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Many of the commonly used analytical techniques for assessing the properties of fluvial suspended particulate matter (SPM) are neither cost effective nor time efficient, making them prohibitive to long-term high-resolution monitoring. We present an in-depth methodology utilizing two types of spectroscopy which, when combined with automatic water samplers, can generate accurate, high-temporal resolution SPM geochemistry data, inexpensively and semi-destructively, directly from sediment covered filter papers. A combined X-ray fluorescence spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy approach is developed to estimate concentrations for a range of elements (Al, Ca, Ce, Fe, K, Mg, Mn, Na, P, Si, Ti) and compounds (organic carbon, Aldithionate, Aloxalate, Fedithionate, and Feoxalate) within SPM trapped on quartz fibre filters at masses as low as 3 mg. Calibration models with small prediction errors are derived, along with mass correction factor models to account for variations in retained SPM mass. Spectral pre-processing methods are shown to enhance the reproducibility of results for some compounds, and the importance of filter paper selection and homogeneous sample preparation in minimizing spectral interference is emphasized. The geochemical signal from sediment covered filter papers is demonstrated to be time stable enabling samples to be stored for several weeks prior to analysis. Example results obtained during a heavy precipitation event in October 2012 demonstrate the methodology presented here has considerable potential to be utilized for high-resolution monitoring of SPM geochemistry under a range of in-stream hydrological conditions. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

THE REMARKABLE RISE OF PROCESS HYDROLOGY IN CHINA Gu was at the leading edge of process hydrology in China during its remarkable ascent in the past several decades. Through the 1980s and 1990s, Gu authored a number of papers in the Chinese and English literature (Gu, [4]; Gu, [5]; Gu, [6]; Gu, [7]; Gu, [8]; Gu, [9], [10] - summarized in an important review paper in Gu et al., [11]) that showed - in many cases for the first time - the controls on the spatial and temporal evolution of soil water, groundwater and streamflow from the catchment. WEI-ZU GU AND HYDROHILL Gu was a research professor at the Nanjing Institute of Hydrology and Water Resources when he set up the Chuzhou Hydrology Laboratory and now-famous Hydrohill catchment. Following the USGS delegation to China, the USGS team reciprocated, and Gu came to the United States about a year later and toured the Mattole watershed, the Panola watershed in Georgia and other USGS research sites. [Extracted from the article]

Adding our leaves: A community-wide perspective on research directions in ecohydrology Ecohydrology encompasses ideas and processes at the interface of hydrology and ecology acknowledging couplings and feedbacks between biology and water-related processes across a broad range of spatial and temporal scales. These papers described ecohydrology as a general concept (such as Newman et al., [53]); or review the state of ecohydrology Asbjornsen et al., [1]) or hydrology (e.g., Eagleson, [19]; Jones & Mulholland, [36]; Rodriguez-Iturbe, [61]). Given that much of ecohydrology research has been conducted under nonstationary climatic conditions, even identifying what baseline feedbacks exist between climate, hydrology, and ecology is challenging. [Extracted from the article]

A letter to the editor is presented in response to three studies conducted by Ozgur Kisi, intended to model reference evapotranspiration by neural network systems, published in "Nordic Hydrology (NH)," "Hydrological Sciences Journal (HSJ)," and "Hydrological Processes (HP)" in 2008.

Analysing a 7 year time series of daily stable water isotope data from precipitation and rainfall, Stevenson et al. (2021) find that appropriate sampling strategies of water isotope data are critical to robust model calibration and reducing model uncertainty. Data assimilation techniques such as Kalman or Particle filtering require data uncertainty information to enable them to correctly balance the information content of model predictions and new data observations (Ocio et al., 2017; Smith et al., 2008). Observational data is the foundation for most of hydrological science. Three of these papers focused on multiple output datasets, that is, using more than one output variable, with total suspended solid data in addition to streamflow (Wu et al., 2021) or stable isotopes together with streamflow data (Stevenson et al., 2021). [Extracted from the article]

Permeable pavements, which not only increase rainwater infiltration and purify surface runoff water but also absorb noise and promote evaporative cooling, are an effective measure for alleviating urban flooding and the heat island effect. Moreover, permeable pavements have significant implications for the urban hydrological cycle and for human development that promotes ecosystem health. This paper reviews the development history of permeable pavements, evaluates the technical aspects and benefits thereof in the context of green city construction, and analyzes existing issues in the development of permeable pavements. This paper mainly discusses the current classifications of permeable pavements, the indicators used to evaluate permeable pavements, and construction techniques with a focus on two aspects: improving strength and removing blockages for planning, and three aspects: enhancing permeability, recycling resources, and preventing pollution for ecohydrological effects. Further, this paper discusses the benefits of permeable pavements and the commonly used methods for evaluating benefits. The main problems in the development and construction of permeable pavements include the limitations of permeable pavements, difficulty in evaluating their benefits, and restrictions on their applications. The following recommendations are proposed: improve the evaluation mechanism for permeable pavements, establish appropriate guidance for construction, scientifically and quantitatively analyse the feasibility of permeable pavement construction, evaluate the rationality of permeable pavement construction in various regions, and encourage the construction of permeable pavements in suitable areas. The importance of developing standards and technical specifications is also emphasized. [ABSTRACT FROM AUTHOR]

Crowd‐based hydrological observations can supplement existing monitoring networks and allow data collection in regions where otherwise no data would be available. In the citizen science project CrowdWater, repeated water level observations using a virtual staff gauge approach result in time series of water level classes (WL‐classes). To investigate the quality of these observations, we compared the WL‐class data with "real" (i.e., measured) water levels from the same stream at a nearby gauging station. We did this for nine locations where citizen scientists reported multiple observations using a smartphone app and at 12 locations where signposts were set up to ask citizens to record observations on a paper form that could be left in a letterbox. The results indicate that the quality of the data collected with the app was better than for the forms. A possible explanation is that for each app location, a single person submitted the vast majority of the observations, whereas at the locations of the forms almost every observation was made by a different person. On average, there were more contributions between May and September than during the other months. Observations were submitted for a range of flow conditions, with a higher fraction of high flow observations for the locations were data were collected with the app. Overall, the results are encouraging for citizen science approaches in hydrology and demonstrate that the smartphone application and the virtual staff gauge are a promising approach for crowd‐based water level class observations. [ABSTRACT FROM AUTHOR]

Integrated Water Resources Management is an approach aimed at achieving sustainable development with a focus on water resources. This management concept is characterized by its catchment approach, inter-sectoral and interdisciplinary approach and multiple management objectives. There is an effort to widen the management scope to include multiple resources and environmental considerations in the river basin management schemes. In order to achieve river basin management objectives and multiple global environmental benefits, an ecosystem approach to river basin management is promoted. The Ecosystem-based River Basin Management aims to maximize and optimize the total value of the ecosystem functions relevant to classified ecosystems within a river basin by conserving and even enhancing these functions for the next generations. A procedure to incorporate such ecosystem functions into policy framework is presented in this paper. Based on this policy framework of the Ecosystem-based River Basin Management, a case study is introduced to apply the concept to the Yangtze River basin. According to the United Nations Environment Programme (UNEP) assessment report, this basin suffers from frequent floods of large magnitudes, which are due to the degradation of ecosystem functions in the basin. In this case, the government of the People's Republic of China introduced Ecosystem Function Conservation Areas to conserve ecosystem functions related to flood events and magnitude, such as soil conservation, agricultural practices and forestry, while producing economic benefits for the local population. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The author presents pieces of advice to young hydrologists based on several decades of his research experience. These include being honest about limitations of what people can know about subsurface water pathways, getting people to read one's paper before having any influence, and collaborating with more established researchers, at the risk of not being seen to establish an independent reputation.

