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Stochastic Time-Variable Rainfall-Runoff Modeling

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... 1. Divide the mean daily discharge data into non-overlapping blocks of N days and calculate the minima for each of these blocks, and let them be called Q1, Q2, Q3, ... The recursive digital filter method with the R software package "EcoHydrRology" The recursive digital filter method with the R software package "EcoHydrRology" was developed by Lyne and Hollick [64] and consists of parameter α estimation, where α is the recession parameter [64][65][66][67][68]. Afterwards, a certain number of passes is applied to identify the runoff and the baseflow parts of the hydrograph. According to the recommendations [64,69], the value of alpha can be defined as 0.900, 0.925 or 0.950 and the number of passes can be set to 3 (one forward, one backward and another forward). ...
... 1. Divide the mean daily discharge data into non-overlapping blocks of N days and calculate the minima for each of these blocks, and let them be called Q1, Q2, Q3, ... The recursive digital filter method with the R software package "EcoHydrRology" The recursive digital filter method with the R software package "EcoHydrRology" was developed by Lyne and Hollick [64] and consists of parameter α estimation, where α is the recession parameter [64][65][66][67][68]. Afterwards, a certain number of passes is applied to identify the runoff and the baseflow parts of the hydrograph. ...
... 1. Divide the mean daily discharge data into non-overlapping blocks of N days and calculate the minima for each of these blocks, and let them be called Q1, Q2, Q3, ... The recursive digital filter method with the R software package "EcoHydrRology" The recursive digital filter method with the R software package "EcoHydrRology" was developed by Lyne and Hollick [64] and consists of parameter α estimation, where α is the recession parameter [64][65][66][67][68]. Afterwards, a certain number of passes is applied to identify the runoff and the baseflow parts of the hydrograph. According to the recommendations [64,69], the value of alpha can be defined as 0.900, 0.925 or 0.950 and the number of passes can be set to 3 (one forward, one backward and another forward). The HYSEP automated method for baseflow separation was implemented by Sloto and Crouse [70] and recently converted to an R code provided by the United States Geological Survey (USGS). ...
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Morphodynamic changes in the riverbed may be accelerated by the climate change-induced effects, mostly through the increase of the frequency of extreme climatic events such as floods. This can lead to scouring of the riverbed around the bridge substructure and consequently reduces its overall stability. In order to better understand hydromorphological processes at the local scale, the influence of floods on bridge scour requires a detailed analysis of several interacting flood hydrograph characteristics. This paper presents a multivariate analysis of the annual maximum (AM) flood discharge data at four gauging stations on the Drava and Sava Rivers in Croatia (Europe). As part of the hydrograph analysis, multiple baseflow separation methods were tested. Flood volumes and durations were derived after extracting the baseflow from measured discharge data. Suitable marginal distribution functions were fitted to the peak discharge (Q), flood volume (V) and duration (D) data. Bivariate copula analyses were conducted for the next pairs: peak discharge and volume (Q–V), hydrograph volume and duration (V–D) and peak discharge and hydrograph duration (Q–D). The results of the bivariate copula analyses were used to derive joint return periods for different flood variable combinations, which may serve as a preliminary analysis for the pilot bridges of the R3PEAT project where the aim is to investigate the influences on the riverbed erosion around bridges with installed scour countermeasures. Hence, a design hydrograph was derived that could be used as input data in the hydraulic model for the investigation of the bridge scour dynamics within the project and a preliminary methodology is proposed to be applied. The results indicate that bivariate frequency analysis can be very sensitive to the selected baseflow separation methodology. Therefore, future studies should test multiple baseflow separation methods and visually inspect the performance.
... The segmentation results of the digital filtering method were reasonable. Automatic base-flow segmentation technology has become mature and widely used (Lyne and Hollick, 1979;Chapman, 1991). The smoothed minimum method proposed by the British Institute of Hydrology was compared with the manual method to segment the base-flow. ...
... It can decompose the signal into a highfrequency signal (surface runoff) and a low-frequency signal (base-flow) through a digital filter to achieve base-flow segmentation (Eckhardt, 2012). Digital filtering methods include Lyne-Hollick filtering (DF1) (Lyne and Hollick, 1979), Chapman-Maxwell filtering (DF2) (Chapman, 1999), Boughton-Champan filtering (DF3) (Boughton, 1993), and Eckhardt filtering (DF4) (Eckhardt, 2005). ...
