Maximum Daily Flow Research Articles

Index-Based Alteration of Long-Term River Flow Regimes Influenced by Land Use Change and Dam Regulation

The growing population and expansion of rural activities, along with changing climatic patterns and the need for water during drought periods, have led to a rise in the water demand worldwide. As a result, the construction of water storage structures such as dams has increased in recent years to meet the water needs. However, dam construction can bring significant alterations to the natural flow regime of rivers, and it is therefore essential to understand the potential effects of human structures on the hydrological regime of rivers to reduce their destructive impacts. This study analyzes the hydrological changes in the Shahrchai River in response to the Shahrchai Dam construction in Urmia, Iran. The study period was from 1950 to 2017 at the Urmia Band station. The Indicators of Hydrological Alteration (IHA) were used to analyze the hydrological changes before and after regulating, accounting for land use changes and climatic factors. The results revealed the adverse effects of the Shahrchai Dam on the hydrological indices. The analysis showed an increase in the average flow rate during the summer season and a decrease in other seasons. However, the combined effects of water transferring for drinking purposes, a decrease in permanent snow cover upstream of the dam, and an increase in water use for irrigation and agricultural purposes resulted in a decrease in the released river flow. Furthermore, the minimum and maximum daily flow rates decreased by approximately 85% and 65%, respectively, after the construction of the Shahrchai Dam. Additionally, the number of days with maximum flow rates increased from 117 days in the pre-dam period to 181 days in the post-dam period. As a concluding remark, the construction of the Shahrchai Dam, land use/cover changes, and a decrease in permanent snow cover had unfavorable effects on the hydrological regime of the river. Therefore, the hydrological indicators should be adjusted to an acceptable level compared to the natural state to preserve the river ecosystem. The findings of this study are expected to guide water resource managers in regulating the sustainable flow regime of permanent rivers.

Multi-century flow reconstruction of the Lhasa River, China

Study regionLhasa River Basin Study focusMulti-century records are needed to characterize flow variability including the magnitude and frequency of occurrence of extreme events. Such long records are not available without integrating well-calibrated hydrological models and climate proxies. To test whether 50–70 years of observations represent the long-term flow variability for water resources management, daily flows (1472–2000) were reconstructed by integrating the Variable Infiltration Capacity (VIC) model with proxy-based precipitation and temperature data for Lhasa River. New hydrological insights for the regionVIC performed well during calibration and validation for 3 gauging stations with the Nash-Sutcliffe coefficient of efficiency (NSE) exceeding 0.52. Proxy-based precipitation, temperature, and reconstructed flow are broadly stationary over the past 529 years, while recent decades show detectable local trends. The inter-annual/decadal variability is aligned with long-term variations in sea surface temperatures and the intensity of south Asian summer monsoon. Moreover, higher long-term average, greater variabilities, and persistent periods of above/below-average flows are detected. The maximum daily flows with small annual recurrence intervals (ARIs) less than 60 years would be overestimated based on observations, and underestimated for ARIs > 60 years. It is the first time to have reconstructed long-term daily flows using hydrological models coupled with proxy-based climate data, and this approach offers invaluable insights into the pre-instrumental flow responses to changing climate conditions in Lhasa River basin.

Assessing the influence of the Al Wahda dam commissioning on flood flows and low water levels in the Gharb Plain, Morocco

The Sebou Basin is one of the most important hydrographic basins in Morocco. When the Wadi Sebou enters the Gharb Plain, it encounters difficulties in evacuating its waters during wet years due to its flattening, resulting in risks of floods. Its flow decreases during drought years and in August and September. For the purpose of this research, we were granted authorization to utilize the hydrometric station located in Bel-Ksiri. This station is most suitable for the study as it was designated as a reference point for the Wadi Sebou's flooding in the lower basin. This study is based on detecting floods in the Wadi Sebou from 1976 to 2020, dividing this period on pre and post 1997, corresponding to periods before and after the construction of the Al Wahda dam, examining the mean daily flow rates. Identifying discontinuities within the maximum daily flow series from 1967 to 2020 was achieved in Microsoft Excel. Additionally, determining flood return periods and examining low water flows are integral aspects of the study. The findings indicate a relative decrease in the frequency and intensity of floods within the Wadi Sebou's basin, coupled with effective control of low water levels. These changes are attributed to the construction of the Al Wahda dam, which guarantees a stable water supply for irrigation purposes in the plain. To ensure the long-term sustainability of water management practices, the adoption of innovative irrigation technologies is deemed necessary.

