We show the utility of ground-based time-lapse cameras for automated monitoring of stream stage and flow characteristics. High-frequency flow stage, water surface width and other information on the state of flow can be acquired for extended time periods with simple local calibration using a low-cost time-lapse camera and a few simple field measurements for calibration and for automated image selection and sorting. The approach is a useful substitute or complement to the conventional stage data. Hide

We use sap velocity measurements from 61 trees on 132 days to gain knowledge about the controls of landscape-scale transpiration, distinguishing tree-, stand- and site-specific controls on sap velocity and sap flow patterns and examining their dynamics during the vegetation period. Our results show that these patterns are not exclusively determined by tree characteristics. Thus, including site characteristics such as geology and aspect could be beneficial for modelling or management purposes. Hide

Responses of inland waters to climate change vary on global and regional scales. Shifts in river discharge regimes act as positive and negative feedbacks in influencing water temperature. The extent of this effect on warming is controlled by the change in river discharge and lake hydraulic residence time. A shift of deep penetrating river intrusions from summer towards winter can potentially counteract the otherwise negative climate effects on deep-water oxygen content. Hide

Seasonal shallow water tables (WTs) in lowlands limit vegetation-buffer efficiency to control runoff pollution. Mechanistic models are needed to quantify true field efficiency. A new simplified algorithm for soil infiltration over WTs is tested against reference models and lab data showing WT effects depend on local settings but are negligible after 2 m depth. The algorithm is coupled to a complete vegetation buffer model in a companion paper to analyze pesticide and sediment control in situ. Hide

Vegetation buffers, often placed in lowlands to control runoff pollution, can exhibit limited efficiency due to seasonal shallow water tables (WTs). A new shallow water table infiltration algorithm developed in a companion paper is coupled to a complete vegetation buffer model to quantify pesticide and sediment control in the field. We evaluated the model on two field experiments in France with and without WT conditions and show WTs can control efficiency depending on land and climate settings. Hide

The new tile drainage routine in the SWAT model provided more realistic and accurate simulation of tile drainage, and the new curve number retention parameter adjustment factor improved surface runoff simulation, and is suitable for surface runoff simulation in mildly sloped watersheds. This study can provide guidance for selection of tile drainage routines for tile drainage simulation, and can allow accurate simulation of hydrological systems at both field and watershed scales. Hide

This paper evaluates the performance of two commonly used land surface models in simulating deforestation-induced change in surface fluxes using paired FLUXNET observations. Our results highlight the shortcomings in the energy partitioning between latent and sensible heat flux over different land cover types, suggesting the need to improve the representation of surface heat flux processes in land models to increase confidence in LULCC-climate simulations. Hide

The theme of the paper is exploration of the potential for seasonal flow forecasting for large lakes using a range of stochastic transfer function techniques with additional insights gained from simple analytical approximations. The methods were evaluated using records for two of the largest lakes in the world. The paper concludes with a discussion of the relevance of the results to operational flow forecasting systems for other large lakes. Hide

The study proposes advancing local-level seasonal rainfall predictions by first conditioning on regional-level predictions, as defined through cluster analysis. This statistical approach is applied to western Ethiopia, where lives and livelihoods are vulnerable to its high spatial–temporal rainfall variability, particularly given the high reliance on rain-fed agriculture. The statistical model improves in skills versus the non-clustered case or dynamical models for some critical regions. Hide

The internal variability of paleomeanders strongly influence water fluxes in alluvial plains. This study presents the results of a hydrogeophysical investigation that provide a very detailed characterization of the geometry of a wide paleomeander. The presented case study, situated in the Seine River basin (France), represents a common sedimentary and geomorphological structure in alluvial plains worldwide. Hide

Certain particles that have the ability to absorb sunlight deposit onto mountain snow via atmospheric transport mechanisms and then lower the snow's ability to reflect sunlight, which increases snowmelt. Herein we present a model aiming to simulate this effect and model the impacts on the streamflow of a southern Norwegian river. We find a significant difference in streamflow between simulations with and without the effect of light absorbing particles applied, in particular during spring melt. Hide

Hydrological fingerprints are introduced as response targets for sensitivity analysis and combined with a conventional approach using streamflow data for a temporally resolved sensitivity analysis. The joint benefit of both approaches is presented for several headwater catchments. The approach allows discerning a clarified pattern for parameter influences pinpointed to diverse response characteristics and detecting even slight regional differences. Hide

