High River Flow Research Articles

Modeling the Nestos River plume dynamics using ELCOM

Results from the first attempt to simulate the Nestos River plume using the three-dimensional nu merical model ELCOM are presented. The numerical model was validated using in-situ CTD data from three field campaigns taking place under variable discharge and meteorologic conditions. Results showed that the model predicted satisfactorily the surface expansion and the shape of Nestos river plume in all cases. The calculated versus observed salinity values showed significant correlations under high, moderate-high and low flow condition. The numerical model revealed that Nestos plume enters the Kavala Gulf only under high and intermediate river flow conditions, and only under favorable east and northeast winds. After validation, the model was used to examine plume behavior under four test cases of variable discharge and winds. These results illustrated that Nestos plume is mostly wind-driven, while river discharge is the key parameter responsible for transporting the plume away from the mouth. The plume directed mainly westwards throughout the year, under the influence of the general water circulation and the predominance of E–NE winds. Local coastal morphology such as the existence of the Thassos Passage also plays a significant role on the plume dispersion and movement.

Effects of hydrological forcing on the structure of a tropical estuarine food web

River flow can impact which sources of particulate organic matter (POM) fuel estuarine food webs. Here, we used stable carbon (C) and nitrogen (N) isotope analyses to compare how contributions of different POM sources (terrestrial, estuarine, and marine) to the diets of zooplankton and juvenile fishes differed between low and high river flow conditions, as well as spatially across a tropical estuary, Hilo Bay, Hawaii, USA. Diets of zooplankton and juvenile fishes were affected by river flow conditions, but the magnitude and the change in the basal resources depended on the location of the station in the estuary relative to the ocean and the river mouths. Consumers from the station most isolated from the ocean and with groundwater and overland flow inputs, utilized a combination of estuarine and terrestrial POM during both low and high river flow conditions and exhibited less variability in their basal resources than stations with direct ocean exchange. Consumers from stations in the Bay most affected by ocean exchange and river inputs utilized a combination of estuarine, terrestrial, and marine POM during low flow conditions, but shifted to marine and terrestrial POM during high river flow conditions. This shift to using terrestrial POM during high river flow conditions was substantial and up to 40% higher than values measured in other estuaries. Factors suspected to be affecting which POM source(s) consumers use in Hilo Bay are gross primary production, biological availability of exported terrestrial OM, and estuarine bacteria biomass, all of which are affected by river flow. Overall, our results suggest that Hilo Bay's food web and possibly those from other tropical estuaries are vulnerable to changes in hydrology, which may be further enhanced by global climate change.

Impact of climate change on the stream flow of the lower Brahmaputra: trends in high and low flows based on discharge-weighted ensemble modelling

Abstract. Climate change is likely to have significant effects on the hydrology. The Ganges-Brahmaputra river basin is one of the most vulnerable areas in the world as it is subject to the combined effects of glacier melt, extreme monsoon rainfall and sea level rise. To what extent climate change will impact river flow in the Brahmaputra basin is yet unclear, as climate model studies show ambiguous results. In this study we investigate the effect of climate change on both low and high flows of the lower Brahmaputra. We apply a novel method of discharge-weighted ensemble modeling using model outputs from a global hydrological models forced with 12 different global climate models (GCMs). Our analysis shows that only a limited number of GCMs are required to reconstruct observed discharge. Based on the GCM outputs and long-term records of observed flow at Bahadurabad station, our method results in a multi-model weighted ensemble of transient stream flow for the period 1961–2100. Using the constructed transients, we subsequently project future trends in low and high river flow. The analysis shows that extreme low flow conditions are likely to occur less frequent in the future. However a very strong increase in peak flows is projected, which may, in combination with projected sea level change, have devastating effects for Bangladesh. The methods presented in this study are more widely applicable, in that existing multi-model streamflow simulations from global hydrological models can be weighted against observed streamflow data to assess at first order the effects of climate change for specific river basins.

Developing indicators to detect changes in the seasonality, frequency and duration of medium and high river flows

AbstractIndicators specifically designed to detect changes in the seasonality, frequency and duration of medium and high river flows have been developed to monitor river flow regimes. Four primary methods to display and interpret the indicator results have been developed to meet the needs of different target audiences. The variability in annual indicator values is accommodated by comparing the probability distributions of the annual values rather than seeking to identify trends in annual values themselves. Changes in the distribution of indicator values are consistent with those anticipated to arise as a result of climate change. This finding is confirmed by calculating the indicators from example flow data for catchments across England and Wales, which has been perturbed to reflect climate change scenario model outputs.

