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Different means of hydrological data collection have developed and used. However, they are constraint in one way or other. This paper therefore revisited the rainfall simulator as potential tool for hydrological research. The research disclosed that there are three different types of rainfall simulators; drop former simulator, pressure nozzle simulator and hybrid simulator. It can further be classified as indoor model and outdoor. The research also showed that precipitation is the driving force in hydrological studies. Consequently, in the design of rainfall simulator, the following should be taken into consideration: nozzle spacing, pump size, nozzle size, nozzle type, nozzle spacing, plot size and pressure. Meanwhile, intensity, distribution uniformity, kinetic energy, rainfall drop size and rainfall terminal velocity should be noted in its evaluation. Factoring-in the aforementioned design considerations, data collection is made easy without necessarily waiting for the natural rainfall. Since the rainfall can be controlled, the erratic and unpredictable changeability of natural rainfall is eliminated. Emanating from the findings, pressurized rainfall simulator produces rainfall characteristics similar to natural rainfall, which is therefore recommended for laboratory use if natural rainfall-like characteristics is the main target.

The emergence of high-resolution observational tools, information and communication technologies, cloud computing and big data are disrupting the water sector in an unprecedented way. In the field of hydrological sciences, research calls aimed at observing, backcasting and forecasting terrestrial water resources at finer space-time resolutions have been made over the past years by the scientific community. Here, we introduce the Hydrological Observatory of Mexico City (OH-IIUNAM), an academic initiative consisting of a dense network of 55 state-of-the-art precipitation sensors (optical disdrometers and weighing rain gauges) located within Mexico City, one of the largest urban centers of the world. The objective of OH-IIUNAM, given its open-data philosophy, is to enable scientific research within urban environments by providing a real-time hydro-meteorological observational platform at the hyper-resolution (dt=1 minute). Potential niches of opportunity ranging from atmospheric processes to hydrological modeling and design in urban areas are envisaged and discussed. Future expansion phases of OH-IIUNAM are expected to incorporate streamflow, groundwater and water quality.HTML aquí.

Global Satellite Mapping of Precipitation (GSMaP), Climate Hazards Group InfraRed Preconception with Station data (CHIRPS), Tropical Rain Measurement Mission Multisatellite Precipitation Analysis (TRMM 3B42 V7) and Rainfall Estimation from Soil Moisture Observations (SM2RAIN) are satellite precipitation products with high applicability, but their applicability in hydrological research in arid mountainous areas is not clear. Based on precipitation and runoff data, this study evaluated the applicability of each product to hydrological research in a typical mountainous basin (the Qaraqash River basin) in an arid region by using two methods: a statistical index and a hydrological model (Soil and Water Assessment Tool, SWAT). Simulation results were evaluated by Nash efficiency coefficient (NS), relative error (PBIAS) and determination coefficient (R2). The results show that: (1) The spatial distributions of precipitation estimated by these four products in the Qaraqash River basin are significantly different, and the multi-year average annual precipitation of GSMaP is 97.11 mm, which is the closest to the weather station interpolation results. (2) On the annual and monthly scales, GSMaP has the highest correlation (R ≥ 0.82) with the observed precipitation and the smallest relative error (BIAS < 6%). On the seasonal scale, the inversion accuracy of GSMaP in spring, summer and autumn is significantly higher than other products. In winter, all four sets of products perform poorly in estimating the actual precipitation. (3) Monthly runoff simulations based on SM2RAIN and GSMaP show good fitting (R2 > 0.6). In daily runoff simulation, GSMaP has the greatest ability to reproduce runoff changes. The study provides a reference for the optimization of precipitation image data and hydrological simulation in data-scarce areas.

