River Runoff Research Articles

Qualitative and quantitative reconstructions of surface water characteristics and recent hydrographical changes in the Trondheimsfjord, central Norway

Abstract. In the present study we investigated dinocyst assemblages in the Trondheimsfjord over the last 25 to 50 yr from three well-dated multi-cores (210Pb and 137Cs) retrieved along the fjord axis. The downcore distribution of the dinocysts is discussed in view of changes in key hydrographic parameters of the surface waters (sea-surface temperatures (SSTs), sea-surface salinities (SSSs), and river discharges) monitored in the fjord. We examine the impact of the North Atlantic Oscillation pattern and of waste water supply from the local industry and agriculture on the fjord ecological state and thus dinocyst species diversity. Our results show that dinocyst production and diversity in the fjord is not evidently affected by human-induced eutrophication. Instead the assemblages appear to be mainly controlled by the NAO-related changes in nutrient availability and the physico-chemical characteristics of the surface mixed layer. Still, discharges of major rivers have been modulated since 1985 by the implementation of hydropower plants, which certainly influences the amounts of nutrients supplied to the fjord. The impact, however, is variable according to the local geographical setting, and barely differentiated from natural changes in river run off. We ultimately test the use of the modern analogue technique (MAT) for the reconstruction of winter and summer SSTs and SSSs and annual primary productivity (PP) in this particular fjord setting. The reconstructed data are compared with time series of summer and winter SSTs and SSSs measured at 10 m water depth, as well as with mean annual PPs along the Norwegian coast and in Scandinavian fjords. The reconstructions are generally in good agreement with the instrumental measurements and observations from other fjords. Major deviations can be attributed to peculiarities in the assemblages linked to the particular fjord setting and the related hydrological structure.

Coral Luminescence Identifies the Pacific Decadal Oscillation as a Primary Driver of River Runoff Variability Impacting the Southern Great Barrier Reef

The Pacific Decadal Oscillation (PDO) is a large-scale climatic phenomenon modulating ocean-atmosphere variability on decadal time scales. While precipitation and river flow variability in the Great Barrier Reef (GBR) catchments are sensitive to PDO phases, the extent to which the PDO influences coral reefs is poorly understood. Here, six Porites coral cores were used to produce a composite record of coral luminescence variability (runoff proxy) and identify drivers of terrestrial influence on the Keppel reefs, southern GBR. We found that coral skeletal luminescence effectively captured seasonal, inter-annual and decadal variability of river discharge and rainfall from the Fitzroy River catchment. Most importantly, although the influence of El Niño-Southern Oscillation (ENSO) events was evident in the luminescence records, the variability in the coral luminescence composite record was significantly explained by the PDO. Negative luminescence anomalies (reduced runoff) were associated with El Niño years during positive PDO phases while positive luminescence anomalies (increased runoff) coincided with strong/moderate La Niña years during negative PDO phases. This study provides clear evidence that not only ENSO but also the PDO have significantly affected runoff regimes at the Keppel reefs for at least a century, and suggests that upcoming hydrological disturbances and ecological responses in the southern GBR region will be mediated by the future evolution of these sources of climate variability.

Ocean Prediction for Aquaculture: An Interview-based system

An interview with aquaculturist was conducted using the Grid Evaluation Method to elicit what predcted information is required from aquaculturist. Inteview’s outcome indicated that the salinity of nearshore water is critical information to reduce mortal risk of scallop in the nursery stage. The nearshore low-salinity water can increase mortality of young scallop cultured in aquafarm. This study showed that the coupled land-ocean, high-resolution model is essential to predict the nearshore low-salinity water in the enclosed bay having the aquafarm. The proposed visualization to concurrently exhibit the low-salinity water, snow cover, and river runoffs may be preferable to provide the helpful information.

Pattern of variation of zooplankton assemblages under the influence of river runoffs: a study case along the Apulian marine coastal waters (southern Italy, Mediterranean Sea)

The distribution and composition of zooplankton assemblages was investigated along the Apulian marine–coastal area (Mediterranean Sea) in the time period between January 2008 and February 2010. Zooplankton samples were collected monthly from 15 monitoring stations located in two sub-basins, namely, the southern Adriatic (11 stations) and the northern Ionian (4 stations). Results indicated a strong influence of river runoffs on zooplankton assemblages in terms of an increase in the abundance of tolerant species and a reduction of overall richness and diversity of species. Compared with the Ionian, in the Adriatic stations, zooplankton standing stocks showed higher abundances. Results also suggest that the zooplankton can be considered a useful biological indicator of water quality for the Apulian coastal waters and could be used in environmental monitoring programs.

