment and expand on some recent publications that have advocated an increased focus on process modelling while de-emphasizing the focus on detailed attention to parameter estimation. In particular, it offers a perspective that emphasizes a more hydraulic approach to development and implementation of hydrological models.
Hydrol. Earth Syst. Sci. Discuss., 12, 12377-12393, doi:10.5194/hessd-12-12377-2015, 2015
Dissolved oxygen prediction using a possibility-theory based fuzzy neural network
Summary: This paper contains a new two-step method to construct fuzzy numbers using observational data. In addition an existing fuzzy neural network is modified to account for fuzzy number inputs. This is combined with possibility-theory based intervals to train the network. Furthermore, model output and a defuzzification technique is used to estimate the risk of low Dissolved Oxygen so that water resource managers can implement strategies to prevent the occurrence of low Dissolved Oxygen.
Hydrol. Earth Syst. Sci. Discuss., 12, 12311-12376, doi:10.5194/hessd-12-12311-2015, 2015
On the validity of effective formulations for transport through heterogeneous porous media
Summary: Geological heterogeneity enhances spreading of solutes, and causes transport to be anomalous with much less mixing and reactivity than suggested by dispersion. We propose formal criteria that should be met by effective transport formalisms to represent advection, spreading and mixing. While relevant for dispersion in heterogeneous porous media, mobile/immobile exchange models induce lower but more sustained resistance to mixing.
Hydrol. Earth Syst. Sci. Discuss., 12, 12281-12310, doi:10.5194/hessd-12-12281-2015, 2015
Technical Note: Three-dimensional transient groundwater flow due to localized recharge with an arbitrary transient rate in unconfined aquifers
Summary: Most previous solutions for groundwater flow due to localized recharge assumed either aquifer incompressibility or 2-D flow without vertical flow. This paper develops a 3-D flow model for hydraulic head change induced by the recharge with random transient rates in a compressible unconfined aquifer. The analytical solution of the model for the head is derived. The quantitative criteria for the validity of those two assumptions are presented by the developed solution.
Hydrol. Earth Syst. Sci. Discuss., 12, 12247-12280, doi:10.5194/hessd-12-12247-2015, 2015
Monitoring infiltration processes with high-resolution surface-based Ground-Penetrating Radar
Summary: The main goal of our work is to quantify near-surface soil water dynamics by advancing non-invasive measurement methods such as surface-based Ground-Penetrating Radar (GPR). Here, we observe soil infiltration processes with a novel dual-frequency GPR system. The high precision of our approach allows (i) closely investigating the dynamic evolution of specific subsurface signals in different materials and (ii) monitoring the longterm effect of infiltration pulses over the course of several months.
Hydrol. Earth Syst. Sci. Discuss., 12, 12215-12246, doi:10.5194/hessd-12-12215-2015, 2015
Identification of the main attribute of river flow temporal variations in the Nile Basin
Summary: To investigate the possible change in catchment behavior, which may interfere with the flow-rainfall relationship, three rainfall-runoff models were applied to the main catchments of the Nile Basin in Africa based on inputs covering the period from 1940 to 2003. There was close agreement between the changes in the observed and simulated overland flow from all the models. Thus, change in catchment behavior due to anthropogenic influence in the Nile basin over the selected time period was minimal.
Hydrol. Earth Syst. Sci. Discuss., 12, 12167-12214, doi:10.5194/hessd-12-12167-2015, 2015
The socio-ecohydrology of rainwater harvesting in India: understanding water storage and release dynamics at tank and catchment scales
Summary: Although village-scale rainwater harvesting (RWH) structures have been used for millennia in India, many of these structures have fallen into disrepair due to increased dependence on groundwater. This dependence has contributed to declines in groundwater resources, and in turn to efforts to revive older RWH systems. In the present study, we use field data to quantify water fluxes in a cascade of irrigation tanks to better our understanding of the impact of RWH systems on the water balance in con
Hydrol. Earth Syst. Sci. Discuss., 12, 12121-12165, doi:10.5194/hessd-12-12121-2015, 2015
Macropore flow at the field scale: predictive performance of empirical models and X-ray CT analyzed macropore characteristics
Hydrol. Earth Syst. Sci. Discuss., 12, 12089-12120, doi:10.5194/hessd-12-12089-2015, 2015
Model-based study of the role of rainfall and land use land cover in the changes in Niger Red floods occurrence and intensity in Niamey between 1953 and 2012
Summary: Since 1950, the Niger River basin has overcome drastic changes. In Niamey city, the highest river levels and the longest flooded period ever recorded occurred in 2003, 2010, 2012 and 2013, with heavy casualties and property damage. The reasons for these changes, and the relative role of climate versus Land Use Land Cover changes are still debated and are investigated in this paper using observations and modelling. We conclude on the successive role of cover and then rainfall variability.