This paper deals with hydrological research in regard to the water resources crisis in the vulnerable areas found in the northern part of China. This area includes three main river basins, namely the basins of the Yellow (Huang) River, the Hai River and the Huai River. Several water problems are becoming very severe. Among them, two are the most critical: the Yellow River has been drained dry in the main course of its lower reaches and along its major tributaries, and the groundwater table has rapidly declined in the floodplains of the three rivers' downstream areas. To counter the problems, particularly the critical issues mentioned above, hydrological research, which serves as the basis of water development and management, has been carried out in the last two decades. This paper addresses three basic scientific problems in North China, namely: (a) water consumption and the capacity for saving water; (b) the changes in hydrological processes and water resources caused by natural change and human activities; and (c) the ability to supply water resources and water safety in terms of both quantity and quality within a changing environment. However, opportunities and challenges for ameliorating the problems exist, and new ideas and methodology to solve the problems have been proposed, such as the interface process study on the interactions in the soil-root interface, the plant-atmosphere interface, the soil-atmosphere interface, and the interface of soil water and groundwater. In order to manage water resources in a sustainable manner, the study of water resources' renewal ability as affected by natural change and human activity is addressed from the viewpoint of both water quantity and quality, and their integration. To reduce the vulnerability of water resources in regional water management, a paradigm of sustainable water resources utilization is also proposed, using water-heat balance, water-salt balance, water-sediment balance, and water supply-demand balance. This approach may help reveal the basic problems and point to possible approaches to solving the water problems in North China in the 21st century. Copyright (C) 2004 John Wiley Sons

is the combined outcome of both the 2001 EGS ses-sion on the ‘Water balance of mountain basins’ in Nice and the 2002 Annual Meeting of the Ger-man Hydrological Working Group in Berlin. A variety of hydrological and meteorological research top-ics presented at these meetings focused on water resources, modelling, parameterization, remote sens-ing, snow and ice melt, evaporation and transpiration. Case studies concentrated especially on moun-tain areas, which ranged in altitude from 1500 to 6000 m, and on a variety of regions, such asthe Himalayas, Karakorum, Hindukush, Yemen Mountain Massif, Norwegian Scandes and Alps. Theanalysis of water balance components was conducted at many different temporal and spatial scales,ranging from annual and seasonal to daily and hourly, and from entire basins to single lysimetricanalyses.The current discussion about climatic–hydrologic change and bio-adaptability reflects the necessityfor more comprehensive and more detailed knowledge about water balance in mountain basins. Sincemountain watersheds are source areas for large rivers, an understanding of the water balance is invalu-able. This should include a variety of components, such as water input, water storage, water loss, andwater transfer potentials on steep, heterogeneous surfaces. Many of the associated processes are insuf-ficiently investigated, although they are of major significance for both hydrologists and water resourcemanagers.AIMIt is the aim of this special issue to present a diverse range of topics and research areas in order to revealthe wide spectrum of research topics and methods on water balance studies in mountain basins. These stud-ies demonstrate both the success and the emerging difficulties and shortcomings in different research fields.Examples from the developed and from the developing world not only promote comparisons, but also newideas about the availability and transferability of methods.

This paper reports some of the achievements in hydrological research associated with the Mackenzie GEWEX Study (MAGS). MAGS is a multifaceted study of the energy and water cycle in the Mackenzie River Basin, north-western Canada, and emphasizes cold-region processes and modelling. It pursues methodologies of scaling-up process studies to a large river basin that has few measurement sites. This methodology involves new developments, adapting mid-latitude algorithms to the high latitude setting and promoting the use of remote sensing tools for scaling-up. Intensive hydrological process studies have been concentrated at a number of sites. These have been chosen to represent different biophysical facets of the Mackenzie River Basin. They include northern basins in open tundra and at tree-line, a western basin representing the hilly and mountainous western side of the basin, central basin sites of wetlands, Precambrian Shield terrain and the Mackenzie Basin counterpart of the large Laurentian Great Lakes. The most southerly site represents a mixed-wood boreal forest site that is undergoing land-use change as a result of forest harvesting. Regional community model analysis indicates that processes of lee cyclogenesis result in differential input of precipitation across the basin. Significant results centre on models of snow accumulation featuring the role of blowing snow, intercepted snow and snowmelt. These models emphasize the importance of snow patchiness to speed of melt. Snowmelt infiltration into frozen soils is important in controlling runoff, and tundra microlandforms play a unique role in determining the surface runoff characteristics. On the western margins of the basin, there is a very significant difference in the hydrological behaviour of slopes of different aspects as a result of differences in permafrost and vegetation. In the central basin, a deeper understanding of components of the water budget is being gained through stable isotope analysis of wetland waters.

