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Atmospheric precipitation is the main source of replenishment for large karst springs in the northern China. The extensive spring area and the high heterogeneity and anisotropy of the karst aquifer can cause a significant lag in the response of spring water level to precipitation. To explore the response characteristics of different flows of groundwater to precipitation, this study took the Jinan spring area as an example and used time series analysis to investigate the response characteristics of spring to rainfall. This study showed that atmospheric precipitation remains the single most important factor affecting spring discharge at present. According to the characteristics of spring discharge recession, the groundwater flows in the Jinan spring area can be divided into conduit-major fissure flow and diffuse-minor fissure flow. This study examined the response characteristics of different groundwater flows to precipitation through correlation and spectral analyses. The response time of conduit-major fissure flow to precipitation ranged 7–16 days and the duration ranged 12–24 days. The response time of diffuse-minor fissure flow to precipitation ranged 36–56 days, and the duration ranged 1–3 hydrological years. Compared with the karst water system in the southern China, the karst water system in the northern China has a stronger regulating effect. On this basis, this study proposed a correlation and spectral analyses and evaluation method suitable for understanding the dynamics of large karst springs in the northern China. [ABSTRACT FROM AUTHOR]

Deep learning (DL) methods have shown great promise for accurately predicting hydrologic processes but have not yet reached the complexity of traditional process‐based hydrologic models (PBHM) in terms of representing the entire hydrologic cycle. The ability of PBHMs to simulate the hydrologic cycle makes them useful for a wide range of modeling and simulation tasks, for which DL methods have not yet been adapted. We argue that we can take advantage of each of these approaches by embedding DL methods into PBHMs to represent individual processes. We demonstrate that this is viable by developing DL‐based representations of turbulent heat fluxes and coupling them into the Structure for Unifying Multiple Modeling Alternatives (SUMMA), a modular PBHM modeling framework. We developed two DL parameterizations and integrated them into SUMMA, resulting in a one‐way coupled implementation which relies only on model inputs and a two‐way coupled implementation, which also incorporates SUMMA‐derived model states. Our results demonstrate that the DL parameterizations are able to outperform calibrated standalone SUMMA benchmark simulations. Further we demonstrate that the two‐way coupling can simulate the long‐term latent heat flux better than the standalone benchmark and one‐way coupled configuration. This shows that DL methods can benefit from PBHM information, and the synergy between these modeling approaches is superior to either approach individually. Plain Language Summary: Machine learning (ML) and process‐based methods are two approaches to hydrologic modeling. Process‐based hydrologic models (PBHMs) represent the hydrologic cycle by solving equations which have been developed from physical theory or experimentation, while ML models make predictions based on patterns learned from large amounts of data. A particular sub‐field of ML called deep learning (DL) has been shown to often outperform process‐based models. However, current DL models do not represent all aspects of the hydrologic cycle (such as streamflow, evaporation, groundwater storage, and snowpack) at once, as is often done in PBHMs. As a result, DL models in hydrology are often single purpose, while PBHMs can be used for many different scientific and/or engineering purposes. We show how individual DL models that simulate evaporation and convective heat transport at the land surface can be incorporated into a PBHM. We show that DL simulated evaporation and convective heat transport better than the PBHM. We also show how the incorporation of deep DL into process‐based models can further improve the DL model itself. We conclude that taking advantage of both modeling perspectives is better than either on its own. Key Points: Deep learned process parameterizations of turbulent heat fluxes outperform physically based parameterizationsDeep learned process parameterizations can be dynamically coupled into process‐based hydrologic modelsIncorporation of process‐based model derived states into deep learning introduces feedbacks that improve long‐term simulations [ABSTRACT FROM AUTHOR]

In the practice of using river resources accumulated in reservoirs, there is a typical problem of unreasonably large water intake for industrial-household needs to the detriment of the aquatic ecosystem. An important tool for balancing these links is to provide environmental flows based on a comprehensive analysis of river functioning patterns. And in terms of a progressing negative impact of reservoirs on the integrity of river ecosystems, the choice of indicator hydrobiota for the calculation of environmental flows should be considered insufficiently substantiated. The solution of this problem, by filling the appropriate methodological niche, allowed substantiating the hydrological-stenobiontic method for determining environmental flows. The developed solutions are based on the minimum possible values of tolerance of aquatic ecosystems stenobionts to water velocity. Five groups of macrozoobenthos represent relevant target organisms. The hydrological calculations presented in the paper are based on the data of daily water flow rate for 80 years and the results of field studies of the river channel depth in the low water period. On this basis, it was determined that for lowland parts of rivers, the flow velocity in the tailwater of reservoirs should be at least 0.2 m/s. Comparison of the curve of the average monthly water velocity dynamics of 95 % runoff availability with the minimum corresponding requirements of stenobionts allowed determining the most threatening period of the year for the aquatic ecosystem – summer low water. For a reservoir in the lowland parts of the river, based on the developed method, the calculations substantiate an increase in the minimum volume of environmental flows by 40 % relative to the current one. It is also estimated that the average annual and average second volumes of environmental flows should be about 38 % of the respective river runoff. The obtained results are close to those found on rivers in China, Iran and the United States in the framework of a comprehensive analysis of hydrological, hydraulic and hydrobiological parameters of the aquatic ecosystem. [ABSTRACT FROM AUTHOR]

Economic losses from floods have become catastrophic due to the increase in the number and scale of their propagation. Existing procedures for passing floods and pre-preparing reservoirs for flood water acceptance are ineffective and need to be improved. Therefore, the task to devise a methodology that would eliminate these shortcomings was urgent. This paper has proposed a procedure for calculating the passage of floods based on the forecasts of water inflow, taking into consideration the characteristics of the flood wave and the mode of reservoir filling, which makes it possible to bring down (reduce) the maximum flow rate through a waterworks by accumulating floodwaters in the reservoir. The software package Mike 11 (Danish Institute, Denmark) was employed to build a hydrodynamic model of floodwater movement along the examined river section from a hydrological station to a waterworks, which makes it possible to determine the levels of water and the flow rate in a reservoir at any time in the form of free surface curves when passing floods of various range. Based on the devised methodology, recommendations have been compiled for the forced discharges of water through hydroelectric turbines (in m³ /s) when passing floods of various probabilities (which is especially important for floods whose probability is 0.01 %). The constructed hydrodynamic model of floodwater movement through a reservoir has allowed the verification of the devised procedure. The procedure was devised in order to effectively pass floodwaters and bring down the maximum flow rate through a waterworks. The introduction of the methodology for calculating the passage of floods could make it possible to avoid idle water discharge through the water drains of waterworks to the lower pool and provide for the most efficient utilization of floodwater resources. [ABSTRACT FROM AUTHOR]

The accurate estimation of terrain characteristics is central in rainfall runoff modelling. In this study, influences of Digital Elevation Models (DEMs) obtained from different sources, resolutions and rescaling techniques are compared for Peak flow prediction in a large-scale watershed by the Topographic driven model (TOPMODEL). The comparison includes graphical representation and statistical assessments using daily time series data. As a result, DEM extracted from contour map (DEM-Con) showed better performance when DEM resolutions increased, but the Advanced Space-borne Thermal Emission and Reflection Radiometer (DEM-Aster) continued to achieve less Relative Error (RE) at low resolution. Moreover, better RE values were found at cubic convolution technique to predict the peaks followed by nearest neighbor and bilinear. In addition, this study indicated that DEM resolution is more sensitive factor for TOPMODEL simulation compared to DEM sources and rescaling techniques for streamflow and peaks prediction. [ABSTRACT FROM AUTHOR]