Hydrol. Earth Syst. Sci. Discuss., 12, 12039-12087, doi:10.5194/hessd-12-12039-2015, 2015
A comprehensive one-dimensional numerical model for solute transport in rivers
Summary: A comprehensive model is presented, that merges numerical schemes with higher order accuracy for solution of advection-dispersion equation with transient storage zones in rivers with irregular cross sections at unsteady flow regime, to obviate the flaws in current models of contaminant transport simulation. For this purpose QUICK scheme due to high stability and law approximation errors have been used in spatial discretization of transport equation with transient storage and kinetic sorption.
Hydrol. Earth Syst. Sci. Discuss., 12, 11959-12037, doi:10.5194/hessd-12-11959-2015, 2015
Mapping evapotranspiration with high resolution aircraft imagery over vineyards using one and two source modeling schemes
Summary: This paper describes a model inter-comparison and validation study conducted using sub-meter resolution thermal data from an aircraft. The model inter-comparison is between a physically-based model and a very simple empirical model. The strengths and weaknesses of both modeling approaches for high resolution mapping of water use in vineyards is described. The findings provide significant insight into the utility of complex versus simple models for precise water resources management.
Hydrol. Earth Syst. Sci. Discuss., 12, 11905-11957, doi:10.5194/hessd-12-11905-2015, 2015
Modeling 25 years of spatio-temporal surface water and inundation dynamics on large river basin scale using time series of earth observation data
Summary: In this study, we modeled surface water and inundation dynamics from a unique Landsat-based time series (1986–2011) for Australia's Murray-Darling Basin as a function of river flow and spatially explicit time series of rainfall, evapotranspiration and soil moisture. We present a highly-automated and data-driven approach that allowed us to model surface water dynamics on finer spatial entities compared to existing studies and to identify local combinations of variables that drive inundation.
Hydrol. Earth Syst. Sci. Discuss., 12, 11847-11903, doi:10.5194/hessd-12-11847-2015, 2015
Effects of DEM scale on the spatial distribution of the TOPMODEL topographic wetness index and its correlations to watershed characteristics
Hydrol. Earth Syst. Sci. Discuss., 12, 11817-11846, doi:10.5194/hessd-12-11817-2015, 2015
Stem-root flow effect on soil–atmosphere interactions and uncertainty assessments
Summary: The stem-root flow mechanism was parameterized and incorporated into the Simplified Simple Biosphere model to analyze its impact on soil moisture and land-atmospheric interactions. By testing against the Lien Hua Chih (Taiwan) and HAPEX-Mobilhy (France) measurements, the model shows that stem-root flow reduced the top-soil moisture content and moistened the deeper soil layers. Such soil moisture redistribution results in significant changes in heat flux exchange between land and atmosphere.
Hydrol. Earth Syst. Sci. Discuss., 12, 11783-11816, doi:10.5194/hessd-12-11783-2015, 2015
Constraining frequency-magnitude-area relationships for precipitation and flood discharges using radar-derived precipitation estimates: example applications in the Upper and Lower Colorado River Basins, USA
Summary: We present a new method that incorporates flood-envelope-curve methods, radar-derived precipitation data, and flow-routing algorithms to calculate frequency-magnitude-area curves (FMAC). Our results show that flood discharges increase as a power-law function for small contributing areas, but start to increase more slowly at higher contributing areas. We find that our FMACs have similar and/or higher flood discharges than published flood-envelope curves for the same areas.
Hydrol. Earth Syst. Sci. Discuss., 12, 11739-11782, doi:10.5194/hessd-12-11739-2015, 2015
Understanding groundwater – students' pre-conceptions and conceptual change by a theory-guided multimedia learning program
Summary: Studies show that young people have difficulties with correctly understanding groundwater. We designed a multimedia learning program about groundwater and tested its learning efficacy with pupils and teacher training students. A novelty is the theory-guided designing of the program on the basis of hydrogeology and science education. The pupils and students greatly profited from working through the multimedia learning program.