Mountains are fragile ecosystems and globally important as water towers of the earth. Sustainable use of mountains depends upon conservation and optimal use of soil and water resources (Ives & Messerli 1989). Despite regional and global efforts to understand the hydrology of the Himalayan region, soil and water conservation (SWC) programmes in this region mainly rely upon engineering measures. For want of cost-effective vegetative (bioengineering) measures (Deoja et al. 1991), and land use and land cover conducive to SWC, the fragile Himalayan watersheds continue to lose soil and water at alarming rates.

The Niger Delta at the southernmost part of Nigeria, is a large and ecologically sensitive region. Natural and anthropogenic activities, such as subsidence, sea-level rise, upstream dams and reservoirs, dredging and overabstraction of groundwater, disturb this equilibrium, leading to adjustments in ecological conditions and boundaries. Ecological changes affecting large areas cannot be explained by local observation. Relating observed effects to causes of environmental behaviour therefore requires a regionalized data collection, that provides a broader perspective of the issues involved with resultant ease in the identification of common problems and formulation of effective solutions.

Groundwater is faced to seawater in the end of its flow system. The shape of the interface of the fresh groundwater and salt water is discussed by Ghyben-Herzberg Low, in the previous studies. However, the groundwater push out the interface to the off-shore side than the low expected and the fresh groundwater flows even in the marine bottom (beneath of the marine bottom). This study summarized the previous studies for the interface and review the data of recent works. Distribution of submarine groundwater discharge and the shape of the seawater / freshwater interface is related strongly each other. The understanding of the groundwater flow property in the bottom end of its flow system will be useful for the development of water resources and evaluation for the environments.

After several decades of interception studies, there are still considerable gaps in the understanding of wet-canopy evaporation. Model development is being obstructed by the lack of techniques for the measurement of state and rate variables which have to be quantified for model validation. The applicability of microwave attenuation measurements for the determination of canopy wetness is examined. The attenuation caused by a single spruce fir in the laboratory and the vertical attenuation profiles of a Douglas fir stand were measured under dry and wet conditions. The results indicate an instant increase of the attenuation upon wetting and a decrease owing to drip and evaporation after rainfall ceased. From the results, conclusions have been drawn on the design of instrumentation for an optimized measuring system which is suitable for unattended automated scanning of canopy water storage. This system has been calibrated, using vertically integrated microwave attenuation profiles and canopy water budgets from precipitation and throughfall measurements. This system will be used for a forest hydrological study in the framework of the Dutch ACIFORN project, a research project on the effect of atmospheric deposition on Douglas fir vitality.

In the past, land consolidation projects in the Netherlands were aimed almost exclusively at increase of crop yields and farm income. Also the improvement of the water management system served agricultural purposes. Hydrological research, therefore, was directed to find optimal agrohydrological conditions. The results were translated into criteria for hydrological variables (like groundwater and surface water levels, discharge coefficients) and design rules for subsurface drainage systems. Initially the need to reduce excessive wetness was emphasized, later yield reduction due to water shortages in summer also became important. Lately the land consolidation projects have been renamed as “land development projects”. This is a result of recent developments in the rural areas, where aspects of nature conservation and outdoor recreation have become important items. Because water management measures in favour of one function often interfere with another, fixed design rules are no longer sufficient. The hydrological consequences for different interests have to be known beforehand. For the calculations of groundwater flow, analytical solutions are being replaced by numerical methods in order to cope with increasingly complex situations. Aspects of water quality are becoming more important. In addition to analyses of water samples, attention is paid to flow paths and stream velocities of groundwater, which give insight into the relation between quality and quantity. In this work, a close cooperation with agronomists and biologists has been established. A review is given of the hydrological models used for this purpose, at present and in the near future.