SEASONAL PATTERNS OF RIVER CONNECTIVITY AND SALTWATER INTRUSION IN TIDAL FRESHWATER FORESTED WETLANDS

ABSTRACTHydrology can be difficult to interpret in tidal freshwater forested wetlands because of several influencing factors including river discharge, tidal stage, local precipitation, evapotranspiration, groundwater and prevailing winds. River discharge and tidal stage are considered the primary factors affecting these wetlands and both vary on a seasonal basis and have potential implications for wetland saltwater intrusion. We examined the hydrologic patterns of tidal freshwater swamps along the lower reach (20 km) of the Apalachicola River system in northwest Florida, USA. Water level recorders were installed in five wetlands along this reach and recorded ground and surface water levels at 15‐min intervals from December 2006 to April 2009 (non‐continuously). Seasonal trends related to flooding frequency and duration were compared to long term (2000–2008) records of creek and river salinities measured in the tidal freshwater forested zone. Tidal freshwater swamps tended to maintain a narrow water level range (often ±20 cm of the ground surface) except during high river flows (>680 cms or 24 000 cfs) when levels increased 1 to 2 m above ground and dampened tidal effects. All tidal forested wetlands had the highest mean water levels and most days tidally pulsed during the Jul–Oct season which coincided with peak river/creek salinities and low river‐flows associated with drought conditions. We explored the implications for the timing of salt water intrusion in these swamps and potential changes related to sea level rise and water management in the Apalachicola River drainage basin. Copyright © 2011 John Wiley & Sons, Ltd.

Spatio-temporal variations in macrozoobenthic assemblage structures in a river-affected lagoon (Idoura Lagoon, Sendai Bay, Japan): Influences of freshwater inflow

Spatio-temporal changes in macrozoobenthic assemblage structure were monitored at 8 stations in a river-affected temperate lagoon (Idoura Lagoon, Japan) from May 1997 to May 1998 to assess animal–environment relationships in estuarine soft-bottom habitats. A total of 29 taxa occurred with a predominance of a few polychaete species including Heteromastus cf. similis, Hediste spp., Pseudopolydora cf. kempi and Prionospio japonica. The community structure differed significantly among four habitat types that were characterized by different salinity, sediment characteristics, and/or bottom elevation. For each habitat, macrozoobenthic community structure changed significantly with time, which was discriminated mostly by the lower density of polyhaline opportunistic species such as P. cf. kempi in warmer period. The salinity in the study area was much lower from May to September, mainly due to irrigation discharge from paddy fields, which seemed to be a lethal factor for the polyhaline species. C/N ratio and δ 13C value of the sediment implied the accumulation of river-derived organic matters during the high river flow period. Present results showed the significant effects of fluctuating river discharge on the estuarine soft-bottom habitats, suggesting a linkage among terrestrial, riverine and estuarine ecosystems.

Polybrominated diphenyl ethers in sediments of the Daliao River Estuary, China: Levels, distribution and their influencing factors

The concentrations, compositional profiles, possible sources of polybrominated diphenyl ethers (PBDEs) in sediments of the Daliao River Estuary as well as the factors influencing the distribution of PBDEs were investigated. The total concentrations of PBDEs ranged from 0.13 to 1.98 ng g −1 d.w. BDE209 was the dominating congener in all sediment samples, indicating the pollution of PBDEs in the Daliao River Estuary mainly came from the use of deca-BDE commercial mixtures. The intrusion of sea waters promoted the deposition of the colloid-associated PBDEs in the estuary. There were significantly negative correlations between PBDE concentration in sediment with pH value and salinity in the bottom water. The higher river flow in the flood season (summer) obviously accelerated the transport of PBDEs, and thereby increased the risk of PBDE contamination to the deep ocean. Moreover, a positive correlation between TOC and PBDE distributions was observed, suggesting that TOC regulated the distributions of PBDEs in sediments of Daliao River Estuary.

RIVERINE ESTUARY CLASSIFICATION FOR THE SAKE OF ENVIRONMENTAL CONSERVATION

The environment of riverine estuaries is characterized by many factors including tidal oscillation, river flow and morphology, and the combination of these factors makes each estuary unique in its environment. However, there are similarities among some estuaries. We have tried to classify Japan’s 109 riverine estuaries based on physical environmental factors like tidal oscillation, wave energy, and high and low river flow. 109 riverine estuaries were divided into 5 classifications. Fish species monitoring data have also been analyzed to categorize riverine estuaries and the results were compared to 5 classifications divided by physical factors. Since our physical and biological classification both seemed to be related to the salinity of the estuary, these two classifications showed fair conformity.