Influence of Amur River Run-Off on the Biogeochemistry of Iron in the Okhotsk Sea

Influence of Amur River Run-Off on the Biogeochemistry of Iron in the Okhotsk Sea

The Phenomenon of General Spread of Poly-Modality of the Distribution Laws Annual Rivers Runoff

Based on the polymodality criterion, the laws of the annual rivers runoff were studied. It is shown that they are polymodal and this polymodality is of general occurrence. At that, there are no single-mode and two-mode laws of the river runoff distribution in nature. The 3-mode and 4-mode laws are the most commonly encountered. It is shown that the annual runoff is also a random discontinuous value. The values of discontinuous occurrences are presented which can provide the basis for the future theory of creation of polymodal laws of the annual runoff distribution.

On the temporal variation of DOM fluorescence on the southwest Florida continental shelf

Dissolved organic matter (DOM) plays a crucial role in the nutrient and carbon cycling in the coastal-shelf-ocean boundary. It is a major reservoir of reduced carbon and carries important information on how sea and landscape have been modified. Due to the complexity of the biogeochemical processes in this boundary, its distribution is not well understood. This study evaluated the Excitation Emission Matrix (EEM) fluorescence method combined with Parallel Factorial Analysis (PARAFAC) modeling to resolve DOM fluorescence components, and their distribution from near-shore to off-shore on the southwest (SW) Florida Shelf. The PARAFAC model derived identified five unique DOM components from 272 Excitation and Emission Matrix (EEM) samples measured across the shelf on May and October 2008, and January and April 2009 cruises. These five different fluorophores consisted of two humic-like components that were attributed to natural (component1: HLC1) and anthropogenic (component 2: HLC2) sources; an unidentified component (component 3); two autochthonous protein components, identified as tryptophan-like (component 4:TLC4); and tyrosine-like (component 5:TLC5) fluorophores. The observed temporal variations of terrestrial and anthropogenic humic-like DOM fluorescent materials were not necessarily dependent on the timing of river runoffs and rainfall frequency on the shelf, but also on other factors (i.e., suspension of sediments in shallow water induced by wind-driven mixing, dilution, hypersalinity conditions). The areal distribution of the resolved terrestrial DOM fluorescence on the mid-shelf indicates evidence of offshore transport of land-derived materials. The evident terrestrial humic-like inputs into the shelf correspond to the increase in the protein-like fluorescence, which was attributed to autochthonous biological degradation. Results from this study demonstrated advances in several aspects of monitoring the temporal distribution of DOM on the continental shelf of Florida using EEM and PARAFAC methods. The methods employed were able to: (1) resolve sources of the individual DOM fluorescence components of the bulk DOM; (2) generate spatial and temporal distribution maps of each of the components on the shelf; and (3) provide insights into biological, chemical, and physical processes that control the DOM variability of each of the resolved DOM components.

Research on Characteristics of New Water in Yichang-Wuhan Reach after Impoundment of the Three Gorges

Reservoir regulation make conditions of flow under the dam change greatly after impoundment of the Three Gorges Project. This paper analyzes change trend and abrupt change situation of incoming water and studies characteristics of new flow of Yichang and Hankou Stations after impoundment of the Three Gorges with Mann-Kendall nonparametric rank test method. The result indicates that operation of the Three Gorges Reservoir has leveled runoff process and shortened dry season and extended median water period; After operation of the Three Gorges Reservoir, monthly river runoff of several months in both of Yichang and Hankou Stations changed abruptly. However, so far as time of abrupt change is concerned, sudden change of annual river runoff or monthly river runoff has little to do with operation of the Three Gorges Project.

Output improvement of Sg. Piah run-off river hydro-electric station with a new computed river flow-based control system

The lower Sg. Piah hydro-electric station is a river run-off hydro scheme with generators capable of generating 55MW of electricity. It is located 30km away from Sg. Siput, a small town in the state of Perak, Malaysia. The station has two turbines (Pelton) to harness energy from water that flow through a 7km tunnel from a small intake dam. The trait of a run-off river hydro station is small-reservoir that cannot store water for a long duration; therefore potential energy carried by the spillage will be wasted if the dam level is not appropriately regulated. To improve the station annual energy output, a new controller based on the computed river flow has been installed. The controller regulates the dam level with an algorithm based on the river flow derived indirectly from the intake-dam water level and other plant parameters. The controller has been able to maintain the dam at optimum water level and regulate the turbines to maximize the total generation output.