Intercepted rainfall may be evaporated during or after the rain event. Intercepted rain is generally determined as the difference between rainfall measurements outside and inside the forest. Such measurements are often used to discriminate between water storage and evaporation during rain as well. Two well-accepted methods underestimate water storage by a factor two as compared to direct observations. The underestimation of storage is compensated by an overestimation of evaporation during rain by a factor of three. The direct observations of water storage and evaporation appear to agree with previous direct observations. Thus, it is concluded that these observations are representative Also, our results based on methods using only rainfall measurements inside and outside the forest appear to agree with previous results, This would result in the conclusion that the common methods systematically underestimate water storage and overestimate evaporation during rain. Indeed, the systematic errors can be explained by the neglect of drainage before saturation. Water storage is better simulated assuming an exponential saturation of a larger storage capacity. A smaller evaporation can be simulated using an appropriate resistance to vapour transport. The observations in dense coniferous forest showed water storage to be the dominant process in rainfall interception, but this conclusion should not be generalized to other forests and climates. Direct observations of water storage and evaporation are recommended to build a realistic set of parameters for rainfall interception studies of the main vegetation types. (C) 1998 Elsevier Science B.V. All rights reserved.

This paper reports the effects of altering an aspen forest cover in Utah on evapotranspiration losses, overland flow, erosion, and mantle storage deficits during three successive growing seasons. These data, together with supplemental measures of winter precipitation and estimates of evaporation from snow, provided a basis for estimating amounts of water available for stream flow. Removal of aspen trees, leaving the herbaceous understory and litter undisturbed, reduced evapotranspiration losses and increased the amount of water available for stream flow by about four inches without seriously increasing overland flow or soil erosion during summer rains. Removal of the remaining herbaceous cover further reduced evapotranspiration losses and increased the amount of water available to streams by an additional four inches but resulted in an undesirable increase in summer rainfall runoff and soil loss.

Currently, the direction of hydrological research, highlighting certain aspects of the influenceof climatic factors on the average annual water discharge of river basins, is changing due to climate change,which is a function of annual atmospheric precipitation and average annual air temperature that characterizeevaporation, that is, hydrometeorological components of the geographical landscape reflecting that is theratio of heat and moisture, which is characteristic of the geographical area. One of the most importanttasks in the field of hydrological research is to study the genesis of long-term fluctuations in the averageannual water discharge and climatic indicators of the catchment area of river basins, and to identify theirregional patterns, modern geographic information systems and algorithms have been developed that makeit possible to quickly and efficiently solve this problem. On the basis of them, a research base was formedcovering the period 1934-2020, which is based on information and analytical materials of the reference andinformation portal «Weather and Climate», the RSE «Kazhydromet», the World Meteorological Organization(WMO) and the RSU «Tobol-Torgay Basin Inspection on the regulation of the use and protection of waterresources». The cyclical nature of the average annual water discharge, average annual air temperatures andannual atmospheric precipitation for the catchment area of the Tobol River basin manifests itself unequallyin separate periods at a particular phase of development, i.e. modeling linear trends and differential integralcurves. To assess the degree of synchronicity of average annual water discharge and average annual air temperatures and atmospheric precipitation, methodological support was developed, implemented in thecatchments of the Tobol River basin, which showed that in the steppe zone of Northern Kazakhstan, theirdegree of synchronicity is low, since the main source of runoff formation in the considered territory the snowcover of the previous year accumulated over the winter, that is, atmospheric precipitation at the end of theautumn and the beginning of the winter period, which are not taken into account when determining the degreeof synchronicity of a real year, which requires the need to clarify the structure of the calculated year, takinginto account the determining conditions for the formation of river flow.