The new ‘surface storage’ concept versus the old ‘sponge effect’ concept: application to the analysis of the spatio-temporal variability of the annual daily maximum flow characteristics in southern Quebec (Canada)

AbstractThis study confronts the new concept of ‘surface storage’ with the old concept of ‘sponge effect’ to explain the spatio-temporal variability of the annual daily maximum flows measured in 17 watersheds of southern Quebec during the period 1930–2019. The new concept takes into account the hydrological impacts of wetlands and other topographic components of the landscape (lakes, depressions, ditches, etc.) while that of the sponge effect only takes into account the hydrological impacts of wetlands. With regard to spatial variability, the area of wetlands and other water bodies is the variable best correlated negatively with the magnitude but positively with the duration of flows. As for the temporal variability, the application of the long-term trend tests revealed a significant increase in the magnitude and, to a lesser extent, the duration of the flows occurring in the watersheds of the north shore characterized by a greater area of wetlands and other water bodies (>5%). This increase is explained by the fact that the storage capacity of these land types, which remains unchanged over time, does not make it possible to store the surplus runoff water brought by the increase in rainfall during the snowmelt season.

Forecasting Magnitude and Frequency of Seasonal Streamflow Extremes Using a Bayesian Hierarchical Framework

AbstractWe develop a space‐time Bayesian hierarchical modeling (BHM) framework for two flood risk attributes—seasonal daily maximum flow and the number of events that exceed a threshold during a season (NEETM)—at a suite of gauge locations on a river network. The model uses generalized extreme value (GEV) and Poisson distributions as marginals for these flood attributes with non‐stationary parameters. The rate parameters of the Poisson distribution and location, scale, and shape parameters of the GEV are modeled as linear functions of suitable covariates. Gaussian copulas are applied to capture the spatial dependence. The best covariates are selected using the Watanabe‐Akaike information criterion (WAIC). The modeling framework results in the posterior distribution of the flood attributes at all the gauges and various lead times. We demonstrate the utility of this modeling framework to forecast the flood risk attributes during the summer peak monsoon season (July‐August) at five gauges in the Narmada River basin (NRB) of West‐Central India for several lead times (0–3 months). As potential covariates, we consider climate indices such as El Niño–Southern Oscillation (ENSO), the Indian Ocean Dipole (IOD), and the Pacific Warm Pool Region (PWPR) from antecedent seasons, which have shown strong teleconnections with the Indian monsoon. We also include new indices related to the East Pacific and West Indian Ocean regions depending on the lead times. We show useful long lead skill from this modeling approach which has a strong potential to enable robust risk‐based flood mitigation and adaptation strategies 3 months before flood occurrences.

Comparison of Spatio-Temporal Variability of Daily Maximum Flows in Cold-Season (Winter and Spring) in Southern Quebec (Canada)

Quebec has experienced a significant decrease in the amount of snow and an increase in temperature during the cold season. The objective of this study is to analyze the impacts of these climate changes on the spatio-temporal variability of the daily maximum flows generated by snowmelt in winter and spring using several statistical tests of correlation (spatial variability) and long-term trend (temporal variability). The study is based on the analysis of flows measured in 17 watersheds (1930–2019) grouped into three hydroclimatic regions. Regarding the spatial variability, the correlation analysis revealed that in winter, the flows are positively correlated with the agricultural area and the daily maximum winter temperature. In the spring, the flows are positively correlated with the drainage density and the snowfall but negatively correlated with the area of wetlands and the daily maximum spring temperature. As for temporal variability (long-term trend), the application of eight statistical tests revealed a generalized increase in flows in winter due to early snowmelt. In the spring, despite the decreased snow cover, no negative trend was observed due to the increase in the spring rainfall, which compensates for the decrease in the snowfall. This temporal evolution of flows in the spring does not correspond to the predictions of climate models. These predict a decrease in the magnitude of spring floods due to the decrease in the snowfall in southern Quebec.

