Quantifying trends in surface energy fluxes is crucial for forecasting ecological responses in Arctic regions. An extensive evaluation using a thermal-based remote sensing model and ground measurements was performed in Alaska's Arctic tundra for 5 years. Results showed an accurate temporal trend of surface energy fluxes in concert with vegetation dynamics. This work builds toward a regional implementation over Arctic ecosystems to assess response of surface energy fluxes to climate change.

This paper reviews how weather radar data can be used in urban hydrological applications. It focuses on three areas of research: (1) temporal and spatial resolution of rainfall data, (2) rainfall estimation, radar data adjustment and data quality, and (3) nowcasting of radar rainfall and real-time applications. Moreover, the paper provides examples of urban hydrological applications which can benefit from radar rainfall data in comparison to tradition rain gauge measurements of rainfall.

Retardation of migrating contaminant vapors in the subsurface may mitigate groundwater contamination or vapor intrusion into buildings. An experimental investigation was conducted to quantify the retardation of carbon disulfide (CS₂) vapor in moist porous media based on the analysis of concentration breakthrough curves. Findings linked retardation to types of porous media and water saturation. Moreover, the first evidence of biodegradation of the CS₂ vapor was found in the column experiments.

This paper analyses the European summer drought of 2015 from a climatological perspective, including its origin and spatial and temporal development, and how it compares with the 2003 event. It discusses the main contributing factors controlling the occurrence and persistence of the event: temperature and precipitation anomalies, blocking episodes and sea surface temperatures. The results represent the outcome of a collaborative initiative of members of UNESCO’s FRIEND-Water program.

We computed stemflow yield and efficiency, and analyzed the influential mechanism at smaller scales of leaf and raindrop. We found that precipitation was the most influential meteorological feature on stemflow. The smaller threshold precipitation to start stemflow and the more beneficial leaf traits might partly explain the larger and more efficient stemflow production. At defoliated period, the newly exposed stems replaced leaves to intercept raindrops and might really matter in stemflow yield.

The paper presents a general methodology that will help understand how freshwater and saltwater may interact in natural porous media, with a particular view at practical applications such as the storage of freshwater underground in critical areas, e.g., semi-arid zones around the Mediterranean sea. The methodology is applied to a case study in Sardinia and shows how a mix of advanced monitoring and mathematical modeling tremendously advance our understanding of these systems.

This study evaluated dynamic climate model sub-seasonal forecasts for important precipitation and temperature indices over the contiguous United States. The presence of active Madden-Julian Oscillation (MJO) events improved weekly mean precipitation forecast skill over most regions. Sub-seasonal forecast indices calculated from the daily forecast showed higher skill than temporally downscaled forecasts, suggesting the usefulness of the daily forecast for sub-seasonal hydrological forecasting.

We constructed an integrated probabilistic assessment to describe, simulate and evaluate the stochasticity of soil erosion in restoration vegetation in the Loess Plateau. We found that morphological structures in vegetation are the source of different stochasticities of soil erosion, and proved that the Poisson model is fit for predicting erosion stochasticity. This assessment could be an important complement to develop restoration strategies to improve understanding of stochasticity of erosion.

The relationship between controlling parameters of annual catchment water balance and climate seasonality (S) and vegetation coverage (M) was discussed under the Budyko framework and an empirical equation was further developed so that the contributions from M to actual evapotranspiration (ET) could be determined more accurately. The results showed that the effects of landscape condition changes to ET variation will be estimated with a large error if the impacts of S are ignored.

Within the framework of the EU project IMPROWARE, our goal was to investigate a Mediterranean coastal aquifer in Egypt and develop scenarios for artificial aquifer remediation and recharge. The results of an extensive hydrogeophysical investigation were successfully used as an input in regional and local hydrological models to understand the hydrological evolution of the area. The research outcomes clearly highlight the effectiveness of using advanced geophysical and modeling methodologies.

In this study dimensionally consistent governing equations of continuity and motion for transient soil water flow and water flux in fractional time and in fractional multiple space dimensions in anisotropic media are developed. By the introduction of the Brooks–Corey constitutive relationships, an explicit form of the equations is obtained. The developed governing equations, in their fractional time but integer space forms, show behavior consistent with the previous experimental observations.

We investigated the relative contribution of the spatial versus climatic rainfall variability for flow peaks by applying an advanced stochastic rainfall generator to simulate rainfall for a small urban catchment and simulate flow dynamics in the sewer system. We found that the main contribution to the total flow variability originates from the natural climate variability. The contribution of spatial rainfall variability to the total flow variability was found to increase with return periods.

The use of general circulation model outputs for streamflow forecasting has developed in the last decade. In parallel, traditional streamflow forecasting is commonly based on historical data. This study investigates the impact of conditioning historical data based on circulation model precipitation forecasts on seasonal streamflow forecast quality. Results highlighted a trade-off between the sharpness and reliability of forecasts.