This study helps hydrologists better understand the parameters in modeling seawater intrusion in a coastal karst aquifer. Local and global sensitivity studies are conducted to evaluate a density-dependent numerical model of seawater intrusion. The sensitivity analysis indicates that karst features are critical for seawater intrusion modeling, and the evaluation of hydraulic conductivity is biased in continuum SEAWAT model. Dispervisity is no longer important in the advection-dominated aquifer. Hide

A global data record for all four terrestrial water budget variables (precipitation, evapotranspiration, runoff, and total water storage change) at 0.5° resolution and monthly scale for the period of 1984–2010 is developed by optimally merging a series of remote sensing products, in situ measurements, land surface model outputs, and atmospheric reanalysis estimates and enforcing the mass balance of water. Initial validations show the data record is reliable for climate related analysis. Hide

We present a two-stage statistical downscaling model for the probabilistic prediction of local precipitation, where the downscaling statistical link is estimated from atmospheric circulation analogs of the current prediction day. The model allows for a day-to-day adaptive and tailored downscaling. It can reveal specific predictors for peculiar and non-frequent weather configurations. This approach noticeably improves the skill of the prediction for both precipitation occurrence and quantity. Hide

Some do not realize the intrinsic importance of water until there is no water left. This is the reality faced by people in southern Peru, a dry area of the world where several economic activities and cities vie for scarce water resources. With the developed season-ahead precipitation prediction model, stakeholders and decision makers in this region will have another tool in their belt to respond to and plan for the negative impacts brought on by drought. Hide

Our results showed that adaptations through designing and updating urban drainage systems are effective in coping with urban flood risk under climate change. In the case study region, the magnitude of urban flood risk reduction through adaptations is more than double that by climate mitigations. We emphasize the importance of accounting for both global-scale climate mitigation and local-scale adaptations in assessing future urban flood risks in a consistent frame. Hide

This paper argues for an alternative approach for socio‒hydrology: detailed case study research. Detailed case study research can increase understanding of how society interacts with hydrology, offers more levers for management than coupled modelling, and facilitates interdisciplinary cooperation. The paper presents a case study of the Dommel Basin in the Netherlands and Belgium and compares this with a published model of the Kissimmee Basin in Florida. Hide

This paper proposes a two-step investigation to illustrate the extent of scale effects in urban hydrology. First, fractal tools are used to highlight the scale dependency observed within GIS data inputted in urban hydrological models. Then an intensive multi-scale modelling work was carried out to confirm effects on model performances. The model was implemented at 17 spatial resolutions ranging from 100 to 5 m. Results allow the understanding of scale challenges in hydrology modelling. Hide

The dynamics of basin-scale water budgets over the Tibetan Plateau (TP) are not well understood nowadays due to the lack of hydro-climatic observations. In this study, we investigate seasonal cycles and trends of water budget components (e.g. precipitation P, evapotranspiration ET and runoff Q) in 18 TP river basins during the period 1982–2011 through the use of multi-source datasets (e.g. in situ observations, satellite retrievals, reanalysis outputs and land surface model simulations). Hide

This paper sheds light on the integration of interdisciplinary knowledge in the assessment of flood vulnerability in Taquari-Antas river basin, Brazil. It shows how stakeholder participation is crucial for increasing not only the acceptance of model results but also its quality. Hide

We investigate the usefulness of assimilating crowdsourced observations from a heterogeneous network of sensors for different scenarios of citizen involvement levels during the flood event occurred in the Bacchiglione catchment in May 2013. We achieve high model performance by integrating crowdsourced data, in particular from citizens motivated by their feeling of belonging to a community. Satisfactory model performance can still be obtained even for decreasing citizen involvement over time. Hide

The effect of storm scale and movement on runoff flows in urban catchments remains poorly understood due to the complexity of urban land use and man-made infrastructure. In this study, interactions among rainfall, urbanisation and peak flows were analyzed based on 15 years of radar rainfall and flow observations. We found that flow-path networks strongly smoothed rainfall peaks. Unexpectedly, the storm position relative to impervious cover within the basins had little effect on flow peaks. Hide

