•Large basins are homes to millions of people who depend on water for survival. Water drives the economic engine.•Use of publicly available model output and satellite data.•Analysis of extreme ...events: droughts and floods.
Numerous large river basins of the world have few and irregular observations of the components of the terrestrial hydrological cycle with the exception of stream gauges at a few locations and at the outlet along with sparsely distributed rain gauges. Using observations from satellite sensors and output from global land surface models, it is possible to study these under-observed river basins. With populations greater than a billion people, some of these rivers (e.g., the Ganga-Brahmaputra, the Yangtze, the Nile and the Mekong) are the economic engines of the countries they transect, yet thorough assessment of their flow dynamics and variability in regard to water resource management is still lacking. In this paper, we use soil moisture (0–2 m) and surface runoff from the NASA Global Land Data Assimilation System (GLDAS), evapotranspiration, and Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and rainfall from the Tropical Rainfall Measuring Mission (TRMM) and total water storage anomaly from the Gravity Recovery and Climate Experiment (GRACE) to examine variability of individual water balance components. To this end, understanding the inter-annual and intra-seasonal variability and the spatial variability of the water balance components in the major river basins of the world will help to plan for improved management of water resources for the future.
•Effects of mattic epipedon coverage on surface water conservation capacity were examined.•Declining mattic epipedon cover decreased surface runoff, especially under moderate rainfall.•Increased ...rainfall and mattic epipedon cover decreased evapotranspiration.•Soil water consumption aggravated with decreasing mattic epipedon coverage under non-rainfall.•Higher mattic epipedon cover maintains higher water conservation capacity under moderate rainfall.
The Qinghai-Tibetan Plateau—known as the roof of the world and the water tower of Asia—is facing serious degradation of its ecosystems, with alpine meadows being particularly threatened. However, little is known about how the loss of mattic epipedon (the characteristic topsoil of alpine meadows) alters the water conservation capacity of the region. Here we examined the effects of different mattic epipedon coverages on surface runoff, evapotranspiration, and soil water storage under different rainfall conditions. Our results showed that the surface runoff was significantly higher under moderate rain conditions (P > 10 mm day−1) than under light rain conditions (P < 10 mm day−1), and that declining coverage significantly increased surface runoff, especially under moderate rain conditions. The average evapotranspiration at 90 %, 60 %, and 30 % mattic epipedon coverages were 5.38 mm, 5.88 mm, and 6.38 mm under non-rainfall conditions, and 0.97 mm, 1.60 mm, and 2.24 mm under moderate rain conditions. Meanwhile, mattic epipedon coverage had a positive effect on the supplementation of soil water under moderate rainfall and on the conservation of soil water under non-rainfall conditions. Overall, alpine meadows with higher mattic epipedon coverage were more effective at maintaining surface runoff and improving soil water conservation. These findings highlight the importance of conserving and restoring alpine meadows to improve the water security in the Qinghai-Tibetan Plateau and other downstream regions.
Climate change's profound implications for Mediterranean agriculture underscores the urgency of adaptation strategies. These strategies, whether incentivized or farmer-driven, are pivotal in ...mitigating crop yield losses and harnessing evolving climatic conditions. While the influence of agronomic adaptations on crop yields is well-explored, the implications for water footprint and water balance components remain largely unexplored.
With this study, we aim to conduct a comprehensive assessment of the adaptive capacity of agricultural systems in the Ombrone catchment, Tuscany. We estimate the impacts of both climate change and adaptation strategies - also referred to as management changes - on crop yields, water footprint and water balance components by comparing simulations with historical and future climate and with and without adaptation strategies.
A Soil and Water Assessment Tool (SWAT+) agro-hydrological model of the Ombrone catchment is calibrated for crop yields of durum wheat, sunflower and irrigated maize. The impacts of climate change are then assessed by forcing the calibrated model with climate data from five bias-corrected regional climate models under Representative Concentration Pathways (RCPs) 4.5 and 8.5. Subsequently, we simulate six autonomous agronomic adaptation strategies (earlier and later sowing, supplemental irrigation, longer crop cycles, zero tillage and cover crops). We quantify their impacts on crop yield, water footprint and water balance components, such as evaporation, water yield and soil moisture.
Our findings reveal negligible and adverse impacts on crop yields under RCPs 4.5 and 8.5 respectively. Agricultural systems show strong adaptive capabilities under both RCPs, particularly when multiple strategies are combined. The most impactful strategies include earlier sowing and extended cropping cycles. Supplemental irrigation and cover crops are beneficial only with specific combinations of climate models and RCPs. While management changes have limited impact on basin-scale water balance components, they induce an average 27% reduction in water yield at the cropland scale, attributed to practices like zero tillage and cover crops.
