Abstracted/indexed

Where plants exist, rain must pass through canopies to reach soils. We studied how rain interacts with dogfennel – a highly problematic weed that is abundant in pastures, grasslands, rangelands, urban forests and along highways. Dogfennels evaporated large portions (approx. one-fifth) of rain and drained significant (at times > 25 %) rain (and dew) down their stems to their roots (via stemflow). This may explain how dogfennel survives and even invades managed landscapes during extended droughts.

August Colding contributed the first law of thermodynamics, evaporation from water and grass, steady free surfaces in conduits, the cross-sectional velocity distribution in conduits, a complete theory for the Gulf Stream, air speed in cyclones, the piezometric surface in confined aquifers, the unconfined elliptic water table in soil between drain pipes, and the wind-induced set-up in the sea during storms.

The Standardized Precipitation Index (SPI) is a widely accepted drought index. SPI normalizes the precipitation distribution via a probability density function (PDF). However, which PDF properly normalizes SPI is still disputed. We suggest using a previously mostly overlooked PDF, namely the exponentiated Weibull distribution. The proposed PDF ensures the normality of the index. We demonstrate this – for the first time – for all common accumulation periods in both observations and simulations.

Assessing model sensitivities with ensemble-based methods can be prohibitively expensive when large parts of the plausible parameter space result in model simulations with nonrealistic results. In a previous work, we used the method of active subspaces to create a proxy model with the purpose of filtering out such unrealistic runs at low cost. This work details a notable improvement in the efficiency of the original sampling scheme, without loss of accuracy.

A spatial interpolator has been proposed for exploring the information content of the data in the light of geostatistics and information theory. It showed comparable results to traditional interpolators, with the advantage of presenting generalization properties. We discussed three different ways of combining distributions and their implications for the probabilistic results. By its construction, the method provides a suitable and flexible framework for uncertainty analysis and decision-making.

The isotopic composition of ambient water vapor is an important source of atmospheric water vapor and has not been able to be estimated to date using the Keeling plot approach. Here we proposed two new methods to estimate the isotopic composition of ambient water vapor: one using the intersection point method and another relying on the intermediate value theorem.

With serious concerns about global change rising in the Mediterranean, we established a new climatic classification to follow hydrological and ecohydrological activities. The classification coincided with a geographical distribution ranging from the most seasonal and driest class in the south to the least seasonal and most humid in the north. RCM scenarios showed that northern classes evolve to southern ones with shorter humid seasons and earlier snowmelt which might affect hydrologic regimes.

The USLE is a commonly used model to estimate soil erosion by water. It quantifies soil loss as a product of six inputs representing rainfall erosivity, soil erodibility, slope length and steepness, plant cover, and support practices. Many methods exist to derive these inputs, which can, however, lead to substantial differences in the estimated soil loss. Here, we analyze the effect of different input representations on the estimated soil loss in a large-scale study in Kenya and Uganda.

Snow processes are crucial for runoff in mountainous areas, but their complexity makes water management difficult. Temperature models are widely used as they are simple and do not require much data, but not much thought is usually given to which model to use, which may lead to bad predictions. We studied the impact of many model alternatives and found that a more complex model does not necessarily perform better. Finding which processes are most important in each area is a much better strategy.

Water isotopes are a scientific tool that can be used to identify sources of water and answer questions such as From which soil depths do plants take up water?, which are highly relevant under changing climatic conditions. In the past, the measurement of water isotopes required tremendous effort. In the last decade methods have advanced and can now be applied in the field. Herein, we review the current status of direct field measurements of water isotopes and discuss future applications.

Identifying and quantifying recharge processes linked to ephemeral surface water features is challenging due to their episodic nature. We use a unique combination of well-established near-surface geophysical methods to provide evidence of a surface and groundwater connection in a flat, semi-arid region north of Adelaide, Australia. We show that a combined geophysical approach can provide a unique perspective that can help shape the hydrogeological conceptualization.

This study aims to identify the response of catchment water storage capacity (CWSC) to meteorological drought by examining the changes of hydrological-model parameters after drought events. This study improves our understanding of possible changes in the CWSC induced by a prolonged meteorological drought, which will help improve our ability to simulate the hydrological system under climate change.