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In recent years, with the deterioration of the ecological environment, runoff in the Yellow River has been decreasing. Given these phenomena, it is necessary to research the base-flow segmentation methods and its characteristics. The Huangfuchuan Basin in the middle reaches of the Yellow River basin was selected as the research area. This paper calculated the base-flow with commonly used base-flow segmentation methods, including Base-flow index method (BFI), Hydrograph-separation techniques (HYSEP), and the digital filtering methods, and compared the applicability of these methods in the study area. Then the variation characteristics, abrupt change year, periodic change, and future trend of the base-flow were analyzed. The results are as follows: 1) Through the analysis and comparison of several common base-flow segmentation methods, these methods had a marked difference in base-flow segmentation. The variance and extreme-ratio of DF4 in the digital filtering methods were small. The correlation between DF4 and other methods was high. DF4 in the digital filtering methods was the most appropriate method in the research area. 2)The runoff and base-flow index presented a decreasing trend. The annual average runoff was 1,100.27 × 104 m3, and the maximum base-flow was 0.21. The base-flow also showed a significant decrease trend by the Mann-Kendall trend test, the average base-flow was 10,578.35 × 104 m3. 3) The base-flow had periodic variations of 3–6, 7–18, and 19–32. In the 19–32 years time scale, three oscillations alternated between abundant and dry. The whole time was 31 years as the center of the periodic change, the first primary cycle of base-flow change. 4) The base-flow mutation occurred in 1986. The Hurst index of base-flow in the Huangfuchuan Basin was 0.84. It was shown that the trend of future development is positively correlated with past change, showing a trend of continuous decrease. Selecting the appropriate method of base-flow segmentation and reasonably analyzing the variation characteristics of base-flow can provide scientific guidance for the ecological environment construction and water resource evaluation in the Huangfuchuan Basin and even the Yellow River Basin.
... Furthermore, Posavec et al. (2010) have developed a fully automated method, which is further illustrated in this manuscript, for separating the master recession curves (MRCs) into two or three segments on the basis of the flow duration curve analysis using daily stream discharge. Lyne and Hollick (1979) proposed a recursive digital filter (RDF) being the second method demonstrated in this manuscript, to separate the baseflow from the daily streamflow records. In this method, the streamflow series was processed as the digital signal. ...
... Digital filters are the common tools for processing and analysing the hydrograph signal, which can be used to separate high-frequency signals and low-frequency signals by selecting an appropriate threshold. The idea of designing a digital recursive filter is supported by the equation of Lyne and Hollick (1979) and returns firstly to the effort of Chapman (1987). In the frequency spectrum of a hydrograph, long waves will be more likely to be associated with baseflow while the high-frequency variability of the streamflow will primarily be caused by direct runoff. ...
... To partition into and , we used the one parameter low-pass filter developed by Lyne & Hollick (1979), following previous studies that also evaluated these streamflow components (Gnann et al., 2019;Lucas et al., 2021;Meira Neto et al., 2020;Sivapalan et al., 2011;Trancoso et al., 2017). As well as Gnann et al. (2019), we applied the recursive filter in a 3-times running (forward-back-forward), setting the filter-parameter to 0.925 -usually adopted in hydrological studies (Ladson et al., 2013;Lucas et al., 2021) ...
Article
Understanding how streamflow and its components, baseflow and quickflow, vary spatially according to climate and landscape characteristics is fundamental for dealing with different water-related issues. Analytical formulations have been proposed to investigate their long-term behavior and additional influencing factors, suggesting that they are mainly controlled by the aridity index (ϕ). Nevertheless, these studies assume the catchment as a closed water balance system, neglecting inter-catchment groundwater flow (IGF). This simplification makes the analysis of the long-term streamflow components and their main control mechanisms challenging, given that many catchments cannot be considered as closed hydrologic entities. Here, we assessed the controls of the mean-annual streamflow components and their behavior under an open water balance assumption, using observed data of 734 Brazilian catchments with diverse hydroclimatic conditions. Our results indicate that indeed streamflow components are primarily controlled by ϕ at the mean annual timescale. The consideration of an open water-balance significantly improved the performance of aridity-based functional forms to describe streamflow components while also elucidating how catchments’ attributes may influence streamflow behavior. Land cover, groundwater, climate seasonality and topographic attributes appeared as the main control mechanisms besides aridity. Overall, our study provides new insights of the main control mechanism of the streamflow behavior at the long-term scale, while shedding light on the importance of the open water-balance assumption for model development and water resources management.