Study on the Dynamics of Stem Sap Flow in Minqin Wind and Sand Control Haloxylon ammodendron Forest, China

In this study, we obtained real-time data on the stem fluid flow of Haloxylon ammodendron in the growing season in Minqin, China, based on thermal diffusion (TDP) monitoring technology, and analyzed the dynamic changes of stem fluid flow in it to provide important supporting evidence for understanding the water consumption of H. ammodendron during its growth. The results indicate that the fluid flow in the stem of the H. ammodendron increases with increasing growth age and also decreases as the H. ammodendron grows older and declines. The average daily sap flow rates of H. ammodendron stems were 0.956, 1.059, 1.460 and 0.570 cm3·(cm2·h)−1 at 5, 10, 15 and 20 years, respectively, and the cumulative sap flow masses during the growing season from May to October were 610.173, 423.386, 1041.186 and 430.212 kg, respectively. H. ammodendron stem sap flow increases with the thickening of H. ammodendron’s ground diameter. The average daily sap flow rate of H. ammodendron stems at different stem levels ranged from 0.276 to 2.132 cm3·(cm2·h)−1, and the cumulative sap flow mass during the growing season ranged from 121.656 to 1722.810 kg. The larger the diameter of the H. ammodendron at different forest ages, the earlier the sap flow initiation time and the higher the peak. The stem flow initiation time was 7:00–8:00, and the average daily maximum fluid flow rate was 2.493–5.536 cm3·(cm2·h)−1, with the peak occurrence time advancing with age. The sap flow variation of H. ammodendron at different stand ages reflects the water-consuming process of H. ammodendron growth and its response to a drought environment, while the sap flow variation of H. ammodendron at different diameter classes shows that the individual growth differences of H. ammodendron also yield obvious competitive advantages. The results of the analysis can provide theoretical support for the estimation of ecological water use in desert H. ammodendron sand-fixing forests.

Rainfall-Runoff Modeling to Predict Maximum Daily Flow under Climate Change Conditions

Rainfall-Runoff Modeling to Predict Maximum Daily Flow under Climate Change Conditions

Maximum Extreme Flow Estimations in Historical Hydrological Series under the Influence of Decadal Variations

The hypothesis of stationarity is a fundamental condition for the application of the statistical theory of extreme values, especially for climate variables. Decadal-scale fluctuations commonly affect maximum and minimum river discharges. Thus, the probability estimates of extreme events need to be considered to enable the selection of most appropriate time series. The current study proposed a methodology to detect the fluctuation of long wet and dry periods. The study was carried out at the gauging station 4C-001 in Pardo River, State of São Paulo, Brazil. The Spearman, Mann–Kendall and Pettitt’s non-parametric tests were also performed to verify the existence of a temporal trend in the maximum annual daily flows. The graph achieved from the Pettitt’s statistical variable allowed for the identification and separation of the longest dry period (1941 to 1975) and the longest wet period (1976 to 2011), decreasing again in 2012. Analysing the series separately, it was observed that both mean and standard deviation were higher than those corresponding to the dry period. The probable maximum flows for the corrected series showed estimates 10% higher than those estimated for the uncorrected historical series. The proposed methodology provided more realistic estimates for the extreme maximum flows.