Over the past decades, a number of water sciences and management programs have been developed to better understand and manage the water cycles at multiple temporal and spatial scales for various purposes, such as ecohydrology, global hydrology, sociohydrology, supply management, demand management, and integrated water resources management (IWRM). At the same time, rapid advancements have also been taking place in tracing, mapping, remote sensing, machine learning, and modelling technologies in hydrological research. Despite those programs and advancements, a water crisis is intensifying globally. The missing link is effective interactions between the hydrological research and water resource management to support implementation of the UN Sustainable Development Goals (SDGs) at multiple spatial scales. Since the watershed is the natural unit for water resources management, watershed science offers the potential to bridge this missing link. This study first reviews the advances in hydrological research and water resources management, and then discusses issues and challenges facing the global water community. Subsequently, it describes the core components of watershed science: (1) hydrological analysis; (2) water-operation policies; (3) governance; (4) management and feedback. The framework takes into account water availability, water uses, and water quality; explicitly focuses on the storage, fluxes, and quality of the hydrological cycle; defines appropriate local water resource thresholds through incorporating the planetary boundary framework; and identifies specific actionable measures for water resources management. It provides a complementary approach to the existing water management programs in addressing the current global water crisis and achieving the UN SDGs.

Snow depth mirrors regional climate change and is a vital parameter for medium- and long-term numerical climate prediction, numerical simulation of land-surface hydrological process, and water resource assessment. However, the quality of the available snow depth products retrieved from remote sensing is inevitably affected by cloud and mountain shadow, and the spatiotemporal resolution of the snow depth data cannot meet the need of hydrological research and decision-making assistance. Therefore, a method to enhance the accuracy of snow depth data is urgently required. In the present study, three kinds of snow depth data which included the D-InSAR data retrieved from the remote sensing images of Sentinel-1 synthetic aperture radar, the automatically measured data using ultrasonic snow depth detectors, and the manually measured data were assimilated based on ensemble Kalman filter. The assimilated snow depth data were spatiotemporally consecutive and integrated. Under the constraint of the measured data, the accuracy of the assimilated snow depth data was higher and met the need of subsequent research. The development of ultrasonic snow depth detector and the application of D-InSAR technology in snow depth inversion had greatly alleviated the insufficiency of snow depth data in types and quantity. At the same time, the assimilation of multi-source snow depth data by ensemble Kalman filter also provides high-precision data to support remote sensing hydrological research, water resource assessment, and snow disaster prevention and control program.

High-elevation grasslands worldwide provide essential hydrological services including water provision, flow regulation, and erosion control. Despite their importance, hydrological research of grasslands in montane regions is usually scarce and disperse, limiting the capacity to improve water resource management. We present a systematic literature review of the hydrological function of high Andean grasslands under conserved, degraded, and restored conditions in ecosystems situated above the tree line in the tropical Andes (paramos, punas, and jalcas). Most hydrological research on these grasslands has been developed in paramos (92%), especially in Ecuador, while research in punas is scarce (6%) despite being the largest grassland extent in the region. For paramos, published literature highlights the importance of conserving grasslands to facilitate water infiltration to soils, which in turn reduces erosive processes. Water-vegetation relations for conserved paramos are well understood, indicating that about 50% of water inputs return to the atmosphere via evapotranspiration, but knowledge about hydrological functions of conserved punas and jalcas is virtually non-existent. Under changing land use, afforestation of grassland ecosystems with exotic tree species, especially pines, reduces soil water storage as well as water yield and flow regulation capacity. Impacts of grazing and agriculture on the hydrological function of paramo grasslands strongly depend on historical land management and current land use practices and are not generalizable. Short-term restoration studies indicate that more than two years are necessary to recover the hydrological function of degraded grasslands, therefore medium and long-term studies are required to determine efficient restoration periods. These knowledge gaps limit the ability to extrapolate and regionalize findings. Future directions aimed to fill them are proposed, and methods successfully used to investigate the hydrology of high Andean grasslands are highlighted. This research not only enlightens what is known about the hydrology of high Andean grasslands, but also seeks to guide future hydrological evaluations to fill identified geographical and topical knowledge gaps precluding improved management of water resources in the tropical Andes.