We present a new catchment model that covers most major pollutants and is suitable for uncertainty analysis. The effects of climate change, population dynamics, socio-economic development, and management strategies on water quality are demonstrated in a small catchment in the Swiss Plateau. Models and data are still the largest sources of uncertainty for some water quality parameters. Uncertainty assessment helps to select robust management and focus research and monitoring efforts.

Seasonal early warning is vital for drought management in arid regions like the Limpopo Basin in southern Africa. This study shows that skilled seasonal forecasts can be achieved with statistical methods built upon driving factors for drought occurrence. These are the hydrological factors for current streamflow and meteorological drivers represented by anomalies in sea surface temperatures of the surrounding oceans, which combine to form unique combinations in the drought forecast models.

We use historical records to extend current understanding of flood risk, examining past spatial and temporal variability and ask are the perceived high-magnitude flood events witnessed in recent years really unprecedented? We identify that there are statistically significant relationships between the British flood index and climatic drivers, whereby the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented.

The notion of a measure to quantify the degree of heterogeneity of a region from which information is required to estimate the magnitude of events at ungauged sites is introduced. These heterogeneity measures are needed to compare regions, evaluate the impact of particular sites, and rank the performance of delineating methods. A framework to define and assess their desirable properties is proposed. Several heterogeneity measures are presented and/or developed to be assessed, giving guidelines.

For impact modeling, infrastructure design, or adaptation strategy planning, high-quality climate data on the point scale are often demanded. Due to the scale gap between gridbox and point scale and biases in climate models, we combine a statistical bias correction and a stochastic downscaling model and apply it to climate model-simulated precipitation. The method performs better in summer than in winter and in winter best for mild winter climate (Mediterranean) and worst for continental winter.

We present a newly developed instrument package that enables the online analysis of stable water isotopes and major ion chemistry at 30 min intervals in the field. The resulting data streams provide an unprecedented view of hydrochemical dynamics on the catchment scale. Based on a detailed analysis of the variable behavior of isotopic and chemical tracers in stream water and precipitation over a 4-week period, we developed a conceptual hypothesis for runoff generation in the studied catchment.

We discuss a dual-domain water transport model in a physics-based snowpack model to account for preferential flow (PF) in addition to matrix flow. So far no operationally used snow model has explicitly accounted for PF. The new approach is compared to existing water transport models and validated against in situ data from sprinkling and natural rain-on-snow (ROS) events. Our work demonstrates the benefit of considering PF in modelling hourly snowpack runoff, especially during ROS conditions.

This paper investigates soil water migration processes in the Loess Plateau using isotopes. The soil water migration is dominated by piston-type flow, but rarely preferential flow. Soil water from the soil lay (20–40 cm) contributed to 6–12% of plant xylem water, while soil water at the depth of 40–60 cm is the largest component (range from 60 to 66 %), soil water below 60 cm depth contributed 8–14 % to plant xylem water, and only 5–8 % is derived from precipitation.

We discuss the estimation of a long-term, high-resolution, continuous and consistent dataset of hydro-meteorological variables for Germany. Here we describe the derivation of national-scale parameter sets and analyze the uncertainty of the estimated hydrologic variables (focusing on the parametric uncertainty). Our study highlights the role of accounting for the parametric uncertainty in model-derived hydrological datasets.

Hydrologic connectivity of geographically isolated wetlands is poorly understood. We develop a model to characterize both the subsurface and surface hydrologic connectivity of these wetlands within the Prairie Pothole Region of North America. We show they are not isolated but have surface and subsurface hydrologic connections that vary in time and distance traveled to reach the river. Distance from the river, which is used to protect wetlands, is not an effective proxy of connectivity.

We compare lysimeter and eddy covariance (EC) flux measurements of evapotranspiration at a research catchment in Switzerland. The measurements are compared on various timescales, and with respect to a 40-year long-term lysimeter time series. Overall, the lysimeter and EC measurements agree well, especially on the annual timescale. Furthermore, we identify that lack of reliable EC data during/after rainfall events significantly contributes to an underestimation of EC evapotranspiration.

This study focuses on predictive uncertainties in the snow hydrology of British Columbia's Fraser River Basin (FRB), using the Variable Infiltration Capacity (VIC) model forced with several gridded climate datasets. Intercomparisons of forcing datasets and VIC simulations are performed to identify their strengths and weaknesses. This reveals widespread differences over FRB's mountains in precipitation and air temperature forcing datasets and their VIC simulations of runoff/snow water equivalent.

Terrestrial water storage is defined as the total volume of water stored within the land surface and sub-surface and is a key variable for tracking long-term variability in the global water cycle. Currently, annual variations in terrestrial water storage can only be measured at extremely coarse spatial resolutions (> 200 000 km²) using gravity-based remote sensing. Here we provide evidence that microwave-based remote sensing of soil moisture can be applied to enhance this resolution.

Accurate estimation of stream/river flows is important in many aspects, including public safety during floods, effective uses of water resources for hydropower generation and irrigation, and environments. In this paper, we investigated a feasibility of the continuous slope area (CSA) method which measures dynamic changes in instantaneous water surface elevations, and the results showed promising capabilities of the suggested method for the accurate estimation of flows in natural streams/rivers.