Later developments included spatially distributed models allowing data inputs and hydrological processes to be simulated at model grid scale, that is, much finer than catchment scale. They calibrate a lumped rainfall-runoff model against three observations targets: (i) only streamflow data; (ii) only rock moisture data; and (iii) both streamflow and rock moisture data. Keywords: calibration; evaluation; hydrological modelling; model structure; process description; uncertainty EN calibration evaluation hydrological modelling model structure process description uncertainty 1 5 5 09/29/23 20230901 NES 230901 INTRODUCTION Catchment modelling has undergone tremendous developments during the past decades. [Extracted from the article]

Prescribed fires are one of the most effective tools to reduce the risk of wildfires but this treatment may negatively affect the hydrological and erosive response of soil, with noticeable increases in surface runoff and soil erosion. Many studies have been published on this matter but there is no consensus in the literature on the magnitude and duration of these effects since the relevant hydrological conditions are site‐specific. Moreover, the relationship between post‐fire hydrology and its main environmental drivers has been little explored. This study has carried out a bibliographic review and a meta‐analysis of the changes resulting from prescribed fire applications (water infiltration, soil water repellency (SWR), surface runoff and soil erosion) using a database of 85 case studies from 41 academic papers that have been published over the last 23 years. The effects of annual precipitation, soil slope, burn severity, fire application season, post‐fire ground cover, and vegetation type on those changes have also been statistically explored. The bibliographic review has revealed that previous case studies have not been equally distributed across the globe but concentrated in only a few countries, mainly the United States and Spain. The meta‐analysis has revealed that (i) water infiltration generally decreases and SWR appears with noticeable increases in surface runoff and soil erosion immediately after the prescribed fire, while the pre‐fire values progressively recover over time; (ii) the window of disturbance in burned soils may last a few months (with some exceptions); (iii) annual precipitation and soil slope significantly influence water infiltration and surface runoff, but not soil erosion, in both the short‐term and medium‐term; (iv) moderate‐to‐high levels of soil burn severity severely enhance surface runoff and soil erosion, and noticeably reduce water infiltration in the short‐term; (v) the level of ground cover burning is important for reducing the runoff rates, but it plays a minor role in water infiltration and soil erosion rates;and (vi) the prescribed fire applied in spring results in lower increases in short‐term runoff and erosion, while fire applications in summer and in shrublands produce the highest increases in soil loss. The following practical recommendations arise from this study: (i) research should be better distributed across all environmental contexts on a global scale; (ii) post‐fire management actions should be immediately implemented after the prescribed fire application; (iii) prescribed fire should be carried out in spring and the soil burn severity should be kept low during burning; (iv) the monitoring studies should be prolonged at least for some years (more than two or three) after prescribed fire; (iv) the catchment‐scale investigations, although more difficult and expensive, should be encouraged (avoiding, however, areas to sparsely burnt in the context of the whole catchment); (v) the monitored variables should also include the most important physical, chemical and biological properties of soil, the cover and structure of regenerating vegetation, as well as the water quality parameters; (vi) the effects of repeated applications of prescribed fire should be experimentally assessed; and (vii) guidelines for standardized and appropriate measurements and analytical methods in experimental activities should be set up. These indications support the use of land managers in the monitoring of the hydrological impacts of the prescribed fire and in the choice of sites where post‐fire management actions must be implemented. The last recommendation of this study is the creation of an experimental database supporting the bibliographic review and the meta‐analysis, which is made available to other researchers and land managers, to create a public, easily‐accessible and comprehensive tool for future research needs and professional use. [ABSTRACT FROM AUTHOR]

Their paper Heathwaite et al. (2021) synthesizes the physical hydrology and biogeochemistry process-based understanding for a lowland groundwater-fed river, representative of systems where the river is continuously recharged by groundwater throughout the year. This Special Issue (SI) of I Hydrological Processes i features invited contributions led by women scientists at an advanced career stage who have made sustained contributions to the study of hydrological processes, advancing the field. The subject matters of the papers address how we can enhance our understanding of hydrological processes, but they are also interdisciplinary and extremely timely with focuses on the dynamics of ecohydrological processes, climate change, and human behaviour: B Dr. Christine Alewell b is a Professor at the University of Basel, Switzerland. She is an expert in physical-ecological interactions in river ecosystems, implications of physical riverine complexity for organic carbon storage, large wood in river floodplains and the effects of beaver activities on downstream fluxes of material in river corridors. [Extracted from the article]

A response by Ozgur Kisi to a letter to the editor about his three studies intended to model reference evapotranspiration by neural network systems, published in "Nordic Hydrology (NH)," "Hydrological Sciences Journal (HSJ)," and "Hydrological Processes (HP)" in 2008, is presented.

The article comments on the work of scholar Leonardo da Vinci on hydrology. Due to his contribution to the field, he may be considered one of the founding fathers of hydrology. Da Vinci's work contains a large amount of research and writings that document his efforts to describe and understand the water cycle. Moreover, he spent an amount of time figuring out the process of water cycle.

The flow duration curve (FDC) is the cumulative distribution function, which represents the relationship between the frequency and magnitude of streamflow, and the precipitation duration curves (PDC) follows the same principle. Nowadays, the correlation between the shape of PDC and FDCs, their respective physical control factors including human activities, and their fitting conditions in unmeasured catchments across China have not been fully understood. In this paper, daily precipitation and streamflow data with 30 years records from 224 hydrological stations in the middle and lower Yangtze River basin were chosen to fit PDC and FDCs through gamma distribution. Framework was proposed for modelling FDCs to analyse the relationship, similarity, regional patterns and response mechanism of fitting parameters between PDC and FDCs, dividing the streamflow time series into fast and base flow and stations into three categories in consideration of human activities to attribute the shapes of PDC and FDCs to catchment meteorological and geographical characteristics and physical processes under natural conditions. Results indicate that the parameters of PDC and certain FDCs (TFDC, FFDC, SFDC) share similar spatial patterns but vary for the different duration and interactions of the processes. The climate and catchment characteristics such as extreme properties of precipitation, base flow index (BFI), Pmax*αp and concentration ratio index (CIM) will influence the shape of PDC and FDCs. The relationship between BFI and SFDC/TFDC can be better reflected in "Regulated watersheds", while CIM/Pmax*αp and PDC/FFDC in "watersheds in the mainstream" are more related. This paper provides a deeper understanding and more accurate way of the application of these parameters in describing and predicting hydrological processes and estimation of PDC and FDCs in unmeasured catchments, and can be applied to more future research about processes based on catchment rainfall‐runoff responses and physical controls. [ABSTRACT FROM AUTHOR]