Despite the uncertain impacts of climate change, our research reveal that changing the management - hence applying adaptation strategies - will be sufficient to maintain or improve current crop yields. Furthermore, we also underscore the non-negligible influence of management changes related to conservation agriculture on water balance components in agricultural catchments. Future adaptation strategy assessments should encompass comprehensive integration to evaluate broader impacts on water resources.
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•Mediterranean countries will face severe climate change impacts due to rising temperatures and altered rainfall patterns.•The adaptive capacity of the agricultural system in Central Italy is comprehensively evaluated with the SWAT+ model.•Autonomous agronomic adaptation strategies will be essential to tackle climate change in the Ombrone catchment.•The impact of management changes on some specific water balance components should not be neglected.•Impact assessments cannot be limited to the evaluation of future yield and should be as comprehensive as possible.
•Overview of water transport processes in sealed urban areas.•Hydrological balances and water retention parameters for paved surfaces.•New sealing degree classification with corresponding ...hydrological balances.•Basis for improved pavement design.
Growing urbanisation and an increase of paved surfaces lead to drastic changes of the urban hydrological cycle. Pavements are often perceived and modelled as runoff generator that prevents any kind of infiltration and inhibits evaporation. This review takes a closer look at different paving materials and examines their water transport processes and the resulting hydrological balance by collecting and evaluating literature data and descriptions. Hydrological balance and water retention capacities are collected for numerous materials, ranging from asphalt to infiltration-active grass pavers, for moist mid-latitude climate. The assessment demonstrates that evaporation and infiltration from paved surfaces play an important role and often exceed the expected values. This results in a new classification of sealing degrees for rough estimations of the annual hydrological balance of different paving materials. Additionally, common modelling concepts and possible sources for detailed land cover data are introduced and reflected. The review concludes that paving materials are much more active and complex systems than often assumed.
•Reliability analysis on flood defences designed without probabilistic criteria.•Characterizing precipitation and evaporation time series•Generation of water level data using copulas, Markov chains, ...and hydrological data.•The resulting probability of failure is consistent with historical sources.
In some cases, hydraulic infrastructures of different sizes and importance are built without formal design criteria and it may be desired to infer the reliability level for which it was originally designed. In this paper, we present a method to perform the reliability analysis of a dike that was, in all likelihood, designed without probabilistic criteria. This is the Nezahualcoyotl dike, an ancient structure built by the Aztec empire around 1445 in modern-day Mexico City. The method consists of 1. Characterizing time-series of relevant environmental variables. We use precipitation and evaporation by combining a discrete time-state Markov chain with a copula-based stochastic process. 2. Simulating from the time series model a large number of observations to “load” the structure of interest and finally, 3. Compute the probability of failure of the structure with respect to a failure mechanism. In this case, we focus on overflow. The proposed model is able to reproduce to a good extent the hydrology of the system. The return period for overflow obtained in our research is consistent with historical accounts. This work can be used as a reference to assess the reliability of other (ancient or present-day) structures whose design is based on informal criteria.
Water availability is essential for the appropriate analysis of its sustainable management. We performed a comparative study of six hydrological balance models (Témez, ABCD, GR2M, AWBM, GUO-5p, and ...Thornthwaite-Mather) in several basins with different climatic conditions within Spain in the 1977–2010 period. We applied six statistical indices to compare the results of the models: the Akaike information criterion (AIC), the Bayesian information criterion (BIC), Nash–Sutcliffe model efficiency coefficient (NSE), coefficient of determination (R2), percent bias (PBIAS), and the relative error between observed and simulated run-off volumes (REV). Furthermore, we applied the FITEVAL software to determine the uncertainty of the model. The results show that when the catchments are more humid the obtained results are better. The GR2M model gave the best fit in peninsular Spain in a UNEP aridity index framework above 1, and NSE values above 0.75 in a 95% confidence interval classify GR2M as very good for humid watersheds. The use of REV is also a key index in the assessment of the margin of error. Flow duration curves show good performance in the probabilities of exceedance lower than 80% in wet watersheds and deviations in low streamflows account for less than 5% of the total streamflow.