Stringency of Water Conservation Determines Drinking Water Quality Trade-Offs: Lessons Learned from a Full-Scale Water Distribution System

Demand variations over time affect the hydraulic and water quality behavior of water distribution systems. Therefore, it is important to assess the network performance under various future water demand scenarios to plan effectively for demand management strategies, considering the network’s topology, volume, and operational conditions. The performance of a full-scale water distribution system is evaluated by means of hydraulic and water quality simulations under different hypothetical demand management strategies. Residential and nonresidential consumptions are varied, resulting in different global multiplicative factors (from 0.53 to 1.18). Criteria including water loss, velocity, water age, free chlorine, and THMs are selected to compare the performance of the network between the current scenario and eight demand scenarios. Water conservation generally increases nodal water age values more in smaller diameter pipes. A nodal chlorine residual reliability index is proposed to account for the duration of low chlorine residuals. With a goal of maintaining a reference free chlorine concentration of ≥0.2 mg/L, the reliability index is less than 0.9 for about 14% of nodes under the reference scenario and this proportion increases to 34% of nodes under the most extreme future water conservation scenario. The robustness of the studied network under different water conservation scenarios is tested by increasing the chlorine residual at the outlet of the WTPs from 1 to 2 mg/L. This is an easily implemented adjustment and dramatically improves the chlorine reliability (<0.9 at only 15% of the nodes), even for the most extreme future water conservation scenario. However, this reliability comes at the cost of higher yet compliant THM concentrations for the low demand scenarios, revealing the challenges of balancing competing water quality goals. With a goal of maintaining a reference level of THMs at ≤80 ug/L, the THM reliability index is ≥0.9 at almost all nodes even under the most extreme conservation scenario. The evaluation of self-cleaning potential velocities shows that sufficient velocities can only be reached at daily maximum flow in 5% of smaller diameter piping even in the reference scenario.

Spatial analysis, assessment and mapping of flood hazard in the alluvial plains of Boumerzoug and Rhumel (city of Constantine, north-eastern Algeria): application to development and urban planning projects

This paper proposes an operational methodology for flood hazard assessment and mapping based on the use of two complementary methods: a geomorphologic analysis and a hydrological modelling method under GIS. The methodology has been applied to the urban and peri-urban areas of Constantine, extended over the flood plains of the Boumerzoug and Rhumel river catchment areas highly exposed to frequent flooding. The spatial analysis of the hazard factors revealed the natural predisposition of the two rivers plains of Rhumel and Boumerzoug to flooding. The hydrological modelling of flood phenomena by adjusting the time series of maximum daily rainfall and flow data of the five stations of the catchment areas to log-normal and normal laws allowed to obtain values of maximum daily rainfall and flows for different return periods of 5, 10, 50, 100 and 200 years. The obtained values are close to the recorded ones during the historical floods, which show the reliability of the used adjustment models. The obtained flood hazard map obtained on the basis of the identification of geomorphological units allowed to define the flood extension areas, the main overflow points and the degrees of hazard. This map can be useful for risk for decision about risk reduction and land use planning in the urban area of Constantine.

Peak Factors for Sewerage System in Upper Egypt Communities

The peak factor (PF) is the proportion of the maximum flow to the average daily flow in a wastewater system. Both of the average and the maximum daily flow are evaluated randomly because there is difference in their values, therefore the corresponding peak factor (PF) may be explained based on a probabilistic theory. In this study, Peak factor equations were developed for different studied areas in Upper Egypt region with different populations and water consumption. Ten years of flow data was collected and measured for the study areas and analyzed to improve the P.F equation. The flow values and P.F values acquired from the developed equations of the studied communities were compared to equations from previous studies

Recent Trend in Hydroclimatic Conditions in the Senegal River Basin

Analyzing trends of annual rainfall and assessing the impacts of these trends on the hydrological regime are crucial in the context of climate change and increasing water use. This research investigates the recent trend of hydroclimatic variables in the Senegal River basin based on 36 rain gauge stations and three hydrometric stations not influenced by hydraulic structures. The Man Kendall and Pettitt’s tests were applied for the annual rainfall time series from 1940 to 2013 to detect the shift and the general trend of the annual rainfall. In addition, trends of average annual flow rate (AAFR), maximum daily flow (MADF), and low flow rate (LFR) were evaluated before and after annual rainfall shift. The results show that the first shift is situated on average at 1969 whereas the second one is at 1994. While the first shift is very consistent between stations (between 1966 and 1972), there is a significant dispersion of the second change-point between 1984 and 2002. After the second shift (1994), an increase of annual rainfall is noticed compared to the previous period (1969–1994) which indicates a not significant, partial rainfall recovery at the basin level. The relative changes of hydrologic variables differ based on the variables and the sub-basin. Relative changes before and after first change-point are significantly negative for all variables. The highest relative changes are observed for the AAFR. Considering the periods before and second shifts, the relative changes are mainly significantly positive except for the LFR.