The reference lists of hydrology textbooks, theses and journal papers are replete with citations of key papers that are widely deemed to be classics. They argued that a similar displacement or translation of stored soil water occurs on hillslopes where vertical infiltration of newer precipitation leads both to downward and downslope translation of older soil water. Goldsmith et al. (2012) pointed out that HH did not imply all pre-event soil water underwent displacement during translatory flow, and that Horton and Hawkins (1965) showed a considerable amount of this pre-event soil water was retained in the soil profile. However, neither does the translatory flow mechanism as described by HH argue for either complete displacement of pre-event soil water or complete mixing of incoming precipitation and pre-event soil water. [Extracted from the article]

This paper presents a taxonomy (hierarchical organization) of hydrological processes; specifically, runoff generation processes in natural watersheds. Over 130 process names were extracted from a literature review of papers describing experimental watersheds, perceptual models, and runoff processes in a range of hydro‐climatic environments. Processes were arranged into a hierarchical structure, and presented as a spreadsheet and interactive diagram. For each process, additional information was provided: a list of alternative names for the same process, a classification into hydrological function (e.g., flux, storage, release) and a unique identifier similar to a hashtag. We hope that the proposed hierarchy will prompt collaboration and debate in the hydrologic community into naming and organizing processes, towards a comprehensive taxonomy. The taxonomy provides a method to label and search hydrological knowledge, thereby facilitating synthesis and comparison of processes across watersheds. [ABSTRACT FROM AUTHOR]

In the past decades, remarkable progresses have been made in developing soil water retention (SWR) functions and relative hydraulic conductivity (kr) models for the full range of matric suction. However, such an existing SWR function and the corresponding kr model were found not to have a consistent prediction performance, that is, for a given soil, the SWR function could perform very well but the kr model might perform poorly or even fail. Given that both water retention and hydraulic conductivity need to be accurately predicted to simulate land‐atmosphere interactions, vadose‐zone soil–water dynamics, and shallow groundwater recharges, this paper proposed an upgraded SWR function and derived a new closed‐form kr model by combining the function with the well‐known Mualem model. The upgradation was done by introducing an exponential function for the pendular (i.e., dry and very dry) range of matric suction. The SWR function and kr model keep the conventional simplicity, reflect the capillary versus adsorptive soil–water mechanisms, eliminate fictitious parameters, and are continuously differentiable with closed forms. The assessment using the experimental data for 35 soils with nine different textures indicated that the upgraded SWR function and new kr model reproduced the data more accurately than the existing functions and models, as measured by visualization plots and four statistics, namely coefficient of determination, sum squared error, root mean squared error, and Nash–Sutcliffe efficiency. The contribution of this paper is to overcome the inconsistent‐performance issue mentioned above. [ABSTRACT FROM AUTHOR]

To describe process knowledge at the watershed scale, hydrologists commonly refer to a 'perceptual model', an expert summary of the watershed and its runoff processes often supported by field observations. Perceptual models are often presented as a schematic figure, although such a figure will necessarily simplify the hydrologist's complex mental model. In this paper, our aim was to understand what constitutes a visual expert summary of watershed process knowledge, and to evaluate how perceptual models could be used to share hydrological process information at larger scales. To do so, we conducted a systematic review of the literature and found 63 perceptual model figures. We counted and categorized the stores and fluxes in each figure using a taxonomic classification and quantified a variety of figure attributes including spatial or temporal zonation, inclusion of vegetation, soils, topographical and geological data and consideration of uncertainty. Our analysis showed that a typical figure has 1 surface flux, 4 subsurface fluxes, 3–4 subsurface stores and 0–1 channel stores; 28 out of 63 figures use sub‐figures to show temporal dynamics (e.g., wet/dry conditions), and 12 out of 63 show spatial zones. Perceptual model figures, therefore, provide a concise summary of watershed processes with a complexity comparable to that of many conceptual hydrological models. However, only four figures showed any information on uncertainty or knowledge gaps. We recommend that perceptual figure value could be easily increased by consistent captioning of figures to assist automated search, and wider use of standard figure annotations such as legends and scale markings to ensure that information is fully conveyed to the user. If perceptual figures are proposed as a primary method for sharing process information, the hydrological community should consider how to link more detailed text descriptions to figures, and how to represent process uncertainty. [ABSTRACT FROM AUTHOR]

This paper analyses a set of random fractional partial differential equations (rfPDEs) for water movement in soils. The rfPDEs for both rigid and swelling soils are solved for both a random flux boundary condition (BC), and random concentration BC. Solutions from a random flux BC are presented for the large‐time and small‐time situations with the large‐time solution as a very simple method for determining the flux through the surface of the soil. The equation of cumulative infiltration is presented with random parameters of the rfPDE subject to a random concentration BC. The simulations using the results of the rfPDE for the two types of BCs yielded encouraging and stable results based on two sets of field data: the first set of the data was measurements at a single site while the second set was from 26 measurements in a small catchment. The results suggest that the presented procedures are very useful methods for the interpolation, extrapolation, and prediction of hydrological variables and parameters such as water content, hydraulic conductivity or the flux through the surface of the soil. The methodologies presented in this paper are able to reveal and reproduce the realistic hydrological processes in nature which are often stochastic and random. [ABSTRACT FROM AUTHOR]

Estuary bays are vulnerable to salinization effects due to relative sea level rise and modification in upland hydrology owing to a variety of factors. Much research has evaluated the one‐sided effect of runoff discharge or sea level on the water exchange and saltwater intrusion for an estuary, while their combined effects have not been evaluated, especially for an estuary bay with narrow river mouth. Taking the Wanquan Estuary Bay (WEB), China, as study case, this paper has revealed the long‐term significant increasing trend of freshwater runoff in non‐flood season during years 1956–2017 using the Man‐Kendall trend analysis, robust principle component regression and Theil–Sen's estimator. A 3‐D hydrodynamic‐salinity‐tracer numerical model is built and calibrated based on the finite‐volume community ocean model, and the effects of runoff increase and sea level rise on the water exchange and saltwater intrusion are investigated. This paper shows the following: (1) The freshwater runoff during non‐flood season in WEB shows significant long‐term increasing trend, and the mean changing magnitude is 0.4546 m3/s/a. (2) The increased runoff accelerates the water exchange, and reduces the turn‐over time and saltwater intrusion in the WEB. The sea level rise reduces the water exchange and increase the saltwater intrusion. (3) For the estuary bay with narrow river mouth, the salinity distributions show more vertical stratification characteristics. The freshwater runoff has power relationships with the average turnover time and salinity, and the sea level has linear relationships. (4) The water exchange and salinity of an estuary bay is more vulnerable to the changed runoff than the sea level rise, while the impacts of sea level rise would increase for estuaries with wide river mouth. This paper provides support for the freshwater exploitation and utilization in estuary bay under the background of climate change and sea level rise. [ABSTRACT FROM AUTHOR]