Environmental impacts and best management of urban stormwater runoff: measures and legislative framework

<p>Urban stormwater runoff constitutes a non-point source pollution, which contributes in degradation of water bodies’ quality (USEPA, 2002). European Union’s environmental policy includes water environment protection and preservation by adopting a series of directives, 2000/60/EC (Water Framework Directive - WFD), 97/11/EEC (Environmental Impact Assessment Directive - EIA), 2001/42/EC (Strategic Environmental Assessment Directive - SEAD) and many others. However, such legislative framework is not strongly related to the issue of urban stormwater runoff management, due to its general content. Pollution control of urban stormwater runoff entails a management strategy based on scientific research and reliable available data. Consequently, the subject of prevention and control of urban stormwater runoff remains still open and it is a motivation for further research and discussion; it also underlines the need to propose detailed specifications both for environmental impact assessment, as well as for the proper formation of a data-base. Thus, within the content of the present paper, the following are included: a) the investigation and presentation of the receiving waters pollution issues from the urban stormwater runoff, b) the examination of the respective pollutant generation and characteristics, c) the presentation of their impacts d) the examination of the measures (structural and non-structural BMPs) f) the presentation of the existing legislation in the EU and Greece. Finally, specific measures, which authorities must take into account in the framework of the programs for runoff river basin management, according to the 2000/60 EC Directive and the Greek Law 3199/2003, are proposed.</p>

Implementing into GIS a Tool to Automate the Calculation of Physiographic Parameters of River Basins

The physiographic characterization of a basin is a fundamental element as it defines the hydrological behavior of that basin. The present work deals with the development and implementation of a tool that allows calculating in an automated manner the physiographic parameters of a basin, as well as those of the surface runoff and main river, besides other graphic elements: hypsometric curve, equivalent rectangle and profile of the main river. Such a tool was developed under Visual Basic 6 programming language and the spatial geographic component ArcObjects by ESRI; they enabled the development of a library as a final product (.dll), which can be loaded and implemented in ArcMap software. In the methodology a Conceptual Model was established, from which it was possible to identify the requirements and methods to obtain the parameters, as well as the conception and implementation of the Logical Model that includes the specific functions and also the input structures, processes and data output. Finally, the tool was tested with actual data from El Caracol river basin, located in central-southern Mexico, which showed the easiness and usefulness of it, besides the effectiveness of the results, not leaving aside the time and resources saved by the user when characterizing a basin, compared with other conventional processes.

Many-year Fluctuations of River Runoff in South-taiga Subzone of the Western Siberia

A detailed analysis of river flow long-term changes in the Southern taiga subzone of Western Siberia has been carried out with the Chaya River basin as an example. Causal statistical analysis of changes in groundwater levels, bog water level, air temperature and atmospheric precipitation has been performed. The conducted studies revealed a statistically significant trend in the increase of surface runoff in the winter low flow of the Chaya River and its large tributaries (the Iksa and the Parbig), as well as the underground runoff component for virtually the entire year. An ambiguous regularity has been observed in the change of the level regime of rivers. The main reason for the observed changes in the water regime of the said territory is the redistribution of atmospheric moisture and shifting of the boundaries of hydrological seasons.

Climatic and Anthropogenic Factors in Long-term Alterations of the Volga River Runoff

The contribution of natural climate and anthropogenic factors in the Volga river runoff changes at Volgograd during the period of instrumental observations (1882–2007). has been revealed. The estimates are based on two independent approaches. One of them is based on the restoration of the annual and seasonal runoff against the riversindicators’ regression dependencies, and the other one is based on the water use statistical data and methods of water balance. The calculations give the total Volga river annual runoff anthropogenic decrease values that are fairly close to each other.

Erosion and Drainage Well Blowout in the Foundation of the Plavinas Powerhouse: Case History

The Plavinas run-off river scheme in Latvia is founded on fine-grained deposits with artesian aquifers. These aquifers are drained with free flowing wells to assure the stability of the structures. In March 1979, one of these wells suddenly discharged high amounts of solids together with the drainage water. After a few days the water discharge stopped, the artesian pressures in the foundation increased and dirty water flew from the bottom of the tailrace channel area. Foundation failure could be mitigated by turning piezometers into free flowing relief wells. However, it was a critical situation for the powerhouse and caused significant permanent displacements of the concrete structures. A root-cause analysis was performed which is presented in this paper. It was found that caverns at the interface of alluvial and fine-grained deposits formed due to erosion of the fine fractions of the alluvium through the drainage wells. Such a cavern collapsed which caused the well blowout and the plugging of the drainage well resulting in increasing pore water pressures and local liquefaction of the powerhouse foundation.