The Watershed Structures in Controlling Runoff - Case Study of Sardasht Basin in IRAN

In order to investigate the performance of constructed structures in Sardasht watershed, Soil and Water Assessment Tools model for simulation of runoff and sediment during the studied period of 1996-2012 was carried out for two cases of existence and absence of flood control structures. From 2007 onwards by performing watershed operations in these sub-basins, the average runoff rate decreased about 250 l/s for sub-basin 1 and 150 l/s for sub-basin 3. This indicates the flood was controlled in these basins. On average, the runoff volume has decreased by 0.25 and 0.15 m3 in the sub-basins 1 and 3 respectively in the presence of the structure compared to the absence of structures. A daily, Monthly simulation time stage and a continuous-time step restrict the usage of the SWAT pattern for comprehensive, occurrence-based flood simulation. The occurrence of acridities and unexpected projections in numerous sectors of IRAN, also the density on basic conveniences precious by mass growth, has owing to a broader difference in deliberation to the problematic of water straight in the alliance. Calibrating a hydrologic model of Sardasht Basin. Using SWAT. Subjective Workload Assessment Technique (SWAT) is a multidimensional scaling method designed to assess time load, mental effort load and stress load. According to the results of Mann-Kendall Test, Watershed management in the Sardasht basin for flood control and runoff can be considered acceptable. Before the watershed operation, the occurrence of runoff with the probability of 80% was zero, which after the operation, the probability of occurrence was reduced by 60%, indicating a positive effect construction of flood and sediment control structures in the Sardasht basin. The results of the hydrological regime curve show that the changes in the monthly runoff ratio to the average monthly runoff before the watershed operations had been more. Due to the limitations, current Soil and Water Assessment Tools simulations in tropical and subtropical regions face a series of problems related to relative humidity, water balance and sediment. Soil and Water Assessment Tools model is also used to estimate the maximum daily flow rate.

Analysis of spatial variability of river streamflow at the catchment area of the Kolyma reservoir

Analysis of the streamflow characteristics of fourteen streams and rivers on the catchment area of the Kolyma reservoir showed that spatial variations of the annual total streamflow agree with the variability of precipitation. The maximum daily flow and duration of the flow period depend on the catchment area. The fraction of different landscapes of the watershed is indicator of such processes as the water discharge from the talik aquifers at the river valleys and the cryogenic redistribution of streamflow that affect the variation coefficient of streamflow, the maximum flow and the duration of the flow period.

Estimation of stochastic traffic capacity using extreme value theory and censoring: A case study in Salem, New Hampshire

In this work, we introduce a method of estimating stochastic freeway capacity using elements of both extreme value theory and survival analysis. First, we define capacity data, or estimates of the capacity of the roadway, as the daily maximum flow values. Then, under a survival analysis premise, we introduce censoring into our definition. That is, on days when flows are sufficiently high and congestion occurs, corresponding flow maxima are considered true estimates of capacity; otherwise, for those days that do not observe high flows or congestion, flow maxima are deemed censored observations and capacities must be higher than the observations. By extreme value theory, the collection of flow maxima (block maxima) can be appropriately approximated with a generalized extreme value (GEV) distribution. Because of small sample sizes and the presence of censoring, a Bayesian framework is pursued for model fitting and parameter estimation. To lend credence to our proposed methodology, the procedure is applied to real-world traffic stream data collected by the New Hampshire Department of Transportation (NHDOT) at a busy location on Interstate I-93 near Salem, New Hampshire. Data were collected over a period of 11 months and raw data were aggregated into 15-minute intervals. To assess our procedure, and to provide proof of concept, several validation procedures are presented. First, using distinct training and validation subsets of our data, the procedure yields accurate predictions of highway capacity. Next, our procedure is applied to a training set to yield random capacities which are then used to predict breakdown in the validation set. The frequency of these predicted breakdowns is found to be statistically similar to observed breakdowns observed in our validation set. Lastly, after comparing our methodology to other methods of stochastic capacity estimation, we find our procedure to be highly successful.