Solute dynamics depend strongly on hydrologic flow paths and transit times within catchments. In this paper, we use a travel time tracking method to simulate stream salinity (as measured by electrical conductivity) in the Duck River catchment, NW Tasmania, Australia. The study couples storage selection function transit time modelling with two alternate approaches to model electrical conductivity (EC). The first approach assumes the catchment has a cyclic salt balance (i.e., rainfall source, stream flow sink) that is in dynamic equilibrium and evapoconcentration of salt is the only process changing concentration. The second approach assumes that the salinity of water in catchment storages is a function of water age in those stores, without explicitly simulating salt mass balance processes. The paper compares these alternate approaches in terms of EC simulation performance, simulated stream water age distributions, and simulated storage age distributions. A split sample calibration‐validation analysis was conducted using the 2008 and 2009 water years. Both EC simulation approaches reproduced stream EC variations very well under both calibration and validation. The simulations using the age‐related EC simulation approach produced less biased results and, consequently, higher model coefficient of efficiency for validation periods. This approach also produced more consistent model parameter estimates between periods. There were systematic differences in the resultant age distributions between models, particularly for the solute balance‐based simulations where parameters (catchment storage size) changed more between the two calibration periods. The effect of time varying versus static storage selection functions were compared, with clear evidence that time varying storage selection functions with parameters linked to catchment conditions (flow) are essential for adequate simulation of EC dynamics during flow events. [ABSTRACT FROM AUTHOR]

Hydrological soil physics also feature prominently in this special issue, with three papers using soil physics with the ultimate goal of better understanding runoff generation processes in soils. They found that a positive correlation between streamflow stable isotope damping ratios and the percentage of wetland area increases variability in the influence of evaporative enrichment. This special issue of Hydrological Processes contains 12 original research papers, one of the largest recent special issues of the Canadian Geophysical Union - Hydrology Section. [Extracted from the article]

Northwest China is both an important coal storage base and an ecologically fragile area, and soil water content (SWC) is a key factor limiting the ecological development of Northwest China. Revealing the characteristics of spatial and temporal distribution changes of soil water content in mining areas under coal mining disturbance and the influencing mechanism is crucial for the protection of water resources in mining areas. In this study, the soil water content (depth 0–1000 cm) of a typical coal mine subsidence area in the western part of Shendong Coal Group was monitored in situ for 1 year after mining, and the absolute value, variability, and spatial distribution of soil water content were temporally analysed by combining classical statistics, 2D Ordinary Kriging and 3D Empirical Bayesian kriging spatial interpolation. sequence analysis. The results showed that the shallow SWC (0 ~ 60 cm) was distributed horizontally in bands, and gradually increased along the direction from northwest to southeast; with the increase of coal mining time, the absolute value of SWC decreased by 0.81% ~ 33.58%, and the coefficient of variation decreased and then increased, with the range of variation from 2.19% ~ 34.49%. The deep SWC (100 ~ 1000 cm) was stratified vertically and increased with soil depth, and the shallow and deeper soil moisture would gradually migrate to the middle layer under the influence of coal mining. In addition, this paper accurately portrays the three‐dimensional spatial and temporal distribution of soil water content by the 3D EBK model, which further reveals the mechanism of coal mining's influence on soil water content. This study can provide technical and data support for predicting and evaluating the potential impacts of mining activities on the water cycle, and help mining areas to formulate policies for managing and protecting water resources. [ABSTRACT FROM AUTHOR]

Evaluation metrics play a pivotal role in the calibration process of hydrological models, serving as objective functions that directly influence the final values of model parameters and significantly affect users' perceptions of model performance. However, the choice and interpretation of evaluation metrics are subjective; therefore, this study provides a more objective framework for assessing model performance. This paper initially explored the applicability of various commonly used evaluation metrics, providing an overview of their limitations. Following this, we decomposed errors by analysing their physical significance and geometric representation in scatter plots, categorizing them into systematic and unsystematic errors. Through the decomposition and derivation of the Nash–Sutcliffe efficiency (NSE) formula, we established the quantitative relationship among various evaluation metrics. The soil and water assessment tool (SWAT) model was utilized to simulate monthly runoff in the Baishan basin (China), for the period 1994–2017, with NSE serving as the objective function for calibration. Our findings are consistent with previous studies, indicating that the model tends to slightly underestimate high flows while significantly overestimating low flows. Further analysis through error decomposition and the examination of relationships among various evaluation metrics revealed that unsystematic errors were dominant during the spring snowmelt runoff period, while systematic errors prevailed in the dry season. By evaluating the runoff series based on the magnitude of runoff or by categorizing it according to seasons and months, a more stringent assessment of the model's performance was achieved. These findings not only highlight the necessity for careful selection of evaluation metrics but also underscore the significance of our methodological advancements in enhancing hydrological model precision and reliability. [ABSTRACT FROM AUTHOR]

Hydrology has a long history, but is still considered a young science due to its lack of a solid scientific foundation as a natural science. Field experimentation is crucial when investigating hydrological processes and mechanisms, and is essential if hydrology is to have a solid, science‐based foundation. Professor Wei‐Zu Gu (1932–2022) was an internationally renowned scientist in the field of hydrology and is recognized as the greatest pioneer of experimental hydrology and isotope hydrology in China. He created the Hydrohill experimental catchment, which serves as both a great public facility for experimental hydrology and a valuable legacy for researchers that will enable them to conduct advanced hydrological experiments in the future. This legacy consists of innovative infrastructure that bridges the gap between natural watershed experiments and artificial physical models. The Hydrohill is an intensively instrumented experimental catchment that allows different elements of the hydrological cycle and their tracing indicators to be comprehensively measured. To provide an in‐depth understanding of the Hydrohill, this paper presents a short history of the site, its experimental objectives, a site description (including location, construction and instrumentation), site conditions (such as soil, hydrological and meteorological properties), and its contributions to hydrological science. We acknowledge Professor Gu for creating the Hydrohill experimental hydrology facility and enhancing our understanding of hydrological processes and mechanisms. Finally, we hope that Chuzhou Scientific Hydrology Laboratory, along with support from Professor Gu's friends, will ensure the continued growth of the Hydrohill so that it can address unsolved problems in hydrology. [ABSTRACT FROM AUTHOR]

3H enters the hydrologic cycle after oxidizing in the 3H1HO molecule and it constitutes a very useful tracer for hydrological studies. One of these applications is streamflow component separation, which provides useful information to understand the hydrological cycle. This application is based on the fact that the contents in precipitation (runoff) tend to be markedly higher than those in groundwater (baseflow) because of decreasing activity in the last as a consequence of radioactive decay. The main objective of this paper is to test 3H for hydrograph separation in sub‐tropical South America, where it is favoured by high values in precipitation. The catchment of the Quequén Grande River, in Argentina, was selected. Total flow in surface water is a mixing between the baseflow and the event flow portion; the separation was done in three sections of the drainage network, and the proportion of baseflow were 36%, 88% and 47%. [ABSTRACT FROM AUTHOR]

This study presents a method that could be used to assess the in‐situ saturated vertical hydraulic conductivity of deeper and more decomposed peat layers. Deeper peat layers may exhibit very low permeability comparable to clayey sediments, where measurements and sediment sample collection are very difficult. More traditional measurement methods, such as slug‐tests and permeameter tests, have proven difficult to carry out in these conditions, necessitating an alternative method. For surpassing these possible constraints, this paper introduces a field method to quantify vertical hydraulic diffusivity, capitalizing on naturally occurring hydraulic pressure fluctuations measured with buried pressure sensors. The determined diffusivity values are used to calculate vertical hydraulic conductivity of peat using separately measured compressibility and specific storage values. Our research demonstrates the feasibility of using this method to evaluate vertical hydraulic diffusivity in lower peat layers. Calculated diffusivity values, combined with peat compressibility measurements, yield reasonable estimates of vertical hydraulic conductivity for dense fen peat comparable with more widely used in‐situ and laboratory methods. It also shows potential for vertical hydraulic characteristics parametrization in the upper less decomposed and compacted peat layers; however, further research is needed to understand the method's limitations in such conditions. Our approach provides a potential method for measuring in‐situ vertical hydraulic properties of less accessible peat layers, often overlooked, while also providing a way to surpass the scale‐dependency constraints inherent in peatlands' heterogeneous structure. Such information is necessary when studying the hydraulic interactions between groundwater aquifers and peatlands. [ABSTRACT FROM AUTHOR]

