Snowmelt Floods Research Articles

Distribution of invasive and native riparian woody plants across the western USA in relation to climate, river flow, floodplain geometry and patterns of introduction

Management of riparian plant invasions across the landscape requires understanding the combined influence of climate, hydrology, geologic constraints and patterns of introduction. We measured abundance of nine riparian woody taxa at 456 stream gages across the western USA. We constructed conditional inference recursive binary partitioning models to discriminate the influence of eleven environmental variables on plant occurrence and abundance, focusing on the two most abundant non‐native taxa, Tamarix spp. and Elaeagnus angustifolia, and their native competitor Populus deltoides. River reaches in this study were distributed along a composite gradient from cooler, wetter higher‐elevation reaches with higher stream power and earlier snowmelt flood peaks to warmer, drier lower‐elevation reaches with lower power and later peaks. Plant distributions were strongly related to climate, hydrologic and geomorphic factors, and introduction history. The strongest associations were with temperature and then precipitation. Among hydrologic and geomorphic variables, stream power, peak flow timing and 10‐yr flood magnitude had stronger associations than did peak flow predictability, low‐flow magnitude, mean annual flow and channel confinement. Nearby intentional planting of Elaeagnus was the best predictor of its occurrence, but planting of Tamarix was rare. Higher temperatures were associated with greater abundance of Tamarix relative to P. deltoides, and greater abundance of P. deltoides relative to Elaeagnus. Populus deltoides abundance was more strongly related to peak flow timing than was that of Elaeagnus or Tamarix. Higher stream power and larger 10‐yr floods were associated with greater abundance of P. deltoides and Tamarix relative to Elaeagnus. Therefore, increases in temperature could increase abundance of Tamarix and decrease that of Elaeagnus relative to P. deltoides, changes in peak flow timing caused by climate change or dam operations could increase abundance of both invasive taxa, and dam‐induced reductions in flood peaks could increase abundance of Elaeagnus relative to Tamarix and P. deltoides.

Characteristics of meteorological disasters and their impacts on the agricultural ecosystems in the northwest of China: a case study in Xinjiang

Abstract Background In recent years, the meteorological extreme events have caused the direct economic losses and human mortality increased significantly. While there has been a paucity of information regarding trends in meteorological disasters in Xinjiang. Based on two extreme climate measurements, i.e., the Palmer Drought Severity Index (PDSI) and the agricultural disaster area, the influence of meteorological disasters on agriculture were analyzed during the period 1960-2010. Results (1) Temperature extremes exhibited patterns consistent with warming, with a large proportion of stations having statistically significant trends. The warming trends in the indices derived using daily minimum temperatures were greater than those obtained using maximum temperatures. Most of the precipitation indices exhibited increasing trends across the region, and the increased precipitation was due to the increase in both precipitation frequency and intensity. (2) The drought indices increased significantly in most regions of Xinjiang, and the seasonal PDSI exhibited significant correlations with the annual PDSI. For the entire geographical study area, two contrasting periods were evident in the PDSI between 1961 and 2010. Wet conditions dominated from 1987 to 2010, whereas persistent drought conditions occurred from 1960 to 1986. (3) Increased climate extremes resulted in increased agricultural disaster area. During warm summers, the droughts intensified; the corresponding snowmelt flood also became stronger. In addition, the sharply reduced effective irrigation area exacerbated the increased agricultural disaster area. Conclusions Climate change has affected the local agricultural oasis ecosystem and the yield and quality of crops in Xinjiang, leading to increased instability in agricultural production.

The winter storms of 2013/2014 in the UK: hydrological responses and impacts

This paper outlines the hydrological aspects of the 2013/2014 winter flooding in the UK, as well as the impacts. The episode is considered in a long-term historical context and wider issues raised by the flood events are discussed briefly.