Hydrol. Earth Syst. Sci. Discuss., 12, 11689-11737, doi:10.5194/hessd-12-11689-2015, 2015
Mekong River flow and hydrological extremes under climate change
Summary: We modelled hydrological changes under climate change in the Mekong River, focusing on extreme events. The scenarios ensemble shows an intensification of the hydrological cycle under climate change. Annual river flow increases between 5% - 16%, depending on locations. Extreme high flows increase substantially in both magnitude and frequency, posing threats to flood safety in the basin. Extreme low flow events are projected to reduce as a result of increased river flow during the dry season.
Hydrol. Earth Syst. Sci. Discuss., 12, 11651-11687, doi:10.5194/hessd-12-11651-2015, 2015
Shift of annual water balance in the Budyko space for a catchment with groundwater dependent evapotranspiration
Summary: This study reveals the effects of groundwater dependent evapotranspiration (GDE) in the shift of annual water balance for a catchment in the Budyko space. The ABCD model is modified to incorporate GDE in simulating the monthly hydrological behaviours of a catchment and the results are aggregated to annual data. GDE enhances the occurrence of excess evapotranspiration (E/P >1) in extreme dry years, which could not be captured by any traditional Budyko curves.
Hydrol. Earth Syst. Sci. Discuss., 12, 11613-11650, doi:10.5194/hessd-12-11613-2015, 2015
Studienlandschaft Schwingbachtal: an out-door full-scale learning tool newly equipped with augmented reality
Summary: Studienlandschaft Schwingbachtal is an out-door full-scale study site since 2008. It deals with hydrology in an interdisciplinary approach and enhances active learning by various means (field monitoring, education trails and geocache). In order to adapt to the change in students habits and to suit better as a communication tool for the locals, it is newly equipped with augmented reality which adds virtual objects on the real landscape, making learning pleasant.
Hydrol. Earth Syst. Sci. Discuss., 12, 11591-11611, doi:10.5194/hessd-12-11591-2015, 2015
Combining satellite observations to develop a daily global soil moisture product for a wide range of applications
Summary: Soil moisture is a crucial variable for a variety of applications, ranging from weather forecasting and agricultural production to the monitoring of floods and droughts. Satellite observations are particularly important in regions, where no in-situ measurements are available. Our study presents a method to integrate near-real time satellite observations from different sensors into one harmonized, daily dataset. A first validation shows good results on a global scale.
Hydrol. Earth Syst. Sci. Discuss., 12, 11549-11589, doi:10.5194/hessd-12-11549-2015, 2015
Reliability of lumped hydrological modeling in a semi-arid mountainous catchment facing water-use changes
Summary: Our paper explores the reliability of conceptual catchment models in the dry Andes. First, it is shown that explicitly accounting for irrigation water-use improves streamflow predictions during dry years. Second, it is shown that sublimation losses can be easily incorporated into temperature-based melt models without increasing too much model complexity. Our work also highlights areas requiring additional research, including the need for a better conceptualization of runoff generation processes.
Hydrol. Earth Syst. Sci. Discuss., 12, 11485-11548, doi:10.5194/hessd-12-11485-2015, 2015
Analysis of the drought resilience of Andosols on southern Ecuadorian Andean páramos
Summary: The drought resilience of the soils in Neotropical Andean grasslands above 3500 m a.s.l. known as “páramo” is studied in this paper. The main aim was to estimate the resilience capacity of the soils during a drought period and the recovery during a subsequent wet period. A typical catchment on the páramo at 3500 m a.s.l. was compared to a lower grassland one at 2600 m a.s.l. The study shows the extraordinary resilience capacity of this type of shallow organic soils during the droughts in 2009 and 2010.
Hydrol. Earth Syst. Sci. Discuss., 12, 11449-11484, doi:10.5194/hessd-12-11449-2015, 2015
A comprehensive evaluation of input data-induced uncertainty in nonpoint source pollution modeling
Summary: Quantifying model uncertainty at the large basin scale is notably complex because of the complexity and interaction of input data, which complicate the application of watershed models. In this paper, an evaluation of the error-transitivity from input data to nonpoint source pollution modeling was conducted by quantifying the effects of four input data.These results provide valuable information for developing watershed model, and can be extrapolated to other model-based research.
Hydrol. Earth Syst. Sci. Discuss., 12, 11421-11447, doi:10.5194/hessd-12-11421-2015, 2015
Can assimilation of crowdsourced streamflow observations in hydrological modelling improve flood prediction?