Multiple-source heterotrophy fueled by aged organic carbon in an urbanized estuary

The lower Hudson River is a highly urbanized estuary that receives large inputs of treated wastewater. To determine how organic matter from wastewater influences carbon cycling in this type of system, we measured chlorophyll a, pCO 2, dissolved organic carbon (DOC), δ 13C-DOC, and Δ 14C-DOC along the salinity gradient and at wastewater treatment plants. Isotopic mixing curves indicate a net removal of DOC that is 13C enriched and 14C depleted. The amount of DOC removed was consistent with CO 2 evasion from the estuary. During two transects at average to low flow, the lower Hudson River Estuary was a heterotrophic system with CO 2 evasion balanced by the utilization of aged DOC derived from wastewater and marine phytoplankton that enter the estuary at the seaward end-member. DOC removals were largest during a period of high river flow, when isotopic mixing curves also suggest large contributions from labile terrestrial OC sources. Overall, our results suggest that net heterotrophy in the lower Hudson River Estuary is fueled by aged labile DOC derived from a combination of sources, which are influenced by seasonal phytoplankton blooms, hydrological conditions, and the nature of wastewater inputs.

The Shaping of An Estuarine Superfund Site: Roles of Evolving Dynamics and Geomorphology

Analysis of moored and shipboard hydrographic data along with suspended sediment data is used to provide the first comprehensive description of the dynamics and sediment transport processes of the Passaic River. The river has been highly depositional since dredging ceased in the 1940s and within this sedimentary record are high levels of contaminants including high levels of dioxins. Moored current meter data indicates that during low freshwater discharge both tidal period and residual flows favor a landward sediment flux. In contrast during moderate to high river flows the salt field is washed out of the system and results in a net downstream sediment flux that overcome the more persistent but weaker upstream flux during low river flow conditions. Consequently, with today’s channel morphology the Passaic exports sediment to Newark Bay that we estimate is approximately equal the annual loadings. This, together with historical bathymetric surveys, suggests that the channel is approaching geomorphological equilibrium. Bathymetric changes in the Passaic River over the past 60 years have significantly altered the river's ability to trap sediments and contaminants and are consistent with the fact that most of the dioxins released to the river in previous decades appear to be trapped within the channel, despite the fact that they were released within a tidal excursion of the mouth. The decline in trapping efficiency is also consistent with a simple scaling analysis that suggests that the salt water intrusion length, and thus the ability to trap sediment, scales with the cube of the channel depth. Consequently, as the estuary shoaled its ability to trap sediments and contaminants diminished rapidly.

Estimation of local extreme suspended sediment concentrations in California Rivers

The total amount of suspended sediment load carried by a stream during a year is usually transported during one or several extreme events related to high river flow and intense rainfall, leading to very high suspended sediment concentrations (SSCs). In this study quantiles of SSC derived from annual maximums and the 99th percentile of SSC series are considered to be estimated locally in a site-specific approach using regional information. Analyses of relationships between physiographic characteristics and the selected indicators were undertaken using the localities of 5-km radius draining of each sampling site. Multiple regression models were built to test the regional estimation for these indicators of suspended sediment transport. To assess the accuracy of the estimates, a Jack-Knife re-sampling procedure was used to compute the relative bias and root mean square error of the models. Results show that for the 19 stations considered in California, the extreme SSCs can be estimated with 40–60% uncertainty, depending on the presence of flow regulation in the basin. This modelling approach is likely to prove functional in other Mediterranean climate watersheds since they appear useful in California, where geologic, climatic, physiographic, and land-use conditions are highly variable.