The Role of Meteorological Factor in Long-Term Variability of the River Streamflow of the Territory of North of the Russian (East European) Plain

As is well-known, the river stream-flow as the main source of water resources, is formed and changed under the influence of climate conditions and physiographic characteristics of watershed basins. Snow storage, liquid precipitation in the period of snow-melt flood, degree of moisture of the area, etc. are the main hydro-climatic factors determining the amount of the annual river flow. On the territory under consideration, in this case the region of the North of the Russian Plain is selected as which, flow fluctuations are well-defined as a result of changes in space and time of the main forming it factors and, mainly, the meteorological factor. In this regard, the main objective of the work is to find the connection between rainfall and river flow, as well as to identify patterns of spatial and temporal changes of river flow and precipitation. During the study, the authors identified the dependencies between precipitation and the layer of the run-off in hydrological seasons. In particular, the closest connection was established between precipitation and the flow of summer-autumn period, where the correlation coefficient (r) for posts of Soyana - Soyana, Mudyug - Patrakeevskaya is r = 0,7 – 0,8, reaching r = 0,9 (Codina - Codino). Comparison of precipitation of the winter-spring period and the spring run-off did not reveal very close connection, except the site location of Sysola - Pervomajskij (the basin of the Northern Dvina), where r = 0,86. It is determined that during a year there are two maxima and two minima in the distribution of precipitation, while in the overland runoff they do not fully coincide with precipitation in time. Synchronous increase of share of precipitation and runoff was observed from May to July and in October, except August (precipitation) and April (run-off), where these periods did not coincide. DOI: 10.5901/mjss.2014.v5n24p256

On the relationship between hydro-meteorological patterns and flood types

Flood generation is triggered by the interaction of the hydrological pre-conditions and the meteorological conditions at different space–time scales. This interaction results in floods of diverse characteristics, e.g. spatial flood extent and temporal flood progression. While previous studies have either linked flood occurrence to weather patterns neglecting the hydrological pre-conditions or categorised floods according to their generating mechanisms into flood types, this study combines both approaches. Exemplary for the Elbe River basin, the influence of pre-event soil moisture as an indicator of hydrological pre-conditions, on the link between weather patterns and flood occurrence is investigated. Flood favouring soil moisture and weather patterns as well as their combined influence on flood occurrence are examined. Flood types are identified and linked to soil moisture and weather patterns. The results show that the flood favouring hydro-meteorological patterns vary between seasons and can be linked to flood types. The highest flood potential for long-rain floods is associated with a weather pattern that is often identified in the presence of so called ‘Vb’ cyclones. Rain-on-snow and snowmelt floods are associated with westerly and north-westerly wind directions. In the analysis period, 18% of weather patterns only caused flooding in case of preceding soil saturation. The presented concept is part of a paradigm shift from pure flood frequency analysis to a frequency analysis that bases itself on process understanding by describing flood occurrence and characteristics in dependence of hydro-meteorological patterns.

Stochastic semi-continuous simulation for extreme flood estimation in catchments with combined rainfall–snowmelt flood regimes

Abstract. Simulation methods for extreme flood estimation represent an important complement to statistical flood frequency analysis because a spectrum of catchment conditions potentially leading to extreme flows can be assessed. In this paper, stochastic, semi-continuous simulation is used to estimate extreme floods in three catchments located in Norway, all of which are characterised by flood regimes in which snowmelt often has a significant role. The simulations are based on SCHADEX, which couples a precipitation probabilistic model with a hydrological simulation such that an exhaustive set of catchment conditions and responses is simulated. The precipitation probabilistic model is conditioned by regional weather patterns, and a bottom–up classification procedure was used to define a set of weather patterns producing extreme precipitation in Norway. SCHADEX estimates for the 1000-year (Q1000) discharge are compared with those of several standard methods, including event-based and long-term simulations which use a single extreme precipitation sequence as input to a hydrological model, statistical flood frequency analysis based on the annual maximum series, and the GRADEX method. The comparison suggests that the combination of a precipitation probabilistic model with a long-term simulation of catchment conditions, including snowmelt, produces estimates for given return periods which are more in line with those based on statistical flood frequency analysis, as compared with the standard simulation methods, in two of the catchments. In the third case, the SCHADEX method gives higher estimates than statistical flood frequency analysis and further suggests that the seasonality of the most likely Q1000 events differs from that of the annual maximum flows. The semi-continuous stochastic simulation method highlights the importance of considering the joint probability of extreme precipitation, snowmelt rates and catchment saturation states when assigning return periods to floods estimated by precipitation-runoff methods. The SCHADEX methodology, as applied here, is dependent on observed discharge data for calibration of a hydrological model, and further study to extend its application to ungauged catchments would significantly enhance its versatility.