Looking at natural hazards and risks, such as landslides, debris flow and floods, we see a broad range of science fields involved: from earth science to engineering science, to management, policy and social science. Although research on natural hazards and risks contains mono-disciplinary aspects, it is best characterized by its multi-disciplinary nature. Moreover, the link to society has always been a very important driver in natural hazards research, pushed by the need for reliable prediction models to be implemented into early warning systems as well as by the required complete understanding of the physical mechanisms for the design of mitigation works. If we focus on landslide and debris flows as in this special issue of HESS, we will see impressive progress in the geotechnical and slope stability modelling needed for hazard analysis. Similarly, the risk management aspects, such as hazard mapping and risk assessment, have received much attention. Hydrology is an important aspect of landslide and debris flow assessment. Precipitation and snowmelt water infiltration, leading to local pore water pressure increase and/or matric suction decrease, is amongst the most common triggers of landslides. Fundamental knowledge about underlying processes affecting this infiltration process, such as macropore and fissure flow, water repellency, soil structure, soil–plant–atmosphere interactions as well as the effects of land use practices (e.g. deforestation, terracing, grazing), has strongly improved in the last decade or so, with a clear focus on more detailed knowledge of hydrological process dynamics. The hydrological process understanding progressed rapidly under pressure of societal needs such as prediction of discharge generation and contaminant transport, to name a few. Although hydrology research is very strongly linked to natural hazards, such as landslides and debris flows, this improved hydrological knowledge has found its way into the landslide community rather modestly. In particular, the incorporation of hydrological processes into large-scale models is still incomplete and their application to landslide prediction limited. Landslide research tends to be more focused on novel methods to include spatial data and on the practical applicability of, e.g. landslide triggering modelling and statistical analyses for regional hazard and risk assessment. However, without stating that these fields have been fully exploited, we see that in our quantitative landslide and debris flow modelling the inclusion of increased process knowledge seems to lag behind. This in depth process understanding needs to be incorporated in our technical predictions in order to improve the reliability of early warning systems, mitigation works and landslide zonation. This special issue aims to present innovative hydrological research applied to landslide studies to improve the understanding of the spatio-temporal patterns of slope movement mechanisms induced by precipitation. The initiative struck a sympathetic note, as many colleagues were facing these challenges. The topic of hydrology and landslides is finding more and more space in hydrological research, as witnessed by the number of relevant papers published, in special issues, e.g. on hydrology of unstable clay shales (Bogaard et al., 2012) and through the organization of workshops and special conference sessions, such as six EGU sessions on hydrology and landslides, three editions of the Italian Workshop on Landslides mainly dedicated to landslide hydrology (www.iwl.unina2.it), and special sessions at IAEG2014. Therefore, this Special Issue discusses the representation of

In the Federal Republic of Germany (West) at the present time 14 forest hydrological research projects with 34 individual catchments are being maintained. In some cases measurements have been extended to several sub-catchments. Mostly, the approaches of ungaged paired-watershed studies or single-watershed studies are used. Only in the Forest Hydrological Research Area of Krofdorf was the procedure of a watershed calibration with two control catchments and two planned experimental catchments carried out for 10 years and subsequently, during the winter of 1982–1983, reductions of forest cover density by cuttings were started. In connection with forest decline caused by air pollution and its effects on amount, timing and quality of discharge there is an increasing demand to use sound long-term quantitative and qualitative precipitation and streamflow measurements of forest catchments such as ‘benchmark-catchments’. However, for this purpose the procedures of a climatic calibration and/or watershed modelling must be realised.