A number of rainfall-runoff models have been developed for hydraulic and hydrological engineering with an emphasis on reproducing river discharge time series. Physicallybased rainfall-runoff models have recently reached a certain level of achievement following the advancement of computers and the development of various geographical and meteorological datasets. However, it has been pointed out that the current physically-based models do not properly reflect observed hillslope water dynamics. The present paper proposes a methodology to examine the capability of a depth-discharge constitutive equation for physicallybased rainfall-runoff modelling to simulate hillslope water dynamics. An application of the methodology suggested that 1) the targeted constitutive equation was capable of representing the depth-discharge relationship on hillslopes under the assumed conditions, 2) the runoff simulations with the constitutive equation described hillslope water flows, at least in the downward direction, and 3) there was a possibility that the parameters in the constitutive equation was determined from the internal structure of hillslope water dynamics. [ABSTRACT FROM AUTHOR]

Focusing on green infrastructure (GI), which utilizes nature's diverse resources, we developed urban flood control measures on three small-scale private tracts in Tokyo and Fukuoka in Japan, experiencing high rainfall. In addition, we implemented these measures and verified the possibility of introduction. Using a target rainfall of 100 mm/h and previous rainfall data, we set our goal of reducing runoff from each site below the capacity of a public sewage pipe. Implementation was conducted by assessing the soil infiltration rate and developing and installing rain gardens and storage layers using crushed stones. These measures satisfied the initially set goals, drastically reducing runoff at all three sites. The target installation cost was set at 100,000 yen per cubic meter of runoff reduction. The target costs were met in the two Fukuoka sites but not at the Tokyo site. The key reasons were the high costs of removing non-permeable surfaces or improving the soil of compacted surfaces, which called for a process to balance the runoff reduction and cost to determine the most effective plan for implementing GI in urban areas. The development and implementation processes were conducted in collaboration with the house owners and concerned parties; the workshops produced constructive ideas being unconstrained by conventional thinking. Visitors highly appreciated ideas related to using water because the techniques were derived from the Japanese culture of lifestyle. Thus, introducing attractive and effective GI may be possible through collaboration. Additionally, sharing experiences led to the formation of new community ties, supporting post-implementation site maintenance. [ABSTRACT FROM AUTHOR]

Continuing urbanization has reduced permeable land areas, causing rainwater runoff volumes to rise, which not only increases the drainage burden placed on rivers and sewerage system, but also increases flood damage risk with the increases in torrential rains brought about by climate change. As physical flood control infrastructure has high costs and requires long planning and construction times, more effective utilization of existing infrastructure is required in addition to new construction. Moreover, as urbanization continues, the use of privately owned land for flood control as well as the limited publicly owned land available is increasingly important. This article reports the results and efficacy of a project to create a rainwater management network by connecting multiple pumping stations with the city's main rainwater pipeline in coordination with river development in a major river drainage basin region, while rebuilding aging pumping stations for continued use, as well as the effectiveness of rainwater storage facilities in underground locations beneath privately owned buildings. [ABSTRACT FROM AUTHOR]

We developed a system that combines urban area rainfall radar (small X-band, dual-polarization radar), short-term rainfall prediction model, and real-time runoff analysis technology, and the demonstration study was conducted on the drainage districts in Fukui City and Toyama City. We demonstrated the effectiveness of the flood damage, by providing the real-time information on rainfall prediction, water level in sewerage pipes, and inland flood prediction to the operators of drainage pump of stormwater storage pipes, and residents in flood-prone areas. During the study for about two years, it was confirmed that the accuracy of the radar rainfall observation was comparable to that of the X-band dual-polarization Doppler weather radar managed by the Ministry of Land, Infrastructure, Transport and Tourism. In the operation of the drainage pump for the Tsukimiminori Stormwater Storage Pipe in Fukui City, we were able to secure the storage capacity for the next rainfall based on the forecast information by maximizing the drainage capacity of the discharge destination. In addition, it was also confirmed that the residents themselves could secure the lead time for setting up water-stop sandbags and moving their vehicles to higher ground. [ABSTRACT FROM AUTHOR]

A dual-polarization, phased array weather radar, also known as the multi-parameter phased array weather radar (MP-PAWR), was developed by the Japanese Cross-ministerial Strategic Innovation Promotion (SIP) Program. Since this weather radar has been made into an active phased array, three-dimensional observation of weather phenomena can be realized at high speed by means of electrical scanning in the elevation direction and mechanical scanning in the azimuth direction. This is expected to shed light on hydrological processes in river basins, such as those of urban rivers, and improve prediction accuracy. In this study, river water levels in urban areas were estimated from vertically integrated liquid (VIL) Nowcast water content results, a meteorological forecasting method based on the three-dimensional observation MP-PAWR data, using a synthesized rational formula. A runoff analysis for urban basins was carried out using the rainfall forecast results based on MP-PAWR observational data. Since it is known that this formula can be used to deliver a rapid response time for runoff phenomena in the basin, it is possible to fully exploit the features of the MP-PAWR. This study shows how MP-PAWR is used in a series of hydrological processes. In this paper, we report the results of a basic study on water level predictions based on MP-PAWR observational data and also present future prospects for the use of this technology. [ABSTRACT FROM AUTHOR]

Compared to pumping stations, pump gates have small sites and are constructed for a low cost over a short period of time. A new type of horizontal axial submersible pump that is optimal for pump gates has recently been developed. Since the new type of pump can be operated at full speed regardless of water level, it is possible to conduct standby operations in preparation for stormwater runoff inflows. In a simulation comparing the conventional pumps and the new type of pump, there was no serious inundation condition in the new pump up to 70 mm/h, which is 140% of the design's rainfall intensity. As a result, it was clarified that standby operations can keep the peak water level low and maximize the water storage capacity of the drainage channel. [ABSTRACT FROM AUTHOR]

In Japan, flood disasters caused by record-breaking heavy rainfall frequently cause significant damages. It is also great concern that heavy rainfall may increase and occur more frequently due to global warming. In July 2013, a heavy rainfall event caused record-flooding of the Kakehashi River in Ishikawa Prefecture. In this study, pseudo global warming (PGW) experiments were implemented for the heavy rainfall in 1998 and 2013 around the Kakehashi River basin. Based on the results of PGW simulations, rainfall with different return periods were generated. Runoff analyses and inundation simulations were carried out by forcings with multiple return periods, and the results were used to estimate the economic losses due to flood inundation. Expected values of the economic losses were calculated using two methods for multiple return periods. Differences between the two expected values indicates the importance of the weighting method for the result of each return period. In addition, variations of spatial distribution of houses and firms in a city (i.e., urban structure) were simulated using a computable urban economics (CUE) model for the area of middle-lower reach of the Kakehashi River basin to examine its impact on economic loss due to flooding. In the simulation using the CUE model, a more severe flood inundation risk and an additional insurance burden for general households were added, and possible variations of urban structure were estimated around the lower part of the Kakehashi River basin. Under the more severe risk condition, relocation proceeded from higher risk areas to safer areas, and possible economic losses decreased in the target area. This result indicates that proper recognition of risk can reduce flood damages. On the other hand, there were small variations in economic losses under the condition with the additional flood insurance burden. [ABSTRACT FROM AUTHOR]