Summary: In this study we assimilate crowdsourced streamflow observations in hydrological modelling. It is found that the increasing the number of crowdsourced observations within the model time step (1h) increases the model performance even if these observations have irregular arrival frequency and accuracy. We demonstrated that integration of observations from social sensors and single physical sensor can improve the flood prediction in case of small number of intermittent crowdsourced observations
Hydrol. Earth Syst. Sci. Discuss., 12, 11371-11419, doi:10.5194/hessd-12-11371-2015, 2015
Identification of anthropogenic and natural inputs of sulfate into a karstic coastal groundwater system in northeast China: evidence from major ions, δ13CDIC and δ34SSO4
Summary: We report new data for carbon and sulfur isotopes of the groundwater flow system in a coastal carbonate aquifer of northeastern China, for. It shows how these can be used to determine the major processes controlling sulphate cycling and transport. Hopefully the study will be of broad international interest, and is expected to improve the understanding of techniques to determine impacts on groundwater quality and flow; leading to improved groundwater protection and monitoring strategies.
Hydrol. Earth Syst. Sci. Discuss., 12, 11331-11370, doi:10.5194/hessd-12-11331-2015, 2015
Urban water sustainability: an integrative framework for regional water management
Summary: This paper introduces a regional integrative framework that enables water managers to systematically identify opportunities for water reliability enhancement, taking advantage of local characteristics to design regional water supply solutions. We compute a numerical sustainability index, including an innovative way to measure the realiability benefits of having diverse supply sources. The framework is applied to the Hetch Hetchy Regional Water System in the San Francisco Bay Area of California.
Hydrol. Earth Syst. Sci. Discuss., 12, 11291-11329, doi:10.5194/hessd-12-11291-2015, 2015
Synchrony of trend shifts in Sahel summer rainfall and global oceanic evaporation, 1950–2012
Summary: Between 1950 and 2012, summer rainfall in the Sahel changed from a multi-decadal decreasing trend to an increasing trend (positive trend shift) in the mid-1980s. We found that this trend shift was synchronous with similar trend shifts in global oceanic evaporation and in land precipitation in all continents except the Americas.
Hydrol. Earth Syst. Sci. Discuss., 12, 11269-11289, doi:10.5194/hessd-12-11269-2015, 2015
Simultaneous calibration of hydrological models in geographical space
Summary: This paper investigates the transfer of the dynamical parameters of hydrological models. Three hydrological models combined with three different performance measures were used in four different numerical experiments to investigate this transferability. Result indicates a good parameter transfer to ungauged catchments can be achieved through simultaneous calibration of hydrological models for a number of catchments.
Hydrol. Earth Syst. Sci. Discuss., 12, 11223-11268, doi:10.5194/hessd-12-11223-2015, 2015
Hydrological, chemical and isotopic budgets of Lake Chad: a quantitative assessment of evaporation, transpiration and infiltration fluxes
Summary: Flows out of Lake Chad are constrained by a modeling of the hydrological, chemical and isotopic budgets. Proportions of evaporation, transpiration and infiltration are determined while the two last flows are often neglected in semi-arid environment. The modeling is based on a review of chemical and isotopic data in the literature along with new data. The innovative approach allows to investigate the lake hydrological and chemical regulations under the large climatic changes in Sahel since 1950.
Hydrol. Earth Syst. Sci. Discuss., 12, 11173-11222, doi:10.5194/hessd-12-11173-2015, 2015
Estimating catchment scale groundwater dynamics from recession analysis – enhanced constraining of hydrological models
Summary: This paper introduces a new formulation of hydrological subsurface dynamics for hydrological models. The frequency distribution of the fluctuations of the catchment scale subsurface moisture is assumed to have the same shape as that of observed recessions. The new formulation of the subsurface has been tested for 73 Norwegian catchments and is found to perform as good as the previous, calibrated subsurface formulation. Recessions are better simulated using the new formulation
Hydrol. Earth Syst. Sci. Discuss., 12, 11129-11171, doi:10.5194/hessd-12-11129-2015, 2015
Empirical streamflow simulation for water resource management in data-scarce seasonal watersheds
Summary: This paper compares six methods for data-driven rainfall-runoff simulation in terms of predictive accuracy, error structure, interpretability, and uncertainty. We demonstrate that autocorrelation in model errors can result in biased estimates of important values and show how certain model structures can be more easily interpreted to yield insights on physical watershed function. Finally, we explore how model structure can impact uncertainty in climate change sensitivity estimates.