Ontogeny of point bars on a river in a cold semi-arid climate

During the extreme flood of May 1978 in Powder River, Montana, USA, three new point bars were created: two by meander cutoffs, and one by 65 m of lateral channel migration. By using annual cross-sectional surveys and by sampling sediment in dug trenches, we documented the creation of point-bar platforms upon which sediments were later deposited to create point-bar features that evolved with time. Our observations of point-bar growth and evolution on Powder River are compared with similar observations of other point bars in humid subtropical and subarctic climates. Powder River is a meandering alluvial river in a cold semi-arid climate, characterized by a diverse flow regime that includes occasional ice-jam floods in late winter, annual snowmelt floods in late spring, episodic flash floods in the summer, and infrequent floods in the fall. The building of the point-bar platform took place during a relatively short time span, by an apparently random process of deposition and erosion of unit bars during floods that gradually changed a concave channel surface to a convex surface upon which the point-bar features evolved. Point-bar features on Powder River were built by a superposition of multiple unit bars associated with five flood types over a period of years rather than during a single year. Erosion was found to be a significant process in the shaping of the point bars. Erosion varied spatially between point bars and temporally at multiple time scales over the 33 yr time span. Erosion at the decadal time scale indicated that on average 19%–41% of the initial deposits (older than 10 yr) were eroded. This quantification of erosion has implications for interpreting the geological record.

An Integrated Approach to Snowmelt Flood Forecasting in Water Resource Management

Water scarcity and floods are the major challenges for human society both present and future. Effective and scientific management of water resources requires a good understanding of water cycles, and a systematic integration of observations can lead to better prediction results. This paper presents an integrated approach to water resource management based on geoinformatics including technologies such as Remote Sensing (RS), Geographical Information Systems (GIS), Global Positioning Systems (GPS), Enterprise Information Systems (EIS), and cloud services. The paper introduces a prototype IIS called Water Resource Management Enterprise Information System (WRMEIS) that integrates functions such as data acquisition, data management and sharing, modeling, and knowledge management. A system called SFFEIS (Snowmelt Flood Forecasting Enterprise Information System) based on the WRMEIS structure has been implemented. It includes operational database, Extraction-Transformation-Loading (ETL), information warehouse, temporal and spatial analysis, simulation/prediction models, knowledge management, and other functions. In this study, a prototype water resource management IIS is developed which integrates geoinformatics, EIS, and cloud service. It also proposes a novel approach to information management that allows any participant play the role as a sensor as well as a contributor to the information warehouse. Both users and public play the role for providing data and knowledge. This study highlights the crucial importance of a systematic approach toward IISs for effective resource and environment management.

Probabilistic Ensemble Forecast of Summertime Temperatures in Pakistan

Snowmelt flooding triggered by intense heat is a major temperature related weather hazard in northern Pakistan, and the frequency of such extreme flood events has increased during the recent years. In this study, the probabilistic temperature forecasts at seasonal and subseasonal time scales based on hindcasts simulations from three state-of-the-art models within the DEMETER project are assessed by the relative operating characteristic (ROC) verification method. Results based on direct model outputs reveal significant skill for hot summers in February 3–5 (ROCarea=0.707with lower 95% confidence limit of 0.538) and February 4-5 (ROCarea=0.771with lower 95% confidence limit of 0.623) forecasts when validated against observations. Results for ERA-40 reanalysis also show skill for hot summers. Skilful probabilistic ensemble forecasts of summertime temperatures may be valuable in providing the foreknowledge of snowmelt flooding and water management in Pakistan.