Recent Concerns about the Environment in Bangladesh

Bangladesh is one of the poorest countries in the world and is affected by natural disasters, pollution and a range of public health hazards. The country's main environmental constraints are its susceptibility to seasonal flooding, inadequate sanitation and its limited infrastructure for wastewater management. Conversion of the Sundarbans to shrimp ponds and rice paddies has reduced the protection provided by this coastal strip. This, along with sedimentation in the western delta region, has increased the flood risk. High river flow rates during the monsoon in the centre and east of the Bay of Bengal are a threat to human and animal safety. Difficulties with installing and maintaining sanitation networks in flood-prone regions are causing pollution problems, and this has become more evident from recent reports about antibiotic-resistant strains of enteric pathogens in coastal shrimps and prawns. Pollution with sewage and wastewaters from the shrimp farming and leather industries are contributing to poor water quality in the rivers and delta. Difficulties in achieving immediate and adequate surveillance during the 2007 avian influenza outbreak may have compromised control standards for this disease. This article gives an overview of these and other environmental and health issues affecting the country.

Concentration-dependent Stable Isotope Analysis of Consumers in the Upper Reaches of a Freshwater-dominated Estuary: Apalachicola Bay, FL, USA

The goals of this study were to quantify organic matter source utilization by consumers in the freshwater-dominated region (East Bay) of a high river flow estuary and compare the results to consumers in marine-influenced sites of the same estuary to understand how organic matter utilization by consumers may be changing along the salinity gradient. We used the results from these evaluations to establish the baseline against which we isotopically determined trophic level for consumers in East Bay. Average isotope values for consumers sampled in East Bay ranged from −20.1‰ to −24.8‰ for carbon and from 8.9‰ to 14.3‰ for sulfur. These values were well-constrained by the four identified sources: plankton, benthic organic matter, macroalgae, and terrestrial detritus. Application of a concentration-corrected mixing model resulted in contributions of benthic production and detrital sources (averaged over the food web) to East Bay consumers of 41% and 33%, respectively, with the remainder made up of plankton and benthic macroalage. While benthic organic matter was an important organic matter source for consumers at both sites, we found that the influence of terrestrial detritus varied significantly throughout the bay. Terrestrial detritus contributed only 18% of average total organic matter in organisms inhabiting marine-influenced sites. Although terrestrial detritus did contribute to all consumers examined, most fish species in Apalachicola Bay reflect a greater reliance on autochthonous sources. Our results suggest that, while terrestrial detritus does appear to be a major contributor to commercially important shellfish species (most notably oysters and penaeid shrimp), it is not the major source fueling the diversity of secondary production in Apalachicola Bay. Thus, production in Apalachicola Bay is highly dependent on riverine influx in two ways: (1) economically important bivalves and crustaceans are being fueled by terrestrial organic matter supplied by river flooding and (2) secondary and above consumer fish species are supported by in situ production which, in turn, is reliant on nutrients supplied by the Apalachicola River. These findings are significant in light of decisions regarding water usage and river flow restrictions in the Apalachicola-Chattahoochee-Flint drainage basin. The results of this study confirm that in situ estuarine organic matter is the dominant source supporting secondary production in this river-dominated estuary.

Simulating property exchange in estuarine ecosystem models at ecologically appropriate scales

A computational scheme has been developed and tested to simulate property exchange by advection and dispersion in estuaries at time and space scales that are well suited to ecological and management simulations, but are coarse relative to the demands of physical hydrodynamic models. An implementation of the Regional Ocean Model System (ROMS) for the Providence River and Narragansett Bay (RI, USA) was used to determine property exchanges between the spatial elements of an ecological box model. The basis for the method is the statistical tabulation of numerical dye experiments done with the full ROMS physical model. The ROMS model domain was subdivided into fifteen coarse boxes, each with two vertical layers, defining 30 elements that were used for the box model simulations. Dye concentrations were set to arbitrary initial concentrations for all ROMS grids in the large elements, and the ROMS model was run for 24 h. The final distribution of the dye among the elements was used as a tracer for property exchange over that day and was used to develop an exchange matrix. Box model predictions of salinity over 77 days in each element compared favorably with ROMS simulated salinity averaged over the same spatial elements, although the disparity was greater in areas where large river inflows caused strong gradients in ROMS within elements assumed to be homogeneous in the box model. The 77-day simulation included periods of high and low river flow. Despite the large size of the spatial elements, dispersion artifacts were small, much less than the modeled daily exchanges. While others have taken a similar approach, we found a number of theoretical and practical considerations deserved careful attention for this approach to perform satisfactorily. Whereas the full ROMS model takes 9 days on a powerful computing cluster to compute the physics simulation for 77 days, the box model simulates physics and biology for the same interval in 5 s on a personal computer, and a full year in under 1 min. The exchange matrix mixing model is a fast, cost effective, and convenient way to simulate daily variation of complex estuarine physics in ecological modeling at appropriate scales of space and time.