Hydrol. Earth Syst. Sci. Discuss., 12, 11083-11127, doi:10.5194/hessd-12-11083-2015, 2015
Comparing CFSR and conventional weather data for discharge and sediment loss modelling with SWAT in small catchments in the Ethiopian Highlands
Summary: The Soil and Water Assessment Tool (SWAT) suggests using the CFSR global rainfall data for modelling discharge and soil erosion in data-scarce parts of the world. This data are freely available and ready to use for SWAT modelling. However, simulations with the CFSR data in the Ethiopian highlands were unable to represent the specific regional climates and showed high discrepancies. This article compares SWAT simulations with conventional rainfall data and with CFSR rainfall data.
Hydrol. Earth Syst. Sci. Discuss., 12, 11053-11082, doi:10.5194/hessd-12-11053-2015, 2015
New interpretation of the role of water balance in an extended Budyko hypothesis in arid regions
Hydrol. Earth Syst. Sci. Discuss., 12, 11013-11052, doi:10.5194/hessd-12-11013-2015, 2015
Factors influencing stream water transit times in tropical montane watersheds
Summary: Stream baseflow MTTs ranged between 1.2 and 2.7 years, suggesting deep and long subsurface flow paths that contribute to sustain catchment flows, particularly during the dry period. Across scales, baseflow MTTs were mainly controlled by catchment slope and the permeability at the soil-bedrock interface. In association with topography, catchment form, land cover and the depth to the soil-bedrock were also identified as important factors influencing MTTs in this humid tropical montane region.
Hydrol. Earth Syst. Sci. Discuss., 12, 10975-11011, doi:10.5194/hessd-12-10975-2015, 2015
Experimental evidence of condensation-driven airflow
Summary: Through physical experiments on 20 cubic metres of enclosed air in a structure consisting of two 5 m tall interconnected columns, water vapour condensation is seen to lead to uni-directional horizontal airflows. The findings support the physics underlying the controversial biotic pump theory. The conclusion is that large-scale deforestation will, through diminished cloud formation, have a devastating impact on intra-continental rain patterns, even leading to desertification.
Hydrol. Earth Syst. Sci. Discuss., 12, 10921-10974, doi:10.5194/hessd-12-10921-2015, 2015
Technical Note: The impact of spatial scale in bias correction of climate model output for hydrologic impact studies
Summary: To translate climate model output from its native coarse scale to a finer scale more representative of that at which societal impacts are experienced, a common method applied is statistical downscaling. A component of many statistical downscaling techniques is quantile mapping (QM). QM can be applied at different spatial scales, and here we study how skill varies with spatial scale. We find the highest skill is generally obtained when applying QM at approximately a 50 km spatial scale.
Hydrol. Earth Syst. Sci. Discuss., 12, 10893-10920, doi:10.5194/hessd-12-10893-2015, 2015
Modeling the distributed effects of forest thinning on the long-term water balance and stream flow extremes for a semi-arid basin in the southwestern US
Summary: We use a distributed hydrologic model to document the potential impacts of a forest restoration project on the mean and extreme hydrologic conditions on a water-supply, semi-arid basin. Results show shifts in spatio-temporal patterns of interception, soil moisture, evapotranspiration, snow persistence and runoff production differently in contrasting aspect slopes. Forest thinning leads to net loss of surface water storage and to a less regulated runoff response during hydrologic extremes.
Hydrol. Earth Syst. Sci. Discuss., 12, 10827-10891, doi:10.5194/hessd-12-10827-2015, 2015
Modelling evapotranspiration during precipitation deficits: identifying critical processes in a land surface model
Hydrol. Earth Syst. Sci. Discuss., 12, 10789-10825, doi:10.5194/hessd-12-10789-2015, 2015
The WACMOS-ET project – Part 1: Tower-scale evaluation of four remote sensing-based evapotranspiration algorithms
Summary: In this study a common reference input data set from satellite and in situ data is used to run 4 established evapotranspiration (ET) algorithms using sub-daily and daily input at tower scale as a testbed for a global ET product. The PT-JPL model and GLEAM provide the best performance for satellite and in situ forcing as well as for the different temporal resolutions. PM-MOD and SEBS perform less convincing: the PM-MOD model is generally underestimating, while SEBS is generally overestimating ET.