Average velocity in streams is a key variable for the analysis and modelling of hydrological and hydraulic processes underpinning water resources science and practice. The present study evaluates the impact of the sampling duration on the quality of average velocity measurements acquired with contemporary instruments such as Acoustic Doppler Velocimeters (ADV) an Acoustic Doppler Current Profilers (ADCP). The evaluation combines considerations on turbulent flows and principles and configurations of acoustic instruments with practical experience in conducting customized analysis for uncertainty analysis purposes. The study sheds new insights on the spatial and temporal variability of the uncertainty in the measurement of average velocities due to variable sampling durations acting in isolation from other sources of uncertainties. Sampling durations of 90 and 150 s are found sufficient for ADV and ADCP, respectively, to obtain reliable average velocities in a flow affected only by natural turbulence and instrument noise. Larger sampling durations are needed for measurements in most of the natural streams exposed to additional sources of data variability. [ABSTRACT FROM AUTHOR]

The importance of discharge measurements is fully acknowledged in many research fields, mostly in hydrology. Numerous measurement devices and various overflow structures have been proposed for discharge measurements; however, their use is based on calibrated simple stage discharge relationships that may cause significant errors when unsteady flow conditions occur. This issue is quite common because of rainfall and runoff temporal variability that inhibits the achievement of the steady state. Although this issue has already been experimentally investigated, it seems that a physically based line of approach has not been attempted before. In this paper, unsteady stage discharge relationships on a theoretical basis are derived for the most common shapes of weirs. According to previous experimental investigations, a transposition of the simple (steady-state) rating curve occurs, with higher input discharges than those under steady state, when the water level rises, and with lower input discharges, when the water level falls. The corresponding time to equilibrium is also studied and two different applications are performed. Finally, when the outflow process is unsteady, an error analysis quantitatively shows that using simple rating curves may determine high errors in discharge measurements, which decrease more and more at the attaining of the steady state, where no transposition of the rating curve occurs. Triangular weirs result more sensitive to the unsteadiness than rectangular weirs, which in turn result more sensitive than the sharp crested orifices. The suggested procedure could be relevant to improve the accuracy in the discharge estimate, as it could be demonstrated by comparing the discharges derived by the proposed procedure and the ones provided by the application of hydrodynamic and rainfall-runoff models. [ABSTRACT FROM AUTHOR]

Floods in small mountainous watersheds cover a wide spectrum of flow. They can range from clear water flows and hyperconcentrated flows to debris floods and debris flows, and calculation of the peak discharge is crucial for predicting and mitigating such hazards. To determine the optimal approach for discharge estimation, this study compared water flow monitoring hydrographs to investigate the performance of five hydrological models that incorporate different runoff yields and influx calculation methods. Two of the models performed well in simulating the peak discharge, peak time, and total flow volume of the water flood. The ratio (γ) of the monitored debris flood discharge (Qd) to the simulated water flow discharge (Qw) was investigated. Qualitatively, γ initially increased with Qw but then decreased when Qw exceeded a certain threshold, which corresponded to rainfall of 95 and 120 mm in a 6‐ and 24‐h event with a normal distribution of precipitation, respectively. The decrease might be attributable to a threshold of sediment availability being reached, beyond which increased flow rate is not matched by increased sediment input in the large watershed. Uncertainty of hydrological calculation was evaluated by dividing the catchment into sub‐basins and adopting different rainfall time steps as input. The efficiency of using a distributed simulation exhibited marginal improvement potential compared with a lumped simulation. Conversely, the rainfall time step input significantly affected the simulation results by delaying the peak time and decreasing the peak discharge. This research demonstrates the applicability of a discharge estimation method that combines a hydrological water flow simulation and an estimation of γ. The results were verified on the basis of monitored flow densities and videos obtained in two watersheds with areas of 2.34 and 32.4 km2. [ABSTRACT FROM AUTHOR]

Modeling the multidimensional flow of liquid water through snow has been limited in spatial and temporal scales to date. Here, we present simulations using the inverse TOUGH2 (iTOUGH2) model informed by the model SNOWPACK, referred to as SnowTOUGH. We use SnowTOUGH to simulate snow metamorphism, melt/freeze processes, and liquid water movement in two-dimensional snowpacks at the plot scale (20 m) on a sloping ground surface during multi-day observation periods at three field sites in northern Colorado, USA. Model results compare well with sites below the treeline and above the treeline but not at a site near the treeline. Results show the importance of longitudinal intra-snowpack flow paths (i.e., parallel to ground surface in the downslope direction and sometimes referred to as lateral flow), particularly during times when the snow surface (i.e., snow–atmosphere interface) is not actively melting. At our above-treeline site, simulations show that longitudinal flow can occur at rates orders of magnitude greater than vertically downward percolating water flow at a mean ratio of 75:1 as a result of hydraulic barriers that divert flow. Our near-treeline site simulations resulted in slightly less longitudinal flow than vertically percolating water, and the below-treeline site resulted in negligible longitudinal flow of liquid water. These results show the increasing influence of longitudinal intra-snowpack flow paths with elevation, similar to field observations. Results of this study suggest that intra-snowpack longitudinal flow may be an important process for consideration in hydrologic modeling for higher-elevation headwater catchments. [ABSTRACT FROM AUTHOR]

Phosphorus (P) load apportionment models (LAMs), requiring only spatially and temporally paired P and flow (Q) measurements, provide outputs of variable accuracy using long-term monthly datasets. Using a novel approach to investigate the impact of catchment characteristics on accuracy variation, 91 watercourses' Q-P datasets were applied to two LAMs, BM and GM, and bootstrapped to ascertain standard errors (SEs). Random forest and regression analysis on data pertaining to catchments' land use, steepness, size, base flow and sinuosity were used to identify the individual relative importance of a variable on SE. For BM, increasing urban cover was influential on raising SEs, accounting for c.19% of observed variation, whilst analysis for GM found no individually important catchment characteristic. Assessment of model fit evidenced BM consistently outperformed GM, modelling P values to ±10% of actual P values in 85.7% of datasets, as opposed to 17.6% by GM. Further catchment characteristics are needed to account for SE variation within both models, whilst interaction between variables may also be present. Future research should focus on quantifying these possible interactions and should expand catchment characteristics included within the random forest. Both LAMs must also be tested on a wide range of high temporal resolution datasets to ascertain if they can adequately model storm events in catchments with diverse characteristics. [ABSTRACT FROM AUTHOR]

Estimation of discharge hydrograph may be needed at river gauging stations where discharge is computed by converting water stage using a stage-discharge relation (a rating curve) or multiplying mean velocity by flow cross-sectional area. The mean velocity is computed by converting the measured maximum velocity to mean velocity using a conversion factor. Estimating the velocity conversion factor at stations where measured discharge data are insufficient remains a challenge. This study develops a novel method for determining the conversion factor by combining the entropy velocity profile, a data-driven technique, and a one-dimensional (1-D) flood routing model, and thus develops a method to determine discharge at the weak gauging sites. The method was used with two different assumptions: constant velocity factor and velocity factor depending on the aspect ratio. Results showed that this method optimally estimated the conversion factor. [ABSTRACT FROM AUTHOR]