Leachable particulate iron in the Columbia River, estuary, and near-field plume

This study examines the distribution of leachable particulate iron (Fe) in the Columbia River, estuary, and near-field plume. Surface samples were collected during late spring and summer of 2004–2006 as part of four River Influence on Shelf Ecosystems (RISE) cruises. Tidal amplitude and river flow are the primary factors influencing the estuary leachable particulate Fe concentrations, with greater values during high flow and/or spring tides. Near the mouth of the estuary, leachable particulate Fe [defined as the particulate Fe solubilized with a 25% acetic acid (pH 2) leach containing a weak reducing agent to reduce Fe oxyhydroxides and a short heating step to access intracellular Fe] averaged 770 nM during either spring tide or high flow, compared to 320 nM during neap tide, low flow conditions. In the near-field Columbia River plume, elevated leachable particulate Fe concentrations occur during spring tides and/or higher river flow, with resuspended shelf sediment as an additional source to the plume during periods of coastal upwelling and spring tides. Near-field plume concentrations of leachable particulate Fe (at a salinity of 20) averaged 660 nM during either spring tide or high flow, compared to 300 nM during neap tide, low flow conditions. Regardless of tidal amplitude and river flow, leachable particulate Fe concentrations in both the river/estuary and near-field plume are consistently one to two orders of magnitude greater than dissolved Fe concentrations. The Columbia River is an important source of reactive Fe to the productive coastal waters off Oregon and Washington, and leachable particulate Fe is available for solubilization following biological drawdown of the dissolved phase. Elevated leachable Fe concentrations allow coastal waters influenced by the Columbia River plume to remain Fe-replete and support phytoplankton production during the spring and summer seasons.

Surface fCO 2 variability in the Loire plume and adjacent shelf waters: High spatio-temporal resolution study using ships of opportunity

The seasonal and spatial variability of CO 2 uptake across the Loire estuary plume and the adjacent continental shelf was investigated over two years (November 2002 to December 2004). A high-frequency time series of the surface CO 2 fugacity (fCO 2 sw) and the air–water CO 2 exchange is reported and discussed. Continuous measurements of salinity, temperature, fCO 2 sw, dissolved oxygen (O 2) and Chl a were performed, on a commercial route between Vigo (Spain) and St. Nazaire (France). A significant biogeochemical gradient was observed along this hydro-geographical continuum, in both space and time. The inner shelf was influenced by river/estuarine inputs which were enriched in CO 2 and by the relative aerial coverage of the resultant plume in coastal areas. This region was typically oversaturated with CO 2 except when favourable conditions for phytoplankton blooms were created by the availability of light, the inputs of riverine nutrients and the haline stratification of the water column. On an annual scale, the non-thermodynamic processes (biological, riverine inputs, etc.) exerted a greater control on the pattern of CO 2 flux in the inner shelf than thermodynamic changes in temperature and salinity. The biogeochemical imprint of the Loire River was noticeable in the mid-shelf during high river flow events and favourable winds, but any signal was almost negligible in the outer shelf, where temperature was the main mechanism controlling the seasonal variability of the fCO 2 sw. During the two-year study period, the estimated air–water CO 2 flux was − 5.2 mmol m − 2 day − 1 and − 7.5 mmol m − 2 day − 1 , in the middle and outer shelves respectively.

Propagule input, transport and deposition in riparian environments: the importance of connectivity for diversity

AbstractQuestion: How important is hydrochory for dispersing propagules along riverbanks and to what extent do the quantity and species composition of deposited propagules reflect the riparian vegetation, represent “new” species that are not present in the vegetation, and vary with river flow and season?Location: River Frome, Dorset, UK.Methods: Over 13 consecutive 6‐week time periods, during which river water levels were continuously monitored, aerial inputs of propagules to riverbanks were sampled using funnels, hydrochorous propagule transport was sampled using drift nets, and deposition across the riverbanks was sampled using astroturf mats. A survey of the riparian vegetation enabled comparison between samples and the standing vegetation, so that “new” species could be identified. Differences in propagule abundance and diversity between sampling methods, time periods and locations were tested using Mann‐Whitney U‐tests and Kruskall‐Wallis ANOVA. DCA established contrasts in the floristic composition of all deposited propagules and “new” propagules between different sample types, time periods and locations.Results: Aerial seed fall generated few propagules of low species richness. Hydrochory introduced large numbers of propagules and new species, resulting in high propagule deposition on the riverbank. The number and diversity of deposited propagules was governed by seasonal patterns of seed release and the hydrological regime. Propagule deposition was significantly greater on the most frequently inundated parts of the riverbank and autumn floods were particularly important for transporting “new” species to the study site and for remobilizing previously released propagules.Conclusions: The abundance and diversity of propagules deposited along riverbanks is dependent upon high river flows, which facilitates connectivity between the channel and the riparian zone.