Extensive deforestation in tropical regions may significantly influence the hydrological cycle. However, subsurface runoff processes in thick soil layers in humid tropical forests are poorly understood; thus, the impact of land-use changes in such regions remains unclear. To understand runoff generation mechanisms in the humid tropics, we monitored groundwater and soil moisture dynamics in a forested hillslope in Sumatra, Indonesia. We also conducted field and laboratory experiments to determine soil hydraulic characteristics and used the results to simulate vertical infiltration and groundwater recharge. Although the soil is categorized as silty clay loam, the high infiltrability and high water retention capacity of the soil enabled infiltration during storm events and recharge to groundwater. Within the 4–5 m thick soil layer at the foot of the hillslope, the shallow groundwater table quickly responded to rainfall and did not drop below a depth of 2–3 m, possibly due to continuous flow contributions from the upslope. Overall, this study demonstrates the importance of subsurface flow and vertical infiltration in thick soil layers in humid tropical regions.

The aim of the study was to analyze the long-term variability of the average annual water runoff of the rivers of the Pripyat basin within Ukraine and to assess its calculated characteristics in the high-water and low-water phases of water content.The research of the cyclical nature of long-term fluctuations of river water flow, which contributes to the establishment of long-term dynamics of water content and potential (forecast) changes – is a topical issue of modern hydrological research. To describe the long-term variability of river water flow and its structure (cycles and phases of water content) the most effective method is stochastic, based on mathematical statistics, the theory of random variables and functions, probability theory. Autocorrelation analysis, various statistical criteria (homogeneity, series, series lengths), total and difference integral curves, probability theory, correlations, statistical estimation of probable errors, etc. were used to identify stochastic regularities of long-term variability. According to the results of the study of long-term variability of the average annual water runoff of the rivers of the Pripyat basin within Ukraine, it is established that cycles with periods of 29±2 years have high reliability and indicate stability of periods of low (10±2 years) and high water content. 17±2 years). According to the identified stochastic patterns, it is assumed that by 2025-26 it is necessary to expect the continuation of the low-water phase of water, then with the duration of 16-17 years the high-water phase will begin and from 2044-45 there will be low water again until 2055-56. According to the proposed regression equations between the average annual water discharge for a long-term period and their average values during the high-water and low-water phases of water content (with very significant approximation coefficients) and the obtained transition coefficients, it is possible to establish the calculated characteristics of the average annual flow of water of various availability in the high-water and low-water phases of water content, thereby giving their forecast estimates.

Simulating streamflow under both high-and low-flows is required for versatile eco-hydrological modeling. Typical streamflow simulators require hydrological data such as river geometry and observed river discharge/water level as upstream/downstream boundary conditions. However, these are not always available in data-sparse regions. Furthermore, because of the potential inaccuracy of digital elevation model (DEM) data around water surfaces, this data has not generally been utilized in streamflow simulations. Therefore, this study explores the potential applicability of DEM data to extract river cross-sections, focusing on the upstream Hiikawa River, Japan. A 1-D streamflow simulation was performed using river cross-sections extracted from a 5 m LiDAR DEM and the observed dam discharge from 2018 to 2020 as the upstream boundary condition. The simulated water depths with Manning’s roughness coefficients of 0.03 to 0.05 m–1/3 s reproduce the observation results with Nash-Sutcliffe coefficients of 0.91–0.97 for the whole period and 0.60–0.97 for a flood event. The accurate results for both low and high flows were considered to reflect the reasonable representations of the river cross-section. Finally, the velocity-based suitability index for Ayu (P. altivelis) was evaluated. We demonstrate applicability and several possible limitations of DEM data for eco-hydrological modeling of data-scarce rivers.