Climate change is decreasing watershed glacial coverage throughout Alaska, impacting the biogeochemistry of downstream ecosystems. We collected streamwater fortnightly over the glacial runoff period from three streams of varying watershed glacier coverage (0–49%) and a subglacial outflow to assess how glacier recession impacts the relative contributions of glacier and terrestrial plant derived dissolved organic matter (DOM) inputs to streams. We show an increase in the fraction of old dissolved organic carbon (up to ∼ 3200 yr old radiocarbon age) with increasing glacial meltwater contribution to streamflow. We use a dual isotopic mixing model (δ13C and Δ14C) to quantify the relative contribution of terrestrial and glacial sources to streamwater DOM. The endmember contributions were further compared to DOM molecular compositional data from Fourier‐transform ion cyclotron resonance mass spectrometry to assess whether DOM composition can be linked to streamwater DOM source in watersheds with varying contributions of glacial runoff. This approach revealed the glacial fraction was positively correlated with percent relative abundance of heteroatom‐containing DOM molecular formulae, aliphatics, and peptide‐like formulae, while the terrestrial fraction was positively correlated with condensed aromatics and polyphenolics. These results provide information about how the retreat of mountain glaciers will impact the composition and thus biogeochemical role of DOM delivered to downstream ecosystems. Our findings highlight that combining an isotopic mixing model and ultrahigh resolution mass spectrometry data can provide novel insights into how changes in watershed landcover impact the source and chemical properties of streamwater DOM. [ABSTRACT FROM AUTHOR]

There is an increasing demand for reliable methods to measure soil loss in order to get a better understanding of sediment movement and to develop process‐based sediment transport models. This study described the design, calibration, and practical application of an instrumented technique that automatically characterized surface flow in situ fields. The instrument consisted of a sampling assembly, a measuring assembly, and a management platform. The special design combined with a volume‐mass conversion relationship was used to determine the exact volume and mass of the sediment‐laden water, thereby allowing the implementation of real‐time measurement and synchronous calculation of runoff rate and sediment concentration. Calibration results showed that normal distributions and an average error of −3.67% were obtained for the target sediment concentrations of 2–1,000 g/L. Compared with the gravimetric method, the average error of the new technique for sediment concentration was 4.82%, and the highest precision was 98.50%. The high repeatability and accuracy of the technique suggest that it can be used with confidence to give satisfactory results in fields. A field experiment under natural rainfall showed that a grass‐covered plot had 18.94% less runoff rate and 42.92% lower sediment concentration than a bare soil plot, illustrating the impact of vegetation cover on reducing soil loss. This uniquely designed instrument provides a new approach to real‐time sediment detection in surface flow. It will be beneficial for rigorously evaluating runoff and sedimentation and for in‐depth research regarding water and soil loss processes. Key Points: An automated instrument with a volume‐mass conversion relationship was developed for measuring surface runoff and suspended sedimentInstrument calibration using a range of sediment concentrations and the gravimetric method yielded high repeatability and accuracyThe instrument could quantify the reduced soil loss due to vegetation cover that was caused by natural rainfall under field conditions [ABSTRACT FROM AUTHOR]

Neck cutoffs are a common morphologic feature of meandering rivers though their occurrence on natural rivers is intermittent. Morphologic adjustments following cutoff initiation are typically rapid making detailed field investigations of the interactions between flow and form challenging. However, numerical models can offer insights into the hydrodynamic characteristics within the early stages of cutoff evolution. Field measurements of channel bathymetry and three‐dimensional velocities were collected during the first two years of morphologic change for a neck cutoff on the White River in Arkansas, USA. These data were used to calibrate a two‐dimensional numerical model to investigate the influence of hydrologic variability on the hydrodynamic characteristics of neck cutoffs during the early stages morphologic adjustment. The modeling results reveal complex patterns of the two‐dimensional flow field, including multiple regions of flow separation and recirculation related to strong redirection of the flow nearly 180 degrees through the cutoff. These regions of recirculation are also shown to vary depending on discharge conditions and affect hydrologic connectivity between the main channel and abandoned bend. Model results for the initial cutoff morphology show a substantial portion of discharge still conveyed by the original bend for all three discharge scenarios, resulting in a shear layer within the downstream limb of the site that limits advection of high‐momentum fluid against the bank opposite of the cutoff. The findings from this investigation are among the first detailed flow structure studies during the initiation of a neck cutoff and are used to improve conceptual models for cutoff dynamics. Key Points: Results show complex two‐dimensional flow field, including zones of flow separation and recirculation that vary with increasing dischargeSuperelevation of water surface and stagnation along bank opposite cutoff leads to recirculation in the exit of the abandoned bendHydrodynamic simulations provide insight into morphologic adjustments during first 2 years of highly curving neck cutoffs [ABSTRACT FROM AUTHOR]

Remotely sensed radar data and in situ rain gauge observations provide complementary information about rainfall. Specifically, radar data inform rainfall location and extent, while rain gauges provide accurate observations of the local rain intensity and its temporal variability. Drawing on the respective strengths of these two data sources, radar and rain gauge data fusion is becoming more and more common to derive both accurate and comprehensive rain estimates. However, combined precipitation estimates are often restricted to a resolution of 1 km in space and 1 h in time. In this paper, I propose to use radar data disaggregation to merge radar and rain gauge observations at a high space‐time resolution. To this end, a stochastic rainfall model is first trained on rain gauge observations and then combined with area‐to‐point geostatistical simulations to simultaneously: (i) disaggregate radar data, (ii) honor rain gauge observations, and (iii) reproduce local rain statistics. The proposed approach is applied to summer rain data collected in a small Alpine catchment, and data fusion provides rainfall reanalysis results at a resolution of 200 m in space and 2 min in time, including remote locations where in‐situ observation was not feasible. Key Points: Radar and rain gauge data are merged to obtain precipitation estimates at a resolution of 200 m in space and 2 min in timeData fusion is based on radar image disaggregationA stochastic rainfall model is used to transpose observed rain statistics into precipitation estimates [ABSTRACT FROM AUTHOR]

Although surface velocities are key in the calibration of physically based urban drainage models, the shallow water depths developed during non-extreme precipitation and the potential risks during flood events limit the availability of this type of data in urban catchments. In this context, imaging velocimetry techniques are being investigated as suitable non-intrusive methods to estimate runoff velocities, when the possible influence of rain has yet to be analyzed. This study carried out a comparative assessment of different seeded and unseeded imaging velocimetry techniques based on large-scale particle image velocimetry (LSPIV) and bubble image velocimetry (BIV) through six realistic but laboratory-controlled experiments, in which the runoff generated by three different rain intensities was recorded. First, the use of naturally generated bubbles and water shadows and glares as tracers allows unseeded techniques to measure extremely shallow flows. However, these techniques are more affected by raindrop impacts, which even lead to erroneous velocities in the case of high rain intensities. At the same time, better results were obtained for high intensities and in complex flows with techniques that use artificial particles. Finally, the study highlights the potential of these imaging techniques for measuring surface velocities in real field applications as well as the importance of considering rain properties to interpret and assess the results obtained. The robustness of the techniques for real-life applications yet remains to be proven by means of further studies in non-controlled environments. [ABSTRACT FROM AUTHOR]

Inspired by a quotation from Howard Cook in 1946, this paper traces the evolution of the infiltration theory of runoff from the work of Robert Horton and LeRoy Sherman in the 1930s to the early digital computer models of the 1970s and 1980s. The reasons for the popularity of the infiltration theory are considered and its impact on the way in which hydrological responses were perceived by several generations of hydrologists. Reconsideration of the perceptual model for many catchments, partly as a result of the greater appreciation of the contribution of subsurface flows to the hydrograph indicated by tracer studies, suggests a more precise utilisation of hydrological terms and, in particular, that the use of runoff and surface runoff should be avoided. [ABSTRACT FROM AUTHOR]

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A joint data repository on flowage lakes of the world and long-term flow variations in the rivers they regulate has been formed. The specific features of the flowage lake parameters have been analyzed along with their dependence on the characteristics of the lakes. A hypothesis has been proposed implying the global invariance of the coefficient of water exchange of lakes with respect to the average volume of flow through the lakes. The effect of the coefficient of lake water exchange on the long-term flow variations of the rivers regulated by the lakes has been studied. It has been shown that an increase in this coefficient is accompanied by a decrease, on the average, of the correlation between the annual, maximal, and minimal flow of successive years, as well as the average orders of the autoregression models describing the long-term variations of all types of flow. The effect of intermittent nonstationarity has been described for the series of annual runoff values for some lake-containing rivers. [ABSTRACT FROM AUTHOR]