Non‐perennial river catchments are characterized by an ever‐changing spatial configuration of their flowing streams. A combination of empirical data and simplified analytical frameworks has been frequently used in the literature to analyse the co‐evolution of the total active stream length (L$$ L $$) and the catchment discharge at the outlet (Q$$ Q $$). However, despite the increasing availability of field data, understanding how runoff generation processes drive the spatio‐temporal dynamics of non‐perennial river reaches remains challenging. In this paper we use CATHY, an integrated surface–subsurface hydrological model (ISSHM), to investigate the impact of saturation‐excess (Dunnian) and infiltration‐excess (Hortonian) runoff generation on the stream network dynamics of two virtual catchments with spatially homogeneous subsurface properties but different morphology. The numerical simulations show that when surface runoff is triggered by saturation‐excess mechanisms, the subsurface domain is slowly saturated, and the stream network gradually expands upstream from the outlet towards the catchment divides. In these conditions, the specific inflow per unit contributing area is relatively uniform along the network, thereby implying that L$$ L $$ and Q$$ Q $$ display a monotonically increasing one‐to‐one relationship. On the other hand, infiltration‐excess mechanisms lead to more heterogeneous saturation patterns in the subsurface domain. In particular, during the wetting phase, Hortonian processes originate highly transient conditions and a non‐uniform spatial distribution of the specific inflow along the stream network. This is reflected by a hysteretic LQ$$ L(Q) $$ relation and a marked asymmetry between the wetting and drying phases of the event. The application of an ISSHM proved to be a useful tool to elucidate the processes that drive stream network expansion and retraction in non‐perennial rivers. [ABSTRACT FROM AUTHOR]

The history of experimental hydrology in China is important but poorly documented. Here we review 94 papers (86 of these in Chinese) from the CNKI and Web of Science websites to chronicle the history of experimental studies in China before 2000. Professor Wei‐Zu Gu—the focus of this Special Issue—factors heavily into this history. Perhaps more than any country, the experimental hydrology history of China is influenced by socioeconomic development and political change. Our analysis shows 4 main periods of development associated with (1) an early development stage before 1949, the founding year of People's Republic of China (PRC), (2) an initial period of rapid transition in experimental studies in China (1949–1965), (3) a struggling and recovering stage for during and shortly after the Cultural Revolution, from 1965 to 1978, and (4) significant progress associated with new policies for reform and opening up in China from 1978 to 2000, that included contributions of Wei‐Zu Gu and other scientists. In terms of experimental hydrological findings, two notable contributions are a mathematical description of saturation overland flow derived from streamflow and precipitation data and calculated water storage deficit in the unsaturated zone by Zhao and Zhuang (1963), several years before its process‐based 'discovery' in the USA (and elsewhere) and the 'interface runoff generation law' of Yu (1985) which was ahead of its time in understanding linking the notion of the commonality of all runoff forms. In terms of model development stemming from experimental studies, the development of the Xinanjiang Model of Zhao (1980) was a significant achievement, later partly adopted into the VIC model in the USA and the ARNO model in Europe. Finally, the Hydrohill catchment developed by Wei‐Zu Gu led the way for the rapid rise in process studies and internationalization of experimental hydrology in China. Overall, the experimental hydrological studies from 1949 to 2000 had a strong engineering focus, with many links to water conservation construction and management. [ABSTRACT FROM AUTHOR]

Stream temperature governs many aquatic ecosystem processes and plays a key role in determining the distribution of cold‐water amphibians and cool‐ and cold‐water fish, including salmonids. Decades of research have focused on the effects of forestry and forest disturbance on stream temperature, and new projects are underway or being planned in jurisdictions including the Provinces of Alberta and British Columbia, Canada, and Washington State, USA. The objective of this paper is to provide a critical review of methodologies employed in previous studies. The review initially focuses on the range of metrics used to quantify stream thermal regimes and the factors that control stream temperature variability in time and space, then focuses on sampling and analytical methodologies used to quantify stream temperature response to forestry activity and forest disturbance. Empirical methods include sampling in time, space, or both, and may or may not include pre‐ and post‐harvest data. Process‐based mechanistic and hybrid empirical‐mechanistic models have also been applied. The advantages and disadvantages of these approaches are discussed, and recommendations provided to support the design and execution of future studies. [ABSTRACT FROM AUTHOR]

Karst aquifers have complex structures and high heterogeneity, making it difficult to describe their hydrogeological characteristics. An essential tool for comprehending karst hydrogeology and identifying the hydraulic characteristics of the karst system is a quantitative analysis of the recession process of the karst spring hydrograph. The recession process of the spring hydrograph following a rainfall event can be utilized to assess the internal structure of the karst system as it relates to the karst aquifer's response to rainfall events. In this study, a laboratory physical experiment model is built based on typical karst hydrogeological circumstances, and a corresponding combined discrete‐continuum (CDC) numerical model is established, coupling conduit and matrix. The primary goal of this paper is to investigate how the recession process of the spring hydrograph responds to various rainfall events. Different rainfall intensities with the same rainfall duration and various rainfall intensities with the same rain amount are examples of rainfall patterns. The simulation results showed that the pattern of rainfall events affects the recession process of the spring hydrograph, and the recession coefficient of the corresponding recession stage, the proportion of water volume released by conduit and matrix with the different rainfall patterns are calculated and analysed, and the impact of rainfall events on the recession coefficient of spring hydrograph and the spring water composition has been explored. The research results can provide a reference and basis for the management of water resources in karst areas. [ABSTRACT FROM AUTHOR]

Cold regions provide water resources for half the global population yet face rapid change. Their hydrology is dominated by snow, ice and frozen soils, and climate warming is having profound effects. Hydrological models have a key role in predicting changing water resources but are challenged in cold regions. Ground‐based data to quantify meteorological forcing and constrain model parameterization are limited, while hydrological processes are complex, often controlled by phase change energetics. River flows are impacted by poorly quantified human activities. This paper discusses the scientific and technical challenges of the large‐scale modelling of cold region systems and reports recent modelling developments, focussing on MESH, the Canadian community hydrological land surface scheme. New cold region process representations include improved blowing snow transport and sublimation, lateral land‐surface flow, prairie pothole pond storage dynamics, frozen ground infiltration and thermodynamics, and improved glacier modelling. New algorithms to represent water management include multistage reservoir operation. Parameterization has been supported by field observations and remotely sensed data; new methods for parameter identification have been used to evaluate model uncertainty and support regionalization. Additionally, MESH has been linked to broader decision‐support frameworks, including river ice simulation and hydrological forecasting. The paper also reports various applications to the Saskatchewan and Mackenzie River basins in western Canada (0.4 and 1.8 million km2). These basins arise in glaciated mountain headwaters, are partly underlain by permafrost, and include remote and incompletely understood forested, wetland, agricultural and tundra ecoregions. These illustrate the current capabilities and limitations of cold region modelling, and the extraordinary challenges to prediction, including the need to overcoming biases in forcing data sets, which can have disproportionate effects on the simulated hydrology. [ABSTRACT FROM AUTHOR]