In eastern Austria, where air temperature rise is double that recorded globally, stream temperatures of a human-impacted river were simulated during heat waves, as calculated by regional climate models until 2100. An increase of up to 3 °C was predicted – thus exceeding thresholds of resident cold-adapted species. Vegetation management scenarios showed that adding vegetation can reduce both absolute temperatures and its rate of increase but is not able to fully mitigate the expected rise. Hide

Glaciers are important hydrological reservoirs. Short-term variability in glacier melt and also glacier retreat can cause droughts in streamflow. In this study, we analyse the effect of glacier changes and different drought threshold approaches on future projections of streamflow droughts in glacierised catchments. We show that these different methodological options result in different drought projections and that these options can be used to study different aspects of streamflow droughts. Hide

The study shows the importance of the connection between groundwater and surface water nutrient chemistry in a lowland delta area – the greater Amsterdam area. We expect that taking account of groundwater–surface water interaction is also important in other subsiding and urbanising deltas around the world, where water is managed intensively in order to enable agricultural productivity and achieve water-sustainable cities. Hide

We explore the signal of a warmer climate in the suspended-sediment dynamics of a regulated and human-impacted Alpine catchment. We demonstrate that temperature-driven enhanced melting of glaciers, which occurred in the mid-1980s, played a dominant role in suspended sediment concentration rise, through increased runoff from sediment-rich proglacial areas, increased contribution of sediment-rich meltwater, and increased sediment supply in proglacial areas due to glacier recession. Hide

Process prediction of seasonal drought is the goal of our study. We developed a drought prediction model based on atmospheric–oceanic anomalies. It is essentially the synchronous statistical relationship between atmospheric–oceanic anomalies and precipitation anomalies, forced by seasonal climate forecast models. It can predict seasonal drought development very well, despite its weakness in drought severity. Hide

There are very few studies found globally where the impact of hydropower on drought issues has been addressed. Furthermore, recent development of hydropower and its impact on streamflow on the downstream is still not explored. This study tries to address the associated impact of hydropower on streamflow drought which may directly affect the irrigation, water, and energy production. The developed method helps the decision makers to identify the potential impact of hydropower on downstream users. Hide

Which is the dominant effect on evapotranspiration in northern forests, an increase by recent forests expansion or a decrease by the water use response due to increasing CO₂ concentrations? We determined the dominant effect during the period 1961–2012 in 65 Swedish basins. We used the Budyko framework to study the hydroclimatic movements in Budyko space. Our findings suggest that forest expansion is the dominant driver of long-term and large-scale evapotranspiration changes. Hide

This study is the first to describe the quantitative association between forest and plantation areas and the flow indicators (surface runoff and baseflow) in a watershed; this understanding is required by spatial planners if they are to balance the ecology and socioeconomic functions of a landscape with the rapid expansion of plantation crops. In addition, our study provides data regarding how SWAT input parameters related to tropical plantations such as oil palm and rubber should be adjusted. Hide

Water resources in the Arkavathy watershed in southern India are changing due to human modification of the landscape, including changing agricultural practices and urbanization. We analyze surface water resources in man-made lakes in satellite imagery over a period of 4 decades and find drying in the northern part of the watershed (characterized by heavy agriculture) and wetting downstream of urban areas. Drying in the watershed is associated with groundwater-irrigated agriculture. Hide

Assessing the potential impacts of extreme events such as drought and flood requires large datasets of such events, especially when looking at the most severe and rare events. Using a state-of-the-art climate modelling infrastructure that is simulating large numbers of weather time series on volunteers' computers, we generate such a large dataset for the United Kingdom. The dataset covers the recent past (1900–2006) as well as two future time periods (2030s and 2080s). Hide

Documenting mean transit times is critical for understanding and managing catchments. Mean transit times in six headwater catchments of the Otway Ranges, Australia, determined using tritium, range from 7 to 230 years. Tritium activities correlate well with streamflow but are difficult to predict from catchment attributes or major ion geochemistry. The long mean transit times suggest that the catchments are buffered from short-term rainfall variations. Hide

This research paper proposes a multi-site daily precipitation model, named GWEX, which aims to reproduce the statistical features of extremely rare events at different temporal and spatial scales. Recent advances and various statistical methods (regionalization, disaggregation) are considered in order to obtain a robust and appropriate representation of the most extreme precipitation fields. Performances are shown with an application to 105 stations, covering a large region in Switzerland. Hide