Statistical Downscaling of River Runoff in a Semi Arid Catchment

Linear and non-linear statistical ‘downscaling’ study is applied to relate large-scale climate information from a general circulation model (GCM) to local-scale river flows in west Iran. This study aims to investigate and evaluate the more promising downscaling techniques, and provides a through inter comparison study using Karkheh catchment as an experimental site in a semi arid region for the years of 2040 to 2069. A hybrid conceptual hydrological model was used in conjunction with modeled outcomes from a General Circulation Model (GCM), HadCM3, along with two downscaling techniques, Statistical Downscaling Model (SDSM) and Artificial Neural Network (ANN), to determine how future streamflow may change in a semi arid catchment. The results show that the choice of a downscaling algorithm having a significant impact on the streamflow estimations for a semi-arid catchment, which are mainly, influenced, respectively, by atmospheric precipitation and temperature projections. According to the SDSM and ANN projections, daily temperature will increase up to +0.58 0C (+3.90 %) and +0.48 0C (+3.48 %), and daily precipitation will decrease up to −0.1 mm (−2.56 %) and −0.4 mm (−2.82 %) respectively. Moreover streamflow changes corresponding to downscaled future projections presented a reduction in mean annual flow of −3.7 m^3/s and −9.47 m^3/s using SDSM and ANN outputs respectively. The results suggest a significant reduction of streamflow in both downscaling projections, particularly in winter. The discussion considers the performance of each statistical method for downscaling future flow at catchment scale as well as the relationship between atmospheric processes and flow variability and changes.

The role of groundwater outflow in the water cycle of a coastal lagoon sporadically opening to the ocean

Summary The water budget of a coastal lagoon, Oikamanai Lagoon, Hokkaido, Japan, sporadically opening to the Pacific Ocean, is estimated by establishing a bathymetric map of high accuracy (0.3 m depth interval), and by monitoring the meteorology, lagoon water level and river stage. The opening to the ocean is produced by incising the sand bar from the overflow and discharge of lagoon water at the lowest site of the sand bar. The overflow results from an increase of the lagoon water level basically by snowmelt or rainfall river runoffs. As a result, the drainage by the opening to the ocean caused the lagoon to decrease the water volume up to more than 96%. The estimate of the water budget at nearly constant water level under closed condition of the lagoon suggests that, as the net groundwater output from the lagoon, the confined groundwater outflow to the ocean across the sand bar prevails. The gravelly confined aquifer was inferred to be at the similar elevation with some thickness along the sand bar about 2000 m long. Meanwhile, during the regrowth of the sand bar at the outlet after the opening, the gravelly sediment first deposited near the sea level. Hence, the spatial distribution of the gravelly aquifer along the sand bar suggests that the whole sand bar was simultaneously broken in the past and then was grown up again.

Distribution and sources of organochlorine pesticides in sediments of the coastal East China Sea

Forty-two surface sediment samples collected from the southern coastal East China Sea (ECS) were analyzed for organochlorine pesticides (OCPs). The results showed high concentrations of DDTs and parent DDT fractions in the nearshore area, suggesting that there is still a fresh input of these species from non-point sources, probably due to the recent usage of relevant products. However, for HCHs, the high concentrations with elevated β-HCH fraction were focused at the local major river estuaries, indicating that soils-released HCH input was mainly from the major river runoffs. The distribution and composition of OCPs in the coastal ECS could be more prominently controlled by the direct regional inputs rather than the general natural sorption process on particulate organic carbon. DDTs and chlordane are more important for their potential ecotoxicological risk on neighboring benthic community in the nearshore region and the local major river estuaries.

Hydrologic Sensitivities of Colorado River Runoff to Changes in Precipitation and Temperature*