Notwithstanding the recognized influence of Biological Soil Crusts (BSCs) on surface roughness and its implication for hydrological processes, limited information is currently available on the effect of BSCs on overland flow resistance. The objective of this paper was to investigate the applicability of a theoretically deduced flow resistance equation, based on a power‐velocity profile, using the experimental data set by Jafarpoor et al. (2022) and Sadeghi et al. (2023) for bare soil, which is a control condition, and three inoculated soils (cyanobacteria, bacteria, cyanobacteria+bacteria). In particular, the available data set was used to calibrate the relationship between the velocity profile parameter Γ and the flow Froude number. The developed analysis allowed for stating that (a) the Darcy‐Weisbach friction factor can be accurately estimated using the proposed theoretical approach, and (b) the available measurements do not allow for detecting a trend with the soil treatment. [ABSTRACT FROM AUTHOR]

Accurate information about the extent, frequency and duration of forest inundation is required to inform ecological, biophysical and hydrological models and enables floodplain managers to quantify the efficacy of flood mitigation/modification activities. Open water classifiers derived from optical remote sensing typically underestimate or fail to detect floodplain forest inundation. This paper presents a new method for detecting forest inundation dynamics using freely available Landsat and Sentinel 2 data, referred to as short‐wave infrared mapping under vegetation. The method uses a dynamic threshold that accounts for the additional shortwave infrared reflectance caused by the presence of tree canopies over floodwater. The method is demonstrated at five Ramsar listed River Red Gum floodplain forest wetlands in southeastern Australia. Accuracy assessment based on independent drone imagery from a wide range of vegetated wetlands showed an absolute accuracy of 67%–70% and a fuzzy accuracy of 81%–83%. We found the method is conservative, and underestimates inundation (16%–18%) but very rarely misclassifies dry pixels as inundated (0.3%–0.6%). When compared to river gauge data, the method shows similar trends to an open water classifier (i.e., the area of inundated vegetation increases with increasing river height). The method is conservative compared to lidar‐based floodplain inundation models but can be applied wherever cloud‐free scenes of Landsat or Sentinel 2 have been acquired, thereby enabling floodplain managers with the ability to quantify changes in inundation dynamics in places/time‐periods where lidar is unavailable. [ABSTRACT FROM AUTHOR]

Separating existing historical precipitation data into solid and liquid precipitation remains a challenge in the study of climate change, extreme precipitation, and hydrological modelling. Based on historical daily air temperature and precipitation data, as well as visual observations of precipitation phase (weather phenomena records) in China mainland, this study proposed a snow‐day direct definition method (SDDM) to determine the threshold air temperature (TAT) of rainfall and snowfall, and analysed the spatial pattern and its influential factors. The main findings include: (1) the TAT based on the SDDM varied from −1.2 to 6.3°C, with a mean value of 2.8°C for the entire study region; (2) TAT was generally higher and more variable in the low‐latitude areas, and the Qinghai‐Tibet Plateau was characterized by an abnormally high average TAT of 5.2°C, almost twice as large as that of the eastern monsoon region; (3) TAT exhibited a significant positive correlation with altitude and negative correlation with precipitation and relative humidity. The results presented in this paper have potential application for studies of large‐scale snowfall climatology and climate change, weather forecasting techniques, and hydrological model parameterization in areas with complex and diverse geographical and climatic conditions. [ABSTRACT FROM AUTHOR]

Rainfall is one of the factors affecting soil erosion, and rainfall kinetic energy or momentum is used to represent the capability of the precipitation to erode soil, named rainfall erosivity. Accurate measurements of rainfall erosivity are useful for a reliable prediction of soil loss. Rainfall momentum and kinetic energy, both calculated per unit time and area, can be obtained using terminal raindrop velocity and the drop size distribution (DSD) measured by disdrometers, which are instruments expensive and not suitable for large scale use. An innovative patented method to measure the rainfall energy is based on the estimation of DSD by simultaneous detection, in a given time interval, of the rainfall intensity I and the number N of raindrops that hit a specific piezoelectric surface. In this paper, advances of this method are presented. In particular, two new theoretical procedures to estimate the parameters μ and Λ of Ulbrich's distribution, that allow for the calculation of the rainfall kinetic energy and momentum, are proposed. Both procedures (Scenario 1 and 2) are based on the frequency distribution of the momentum M(D) of raindrops detected in a sampling time interval. Specifically, in the Scenario 1, μ and Λ are estimated by using I, N and the standard deviation, s(D), of the drop diameters obtained from the measured momentum distribution. In the Scenario 2 the parameters are estimated using I, N and the mean value, m(D), of the drop diameters deriving from the momentum distribution. The reliability of the proposed procedures was tested using DSD measurements recorded in three different experimental sites. The developed analysis demonstrated that Scenario 2 is the best method to estimate μ and Λ, and to reproduce the DSD, accordingly. The proposed method, associated with a patented device, not yet build, will allow the direct measurement of the rainfall energy characteristics, which are usually roughly estimated from rainfall intensity. The possibility to easily measure these energy variables can support the development of research in the field of soil erosion and, in general, of hydrogeological instability. In particular, the proposed measurement method and the construction of the device could stimulate the scientific community to deepen the study of the effect of the rainfall energy on soil erosion for improving the predictive capability of water erosion models. [ABSTRACT FROM AUTHOR]

In this paper, we analyse the uncertainty and parameter sensitivity of a conceptual water quality model, based on a travel time distribution (TTD) approach, simulating electrical conductivity (EC) in the Duck River, Northwest Tasmania, Australia for a 2‐year period. Dynamic TTDs of stream water were estimated using the StorAge Selection (SAS) approach, which was coupled with two alternate methods to model stream water EC: (1) a solute‐balance approach and (2) a water age‐based approach. Uncertainty analysis using the Differential Evaluation Adoptive Metropolis (DREAM) algorithm showed that: 1. parameter uncertainty was a small contribution to the overall uncertainty; 2. most uncertainty was related to input data uncertainty and model structure; 3. slightly lower total error was obtained in the water age‐based model than the solute‐balance model; 4. using time‐variant SAS functions reduced the model uncertainty markedly, which likely reflects the effect of dynamic hydrological conditions over the year affecting the relative importance of different flow pathways over time. Model parameter sensitivity analysis using the Variogram Analysis of Response Surfaces (VARS‐TOOL) framework found that parameters directly related to the EC concentration were most sensitive. In the solute‐balance model, the rainfall concentration Crain and in the age‐based model, the parameter controlling the rate of change of EC with age (λ) were the most sensitive parameter. Model parameters controlling the age mixes of both evapotranspiration and streamflow water fluxes (i.e., the SAS function parameters) were influential for the solute‐balance model. Little change in parameter sensitivity over time was found for the age‐based concentration relationship; however, the parameter sensitivity was quite dynamic over time for the solute‐balance approach. The overarching outcomes provide water quality modellers, engineers and managers greater insight into catchment functioning and its dependence on hydrological conditions. [ABSTRACT FROM AUTHOR]