Water relations of drought-stressed temperate trees benefit from short drought-intermitting rainfall events

Decreasing amounts of precipitation and more frequent dry periods will challenge temperate European forests in the future. During such dry periods, short drought-intermitting rainfall events might be the only renewing water source for trees. We investigated the effects of short drought-intermitting rainfall events on the water relations of mature individuals of six different tree species in a near-natural temperate forest during the exceptionally dry summer of 2015. We found the trees to strongly respond to short drought-intermitting rainfall events: maximum daily sap flow recovered already at precipitation amounts of 1.5 mm by up to 20%, and tree water deficit (TWD) and midday shoot water potential (Ψmidday) improved by up to 60% from rainfall amounts of >4.5 mm. We speculate that a mix of foliar and root water uptake as well as relaxation of canopy VPD and thus stomatal water control lead to the observed recoveries. Hydraulic conductivity was found to partly explain the differences in TWD recovery among species. Duration of the rainfall-facilitated recovery of tree water relations was on average 3 days in the coniferous species and Q. petraea but distinctly longer in C. betulus and F. sylvatica for which it reached 9 days. These results show that drought-intermitting short rainfall events strongly facilitate the relaxation of water stress in temperate tree species during drought events and possibly contribute as such to the ability of temperate trees to withstand longer periods of drought.

Stochastic Models for the Maximum and Minimum Daily Flows of Tigris and Khabur Rivers

Stochastic Models for the Maximum and Minimum Daily Flows of Tigris and Khabur Rivers

Effects of soil‐type datasets on regional terrestrial water cycle simulations under different climatic regimes

AbstractHydrological simulations play an important role in estimating terrestrial water budgets and monitoring extreme events such as floods. This study investigates how these simulations are affected by soil‐type datasets and characterizes how these effects vary with climate. We study the differences between two ensemble simulations in China with the Noah‐MP land surface model using two soil datasets from the Food and Agriculture Organization and Beijing Normal University. The differences in ensemble means are analyzed over a 10 year period from 2003 to 2012 with respect to estimated soil moisture, the partition of precipitation between evapotranspiration and runoff, and a flood magnitude index. Results show that the hydrological simulations using sandier soil types result in lower soil moisture, lower evapotranspiration, and higher subsurface runoff. Each of these effects varies uniquely with aridity. The changes in soil moisture decrease with increasing aridity, while the changes in water balance components (evapotranspiration and runoff) peak in the transitional zone between humid and arid regions. The flood magnitude, expressed as the maximum daily flow normalized by annual flow, is also substantially influenced by the input soil type. Soil types with more clay and less sand content yield significantly bigger floods, especially in arid regions.

Relation between design floods based on daily maxima and daily means: use of the Peak Over Threshold approach in the Upper Nysa Kłodzka Basin (SW Poland)

ABSTRACTThe estimation of flood quantiles is crucial in the assessment of the magnitude and frequency of floods. We carried out a comparative analysis of design discharges estimated from both daily maximum flows and daily mean flows for four mountainous catchments located in the Upper Nysa Kłodzka river basin (SW Poland). After separation of baseflow, split of the riverflow time series in independent events, and selection of the Peak Over Threshold sample, the parameters of the Generalized Pareto Distribution were estimated using the Hill statistic, after bias correction, and considering asymptotic properties. The comparison was performed for various return periods, where the long return periods were of main concern. The jack-knife approach was used to assess the uncertainty of the predicted flood quantiles, and comparison was made with an alternative approach based on annual maxima. We found a meaningful level of differences between daily maximum and mean design discharges and between the rate of change of flood magnitude for which the level (i) stabilized with increasing return period, (ii) decreased downstream, and (iii) was large for catchments susceptible to flooding and with high elevation change. Results are useful in practice when daily maximum discharge is not routinely recorded.