... The model results are tested against (1) streamflow at the gage sites ( Figure 9 and Table 2), (2) groundwater head at the monitoring wells ( Figure 10), and (3) baseflow. The latter is calculated using the recursive digital filter commonly used in signal analysis and processing [44]. It was used by Nathan and McMahon [45], among others, providing a subjective and repeatable estimate of baseflow that is easily automated. ...
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In this article, we present the use of the coupled land surface model and groundwater flow model SWAT-MODFLOW with the decision support tool WEAP (Water Evaluation and Planning soft-ware) to predict future surface-water abstraction scenarios in a complex river basin under condi-tions of climate change. The modelling framework is applied to the Dee River catchment in Wales, United Kingdom. Regarding hydrology, the coupled model improves overall water balance and low-streamflow conditions compared with a stand-alone SWAT model. The calibrated SWAT-MODFLOW is employed with high-resolution climate model data from the UKCP18 project with the future scenario of RCP85 from 2020 to 2040. Then, water supply results from SWAT-MODFLOW are fed into WEAP as input for the river reach in the downstream region of the river basin. This system is utilized to create various future scenarios of the surface-water abstraction of public water supply in the downstream region—maximum licensed withdraw, 50% authorized abstractions, monthly time series with 1% increases in water use, and maximum water withdraw per year based on historical records repeated every year with 1% increases in water use—to estimate the unmet demands and streamflow requirement. This modelling approach can be used in other river basins to manage scenarios of supply and demand.
... To detect the quickflow component from each storm event, the baseflow separation method by Lyne and Hollick was applied, using a low-pass numerical filtering that splits the hydrograph into multiple signals, analogous to the filtering of electronic frequencies [70]. This method has been adapted as an automated function in the EcoHydRology R package [71], which was used to derive baseflow and stormflow hydrograph components consistently between sites. ...
Article
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Wildfire increases the magnitude of runoff in catchments, leading to the degradation of ecosystems, risk to infrastructure, and loss of life. The Labor Day Fires of 2020 provided an opportunity to compare multiple large and severe wildfires with the objective of determining potential changes to hydrologic processes in Oregon Cascades watersheds. Geographic information systems (GIS) were implemented to determine the total percentage burned and percentage of high burn severity class of six watersheds on the west slope of the Oregon Cascade Range. In addition, two control watersheds were included to contrast the influence of climatic effects. Spatial arrangements of burned patches were investigated for correlation to streamflow response by utilizing landscape metrics algorithms, including Largest Patch Index (LPI), mean gyration (GYRATE), Contiguity Index (CONTIG), Patch Cohesion Index (COHESION), and Clumpiness Index (CLUMPY). Results of the first-year post-fire response were consistent with other studies of fire effects in the Pacific Northwest (PNW) and indicated changes to runoff dynamics were difficult to detect with inferential statistics, but the largest changes in runoff coefficients occurred in watersheds having the greatest percentage burned. Correlation analysis indicated relationships between event runoff coefficients and percentage burned during the 2020 fire season. Control watersheds show confounding runoff coefficients, point to the influence of ongoing drought, and complicate conclusions about the role of spatial burn severity patterns. These results could guide future post-fire studies of spatial patterns of burn severity and could assist watershed managers to prioritize at-risk PNW catchments to minimize harm to ecological and societal values.
... Model results are tested against (1) streamflow at the gage sites (Figure 8), (2) groundwater head at the monitoring well (Figure 9), and (3) baseflow. The latter is calculated using the recursive digital filter commonly used in signal analysis and processing [36] is used in this study. It was used by Nathan and McMahon [37] among others, providing a subjective and repeatable estimate of baseflow that is easily automated. ...