In this paper we propose adaptive clustering as a new method for reducing the computational efforts of distributed modelling. It consists of identifying similar-acting model elements during the runtime, clustering them, running the model for just a few representatives per cluster, and mapping their results to the remaining model elements in the cluster. With the example of a hydrological model, we show that this saves considerable computation time, while largely maintaining the output quality.

This research paper proposes a weather generator combining two sampling approaches. A first generator recombines large-scale atmospheric situations. A second generator is applied to these atmospheric trajectories in order to simulate long time series of daily regional precipitation and temperature. The method is applied to daily time series in Switzerland. It reproduces adequately the observed climatology and improves the reproduction of extreme precipitation values.

Multi-year droughts in Mediterranean climates often see a lower fraction of precipitation allocated to runoff compared to non-drought years. By comparing observed water-balance components with simulations by a hydrologic model (PRMS), we reinterpret these shifts as a hysteretic response of the water budget to climate elasticity of evapotranspiration. Our results point to a general improvement in hydrologic predictions across drought and recovery cycles by including this mechanism.

LDAS-Monde is a global offline land data assimilation system (LDAS) that jointly assimilates satellite-derived observations of surface soil moisture (SSM) and leaf area index (LAI) into the ISBA (Interaction between Soil Biosphere and Atmosphere) land surface model (LSM). This study demonstrates that LDAS-Monde is able to detect, monitor and forecast the impact of extreme weather on land surface states.

The simulation of flow in a karst aquifer in a Mediterranean region using a semi-distributed linear reservoir model (geometry and parameterization) is calibrated and validated based on the analysis of high-resolution time series. The model is used to predict the effect of climatic variation. Although the spring is highly sensitive to rainfall variations, it is also resilient to warming temperature. Finally, this integrated conceptual method is reproducible for karst in semiarid regions.

Stormwater infiltration systems (SISs) are a source of pollution that may have adverse ecological and sanitary impacts. The incidence of a SIS on the coalescence of microbial communities from runoff waters and aboveground sediments with those of an aquifer was investigated. Aquifer waters showed lower coalescence with aboveground bacterial taxa than aquifer biofilms. These biofilms were colonized by bacterial hydrocarbon degraders and harboured undesirable human-opportunistic pathogens.

Soil erosion by water has been emphasized as a key problem to be faced in the 21st century. Thus, it is critical to understand land degradation and to answer fundamental questions regarding how and why such processes occur. Here, we present a model for gully erosion (channels carved by rainwater) based on existing equations, and we identify some major variables that influence the initiation and evolution of this process. The successful model can help in planning soil conservation practices.

We have developed an integrated surrogate model for arid irrigated areas with shallow groundwater that links crop growth with soil water and salinity in the vadose zone. The model recognizes that field capacity is reached when the matric potential is equal to the height above the groundwater table. The model applies areas with shallow groundwater for which only very few surrogate models are available for most surface irrigation systems in the world without suffering from high groundwater.

Water that evaporates from Africa's tropical forests provides rainfall throughout the continent. However, there are few sources of meteorological data in central Africa, so we use observations from satellites to estimate evaporation from the Congo Basin at different times of the year. We find that existing evaporation estimates in tropical Africa do not accurately capture seasonal variations in evaporation and that fluctuations in soil moisture and solar radiation drive evaporation rates.

This study mainly explores the hydraulic relations, recharge–drainage relations and their transformation paths, and the processes of each water body. It determines the composition of runoff, quantifies the contribution of each runoff component to different types of tributaries, and analyzes the hydrological effects of the temporal and spatial variation in runoff components. More importantly, we discuss the hydrological significance of permafrost and hydrological processes.

The study compares the uncertainty of discharge curves for vegetated channels, calculated using several methods, including the simplest ones, based on the Manning formula and advanced approaches, providing a detailed physical representation of the channel flow processes. Parameters of each method were identified for the same data sets. The outcomes of the study include the widths of confidence intervals, showing which method was the most successful in explaining observations.