The global water and carbon cycles are greatly influenced by terrestrial vegetation, making trustworthy representations of dynamic biosphere--hydrosphere interactions a crucial component of both ecosystem and climate models. This paper comprehensively evaluates the hydrological performance of a leading dynamic global vegetation model Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS), using a broad range of the latest available global observation-based gridded datasets that cover the main components of the hydrological cycle. Overall, we find that the hydrological components modelled by LPJ-GUESS agree well with global gridded datasets of runoff, evapotranspiration and surface soil moisture, though there are discrepancies in some regions and periods. Furthermore, LPJ-GUESS accurately captures both interand intra-annual variations of runoff in most regions and catchment areas, including the Danube, Murray, Yangtze, Yenisei and Nile basins. Total evapotranspiration modelled by LPJ-GUESS agrees closely with the evapotranspiration estimates of the Global Land Evaporation Amsterdam Model and PML-V2 datasets, but with some disagreement in the individual components, especially for evaporation. The surface soil moisture simulated by LPJ-GUESS aligns with ESA-CCI (v5.3) surface soil moisture datasets in most regions, with greatest discrepancies in subarctic areas. We attribute these discrepancies to two main sources: (1) absent or poor representation of processes such as river routing, storage and supply of water bodies, and cropland irrigation; and (2) uncertainties in both reference datasets and input to the model, including precipitation, soil texture, and land use. [ABSTRACT FROM AUTHOR]

Drought produces cross-system impacts, and these interactions between multiple systems are also referred to as drought propagation. However, the complex natural processes and anthropogenic disturbances lead to the drought propagation process being non-linear and systems feedback, which is still lack of knowledge in large-scale basins. To address these challenges, we propose a hydro-economic coupled model and investigate drought propagation across meteorological-hydrological-agricultural systems. The results from the Lancang-Mekong River Basin show that drought propagates from the meteorological system to the hydrological system and is weakened by the basin buffer and storage capacity. This propagation process shows spatial heterogeneity caused by basin characteristics, highlighting that the upstream (CS location) and downstream (KR and KC locations) are more prone to hydrological drought vulnerability. As drought further propagates to the agricultural system, water abstraction behaviours can alleviate the drought situation, leading to crop yield increases ranging from 4.6% to 39.2% through irrigation pathways. Unfortunately, irrigation behaviour also worsens hydrological drought in a feedback loop, where downstream VT (annual discharge decreases by around 1346 m³/s) shows more intense variation than upstream LP (annual discharge decreases by almost 135 m³/s), illustrating the feedback among multi-systems and accumulation in spatial. Moreover, upstream hydropower and downstream agricultural water use show synergistic relationships, revealing that efficient anthropogenic interventions can positively mitigate the impact of drought on human well-being. This paper provides an in-depth understanding of the complex drought propagation process in nature-human highly coupled Lancang-Mekong, which may help policymakers and basin managers to better cope with drought. [ABSTRACT FROM AUTHOR]

Seawater intrusion (SWI) is a consequence of communication between the ocean and inland groundwater entailed by overexploitation and has been a global issue harming production, life and ecology in coastal regions. This paper established a numerical model to identify SWI features in a wider space under different pumping-well layouts based on the number of wells (N), distance between the coastline and wells (Dcw), and distance between wells (Dww) and further researched the influence of the location of the screen (Ls) and calculated S as an index inferring the SWI degree. An evaluation index (EI) was proposed considering two contradictory parameters: the corresponding total critical pumping rate (Qc) indicated the critical situation in which saltwater was almost pumped, played a good role as the resource function, and S referred the negative environmental impact. Sensitivity analysis was performed to explore the relationship between the evaluation indexes and the parameters of pumping well layouts. The results revealed how seawater intruded inland groundwater under different pumping well layouts and the anthropogenic impact factors influencing the SWI process. Sensitivity analysis verified that Dcw was the key factor in optimizing pumping well layouts to maximize the quantity of groundwater resources and minimize the environmental damage of SWI. Research on Ls revealed that a higher location of the screen of the well could effectively abate SWI. This research fully explained SWI characteristics under different pumping well layouts and proposed the key factors during coastal groundwater exploitation work, which enhanced the understanding of SWI and contributed to the arrangement of realworld water pumping activities in coastal regions. [ABSTRACT FROM AUTHOR]

Limited information is currently available on how sediment transport affects rill flow resistance and the influence of hydraulic variables, as stream power, on sediment transport capacity for rill flows. In this paper, the available measurements of hydraulic variables (flow depth, channel slope, mean flow velocity, Reynolds number, Froude number, and Darcy–Weisbach friction factor) carried out by Ban et al. (Measurement of rill and ephemeral gully flow velocities and their model expression affected by flow rate and slope gradient. Journal of Hydrology, 589, 125172) and Ban (Measurements and estimation of flow velocity in mobile bed rills. International Journal of Sediment Research, 38(1), 97–104) for fixed and mobile bed rills are used to test the applicability of a theoretically deduced rill flow resistance equation based on a power‐velocity profile. The results allowed for stating that (i) the theoretical flow resistance approach can predict Darcy–Weisbach friction factor for flows over fixed and mobile beds, (ii) the stream power, dependent on flow discharge and slope, determines different flow behaviour, and (iii) the data are supportive of the slope independence hypothesis of rill velocity, for the mobile bed condition, only for the highest investigated discharge values (greater than 0.133 L s−1). [ABSTRACT FROM AUTHOR]

Groundwater exploitations in semi‐arid regions result in significant declines of groundwater levels and streamflow and even trigger seasonal streamflow drying up, which may bring adverse impacts on riparian ecosystems. It is critical to explore future streamflow changes caused by variable climate scenarios and groundwater exploitation intensities; however, a comprehensive assessment of the streamflow drying up frequency remains lacking. Furthermore, the thresholds of controlling factors beyond which streamflow drying up occurs have rarely been explored. Here we develop an integrated surface water‐groundwater model for the Taoer River Basin (TRB), a typical semi‐arid watershed in northeast China. We apply the model to multiple future scenarios to reveal the frequency of potential streamflow drying up and explore the thresholds of controlling factors of streamflow drying up based on a decision tree method. We find that the groundwater level in the lower region of the TRB (LTRB) is hard to recover to the riverbed elevation and the streamflow drying up frequency is still high unless the groundwater exploitation is reduced by 50%. However, this leads to a competition between the ecological and economic objectives. Our results also show that the streamflow drying up frequency in the LTRB is very sensitive to the upstream water inflow that can be regulated through the reservoir operation or inter‐basin water diversion, indicating the importance of a basin scale strategic management. The findings of this paper can help policy makers sustainably exploit water resources in semi‐arid regions. [ABSTRACT FROM AUTHOR]

We present here, and make freely available, two long‐term datasets on the hydrology and hydrochemistry of two small catchments totally or partially covered by holm oak (Quercus ilex) forests. Data have been collected over four decades of research on the ecology of Mediterranean evergreen forests. The datasets contain data on water fluxes in precipitation and runoff, and on the ion concentrations and fluxes in precipitation, throughfall and streamwater. Among other applications, these data have been used to obtain catchment budgets of water and elements, to document decadal changes in atmospheric deposition and streamwater chemistry, to assess the role of Saharo‐Sahelian dust on forest nutrient cycling, and to model habitat suitability for an endangered amphibian under future climates. To encourage their further use by the scientific community, in this paper we summarize the data context and methods, and give a nutshell of obtained results. We provide the links to these datasets on the Zenodo platform. [ABSTRACT FROM AUTHOR]