Preprint
In this article, we present the use of the coupled land surface model and groundwater flow model SWAT-MODFLOW with the decision support tool WEAP (Water Evaluation and Planning software) to predict future surface water abstraction scenarios in a complex river basin, under conditions of climate change. The modeling framework is applied to the Dee River catchment in Wales, United Kingdom. Regarding hydrology, the coupled model improves overall water balance and low streamflow conditions, compared to a stand-alone SWAT model. The calibrated SWAT-MODFLOW is employed with high resolution climate model data from the UKCP18 project with future scenario of RCP85 from 2020 to 2040. Then, water supply results from SWAT-MODFLOW are fed into WEAP as input for the river reach in the downstream region of the river basin. This system is utilized to create various future scenarios of surface water abstraction of public water supply in the downstream region: maximum licensed withdraw, 50 % authorized abstractions, monthly time series with 1% increase of water use, and maximum water withdraw year based on historical records repeated every year with 1% increase of water use, to estimate the unmet demands and streamflow requirement. This modeling approach can be used in other river basins to manage scenarios of supply and demand.
... Brucknell Creek is a perennial stream, even during the Millennium Drought, and has the highest RR ratio (0.14), a baseflow index (BFI as per Lyne & Hollick, 1979;Nathan & McMahon, 1990) of 0.27 while in the other catchments BFI is below 0.13. Also, the intra-annual variation of monthly SF is more than 30% smaller in Brucknell Creek than in Ford or Sunday Creek. ...
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Groundwater (GW) is commonly conceptualized as causally linked to streamflow (SF). However, confirming where and how it occurs is challenging given the expense of experimental field monitoring. Therefore, hydrological modeling and water management often rely on expert knowledge to draw causality between SF and GW. This paper investigates the potential of convergent cross‐mapping (CCM) to identify causal interactions between SF and GW head. Widely used in ecology, CCM is a nonparametric method to identify causality in nonlinear dynamic systems. To apply CCM between variables the only required inputs are time‐series data (stream gauge and bore), so it may be an attractive alternative or complement to expensive field‐based studies of causality. Three upland catchments across different hydrogeologic settings and climatic conditions in Victoria, Australia, are adopted as case studies. The outputs of the method seem to largely agree with a priori perceptual understanding of the study areas and offered additional insights about hydrological processes. For instance, it suggested weaker SF‐GW interactions during and after the Millennium Drought than in the previous wet periods. However, we show that CCM limitations around seasonality, data sampling frequency, and long‐term trends could impact the variability and significance of causal links. Hence, care must be taken while physically interpreting the causal links suggested by CCM. Overall, this study shows that CCM can provide valuable causal information from common hydrological time‐series, which is relevant to a wide range of applications, but it should be used and interpreted with care and future research is needed.
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Groundwater and surface water are hydrologically interconnected systems that exhibit dynamic water, heat and mass exchanges. In this study, a conceptual framework was used to investigate groundwater behaviors and associated hydrological exchanges by combining field measurements, digital filtering and analytical approaches, exemplified by a linked catchment-floodplain-lake system (Poyang Lake, China). The results show that the hydrological regime for both groundwater and surface water exhibit a seasonal variability in the lake catchment. Topographically, the lake catchment can be divided into the mountainous baseflow, ungauged lateral groundwater and floodplain groundwater that contribute to the lake storage changes. Although groundwater flow is generally from the mountainous catchment to the lake floodplain areas due to topographic effects, precipitation provides an additional input for the shallow groundwater and is expected to enhance the groundwater dynamics in terms of spatially heterogeneous responses. The estimation indicates that about 40 % of the catchment river discharge may be coming from the mountainous baseflow (~290 × 10⁸ m³/yr) and discharged into the lake through a surface flow pathway. The ungauged groundwater-lake interaction shows the annual discharge volume is up to 10 × 10⁸ m³/yr and associated exchange fluxes tend to be stronger during spring-summer months (23–45 m³/s) than those of autumn-winter months (9–22 m³/s). Additionally, the floodplain groundwater-lake exchange (~9.5 × 10⁸ m³/yr) indicates that groundwater generally receives the lake water during summer months (mean flux = 110 m³/s) and discharges into the lake during other months (90 m³/s) through a subsurface pathway. This study highlights the importance of groundwater's contributions to the surface river-lake system in terms of the flux variability and different transport pathways. The outcomes of this work will benefit future water resources management and applications by providing a methodology for predicting the groundwater hydrology of large lake-catchment systems.
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