Hydrological influences on the distribution of vegetation and tree height of Alnus japonica (Thunb.) Steud. in the Kushiro Mire, Japan

The relationship between the hydrology and plant communities assessed by continuous measurement of water, soil environment and vegetation, mainly in an alder forest, was studied in Kushiro Mire, Hokkaido, Japan. Seasonal changes in the water level were not detected, except in the willow forest located in the Kuchoro River, which showed a drawdown of the water level in summer. The height of the alder trees correlated with the mean and lowest water levels which would supply oxygen. The peak water level also affected the height of the alder forest, suggesting that waterlogging (reduction and lack of oxygen) inhibited the height of the alder trees. An overflow was only observed during the strong low pressure, typhoon or snowmelt flooding, as a result of the high peak water level. In snowmelt season, alder did not foliation stage. This suggests that the river water may only overflow the natural levee during a such large rain event, which supports the establishment of alder forests in the inflow area. Furthermore, the height of alder trees weakly negatively correlated with the carbon/nitrogen ratio of the soil, suggesting a difference in the deposition of peat. Reed-sedge community showed a large fluctuation of the water level, and resistant to drawdown of the water level, which would inhibit the invasion of alder.

First look at changes in flood hazard in the Inter-Sectoral Impact Model Intercomparison Project ensemble.

Climate change due to anthropogenic greenhouse gas emissions is expected to increase the frequency and intensity of precipitation events, which is likely to affect the probability of flooding into the future. In this paper we use river flow simulations from nine global hydrology and land surface models to explore uncertainties in the potential impacts of climate change on flood hazard at global scale. As an indicator of flood hazard we looked at changes in the 30-y return level of 5-d average peak flows under representative concentration pathway RCP8.5 at the end of this century. Not everywhere does climate change result in an increase in flood hazard: decreases in the magnitude and frequency of the 30-y return level of river flow occur at roughly one-third (20-45%) of the global land grid points, particularly in areas where the hydrograph is dominated by the snowmelt flood peak in spring. In most model experiments, however, an increase in flooding frequency was found in more than half of the grid points. The current 30-y flood peak is projected to occur in more than 1 in 5 y across 5-30% of land grid points. The large-scale patterns of change are remarkably consistent among impact models and even the driving climate models, but at local scale and in individual river basins there can be disagreement even on the sign of change, indicating large modeling uncertainty which needs to be taken into account in local adaptation studies.

The relative contributions of refugium types to the persistence of benthic invertebrates in a seasonal snowmelt flood

Summary Flow refugia, characterised by low hydraulic stress during a flood, are key habitats that contribute to the persistence of benthic invertebrate. We investigated the use of different refugium types distributed across stream and floodplains and clarified which refugia contributed most to the persistence of assemblage and population during a seasonal snowmelt flood. We sampled invertebrates and measured physical variables from six or nine types of channel units (‘riffle’, ‘run ‘, ‘lateral pool’, ‘backwater’, ‘abandoned pool’ and ‘tributary’ at base flow, plus ‘fast inundated area’, ‘slow inundated area’ and ‘side channel’ at high flow) at four times (before, during, immediately after and after a flood). We analysed the use of refugia by assemblages, species with different ecological ‘lifestyles’ (a classification into different modes of mobility: burrower, climber, sprawler, clinger and swimmer) and populations. Total density and species richness decreased significantly with flooding in riffles, runs and lateral pools. In contrast, total density and species richness did not change significantly in the other six types of channel units; therefore, these were distinguished as refugia. Among the six refugia, backwaters, tributaries and slow inundated areas had higher total densities than other refugia. The densities of the five lifestyles also decreased with flooding in riffles, runs and lateral pools. During flooding, high densities in backwaters and slow inundated areas were common for all lifestyles, whereas densities in other refugia varied with lifestyle. The results for five common species showed that refugium use is species‐dependent. The mayfly Paraleptophlebia japonica (Leptophlebiidae) and the cased caddisfly Neophylax ussuriensis (Uenoidae) were more numerous in refugia during flooding and recovered rapidly after flooding. In contrast, the mayfly Epeorus latifolium (Heptageniidae) and the net‐spinning caddisfly Hydropsyche orientalis (Hydropsychidae) were rare in all types of channel units during and immediately after flooding. The cased caddisfly Allomyia delicatula (Apataniidae) was specific to tributaries and persisted throughout the research period. Although some species did not use refugia effectively, various species with different mobility and ecological traits did persist and were found in refugia. Specifically, habitats with slowly flowing water that were spatially close to the main channel favoured the persistence of benthic invertebrates.