Hydrologic models are simplified representations of natural hydrologic systems. Since these models rely on assumptions and simplifications to capture some aspects of hydrological processes, calibration of parameters is unavoidable. However, utilizing the philosophy of a recent modelling framework proposed by Bahremand (2016), we show how calibration of most model parameters can be avoided by allocating or presetting these parameters utilizing knowledge gained from sensitivity analyses, field observations and a priori specifications as a part of a parameter allocation procedure. This paper details the simulation of daily river flow of the Shemshak‐Roudak watershed performed using the Python version of the WetSpa model. The WetSpa‐Python model is a distributed model of hydrological processes applied at the watershed scale. The model was applied to the Shemshak‐Roudak watershed of Iran with parameter allocation. Model calibration involved only two parameters. Straightforward methods were proposed for allocating model parameters, including three baseflow‐related parameters and the determination of maximum active groundwater storage using a mass curve technique. Also, the Budyko curve was used to constrain a correction factor for potential evapotranspiration. The WetSpa‐Python model was extended to include the influence of snowmelt. A failure to include snow in the hydrological processes of the WetSpa‐Python model creates a significant discrepancy between the observed and simulated hydrographs during the spring. The results of daily simulations for 12 years (2002–2014) are in good agreement with observations of discharge (Kling‐Gupta Efficiency = 0.84). These results demonstrate that it is feasible to simulate hydrographs with limited calibration given a knowledge of hydrological processes and an understanding of relationships between catchment characteristics and model parameters. [ABSTRACT FROM AUTHOR]

Drainage networks delineated from Digital Elevation Models (DEMs), are the basis for the modelling of geomorphological and hydrological processes, biogeochemical cycling, and water resources management. Besides providing effective models of water flows, automatically extracted drainage networks based on topography can diverge from reality to varying degrees. The variability of such disagreement within catchments has rarely been examined as a function of the heterogeneity of land cover, soil type, and slope in the catchment of interest. This research gap might not only substantially limit our knowledge of the uncertainty of hydrological prediction, but can also cause problems for users attempting to use the data at a local scale. Using 1:100000 scale land cover maps, Quaternary deposits maps, and 2 m resolution DEMs, it is found that the accuracy of delineated drainage networks tends to be lower in areas with denser vegetation, lower hydraulic conductivity, and higher erodibility. The findings of this study could serve as a guide for the more thoughtful usage of delineated drainage networks in environmental planning, and in the uncertainty analysis of hydrological and biochemical predictions. Therefore, this study makes a first attempt at filling the knowledge gap described above. [ABSTRACT FROM AUTHOR]

Managing sloping landscapes to control soil erosion processes due to rainfall and runoff is a relevant problem, especially when the vegetation is absent or sparse. The aim of this paper was to investigate the applicability of a theoretically resistance law for overland flow under simulated rainfall, based on a power‐velocity profile, using field measurements carried out by Li and Pan for three plots with planted forage species (Astragalus adsurgens, Medicago sativa and Cosmos bipinnatus).The relationship between the velocity profile parameter Γ, the flow Froude number and the rain Reynolds number was calibrated using the data by Li and Pan. The obtained overland flow resistance law was also verified by independent field measurements carried out by Li and Pan in the same plots with the same forage species subjected to three different treatments (intact grass control IG, no litter or leaves NLL (only the grass stems and roots were reserved) and only roots remaining OR). The theoretical approach and the measurements carried out in the investigated conditions allowed to state that a) the Darcy‐Weisbach friction factor can be accurately estimated using the proposed theoretical approach, b) the Darcy‐Weisbach friction factor varies with rainfall intensity and c) for the investigated forage species, the vegetation treatment (IG, NLL, OR) does not significantly affect the flow resistance in laminar regime. [ABSTRACT FROM AUTHOR]

Saturated hydraulic conductivity (Ks) is a key parameter in hydrology, although obtaining representative Ks values especially in natural watersheds is challenging due to its variability in space and time and the difficulties in field measurements. In this study, the challenges and limitations in characterizing the surface soil layer Ks in a Mediterranean natural watershed are presented, based on the analysis of long-term field data and of detailed hydrological data covering a 14-year period (2005–2018). The obtained results indicate a generally high spatial variability at all scales, while there seems to be a dominance of small-scale variability, which complicates the determination of representative Ks values characterizing the watershed. The temporal variability was less profound; however, temporal stability of Ks seems to be a significant issue after major disturbances such as wildfires. The results highlight the challenges and limitations in the setup and parameterization of hydrological models, especially in ungauged watersheds. [ABSTRACT FROM AUTHOR]

A correct understanding of the variation pattern of water and sediment conditions as well as erosion and deposition characteristics in the reach between Three Gorges Dam and Gezhou Dam is essential for studying the many engineering problems in the reach. In this study, abundant water-sediment topographic data were analyzed, and the application of the theory of sediment incipient motion in erosion prediction was discussed. Owing to reservoir construction in the upper reaches of the Yangtze River and the successive operation of the two major hubs, the annual runoff in the reach was slightly reduced, the monthly average runoff was redistributed by “peak load shifting?” the annual sediment discharge declined considerably, and the water-sediment relationship in the reach was significantly changed. The cumulative erosion and deposition quantity in the reach was under short- and long-term control by the extreme hydrological conditions and scheduling of the hubs. In terms of time, there were apparent phased characteristics, in terms of space, some sub-reaches were in an active state. The bed sediment was refined and coarsened successively with the operation of the hub. The incipient critical condition curve was drawn based on Sha's incipient velocity equation, and the estimation of the maximum particle size of movable bed sediment or critical water flow of the cross-section provided a reference for predicting the possibility of riverbed erosion. [ABSTRACT FROM AUTHOR]

Wetlands provide valuable hydrological, ecological, and biogeochemical functions, both alone and in combination with other elements comprising the wetlandscape. Understanding the processes and mechanisms that drive wetlandscape functions, as well as their sensitivity to natural and man‐made alterations, requires a sound physical understanding of wetland hydrodynamics. Here, we develop and apply a single reservoir hydrologic model to a low‐relief karst wetlandscape in southwest Florida (≈103 km2 of Big Cypress National Preserve) using precipitation P and potential evapotranspiration PET as climatic drivers. This simple approach captures the dynamics of storage for individual wetlands across the entire wetlandscape and accurately predicts landscape discharge. Key model insights are the importance of depth‐dependent extinction of evapotranspiration ET and the negligible effects of depth‐dependent specific yield, the effects of which are diluted by landscape relief. We identify three phases of the wetlandscape hydrological regime: dry, wet‐stagnant, and wet‐flowing. The model allowed a simple steady‐state analysis, which demonstrated the sudden seasonal shift between wet‐stagnant and wet‐flowing states, indicating a consistent threshold at P ≈ PET. Notably, stage data from any single wetland appears sufficient for accurate whole‐landscape discharge prediction because of the relative homogeneity in timing and duration of local wetland hydrologic connectivity in this landscape. We also show that this method will be transferable to other wetlandscapes, where individual storage elements respond hydrologically synchronously, whereas model performance is expected to deteriorate for hydrologically more heterogeneous wetlandscapes. Key Points: We extend a reduced‐complexity catchment model framework to wetlandscapes and demonstrate it for Big Cypress National Preserve, FloridaDepth‐dependent extinction of evapotranspiration controls wetlandscape stage and discharge dynamics driven by hydroclimatic fluctuationHydrological regime shifts between wet‐stagnant and wet‐flowing landscape states are explained by steady‐state stage stability analysis [ABSTRACT FROM AUTHOR]