In this paper we propose a simple approach for modelling the functioning of a cluster of interconnected infiltration basins: such a modelling is crucial for correctly managing artificial aquifer recharge. We model and dynamically quantify the flow from the bottom of each basin, towards the outer walls of the cluster, and between adjacent basins: as a result of this modelling, saturated hydraulic conductivity parameters are estimated. This goal is accomplished simply by using mass balance arguments and Darcy's law, considering only water levels data and the total water inflow daily bestowed to the trenches; by using a declipping technique, automated recorded data are suitably filtered; then, from these data, an efficient algorithm is implemented for determining which basin is instantaneously fed. This approach can be used for managing the efficiency and performance of such facilities over time, and it can be easily generalized. The model is tested over a real‐life site in Castellana Grotte (Southeastern Italy), where an infiltration basins cluster is used as final receptor of the effluents from a tertiary treatment wastewater plant. Novelty and International Appeal Statement: We propose a simple approach for modelling the functioning of a cluster of interconnected infiltration basins. By a dynamical systems approach, we model the flow from the bottom of each basin, towards outer walls of the cluster, and between adjacent basins: as a result, saturated hydraulic conductivity parameters are estimated. [ABSTRACT FROM AUTHOR]

The definition of simple and accurate methods to estimate flow resistance in vegetated channels is still a challenging issue in soil bioengineering practices and programming riparian vegetation management to control channel conveyance capacity, sediment deposition, and flooding propensity. In this paper, measurements collected by Errico et al. (2018, 2019) in drainage channels colonized by common reed (Phragmites australis) were used to study the effect of flexible vegetation and its management in flow resistance estimate. At first, a theoretical flow resistance equation, obtained applying dimensional analysis and incomplete self‐similarity condition for the velocity distribution of an open channel flow, was briefly summarized. Then, this flow resistance equation was calibrated and tested by open‐field hydraulic experiments carried out by Errico et al. (2018, 2019) at the real scale of existing vegetated drainage channels. In particular, the Γ function of the power velocity profile was empirically related to the slope energy and the flow Froude number by using the available measurements. Taking into account the hydrological regime of the flow in the investigated channels, the original data set was divided into two sub‐data sets (calibrating and testing data set) exploring the same range of measured discharges. The calibration and testing of the flow resistance equation were carried out without distinguishing measurements corresponding to different vegetation conditions (full‐vegetated, half‐vegetated, non‐vegetated, central vegetation cut, extensive vegetation cut). The analysis demonstrated that the theoretical flow resistance equation allows an accurate estimate of the Darcy‐Weisbach friction factor which is characterized by errors that are always less than 10% and less than or equal to 5% for 90.9% of the investigated cases. The finding of this study also allowed to evaluate the effects of different vegetation management scenarios on flow resistance. [ABSTRACT FROM AUTHOR]

The final form of the relationship presented varies in detail between the papers, but a typical example (Di Stefano et al., 2017, equation (14)) proposes 1 HT ht where I i =1.5/ln( I Re i ). The first term on the right hand side is HT ht . [Extracted from the article]

When the unsaturated zone of the unconfined aquifer is covered by a low‐permeability upper layer, significant airflow will be generated in the unsaturated zone during water pumping. However, high permeability preferential flow zones (PFZs) such as fractures and macropores are frequently present in the unsaturated zone, forming the preferential fluid flow paths, which may change the original airflow pattern in the unsaturated zone during the pumping test and consequently affect the precision of obtained aquifer hydraulic parameters. The main objective of this paper is to investigate the effect of PFZs in low‐permeability upper layer on pumping‐induced airflow in the unsaturated zone by numerical simulations of transient three‐dimensional air‐water two‐phase flow and to quantify errors in the aquifer hydraulic parameters obtained during pumping test. The results demonstrate that a large amount of air flows quickly from the atmosphere into the unsaturated zone through the PFZs, and that the PFZs can draw some air from the nearby low‐permeability soils as well. The significant influx of air through PFZs also reduces the negative air pressure in the unsaturated zone and decreases the drawdown in the saturated zone at intermediate times, which are nevertheless still greater than the results obtained in the homogeneous aquifer. Estimations of the aquifer hydraulic parameters reveal that errors of these parameters obtained are smaller when the PFZs with favourable combinations of permeability, width and quantities facilitate more air to flow into the unsaturated zone. [ABSTRACT FROM AUTHOR]

The emergence of floodplain vegetation enhances the local drag and affects the velocity distribution of the overbank flow in a two‐stage channel. Numerous analytical models (e.g., the modified SKM models) have been established to simulate the transverse velocity distributions of overbank flows with vegetation. However, the dimensionless eddy viscosity (λ) was simplified to be a constant in these models when quantifying transverse momentum exchange. In this paper, we develop a novel analytical model to simulate the depth average velocity profiles of overbank flows with floodplain vegetation. Considering a micro‐hexahedral element on a vegetated‐bed area for a two‐stage rectangular channel, the governing equation of the vegetated overbank flow is derived. An improved eddy viscosity model that considers the transverse variation of the λ is employed to quantify the transverse momentum transfer, and a linear empirical function simplifies the secondary current. The simulated depth average velocities agreed well with the published measurements. In comparison with existing models, the proposed model shows better prediction accuracy, particularly in the shearing layer domain. More importantly, for the optimized model parameters, we found that the dimensionless eddy viscosity plays the most influential role when simulating depth‐averaged velocities in the shearing layer domain, whereas the drag force dominates for vegetated floodplains. This study provides a convenient method for predicting the flow velocity in overbank floods with vegetation. [ABSTRACT FROM AUTHOR]

In frequency analysis of annual maximum flood series (AMFS), it is mechanism‐based and significant to incorporate the information of the underlying "ordinary" daily streamflow events for improving accuracy of flood risk estimation and appropriate management. In previous studies related to flood nonstationarity, the classical norming constants method (C‐NCM) has been used to derive statistical parameters of annual maximum flood distribution from daily streamflow distribution. However, C‐NCM does not flexibly consider the feasible range of the scale parameter of annual maximum flood distributions, which can result in the inability to provide sufficient and reliable models to fit AMFS. This paper aims to investigate the potential of two alternative norming constants methods in fitting annual maximum floods, namely the Hall's norming constants method (H‐NCM) and the Fisher and Tippetts' norming constants method (FT‐NCM) respectively. A comparative study of these three methods was carried out using hydrological streamflow series of 77 stations in the Yangtze and Yellow River basins, China. The results found that H‐NCM outperforms both C‐NCM and FT‐NCM for the stations with relatively low‐skewness coefficient of AMFS. Therefore, H‐NCM is recommended to prioritize for practical applications when considering daily streamflow rather than small samples of flood events. Furthermore, if the skewness coefficient exceeds Cs,Gumbel≈1.14, the overall modelling performance of these three methods is significantly deteriorated. This can provide some reference for the applicability of the norming constants method in flood frequency analysis. [ABSTRACT FROM AUTHOR]