An integrated information system for snowmelt flood early-warning based on internet of things

Floods and water resource management are major challenges for human in present and the near future, and snowmelt floods which usually break out in arid or semi-arid regions often cause tremendous social and economic losses, and integrated information system (IIS) is valuable to scientific and public decision-making. This paper presents an integrated approach to snowmelt floods early-warning based on geoinformatics (i.e. remote sensing (RS), geographical information systems (GIS) and global positioning systems (GPS)), Internet of Things (IoT) and cloud services. It consists of main components such as infrastructure and devices in IoT, cloud information warehouse, management tools, applications and services, the results from a case study shows that the effectiveness of flood prediction and decision-making can be improved by using the IIS. The prototype system implemented in this paper is valuable to the acquisition, management and sharing of multi-source information in snowmelt flood early-warning even in other tasks of water resource management. The contribution of this work includes developing a prototype IIS for snowmelt flood early-warning in water resource management with the combination of IoT, Geoinformatics and Cloud Service, with the IIS, everyone could be a sensor of IoT and a contributor of the information warehouse, professional users and public are both servers and clients for information management and services. Furthermore, the IIS provides a preliminary framework of e-Science in resources management and environment science. This study highlights the crucial significance of a systematic approach toward IISs for effective resource and environment management.

Errors in taking account of the runoff of the rivers with diurnal variations of the water level at the absence of increased-frequency observations

Estimated are additional errors in taking account of the river runoff during different phases of high water and snowmelt floods using the observational data from gaging stations at the absence of increased-frequency measurements of the water level (due to the lack or downtime of recorders). Described is a method for determination of these errors. Using the data collected on 118 gaging stations on 58 rivers in different regions of Russia and the former USSR for seven years of observations, determined are the possible additional errors of average daily, monthly and annual water flows of the rivers of different sizes as well as the total errors that take account of the additional errors.

The relationship between the snowmelt flood and the establishment of non‐native brown trout (Salmo trutta) in streams of theChitoseRiver,Hokkaido, northernJapan

AbstractFlow regime is one of the major determinants of establishment success for non‐native aquatic organisms. Here, we examine the influence of flow variability associated with snowmelt flood on the establishment success of non‐native brown trout in 10 streams in northern Japan. We regarded the presence ofAge‐0 brown trout as the index of the successful establishment. The emergence ofAge‐0 brown trout in our study region begins in May, a time that overlaps with the occurrence of snowmelt flood. The presence ofAge‐0 brown trout was negatively associated with flow variability, and it was also negatively associated with summer water temperature. Our results indicate that the non‐native brown trout tends to establish in the streams with smaller snowmelt floods and lower summer water temperatures. Brown trout is an invasive, non‐native species that is problematic all over the world, and effective management strategies for preventing their further expansion are urgently needed. This study suggests that river managers should recognise that stable streams such as spring‐fed streams (i.e., low flow and summer water temperature) and flow‐regulated streams, have a higher potential risk of brown trout invasion.

Correlation between the total precipitation and the mean and maximum runoff during the snowmelt flood in the Belaya River basin

Presented are the results of analyzing the correlation between the total winter and autumn precipitation and the parameters of spring water runoff in the Belaya River basin for the period of 1936–2000. Five regions are defined, and major factors influencing the runoff formation in each of them are listed. The correlation between the runoff characteristics and the total precipitation is estimated; it can be used for developing the methodological instructions for the runoff forecast in different areas of Bashkortostan.

Spatial distribution of the extreme hydrological events in Xinjiang, north-west of China

We examined spatial distribution characteristics of extreme hydrological events in Xinjiang, China, using district data from 1901 to 2010. Frequency distribution showed a general symmetry along the Tianshan Mountains, with even distribution in Junggar Basin and Tarim Basin. Frequency was more in the north-west than in the south-east. The maximum incidence was in west Tianshan Mountains and generally decreased south-eastward. There were significant regional variations in type distribution. Rainstorm floods were more common in central Xinjiang. Hailstorms mainly occurred in the central Junggar Basin, the southern slope of the western Tianshan Mountains and north-west of Tarim Basin. Debris flow was mainly distributed in Ili Valley and the central northern Tianshan Mountains. Glacier lake outburst floods were more common in the Karakorum Mountains and southern slopes of the western Tianshan Mountains. Ice floods were mainly distributed in the western Tianshan Mountains. Snow hazards were mainly distributed in the wide northern areas, especially the Altai Mountains and Hamilton Basin. Snowmelt floods were mainly distributed in the Tacheng Basin and Ili Valley. The incidence of extreme hydrological events was greatly affected by weather systems and terrain features.