Ice layers may form deep in the snowpack due to preferential water flow, with impacts on the snowpack mechanical, hydrological and thermodynamical properties. This detailed study at a high-altitude alpine site aims to monitor their formation and evolution thanks to the combined use of a comprehensive observation dataset at a daily frequency and state-of-the-art snow-cover modeling with improved ice formation representation. In particular, daily SnowMicroPen penetration resistance profiles enabled us to better identify ice layer temporal and spatial heterogeneity when associated with traditional snowpack profiles and measurements, while upward-looking ground penetrating radar measurements enabled us to detect the water front and better describe the snowpack wetting when associated with lysimeter runoff measurements. A new ice reservoir was implemented in the one-dimensional SNOWPACK model, which enabled us to successfully represent the formation of some ice layers when using Richards equation and preferential flow domain parameterization during winter 2017. The simulation of unobserved melt-freeze crusts was also reduced. These improved results were confirmed over 17 winters. Detailed snowpack simulations with snow microstructure representation associated with a high-resolution comprehensive observation dataset were shown to be relevant for studying and modeling such complex phenomena despite limitations inherent to one-dimensional modeling. [ABSTRACT FROM AUTHOR]

Whereas current erosion models are successful in quantitative estimates of soil erosion by water flow, modeling the coevolution of geomorphological features, particularly rill network properties and soil erosion on hillslopes, is still a major challenge. In this study, we propose a rill evolution modeling approach and combine it with a rainfall‐runoff and soil erosion model to simulate the feedback loop of hillslope geomorphic development and soil erosion processes. Rill evolution is mainly characterized by three rill network attributes, rill density, orientation angle, and rill width, all modeled with physical equations. The entire rainfall‐runoff‐erosion and rill evolution model is tested against a set of rill network evolution and soil erosion data from an experimental hillslope subjected to successive rainfall events. The simulated spatial and temporal variations of rill network characteristics and soil erosion agree well with the measured data. The results demonstrate that the three rill network characteristics continually alter the partitioning of interrill and rill flows and affect the interrill and rill flow erosivity and soil erosion, which in turn modify the rill geometry and rill network planform. Comparatively, existing approaches such as Water Erosion Prediction Project (WEPP) that ignore the rill evolution processes largely underestimate the hillslope soil erosion when using time independent model parameters. Moreover, a sensitivity analysis indicates that both the rill evolution and soil erosion processes are sensitive to the rill evolution parameters, rainfall intensity, and slope angle. These results can inform the development of general geomorphic evolution and soil erosion models on evolving rilled hillslopes. Key Points: A set of conceptual equations using flow hydraulic and erosion properties are proposed to simulate evolving rill characteristicsA theoretical framework is presented to simulate coupled rill evolution and soil erosion processesThe coupled model is sensitive to the rill evolution parameters, rainfall intensity, and slope angle [ABSTRACT FROM AUTHOR]

This study investigated the added value of different data for calibrating a runoff model for small basins. The analysis was performed in the 66 ha Hydrological Open Air Laboratory, in Austria. An Hydrologiska Byråns Vattenbalansavdelning (HBV) type, spatially lumped hydrologic model was parameterized following two approaches. First, the model was calibrated using only runoff data. Second, a step‐by‐step approach was followed, where the modules of the model (snow, soil moisture, and runoff generation) were calibrated using measurements of runoff and model state variables and output fluxes. These measurements comprised laser‐based measurements of precipitation, satellite and camera observations of snow, ultrasonic measurements of snow depth, eddy covariance measurements of evapotranspiration, time domain transmissometry‐based soil moisture measurements, time‐lapse photography of overland flow, and groundwater level measurements by piezometers. The two model parameterizations were evaluated on annual, seasonal, and daily time scales, in terms of how well they simulated snow, soil moisture, evapotranspiration, overland flow, storage change in the saturated zone, and runoff. Using the proposed step‐by‐step approach, the relative runoff volume errors in the calibration and validation periods were 0.00 and −0.01, the monthly Pearson correlation coefficients were 0.92 and 0.82, and the daily logarithmic Nash Sutcliffe efficiencies were 0.59 and 0.18, respectively. By using different sources of data besides runoff, the overall process consistency improved, compared to the case when only runoff was used for calibration. Soil moisture and evapotranspiration observations had the largest influence on simulated runoff, while the parameterization of the snow and runoff generation modules had a smaller influence. Key Points: A new framework is presented for stepwise runoff model parameter estimation from observed runoff and model state variables and fluxesFor the study catchment, correlation coefficient of monthly runoff in the validation period is 0.82, and the relative volume error is −1%Combination of soil moisture and evapotranspiration observations had the largest influence on parameter estimation [ABSTRACT FROM AUTHOR]

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Flow intermittency occurs naturally in alpine streams. However, changing rainfall patterns and glacier retreat are predicted to increase the occurrence of flow intermittency in alpine catchments, with largely unknown effects on ecosystem structure and function. We conducted a flow manipulation experiment within a headwater stream of Val Roseg, a glacierized alpine catchment, to determine the effects of increased flow intermittency on aquatic macroinvertebrates, periphyton, benthic organic matter, and trophic structure. Compared to an adjacent reference channel, an increase in flow intermittency reduced macroinvertebrate density, taxa richness, and the proportion of rheophilic taxa. Density and richness remained low in the manipulated channel after resumption of natural flow. Flow intermittency did not affect organic matter standing stocks, but increased assimilation of periphyton by aquatic macroinvertebrates. Predation on aquatic invertebrates by riparian spiders also increased. We attribute many of these patterns to the timing of drying, which likely excluded summer-growing cohorts of rheophilic, aerial dispersers. This study suggests that reductions in summer glacial melt and rainfall events might increase flow intermittency and lead to fundamental changes in diversity and function of alpine fluvial networks. [ABSTRACT FROM AUTHOR]

Introduction: The distribution of aquatic macroinvertebrates in rivers may be determined by the type of substrate, the shape of the river channel, the hydrological regime, and interactions with biotic and abiotic factors. Variations in the distribution of aquatic macroinvertebrates due to transitions and variations in physicochemical and hydrological characteristics are unknown in most rivers. Objectives: 1) to study the change in the aquatic macroinvertebrates assemblages in two sites in Naranjo River, during the four hydrological seasons; 2) to determine the relationship between the physicochemical variables, substrate and flow with the assemblages. Methodology: The study was conducted in the Naranjo River, Costa Rica, at two sampling sites during one year, evaluating the four seasons of the year. In each station we measure, values of water velocity and depth, flow rate, dissolved oxygen, pH, conductivity, sulfates, ammonium, nitrate, silicates, phosphates, and substrate were obtained, and a sample of aquatic macroinvertebrates was obtained for each type of microhabitat determined by water velocity. Two-way PERMANOVA was made to determine if there is a difference among aquatic macroinvertebrate abundance, per period and between sites. Canonical correspondence analysis was used to observe the relationship between aquatic macroinvertebrates and environmental factors. Finally, a Spearman's rank correlation coefficient was performed to determine the positive or negative relationship of variables with macroinvertebrates. Results: There was a greater abundance during the dry season, while during the transition from dry to the rainy season, the lowest abundance of organisms was recorded. The CCA indicates that the first axis presented a positive relationship with the silt and sand substrate and a negative relationship for the current velocity and rock substrate variables. The second axis showed a positive relationship with flow and nitrates and negative for the pebble substrate. Most organisms showed a negative response to increased flow and nitrates. Discussion: As flow increases, current velocity increases, and not all organisms recorded in the Naranjo River have the characteristics to survive these conditions. In addition, the depth also increases along with the drag force, causing movement of smaller substrates and removal of organisms. Increased nitrates can lead to a decrease in more sensitive organisms, such as Plecoptera and Ephemeroptera. In spite of the physicochemical and flow variations registered in the Naranjo River, these were not strong enough to vary the assemblages of aquatic macroinvertebrates, so the basin does not have stressful factors that eliminate organisms during one or several months of the year. [ABSTRACT FROM AUTHOR]