Hydrol. Earth Syst. Sci. Discuss., 12, 10739-10787, doi:10.5194/hessd-12-10739-2015, 2015
The inbuilt long-term unfeasibility of environmental flows when disregarding riparian vegetation requirements
Summary: We evaluated the effects of environmental flow regimes disregarding riparian vegetation in the long-term perspective of the fluvial ecosystem. Environmental flow regimes influence riparian vegetation. Fish habitat availability changes accordingly to the long-term structural adjustments of riparian habitat. Incorporating riparian requirements on environmental flows is mandatory to assure the effectiveness of environmental flow regimes in the long-term perspective of the fluvial ecosystem.
Hydrol. Earth Syst. Sci. Discuss., 12, 10701-10737, doi:10.5194/hessd-12-10701-2015, 2015
The WACMOS-ET project – Part 2: Evaluation of global terrestrial evaporation data sets
Summary: The WACMOS-ET project aims to advance the development of land evaporation estimates at global and regional scales. We have evaluated current products at the global scale and concluded that they all manifest large dissimilarities during conditions of water stress and drought, and deficiencies in the way evaporation is partition into several components. Different models perform better under different conditions, highlighting the potential for considering biome- or climate-specific model ensembles.
Hydrol. Earth Syst. Sci. Discuss., 12, 10651-10700, doi:10.5194/hessd-12-10651-2015, 2015
Improving flood forecasting capability of physically based distributed hydrological model by parameter optimization
Hydrol. Earth Syst. Sci. Discuss., 12, 10603-10649, doi:10.5194/hessd-12-10603-2015, 2015
Improved large-scale hydrological modelling through the assimilation of streamflow and downscaled satellite soil moisture observations
Summary: We perform a joint assimilation experiment of high resolution satellite soil moisture and discharge observations in the Murrumbidgee river basin with a large-scale hydrological model. Additionally, we study the impact of high and low resolution meteorological forcing on the model performance. We show that the assimilation of high resolution satellite soil moisture and discharge observations has a significant impact on discharge simulations and can bring them closer to locally calibrated models.
Hydrol. Earth Syst. Sci. Discuss., 12, 10559-10601, doi:10.5194/hessd-12-10559-2015, 2015
A scaling approach to Budyko's framework and the complementary relationship of evapotranspiration in humid environments: case study of the Amazon River basin
Summary: We study a 3-D generalization of Budyko's framework that captures the interdependence among actual and potential evapotranspiration and precipitation. We demonstrate that Budyko-type equations present an inconsistency in humid environments, which we overcome by proposing a physically consistent power law that incorporates the complementary relationship of evapotranspiration into the Budyko curve. Evidence of space-time symmetry and signs of co-evolution of catchments are found in Amazonia.
Hydrol. Earth Syst. Sci. Discuss., 12, 10515-10557, doi:10.5194/hessd-12-10515-2015, 2015
Recent changes in climate, hydrology and sediment load in the Wadi Abd, Algeria (1970–2010)
Summary: Changes of T, P, Q and sediment fluxes in a semi-arid basin little affected by human activities are analyzed from 40-years of measurements. T increased, P decreased, an earlier onset of first summer rains occurred. The flow regime shifted from perennial to intermittent. Sediment flux almost doubled every decade. The sediment regime shifted from two equivalent seasons of sediment delivery to a single major season regime. The C-Q rating curve ability declined due to enhanced hysteresis effects.
Hydrol. Earth Syst. Sci. Discuss., 12, 10457-10513, doi:10.5194/hessd-12-10457-2015, 2015
Comparison of methods for separating flood frequency of reservoir by sub-seasons
Hydrol. Earth Syst. Sci. Discuss., 12, 10431-10455, doi:10.5194/hessd-12-10431-2015, 2015
Assessment of small-scale variability of rainfall and multisatellite precipitation estimates using a meso-rain gauge network measurements from southern peninsular India
Hydrol. Earth Syst. Sci. Discuss., 12, 10389-10429, doi:10.5194/hessd-12-10389-2015, 2015
Comment on "Using groundwater age and hydrochemistry to understand sources and dynamics of nutrient contamination through the catchment into Lake Rotorua, New Zealand" by Morgenstern et al. (2015)
Summary: We comment on “Using groundwater age and hydrochemistry to understand sources and dynamics of nutrient contamination through the catchment into Lake Rotorua, New Zealand” by Morgenstern et al. (2015). They propose that "the only effective way to limit algae blooms and improve lake water quality in such environments is by limiting the nitrate load". We outline four reasons why we believe it is important to limit both phosphorus and nitrogen loads to this iconic lake.
