1,721,171 research outputs found
Spatial-temporal variability of soil moisture: Addressing the monitoring at the catchment scale
Full text linkSoil moisture plays a fundamental role in the mass and energy balance between the land surface and the atmosphere, making its knowledge essential for several hydrological and climatic applications. The aim of this study is to extend the current knowledge of soil moisture spatial-temporal variability at the catchment scale (up to 500 km 2 ). The main implication is to provide guidelines to obtain soil moisture values representative of the mean behaviour at the medium-sized river basin scale, which is useful for remote sensing validation analysis and rainfall-runoff modeling. To this end, 23 measurements campaigns were carried out during a time span of 14 months at 20 sites located within the Upper Chiascio River Basin, a catchment with a drainage area of about 460 km 2 in the Umbria Region (central Italy). The data set allowed the analysis of both soil moisture temporal stability and its dynamics. On the basis of statistical and temporal stability approaches, it was investigated how factors such as climatic regime and geomorphology influence soil moisture behaviour. For the investigated area, the spatial variability of soil moisture was higher in dry periods with respect to wet periods, mainly due to the rainfall pattern characteristics during different periods of the year. Soil moisture values recorded during wet periods showed a better correlation than those recorded during dry periods. The maximum number of required samples, to obtain the mean areal soil moisture with an absolute error of 3% vol/vol, was found equal to 12. The temporal stability analysis showed that during wet periods just one “optimal” measurement point can provide values of soil moisture representative of the catchment-mean behaviour, while during dry periods the number of “optimal” measurement points became equal to two. Therefore, at the adopted spatial scale the use of a single measurement point can lead to significant errors. From the perspective of soil moisture dynamics, the decomposition of the spatial variance showed that the contribution of the time-invariant component (temporal mean of each site) was predominant on respect to the total spatial variance of absolute soil moisture data, for almost the whole observation period. Results provided guidance to optimize soil moisture sampling by performing targeted measurements at a few selected points representative of the catchment-mean behaviour
From drought to Storm Daniel: an overall assessment on the fragility of the Mediterranean region
No full textUsing satellite soil moisture and rainfall data for the monitoring and the prediction of natural hazards
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An integrated model for prediction of shallow landslides at regional scale with the integration of satellite hydrological data
No full textEditorial: River basin hydrology and natural hazards: Monitoring, prediction and prevention
No full textThe 5th edition of the ‘Hydrology Days’ of the Italian Hydrological Society was held in Perugia, Italy, 6–8 October 2015, to provide a joint forum of hydrologists and a broad range of stakeholders for commenting and discussing on ‘River basin hydrology and natural hazards: monitoring, prediction and prevention’. A total of 58 abstracts were presented at the workshop. The 21⁄2-day conference was organized by the ‘Hydrology Group’ of the Research Institute for Geo-Hydrological Protection (National Research Council of Italy) in collaboration with the Italian Hydrological Society, the Tiber River Basin Authority and the professional association of Engineers of Perugia. Specifically, the Italian Hydrological Society (SII-IHS) was founded in 2009 to foster progress, enhancement and dissemination of hydrological sciences in Italy, including all aspects related to water resources systems management and possible interaction with human activity. In this perspective, one of the main objectives of the Association is to stimulate interdisciplinary collaboration among academia, research institutes, institutional stakeholders and private operators.
This Special Issue of Hydrology Research contains a selection of 14 peer-reviewed papers that reflect the multidisciplinary aim of the conference
Downscaling near-surface soil moisture from field to plot scale: A comparative analysis under different environmental conditions.
Full text linkIndirect measurements of field-scale (hectometer grid-size) spatial-average near-surface soil moisture are becoming increasingly available by exploiting new-generation ground-based and satellite sensors. Nonetheless, modeling applications for water resources management require knowledge of plot-scale (1–5 m grid-size) soil moisture by using measurements through spatially-distributed sensor network systems. Since efforts to fulfill such requirements are not always possible due to time and budget constraints, alternative approaches are desirable. In this study, we explore the feasibility of determining spatial-average soil moisture and soil moisture patterns given the knowledge of long-term records of climate forcing data and topographic attributes. A downscaling approach is proposed that couples two different models: the Eco-Hydrological Bucket and Equilibrium Moisture from Topography. This approach helps identify the relative importance of two compound topographic indexes in explaining the spatial variation of soil moisture patterns, indicating valley- and hillslope-dependence controlled by lateral flow and radiative processes, respectively. The integrated model also detects temporal instability if the dominant type of topographic dependence changes with spatial-average soil moisture. Model application was carried out at three sites in different parts of Italy, each characterized by different environmental conditions. Prior calibration was performed by using sparse and sporadic soil moisture values measured by portable time domain reflectometry devices. Cross-site comparisons offer different interpretations in the explained spatial variation of soil moisture patterns, with time-invariant valley-dependence (site in northern Italy) and hillslope-dependence (site in southern Italy). The sources of soil moisture spatial variation at the site in central Italy are time-variant within the year and the seasonal change of topographic dependence can be conveniently correlated to a climate indicator such as the aridity index
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Hydraulic model calibration by using satellite altimetry: comparison of different products
Full text linkMonitoring of freshwater represents the base for development and management of global water resources. However, the high cost related to the set-up and maintenance of traditional monitoring networks makes the density of observed data very limited, or even absent, in vast parts of the globe. On the contrary, the last decades have seen a great evolution on the capability to acquire remotely sensed observations, providing an increasing availability of spatially distributed data to be used for monitoring inland water. In this study, using data collected by different satellite missions (i.e., ENVISAT, ENVISAT XT, TOPEX/Poseidon and SARAL/Altika), we investigate the usefulness of remotely sensed water surface elevation for the calibration of a hydraulic model implemented for the middle-lower portion of the Po River. We compare the performance and the accuracy of different satellite altimetry products assessing whether their integration can improve the calibration accuracy and reduce the overall model uncertainty
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