Runoff entering urban drainage systems contains suspended solids, which carry pollutants and may cause blockages in downstream parts of the system (for example infiltration facilities). Suspended solids inflow should, therefore, preferably be controlled by solids removal at gully pots. This paper presents the results of lab experiments on the solids accumulation in gully pots in a scale 1:1 setup. The accumulation process is initially dominated by settling in the gully pot. When a substantial sediment bed is created, the bed starts to interact with the flow, the removal efficiency of solids decreases, and the bed eventually reaches an equilibrium level. The effects of the discharge, sediment size, and geometry on these processes are assessed. The accumulation rate and equilibrium bed level are strongly affected by the flow pattern which is influenced by the combination of the position the jets impinge on the water and the gully pot's outlet position. [ABSTRACT FROM AUTHOR]

Stay cables on several cable-stayed bridges all over the world have been found to experience rain-wind-induced vibrations under the combined action of rain and wind. Meanwhile, the bridge deck might also have obvious oscillation under the wind and/or traffic loads. The coupled responses of a stay cable under the combined rain–wind and support excitations are numerically investigated in this article. The equations of motion of a three-dimensional continuous stay cable are derived by considering the high-order nonlinear components of the dynamic cable tension, together with the equation of motion of the rivulet on the cable surface. The forces induced by rain–wind excitation are determined by the quasi-steady theory, and the support excitation is achieved by the boundary condition. The coupled equations of the cable and the rivulet are numerically solved by using the finite difference method and the fourth-order Runge–Kutta method, respectively. The numerical results show that the high-order nonlinear components of the dynamic cable tension should be taken into account to numerically reproduce the parametric vibration of the stay cable, whereas they hardly have any effects on the rain-wind-induced vibration and the resonance vibration of the stay cable. The responses of stay cable under vertical support oscillation only and the rain–wind excitation only obtained from this study agree well with the literature results. Compared with the results induced by single-source excitation, the cable response amplitude under the combined excitations is smaller than that induced only by support excitation and larger than that induced only by rain–wind excitation. The rivulet is prone to be thrown from the cable surface if the parametric vibration of the stay cable is evoked. [ABSTRACT FROM AUTHOR]

In order to reveal the hydrodynamic characteristics of the karst aquifer system, the water temperature dynamic data of a hydrological year in the direct recharge area of Jinan spring area were analyzed using the temperature tracer method, and the runoff intensity of karst water was estimated. The results revealed that, affected by the regional groundwater flow, the vertical temperature profile of the study area consists of four types, a gradual cooling type, a gradual heating type, a temperature‐increasing type, and "S" type. Based on these four geothermal types, three heat transfer models adapted to the region were developed. The inflection point method is used to discriminate the horizontal runoff channels of the three depth segments in the Ordovician strata in the recharge area, and the shallow groundwater horizontal runoff intensity is greater than the deep. According to the calculation of the thermal transport model, the Ordovician limestone in the direct recharge area of the spring area is shallow (at a depth of 100 m), and the vertical flow velocity of the groundwater is around 1.28 × 10−7–3 × 10−6 cm/s, and the flow rate is slow. Based on the field tracer test, the visual flow of the karst water system was found to range between 29.41 and 115.02 m/day, indicating that the karst water is dominated by horizontal motion. Since the method of temperature measurement in the hole is relatively simple, the temperature change signal could be used to reveal the seepage characteristics of the groundwater. Key Points: The temperature change signal could be used to reveal the seepage characteristics of the groundwaterThe groundwater tracer technology confirmed that the karst development and seepage characteristics of Jinan spring area have heterogeneous characteristics [ABSTRACT FROM AUTHOR]

This study evaluated the spatial variability of streambed vertical hydraulic conductivity (Kv) in different stream morphologies in the Frenchman Creek Watershed, Western Nebraska, using different variogram models. Streambed Kv values were determined in situ using permeameter tests at 10 sites in Frenchman, Stinking Water and Spring Creeks during the dry season at baseflow conditions. Measurements were taken both in straight and meandering stream channels during a 5 day period at similar flow conditions. Each test site comprised of at least three transects and each transect comprised of at least three Kv measurements. Linear, Gaussian, exponential and spherical variogram models were used with Kriging gridding method for the 10 sites. As a goodness‐of‐fit statistic for the variogram models, cross‐validation results showed differences in the median absolute deviation and the standard deviation of the cross‐validation residuals. Results show that using the geometric means of the 10 sites for gridding performs better than using either all the Kv values from the 93 permeameter tests or 10 Kv values from the middle transects and centre permeameters. Incorporating both the spatial variability and the uncertainty involved in the measurement at a reach segment can yield more accurate grid results that can be useful in calibrating Kv at watershed or sub‐watershed scales in distributed hydrological models. [ABSTRACT FROM AUTHOR]

Climate-induced warming increasingly leads to degradation of high-alpine permafrost. In order to develop early warning systems for imminent slope destabilization, knowledge about hydrological flow processes in the subsurface is urgently needed. Due to the fast dynamics associated with slope failures, non- or minimally invasive methods are required for inexpensive and timely characterization and monitoring of potential failure sites to allow in-time responses. These requirements can potentially be met by geophysical methods usually applied in near-surface geophysical settings, such as electrical resistivity tomography (ERT), ground-penetrating radar (GPR), various seismic methods, and self-potential (SP) measurements. While ERT and GPR have their primary uses in detecting lithological subsurface structure and liquid water/ice content variations, SP measurements are sensitive to active water flow in the subsurface. Combined, these methods provide huge potential to monitor the dynamic hydrological evolution of permafrost systems. However, while conceptually simple, the technical application of the SP method in high-alpine mountain regions is challenging, especially if spatially resolved information is required. We here report on the design, construction, and testing phase of a multi-electrode SP measurement system aimed at characterizing surface runoff and meltwater flow on the Schilthorn, Bernese Alps, Switzerland. Design requirements for a year-round measurement system are discussed; the hardware and software of the constructed system, as well as test measurements are presented, including detailed quality-assessment studies. On-site noise measurements and one laboratory experiment on freezing and thawing characteristics of the SP electrodes provide supporting information. It was found that a detailed quality assessment of the measured data is important for such challenging field site operations, requiring adapted measurement schemes to allow for the extraction of robust data in light of an environment highly contaminated by anthropogenic and natural noise components. Finally, possible short- and long-term improvements to the system are discussed and recommendations for future installations are developed. [ABSTRACT FROM AUTHOR]