Hydrol. Earth Syst. Sci. Discuss., 12, 10379-10388, doi:10.5194/hessd-12-10379-2015, 2015
Assessment of the influence of bias correction on meteorological drought projections for Poland
Hydrol. Earth Syst. Sci. Discuss., 12, 10331-10377, doi:10.5194/hessd-12-10331-2015, 2015
Evaluation of five hydrological models across Europe and their suitability for making projections under climate change
Summary: The main aims of this paper are the evaluation of five large-scale hydrological models across Europe and the assessment of the suitability of the models for making projections under climate change. While we found large inter-model differences in biases, the skill to simulate interannual variability in discharge did not differ much between the models. Assuming that the skill of a model to simulate interannual variability provides a measure for the model’s ability to make projections under climate
Hydrol. Earth Syst. Sci. Discuss., 12, 10289-10330, doi:10.5194/hessd-12-10289-2015, 2015
Precipitation ensembles conforming to natural variations derived from Regional Climate Model using a new bias correction scheme
Summary: A primary advantage of using model ensembles for climate change impact studies is to represent the uncertainties associated with models through the ensemble spread. Currently, most of the conventional bias correction methods adjust all the ensemble members to one reference observation. As a result, the ensemble spread is degraded during bias correction. However the proposed method is able to correct the bias and conform to the ensemble spread so that the ensemble information can be better used.
Hydrol. Earth Syst. Sci. Discuss., 12, 10261-10287, doi:10.5194/hessd-12-10261-2015, 2015
Quantifying the nutrient flux within a lowland karstic catchment
Summary: In this study, the nutrient flux occurring within the surface and groundwaters of a lowland karst catchment in western Ireland was investigated with the aid of alkalinity sampling and a hydrological model. Results indicated that denitrification within a number of ephemeral lakes is the main process reducing nitrogen concentrations within the turloughs whereas phosphorus loss is thought to occur mostly via sedimentation and subsequent soil deposition.
Hydrol. Earth Syst. Sci. Discuss., 12, 10221-10260, doi:10.5194/hessd-12-10221-2015, 2015
A comparison of the modern Lie scaling method to classical scaling techniques
Summary: This article summarizes the theory and demonstrates the technique of a new scaling method known as the Lie scaling. In the course of applying the method to two example problems, classical notions of dynamical and kinematic scaling are incorporated. The two example problems are: a 2D unconfined groundwater problem in a heterogeneous soil, and a 1D contaminant transport problem. The article concludes with comments on the relative strengths and weaknesses of Lie scaling and classical scaling.
Hydrol. Earth Syst. Sci. Discuss., 12, 10197-10219, doi:10.5194/hessd-12-10197-2015, 2015
Impacts of climate change under CMIP5 RCP scenarios on the streamflow in the Dinder River and ecosystem habitats in Dinder National Park, Sudan
Summary: We assess the impact of future climate change on the Dinder River streamflow-Sudan, and infer its relative possible effects on the Dinder National Park (DNP) ecosystem habitats. Two GCMs from CMIP5 and two statistical downscaling approaches combined with SWAT were used. Climate over the basin will become warmer and wetter and the streamflow will likely increase, accordingly the ecosystems in DNP will be affected positively and promote the ecological restoration of the flora and fauna habitats’.
Hydrol. Earth Syst. Sci. Discuss., 12, 10157-10195, doi:10.5194/hessd-12-10157-2015, 2015
Impact of climate change on groundwater in a confined Mediterranean aquifer
Hydrol. Earth Syst. Sci. Discuss., 12, 10109-10156, doi:10.5194/hessd-12-10109-2015, 2015
Parameter regionalization of a monthly water balance model for the conterminous United States
Hydrol. Earth Syst. Sci. Discuss., 12, 10023-10066, doi:10.5194/hessd-12-10023-2015, 2015
Investigating effects of different evapotranspiration (ET) schemes on soil water dynamics and ET partitioning: a large lysimeter case of summer maize in a semi-arid environment northwest of China
Summary: The coupled water vapor and heat transport model with two different ET (ETdir, ETind) schemes differ in simulating soil water content and evapotranspiration components while agree well for the simulation of soil temperature. Considering the aerodynamic and surface resistance terms make the ETdir scheme better in simulating soil evaporation especially after irrigation. The interactive effect of crop growth parameters with changing environment play an important role in estimating ET components.