鵡川沿岸の基礎生産に対する融雪出水の効果について

鵡川沿岸の基礎生産に対する融雪出水の効果について

Flows, floods, floodplains and river restoration

Returning water to rivers as environmental flows is now a major tool for restoration. Many plans for environmental flows have been modelled and devised but few have been delivered, at least in Australia. Nevertheless, as planned in the latest version of the Murray‐Darling Basin Authority’s (2011) Draft Basin Plan, water recovery for environmental flows is firmly advocated. In environmental flow planning, a key component to restore is periodic (seasonal) floods. Thus, in upland rivers that have been dammed, below-dam floods are seen as vital to reshape channels, to remove unnaturally high levels of sediments accumulated since dams were built and to improve water quality. An example of this is the restoration of the Snowy River below Jindabyne Dam (NSW Office of Water 2010). Environmental flows are released to lift base flow and to introduce variability that mimics pre-dam levels and the seasonal snow-melt flood. The flood is not of the magnitude of the pre-dam flows, but is designed to improve the river by remoulding the channel, removing accumulated sediments and detritus, improving water quality and rebuilding habitats typical of an upland river. In general, restoring floods in constrained upland rivers aims to improve channel conditions. Lowland rivers are usually floodplain rivers, which, in their intact state, regularly (seasonally) flood their floodplains. When the floodplains were flooded, as still occurs in the few remaining unregulated rivers (e.g. Ovens River, Victoria), there is a boom of primary production (bacteria, phytoplankton, macrophytes, tree growth) followed by a pulse of secondary production both of aquatic (zooplankton, macroinvertebrates, fish) and terrestrial fauna (e.g. birds, amphibians, reptiles). The high primary production is fuelled by nutrients coming in with the flood but also by nutrients and organic carbon released from the floodplain (Baldwin & Mitchell 2000). Flooded, intact floodplains are one of the most productive types of ecosystems in the world. The loss of that ecological production arising from river regulation and floodplain alienation in dammed lowland rivers is known, but its size and value are seldom acknowledged in developing outcomes for managed flows. Floods in upland rivers are pulse (sometimes intense) disturbances, whereas in floodplain rivers, floods are regenerative or restorative disturbances, notwithstanding some disruptions of the terrestrial biota (Lake et al. 2006). The ongoing viability of the biota of floodplain ecosystems lies in their capacity to capitalize on floods and to survive the dry periods between floods. To maintain the ecological integrity of floodplains, regular flooding covering the floodplain is essential.

Environmental and land use factors affecting phosphate hysteresis patterns of stream water during flood events (Carpathian Foothills, Poland)

AbstractFlood events play a substantial role in the circulation of catchment phosphate (PO43−). The purpose of the research was to analyze the factors determining PO43− hysteresis patterns (direction and width) during four types of floods: short and long rainfall floods and snowmelt floods on frozen and thawed soil. The research took place in small catchments (forested, agricultural, mixed‐use) in the Carpathian Foothills in Poland. Anticlockwise hysteresis was identified in the forested catchment during short and long rainfall floods. Under the same conditions, the clockwise direction was observed in the agricultural catchment. In the mixed‐use catchment, the direction of PO43− hysteresis loops was various, driven by the share of water flowing from each part of the catchment. For snowmelt floods, the PO43− hysteresis pattern was similar in all the streams studied (usually clockwise). The direction of PO43− hysteresis loops depends on water circulation patterns, which are determined by the different influx times of particular runoff components. The stream recharge mechanism during a flood event is affected both by the factor initiating the event (precipitation, snowmelt) as well as by land use in the given catchment. Hysteresis loop width was determined by the pool of PO43− in a given catchment during the time period immediately preceding a flood event as well as by the quantity of PO43− flushed out of the soil. The greater a catchment's pool of PO43− and the greater its ability to flush PO43− out of the soil and into surface flow, the wider the hysteresis loops. Copyright © 2012 John Wiley & Sons, Ltd.