In this study, the impacts of Typhoon Morakot's (2009) vortex structure on the extreme rainfall in Taiwan were investigated using piecewise potential vorticity (PV) inversion. The control (CTL) experiment, starting at 0000 UTC 7 August or 15 h before landfall, reproduced the event realistically and was validated against the observations. By altering the PV perturbation inside 750 km from its center, we conducted sensitivity experiments in which the size and circulation strength of TY Morakot were reduced/weakened in the initial field in several different ways. In the sensitivity tests, particularly those in which the initial PV within the inner core (= 250 km) was significantly weakened, the storm made landfall earlier, stayed over land longer, and exited Taiwan later. Such track changes were accompanied by a contraction and spin-up of the inner core at the early stages of the integration, caused by convection/latent heating within the inner core under large-scale, low-level southwesterly flow. As a result, Taiwan received an overall rainfall amount either comparable to or even more (up to 12%) than that of the CTL in all tests. Thus, a weaker TY Morakot does not necessarily lead to less total rainfall over Taiwan, and the strong southwesterly flow and its moisture supply were bigger factors than the vortex structure in this event. On the other hand, the rainfall in the southern Central Mountain Range on 8 August, which was the most-rainy area and period in reality, tended to decrease by up to 40% with the contraction and a weaker outer circulation. Thus, the rainfall patterns and evolution in the sensitivity tests were considerably different from those in CTL, indicating that the vortex structure plays a significant role in the rainfall in this region. [ABSTRACT FROM AUTHOR]

This study aimed at measuring the effect of vermicompost on soil physical and chemical properties and runoff quality and quantity in agro-ecosystems in Northern Iran. Thus, runoff measurement plots of 1 × 5 m were set up in sloping lands under natural rainfall during 5 months. Runoff quality and quantity, soil properties, and plant growth were measured. This study shows that the amount of runoff water and its quality (sediment yields, nitrate content, pH, and conductivity) were not influenced by the fertilization treatments (vermicompost alone, chemical fertilization alone, or their mixture), except for the first month of the experiment where a lower runoff amount was measured when vermicompost was applied alone. Although no difference in plant growth was found, our results showed a significant improvement of soil properties when vermicompost was used as a fertilizer. Consequently, this study shows that vermicompost can be considered as an alternative application for reducing the use of chemical fertilizers and improving soil properties but its impact on plant growth and runoff is limited to the short term. [ABSTRACT FROM AUTHOR]

This paper considers a Cournot–Bertrand game model based on the relative profit maximization with bounded rational players. The existence and stability of the Nash equilibrium of the dynamic model are investigated. The influence of product differentiation degree and the adjustment speed on the stability of the dynamic system is discussed. Furthermore, some complex properties and global stability of the dynamic system are explored. The results find that the higher degree of product differentiation enlarges the stable range of the dynamic system, while the higher unit product cost decreases the stable range of price adjustment and increases the one of output adjustment; period cycles and aperiodic oscillation (quasi-period and chaos) occur via period-doubling or Neimark–Sacker bifurcation, and the attraction domain shrinks with the increase of adjustment speed values. By selecting appropriate control parameters, the chaotic system can return to the stable state. The research of this paper is of great significance to the decision-makers' price decision and quantity decision. [ABSTRACT FROM AUTHOR]

Estimation of watersheds base flow as a component of subsurface runoff is of significant importance, in particular, in watersheds of high permeability where the contribution of base flow to total runoff is large compared to that of surface flow. Complex hillslopes in nature have a different profile curvatures (concave, straight, and convex) and plan shapes (convergent, parallel, and divergent). In this study, an excess saturation model is developed to estimate the soil moisture deficit (SMD) profile along complex hillslopes. A new equation is presented which can predict base flow of hillslopes according to the spatially averaged SMD and topographic index over the hillslope surface. It is concluded that the hillslope geometry can obviously affect hillslope saturation and SMD. Moreover, the effect of convergence on SMD is higher than that of divergence. The largest and smallest effects on SMD are related to the convex convergent hillslope and the straight divergent one, respectively. Finally, the results of the developed model are compared to those derived from the solution of the hillslope-storage Boussinesq (HSB) equations for complex hillslopes. [ABSTRACT FROM AUTHOR]

Various models were developed in the past to simulate different hydrological processes. However, discrepancies between simulated and observed values are still significant and pose a challenge to many researchers. Models contain many parameters that cannot be directly measured. The values of most of these parameters are determined in the calibration process conditioning the efficiency of such models. This paper introduces the use of the enhanced Gauss–Levenberg–Marquardt (GLM) procedure in combination with the singular value decomposition (SVD) and Tikhonov regularization to improve the process of hydrological model calibration. The procedure is tested on a freely available hydrological model using a synthetic dataset. Based on several efficiency measures, the GLM procedure, in combination with SVD and Tikhonov regularization, was found to provide efficient model history matching and almost perfect parameter calibration. Moreover, by comparing the results of the proposed procedure with the results of global evolutionary calibration procedures, it was found that the only calibration using the combined GLM procedure gave a perfect fit in low flows. Last but not least, the noise in the calculation results with the combined GLM method was practically the same in either the calibration or validation procedure, suggesting that only computational noise remained in the results. [ABSTRACT FROM AUTHOR]

Featured Application: The application of this study contributes on the urban stormwater channels that reduce the required length of such channel and thereby reduce the land use, construction and maintenance-related costs. The check dams in grassed stormwater channels enhance infiltration capacity by temporarily blocking water flow. However, the design properties of check dams, such as their height and spacing, have a significant influence on the flow regime in grassed stormwater channels and thus channel infiltration capacity. In this study, a mass-balance method was applied to a grassed channel model to investigate the effects of height and spacing of check dams on channel infiltration capacity. Moreover, an empirical infiltration model was derived by improving the modified Kostiakov model for reliable estimation of infiltration capacity of a grassed stormwater channel due to check dams from four hydraulic parameters of channels, namely, the water level, channel base width, channel side slope, and flow velocity. The result revealed that channel infiltration was increased from 12% to 20% with the increase of check dam height from 10 to 20 cm. However, the infiltration was found to decrease from 20% to 19% when a 20 cm height check dam spacing was increased from 10 to 30 m. These results indicate the effectiveness of increasing height of check dams for maximizing the infiltration capacity of grassed stormwater channels and reduction of runoff volume. [ABSTRACT FROM AUTHOR]

Intensive agricultural practices on sensitive soils induce high erosion rates in central Belgium. Expert‐rules models quantify runoff and erosion at catchment scale, avoiding over‐parameterization, and can include some direct or indirect connectivity features. The aim of this article is to test the ability of an expert‐based model, LandSoil, to quantify runoff and to locate erosion and sedimentation areas in a small cultivated loamy catchment in Belgium during the years 2014, 2015 and 2016. Spatialized data are important for assessing model outputs and the erosive response. Measurements of runoff and observation of spatial erosion/deposition patterns, especially around major connectivity points, permitted an assessment of the reliability of the model results. Runoff modelling gave contrasting results (good linear adjustment at the outlet of the 83 ha sub‐catchment (point 1): r2 of 0.96, Nash–Sutcliffe criterion of 0.95; less good at the outlet of the 3.9 ha sub‐catchment (point 2): r2 of 0.28, Nash–Sutcliffe criterion of –0.47). For point 2 the poor results are explained by the very few runoff events observed, a scaling effect and the small area with a single land use. Graduated rulers demonstrate that the model is able to provide a coherent pattern of erosion/deposition. The study highlights great sensitivity to the effect of land use, land allocation, landscape design and slope gradients. Grass strips induce deposition of eroded particles when slopes are gentle (< 2%). Woodland strips decrease connectivity by being in the stream but deposit thinner sediment layers. Field boundaries have a role in the transport, but not really the quantity, of sediments. This model validation in the Belgian loess context allows us to use LandSoil in other similar environments in order to estimate the effects of landscape management scenarios. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]