Precipitation is an important part of the global hydrological cycle. The large- scale, high-precision continuous precipitation data obtained by satellite remote sensing detection technology has become an important source of spatial precipitation data. However, because the spatial resolution of remote sensing precipitation data is still low, it is difficult to meet the needs of hydrological research, which restricts their application in drought and flood analysis, hydrological simulation, etc. In response to this problem, this paper takes the Beijing-Tianjin-Hebei region as the research area, downscaling the TRMM data and the GPM data space of the continuation plan, and increasing the spatial resolution of the data to 1 km. Compared with the original data, spatial downscaling data not only greatly improves the spatial resolution, but also increases the accuracy of the data, which has better applicability.

The Matusagaratí wetland in the Panamanian Darien is one of the largest and most biologically diverse wetland ecosystems in Central America. Despite this, no hydrological studies have been conducted in the area due to its remoteness and difficult access. The aim of this research is to define the relationship between surface water and groundwater through the field and laboratory data obtained from the first monitoring network installed in the Matusagaratí wetland. Variations registered in the isotopic relationships in surface water and groundwater show that the wetland receives contributions from rainfall as well as fluvial and estuarine water. There are areas of the wetland where one of these sources predominates, and others where they mix. In the wetland sector downstream the Tuira river, the groundwater presents a combination of freshwaters coming from Filo del Tallo and those coming from the Tuira river, whose high salinity reflects the estuary's influence. Meanwhile, in the upstream sector of the wetland, the groundwater is a mixture of river water and rainwater on the river´s levee but behind it, rainwater predominates. In all cases, groundwater has Rare Earth Elements patterns like those of the Tuira river, highlighting the importance of river flooding as a source and support system for the wetland groundwater. Hydrological research such as this, presents a valuable opportunity to provide sound scientific information to promote sustainable management and environmental conservation of this unique wetland that is rapidly being transformed to cattle pasture and palm and rice cultivation. Fil: Carol, Eleonora Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: Alvarez, Maria del Pilar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina Fil: Candanedo, Indra. Universidad Tecnologica de Panamá.; Panamá Fil: Saavedra, Sidney. Universidad Tecnologica de Panamá.; Panamá Fil: Arcia, Manuel. Universidad Tecnologica de Panamá.; Panamá Fil: Franco, Ana. Universidad Tecnologica de Panamá.; Panamá

We introduce a new catchment dataset for large-sample hydrological studies in Brazil. This dataset encompasses daily time series of observed streamflow from 3713 gauges, as well as meteorological forcing (precipitation, evapotranspiration and temperature) for 897 selected catchments. It also includes 63 attributes covering a range of topographic, climatic, hydrologic, land cover, geologic, soil and human intervention variables, as well as data quality indicators. This paper describes how the hydrometeorological time series and attributes were produced, their primary limitations and their main spatial features. To facilitate comparisons with catchments from other countries, the data follow the same standards as the previous CAMELS (Catchment Attributes and MEteorology for Large-sample Studies) datasets for the United States, Chile and Great Britain. CAMELS-BR complements the other CAMELS datasets by providing data for hundreds of catchments in the tropics and in the Amazon rainforest. Importantly, precipitation and evapotranspiration uncertainties are assessed using several gridded products and quantitative estimates of water consumption are provided to characterize human impacts on water resources. By extracting and combining data from these different data products and making CAMELS-BR publicly available, we aim to create new opportunities for hydrological research in Brazil and to facilitate the inclusion of Brazilian basins in continental to global large-sample studies. We envision that this dataset will enable the community to gain new insights into the drivers of hydrological behavior, better characterize extreme hydroclimatic events, and explore the impacts of climate change and human activities on water resources in Brazil. The CAMELS-BR dataset is freely available at https://doi.org/10.5281/zenodo.3709338 (Chagas et al., 2020).