Here, the first assessment of future changes in extreme precipitation in small Mediterranean watersheds is done through three watersheds frequently subjected to flash floods. Collaboration between Spanish and French laboratories enabled us to conclude that the intensity of high precipitation will increase at the end of the century. A high degree of confidence results from the multi-model approach used here with eight regional climate models (RCMs) developed in the Med and Euro-CORDEX project. Hide

Climate change is expected to worsen water quality in the Chesapeake Bay Watershed. To efficiently mitigate climate change impacts, it is important to understand changes in hydrology and nutrient cycles under climate change. This study examined key factors vulnerable to climate change considering local characteristics. Croplands were a decisive factor in degrading water quality for this region. Thus, mitigation activities should be prepared for croplands to reduce water quality degradation. Hide

We applied the Variable Infiltration Capacity hydrologic model to examine scenarios of change under climate and landscape disturbances in the San Juan River basin, a major sub-watershed of the Colorado River basin. Climate change coupled with landscape disturbance leads to reduced streamflow in the San Juan River basin. Disturbances are expected to be widespread in this region. Therefore, accounting for these changes within the context of climate change is imperative for water resource planning. Hide

Extreme rainfall is one of the most significant natural hazards. However, estimating very large events is highly uncertain. We present a new approach to construct intense rainfall using the structure of rainfall generation in clouds. The method is particularly effective at estimating short-duration extremes, which can be the most damaging. This is expected to have immediate impact for the estimation of very rare downpours, with the potential to improve climate resilience and hazard preparedness. Hide

Our interest is focused on developing the hydrophone technique to estimate the size of particles transported in rivers. The analytic spectral solution of the impact between rigid particles is used to model the power spectrum of a sediment mixture, or the sediment-generated noise. Estimations of grain size distributions in the Isère River using real measured spectra are successfully validated by the physical sampling techniques. Moreover, the grain size sorting process is revealed by acoustics. Hide

Six schemes were added to the H08 global hydrological model (GHM) to represent human water abstraction more accurately and ensure that all water fluxes and storage are traceable in each grid cell at a daily interval. The schemes of local reservoirs, aqueduct water transfer, and seawater desalination were incorporated into GHMs for the first time, to the best of our knowledge. H08 has become one of the most detailed GHMs for attributing water sources available to humanity. Hide

Using the DTS technology, we measured the evaporation of a forest using fibre optic cables. The cables work like long thermometers, with a measurement every 12.5 cm. We placed the cables vertically along the tower, one cable being dry, the other kept wet. By looking at the dry and wet cable temperatures over the height we are able to study heat storage and the amount of water the forest is evaporating. These results can be used to better understand the storage and heat exchange of forests. Hide

Global hydrological models aim to model hydrological processes, like flows in a river, on a global scale, as opposed to traditional models which are regional. A big challenge in creating these models is the inclusion of impacts on the hydrological cycle caused by humans, for example by the operation of large (hydropower) dams. The presented study investigates a new way to include these impacts by dams into global hydrological models. Hide

Numerical weather prediction (NWP) models are fundamental for flood early warning, particularly in tropical mountainous watersheds. This paper aims to assess the potential of NWP for flood early warning purposes, and the possible improvement that the post-processing of forecasts can provide, in a tropical mountainous area. The results show the potential of NWP but also the need for more detailed evaluation of the meteorological model in the study area. Hide

This work developed models to predict how much water will be available in the next month to maximise environmental and social outcomes in southern Australia. Initialising the models with observed streamflow data, instead of warmed up by rainfall data, improved the results, even at a monthly lead time, making sure only data representative of the forecast period to develop the models were also important. If this step was ignored, and instead all data were used, poor predictions could be produced. Hide

In China, droughts represent a severe threat to socioeconomic development and ecosystems. It is thus necessary to characterize these events in order to reduce and anticipate their impacts. This study proposes an innovative approach for a catchment-wide drought detection and characterization. Two overall drought indicators have been defined and calibrated with real historical events, which have been collected and cataloged. Hide

We provide a detailed spatial analysis of hydrological impacts of land use change in Amazonia, focusing on the aspect of aerial rivers. Our approach of observation-based atmospheric moisture tracking allows us to recognize potential teleconnection between source and sink regions of atmospheric moisture. Relying on a quantitative assessment, we identified regions where water availability is most sensitive to land use change and regions where land use change is critical for a given sink region. Hide