This paper studies the hydraulic performance of two swales composed of filters for stormwater management (filtering swales) in a large-scale experimental study and compares them to the performance of ...a swale composed of traditional bioretention soil (bioswale). Using experimental data, dimensionless formulations are derived to reflect the influence of swale design parameters on hydraulic performance. The developed formulas can be used to design swales accounting for practical factors for decision makers such as local rainfall patterns, volume capture requirements, and drainage area. The experimental data show that while the bioswale is characterized by large overland flows, the tested filtering swales manage, in the majority of cases, the complete inflow volume without overland flow. The longitudinal slope of the swales does not affect the infiltration capacity of the filtering swales for the tested experimental boundary conditions, only the inflow rate and media water content are found to be statistically significant. As an example, filtering swales tested in this study captured 90% of the runoff generated by a 12.2 mm/h storm (approximately a 5-year return period 1-h duration storm event in the city of Trondheim) on a road 40 times larger than the swale. This highlights the capacity of such swales for handling infrequent events.
•Filtering swales showed better hydrological response than the bioswale.•Filtering swales are able to handle infrequent events such as 10-year return period.•Longitudinal slope showed no impact on the hydrological response of filtering swales.•Empirical relationships are proposed for dimensioning filtering swales.
This study is focused on 12 basins in mainland Spain where monthly series longer than 30 years of near-natural streamflow measurements are available. It covers areas with different climate ...conditions.
The potential impact of future climate change scenarios on water resources in the Spanish basins is studied. It takes into account uncertainties in the estimation of local climate conditions, and the propagation of the impact due to the structural uncertainties related with the adopted conceptual-numerical approach. Local climate scenarios are derived from available Regional Climate Model (RCM) simulations after statistical downscaling. The future scenarios have been generated assuming two hypotheses of future warming for two basins in mainland Spain: 1.5ºC and 3ºC. In each of these basins, the local climate scenarios have been propagated by using 4 hydrological models, with sufficient capacity to reproduce the historical dynamic, providing values of above 5 in a 0–9 range for the grading method used.
The results show a significant spatial heterogeneity of the impact of climate change on the mean streamflow in Spanish basins. The highest reductions of flow appear in the wetter northern basins. The seasonality of the impact is also significant, with the highest reductions during autumn, and the smallest changes in the summer months. Finally, the highest uncertainties in this climate change impact assessment are due to the RCM projections, with the influence of the hydrological models being significantly smaller.
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•Effects of prescribed burning on topsoil interception evaporation were assayed.•Water and 2H and 18O mass balances were performed by a lysimeter study in the lab.•Isotope mass ...balance results show an identical trend as the water balance method.•Both approaches showed lower evaporation in burned areas compared to unburned ones.•Lower evaporation in burned areas could be due to thinner litter layers in burned vs unburned areas.
Wildfires are a growing concern in the Mediterranean area. Prescribed burning (PB) is often used to reduce fire risk, through fine fuel reduction. However, the monitoring of PB effects on ecosystem processes is mandatory before its spread. This study aims to assess hydrological effects of PB on the topsoil by controlled laboratory experiments. The evaporation flux successive to interception of a simulated rain in the litter and the fermentation layers was determined using both a water balance approach and an experimental 2H and 18O isotopes mass balance approach. PB was performed in spring 2014 in three Southern Italy pine plantations, dominated, respectively, by Pinus pinea L. (in Castel Volturno Nature State Reserve), P. halepensis Mill. (in Cilento, Vallo di Diano e Alburni National Park) and P. pinaster Ait. (in Tirone Alto-Vesuvio Nature State Reserve). In each study site, two cores, both including litter and fermentation layers, were sampled, 18 months after PB, in burned and in near unburned (control) areas, respectively, by means of customized collectors allowing to extract “undisturbed” cores. Afterwards, each core was moved into a lysimeter set-up in the laboratory, under controlled conditions (temperature of 22 °C, relative humidity of 50%), to carry out duplicate infiltration and evaporation experiments. To simulate rainfall, 1 L of tap water (=32 mm of rain) was sprinkled uniformly on the litter layer in the lysimeter and intercepted water from the litter and fermentation layer was collected for isotope analysis at two different depths for each layer, two times per day until 2 days after the rain simulation. The results of the water balance and isotope mass balance showed a slightly lower evaporation of intercepted water from the forest floor in burned areas, compared to unburned ones, but in most cases not statistically significant. The isotopic profiles of 2H and 18O also confirmed independently this finding, since they showed more enrichment in the unburned areas compared to the areas treated with PB. This could be due to thinner litter layers in burned areas of the three plantations, at least up to 18 months after treatment.
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