Characterization of time and spatial scales of a migrating rivermouth

By analysis of a unique and extensive photographic and written record spanning several decades, we characterized the spatial and temporal scales of morphological adjustment of the inlet of the Russian River Estuary, on the California coast. We paired this record with in situ measurements of beach features to create a dataset consisting of daily values of inlet width, length, shape, and position for the period of 1991–2006. Available wave, tide, and river flow data were compared with these measurements. We show that the spatial and temporal scales associated with adjustments in inlet geometry and position are dictated by different mechanisms during periods of high and low river flow and also vary with periods of large‐scale climate oscillations. Our analysis of inlet shape reveals that several classes of inlet curvature correspond to unique flow, geometry, and risk of closure conditions.

A conceptual model of the strongly tidal Columbia River plume

The Columbia River plume is typical of large-scale, high discharge, mid-latitude plumes. In the absence of strong upwelling winds, freshwater from the river executes a rightward turn and forms an anticyclonic bulge before moving north along the Washington coast. In addition to the above dynamics, however, the river plume outflow is subject to large tides, which modify the structure of the plume in the region near the river mouth. Observations based on data acquired during a summer 2005 cruise indicate that the plume consists of four distinct water masses; source water at the lift-off point, and the tidal, re-circulating and far-field plumes. In contrast to most plume models that describe the discharge of low-salinity estuary water into ambient high-salinity coastal water, we describe the Columbia plume as the superposition of these four plume types. We focus primarily on a conceptual summary of the dynamics and mutual interaction of the tidal and re-circulating plumes. The new tidal plume flows over top of the re-circulating plume and is typically bounded by strong fronts. Soon after the end of ebb tide, it covers roughly 50–100% of the re-circulating plume surface area. The fronts may penetrate well below the re-circulating plume water and eventually spawn internal waves that mix the re-circulating plume further. The re-circulating plume persists throughout the tidal cycle and corresponds to a freshwater volume equivalent to 3–4 days of river discharge. Finally, the plume water masses are distinguished from one another in term of surface chlorophyll concentration, suggesting that the above classification may also describe different biological growth regimes. The low-salinity re-circulating plume serves as an extension of the estuary into the coastal ocean, or an “estuary at sea”, because residence times during periods of high river flow are greater than those in the estuary.

Genetic modeling for the optimal forecasting of hydrologic time-series: Application in Nestos River

Summary River flow forecasting consists one of the most important applications in modern hydrology, especially for the effective hydropower reservoir management. In this paper, an innovative non-linear time-series fitting and forecasting model is proposed, consisting of the following sub-modules: (a) the division of the time-series into generations, by identifying the structural change points, (b) the generation decomposition into linear trend, harmonic component and autoregressive component, consisting of several gene ARMA models, (c) the use of fuzzy methods to determine the relative weight of each gene model, and (d) the time-series expansion for the optimal forecasting. The method was applied to the mean monthly Nestos River discharge data for the 1966–2006 period, recorded at the Greek–Bulgarian border, serving as inflow to the Thissavros Hydropower Reservoir. The selected series was divided into five distinctive generations representing periods of gradual surface runoff reduction. It occurred that mean monthly discharge during the fifth generation was almost halved, compared to the corresponding value of the first generation. Harmonic decomposition produced periods in agreement with the large-scale atmospheric fluctuations, while ARIMA modeling performed on the residuals from a pre-defined gene model-base, produced satisfactory fitting to the measured flow series. Model expansion for the last 2 years (2005–2006) of the time-series illustrated reasonable good approximations. Model forecasts during 2005 followed closely the recorded variability, with MAPE and RMSE statistics indicating increased model accuracy. Overall, it is evident that the model slightly underpredicts Nestos River discharge, while slight overestimation occurs under high river flow conditions (winter 2006). Although current research proved model’s distinct capability and advantages in river flow fitting and medium-scale forecast, future improvement could facilitate the use of more elaborative models (ARCH, fuzzy, ANN), in the developed gene model-base.