Abstract The Colorado River is the primary water source for much of the rapidly growing southwestern United States. Recent studies have projected reductions in Colorado River flows from less than 10% to almost 50% by midcentury because of climate change—a range that has clouded potential management responses. These differences in projections are attributable to variations in climate model projections but also to differing land surface model (LSM) sensitivities. This second contribution to uncertainty—specifically, variations in LSM runoff change with respect to precipitation (elasticities) and temperature (sensitivities)—are evaluated here through comparisons of multidecadal simulations from five commonly used LSMs (Catchment, Community Land Model, Noah, Sacramento Soil Moisture Accounting model, and Variable Infiltration Capacity model) all applied over the Colorado River basin at ⅛° latitude by longitude spatial resolution. The annual elasticity of modeled runoff (fractional change in annual runoff divided by fractional change in annual precipitation) at Lees Ferry ranges from two to six for the different LSMs. Elasticities generally are higher in lower precipitation and/or runoff regimes; hence, the highest values are for models biased low in runoff production, and the range of elasticities is reduced to two to three when adjusted to current runoff climatology. Annual temperature sensitivities (percent change in annual runoff per degree change in annual temperature) range from declines of 2% to as much as 9% per degree Celsius increase at Lees Ferry. For some LSMs, small areas, primarily at midelevation, have increasing runoff with increasing temperature; however, on a spatial basis, most sensitivities are negative.

Water quality monitoring in Basque coastal areas using local chlorophyll-<inline-formula><math display="inline" overflow="scroll"><mrow><mi>a</mi></mrow></math></inline-formula> algorithm and MERIS images

Accurate estimation of chlorophyll-a (chl-a), a proxy of the eutrophication risk, is necessary in coastal areas for the assessment of water quality in accordance with European Direc- tives. Local parameterization of remote sensing algorithms is useful to cope with the variability and specificity of optically-active in-water constituents. Using the Bay of Biscay coastal waters, affected by Basque river runoffs, as a case study, the objectives of this investigation are to: 1. develop an empirical algorithm to estimate water surface chl-a for the optically-complex Basque coastal waters; 2. explore the influence of suspended matter, phytoplankton species, and pigment content on the algorithm developed for medium resolution imaging spectrometer instrument (MERIS) imagery; 3. compare the local algorithm to three ocean color algorithms (OC4v6, Gitelson's algorithm, and the OC5); and 4. apply the local algorithm to the MERIS images. For this purpose, two surveys were undertaken within the study area, the Batel-1 survey in 2007, and the Batel-2, in 2009. The empirical algorithm was developed with remote sensing reflectances (Rrs), undertaken with a TriOS field spectrometer, and chl-a measured in situ from the Batel-2 survey. The algorithm was not affected by different concentrations of suspended matter in surface waters, within the range from 0.0 to 6.6 g · m −3 . There was no significant effect of 23 accessory pigments found in the area on the algorithm. Eighty-four Rrs and chl-a measure- ments from the Batel-1 survey were used to validate the local algorithm and to compare it with output of the other algorithms. The local algorithm provided the lowest root-mean-square differ- ence (RMS ¼ 1.7 mg · m −3 ), the best correlation with the observed data (R ¼ 0.8), together with the best slope-intercept combination between predicted and observed chl-a (slope ¼ 0.5, intercept ¼ 0.6). The chl-a algorithm developed here for MERIS imagery can assist in the assess- ment of water ecological status in the southeastern part of the Bay of Biscay, in a cost-effective manner. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). (DOI: 10.1117/ 1.JRS.6.063519)

Remote Sensing of Sea Surface Salinity From CAROLS L-Band Radiometer in the Gulf of Biscay

A renewal of interest for the radiometric L-band Sea Surface Salinity (SSS) remote sensing appeared in the 1990s and led to the Soil Moisture and Ocean Salinity (SMOS) satellite launched in November 2009 and to the Aquarius mission (launched in June 2011). However, due to low signal to noise ratio, retrieving SSS from L-band radiometry is very challenging. In order to validate and improve L-band radiative transfer model and salinity retrieval method used in SMOS data processing, the Cooperative Airborne Radiometer for Ocean and Land Studies (CAROLS) was developed. We analyze here a coastal flight (20 May 2009), in the Gulf of Biscay, characterized by strong SSS gradients (28 to 35 pss-78). Extensive in-situ measurements were gathered along the plane track. Brightness temperature (Tb) integrated over 800 ms correlates well with simulated Tb (correlation coefficients between 0.80 and 0.96; standard deviations of the difference of 0.2 K). Over the whole flight, the standard deviation of the difference between CAROLS and in-situ SSS is about 0.3 pss-78 more accurate than SSS fields derived from coastal numerical model or objective analysis. In the northern part of the flight, CAROLS and in-situ SSS agree. In the southern part, the best agreement is found when using only V-polarization measured at 30° incidence angle or when using a multiparameter retrieval assuming large error on Tb (suggesting the presence of biases on H-polarization). When compared to high-resolution model SSS, the CAROLS SSS underlines the high SSS temporal variability in river plume and on continental shelf border, and the importance of using realistic river run-offs for modeling coastal SSS.