Hydrol. Earth Syst. Sci. Discuss., 12, 9977-10022, doi:10.5194/hessd-12-9977-2015, 2015
Stream flow recession patterns can help unravel the role of climate and humans in landscape co-evolution
Summary: We analyse how stream discharge declines after rain storms. This "recession" behaviour contains information about the capacity of the catchment to hold or release water. Looking at many rivers in Sweden, we were able to link distinct recession regimes to land use and catchment characteristics. Trends in recession behaviour are found to correspond to intensifying agriculture and extensive reforestation. We conclude that both men and nature reorganizes the soil in order to enhance efficiency.
Hydrol. Earth Syst. Sci. Discuss., 12, 9865-9913, doi:10.5194/hessd-12-9865-2015, 2015
Modeling runoff and erosion risk in a~small steep cultivated watershed using different data sources: from on-site measurements to farmers' perceptions
Hydrol. Earth Syst. Sci. Discuss., 12, 9701-9740, doi:10.5194/hessd-12-9701-2015, 2015
A quantitative analysis to objectively appraise drought indicators and model drought impacts
Summary: To date, there is little empirical evidence as to which indicator best represents drought impact occurrence for any given region and/or sector. We therefore exploited text-based data from the European Drought Impact report Inventory (EDII) to evaluate drought indicators, empirically determine indicator thresholds, and model drought impacts. A quantitative analysis using Germany and the UK as a testbed proved to be a useful tool for objectively appraising drought indicators.
Hydrol. Earth Syst. Sci. Discuss., 12, 9437-9488, doi:10.5194/hessd-12-9437-2015, 2015
Sustainability of water uses in managed hydrosystems: human- and climate-induced changes for the mid-21st century
Summary: We assess the sustainability of planned water uses in complex mesoscale river basins by modeling water demand and availability under climatic and anthropogenic changes. We present an analysis through indicators that relate to water management goals. The impacts of climate projections on both water availability and demand question the water allocations and environmental constraints currently planned for the coming decades.This work brings an essential long-term perspective to water sharing plans.
Hydrol. Earth Syst. Sci. Discuss., 12, 9247-9293, doi:10.5194/hessd-12-9247-2015, 2015
Using geochemical tracers to distinguish groundwater and parafluvial inflows in rivers (the Avon Catchment, SE Australia)
Summary: This paper uses the natural geochemical tracer Rn together with streamflow measurements to differentiate between groundwater inflows to rivers and water that exits the river, flows through the near-river sediments, and subsequently re-enters the river downstream (parafluvial flow). Distinguishing between these two components is important to understanding the water balance and in managing and protecting surface water resources.
Hydrol. Earth Syst. Sci. Discuss., 12, 9205-9246, doi:10.5194/hessd-12-9205-2015, 2015
Determinants of modelling choices for 1-D free-surface flow and erosion issues in hydrology: a review
Summary: This paper investigates the determinants of modelling choices, for 1-D free-surface flow and erosion issues, across multiple spatiotemporal scales. These determinants are sought in the interplay between flow typologies, cross-scale and scale-independent arguments. This review helps modellers positioning their choices with respect to the most frequent practices, within a generic, normative procedure possibly enriched by the community for a comprehensive, updatable image of modelling strategies.
Hydrol. Earth Syst. Sci. Discuss., 12, 9091-9155, doi:10.5194/hessd-12-9091-2015, 2015
High-end climate change impact on European water availability and stress: exploring the presence of biases
Summary: A set of the new Euro-CORDEX projections is used to examine the impact of high-end scenarios on water availability and stress at pan-European scale. Drought climatology is investigated for five major European basins along with the impact of +2C versus +4C warming. The effect of bias correction is also examined. The selection of the observational dataset used for bias adjustment has an impact on the projected signal that could be of the same order of magnitude as the selection of the RCM.
Hydrol. Earth Syst. Sci. Discuss., 12, 7267-7325, doi:10.5194/hessd-12-7267-2015, 2015
Linking biogeochemistry to hydro-geometrical variability in tidal estuaries: a generic modeling approach
Summary: A generic estuarine model is applied to three idealized tidal estuaries representing the main hydro-geometrical estuarine classes. The study provides insight on the estuarine biogeochemical dynamics, in particular the air-water CO2 flux, as well as on the potential response to future environmental changes and to uncertainties in model parameter values. We believe that our approach could help improving upscaling strategies to better integrate estuaries in regional/global biogeochemical studies.
Hydrol. Earth Syst. Sci. Discuss., 12, 6351-6435, doi:10.5194/hessd-12-6351-2015, 2015