Coastal River Basins Research Articles

PAHs and PCBs deposited in surficial sediments along a rural to urban transect in a Mid-Atlantic coastal river basin (USA)

PAHs and PCBs were measured in river sediments along a 226 km longitudinal transect that spanned rural to urban land use settings through Valley and Ridge, Piedmont Plateau and Coastal Plain physiographic provinces in the Potomac River basin (mid-Atlantic USA). A gradient in PAH concentrations was found in river bed sediments along the upstream transect in the Potomac and Shenandoah Rivers that correlated with population densities in the nearby sub-basins. Sediment PAH concentrations halved per each ∼40 km of transect distance upstream (i.e., the half-concentration distance) from the urban center (Washington, DC) of the Potomac River basin in direct proportion to population density. The PAH molecular composition was consistent across all geologic provinces, revealing a dominant pyrogenic source. Fluoranthene to perylene ratios served as useful markers for urban inputs, with a ratio > 2.4 observed in sediments near urban structures such as roadways, bridges and sewer outfalls. PCBs in sediments were not well correlated with population densities along the river basin transect, but the highest concentrations were found in the urban Coastal Plain region near Washington, DC and in the Shenandoah River near a known industrial Superfund site. PAHs were moderately correlated with sediment total organic carbon (TOC) in the Shenandoah River and Coastal Plain Potomac River regions, but TOC was poorly correlated with PCB concentrations throughout the entire basin. Although both PAHs and PCBs are widely recognized as urban-derived contaminants, their concentration profiles and geochemistry in river sediments were uniquely different throughout the upper Potomac River basin.

Probable Flood Predictions in Ungauged Coastal Basins of El Salvador

A regionalization procedure is presented and used to predict probable flooding in four ungauged coastal river basins of El Salvador: Paz, Jiboa, Grande de San Miguel, and Goascoran. The flood-prediction problem is sequentially solved for two regions: upstream mountains and downstream alluvial plains. In the upstream mountains, a set of rainfall-runoff parameter values and recurrent peak-flow discharge hydrographs are simultaneously estimated for 20 tributary-basin models. Application of dissimilarity equations among tributary basins (soft prior information) permitted development of a parsimonious parameter structure subject to information content in the recurrent peak-flow discharge values derived using regression equations based on measurements recorded outside the ungauged study basins. The estimated joint set of parameter values formed the basis from which probable minimum and maximum peak-flow discharge limits were then estimated revealing that prediction uncertainty increases with basin size. In the ...

Regularized joint inverse estimation of extreme rainfall amounts in ungauged coastal basins of El Salvador

A regularized joint inverse procedure is presented and used to estimate the magnitude of extreme rainfall events in ungauged coastal river basins of El Salvador: Paz, Jiboa, Grande de San Miguel, and Goascoran. Since streamflow measurements reflect temporal and spatial rainfall information, peak-flow discharge is hypothesized to represent a similarity measure suitable for regionalization. To test this hypothesis, peak-flow discharge values determined from streamflow recurrence information (10-year, 25-year, and 100-year) collected outside the study basins are used to develop regional (country-wide) regression equations. Peak-flow discharge derived from these equations together with preferred spatial parameter relations as soft prior information are used to constrain the simultaneous calibration of 20 tributary basin models. The nonlinear range of uncertainty in estimated parameter values (1 curve number and 3 recurrent rainfall amounts for each model) is determined using an inverse calibration-constrained Monte Carlo approach. Cumulative probability distributions for rainfall amounts indicate differences among basins for a given return period and an increase in magnitude and range among basins with increasing return interval. Comparison of the estimated median rainfall amounts for all return periods were reasonable but larger (3.2–26%) than rainfall estimates computed using the frequency-duration (traditional) approach and individual rain gauge data. The observed 25-year recurrence rainfall amount at La Hachadura in the Paz River basin during Hurricane Mitch (1998) is similar in value to, but outside and slightly less than, the estimated rainfall confidence limits. The similarity in joint inverse and traditionally computed rainfall events, however, suggests that the rainfall observation may likely be due to under-catch and not model bias.

A SRES-based gridded global population dataset for 1990–2100

Spatially explicit population data can play an important role in studies on environment and sustainability. Several gridded datasets on the present population exist, but global data on future populations are largely lacking. This paper presents a dataset covering three global population forecasts for the period 1990–2100 at 0.5-degrees resolution. The basis for these forecasts is the SRES scenarios developed for the IPCC climate-modeling framework. In addition, a gridded dataset of urban and rural populations for the period 1990–2050 is presented. To illustrate how the datasets can be used, future changes in population density and urbanization were analyzed for some of the world’s major river basins. This analysis shows that the population density in the Ganges basin, which is already very high, is likely to increase considerably. The highest future increase rates were found in some African and Middle-Eastern basins. The population dataset for 2015 was compared with one previously published gridded dataset. The comparison shows some differences in population density, mainly in small, highly urbanized coastal river basins, while for large basins, the two datasets agree fairly well. We hope that the datasets here presented will prove to be a useful resource also for other researchers of global environmental change and sustainable development.

A new Scleromystax species (Siluriformes: Callichthyidae) from coastal rivers of southern Brazil

The recently resurrected callichthyid catfish genus Scleromystax includes species occurring in several Brazilian coastal river basins from southern Bahia to southern Santa Catarina. Several character states, especially those related to sexual dimorphism, demonstrate the monophyly of Scleromystax. Examination of Scleromystax specimens sampled from streams in the Ilha de Santa Catarina and Nova Veneza, and the rio Mampituba basin, Santa Catarina and Rio Grande do Sul States, revealed that they constitute a new taxon, and thus the southernmost record for the genus. Scleromystax salmacis, new species, has coloration similar to that of S. macropterus, differing from that species mainly by the absence of a black spot on the base of the median caudal-fin rays, and transverse blotches along the body more irregular than those in S. macropterus. In addition to differences in coloration and external and osteological characters, the new species differs from S. barbatus and S. prionotos by its more rounded snout. The new taxon is also distinguished from its congeners by the presence of a single perforated dorsolateral body plate, similar to the condition found in some Aspidoras species, orientation of the ventral keel of the scapulocoracoid, and by the absence of sexually dimorphic features.

Hoplosternum littorale (Teleostei, Callichthyidae) from a Coastal River basin in Brazil - Cytogenetic analysis and gene mapping of 5S and 18S rDNA

Abstract Cytogenetic studies were carried out in a population of Hoplosternum littorale from a coastal river basin in the southeastern region of Brazil. The results were identical to those of all populations already described for this species, involving the maintenance of karyotype macrostructure and the distribution pattern of heterochromatin, as well as its composition. The report on localization of ribosomal genes is new for this species. The diploid number observed was 2n=60 chromosomes (6M+2SM+52A) for both sexes. A single pair of acrocentric chromosomes bearing rDNA sites on the short arms was identified, both by silver nitrate staining and by FISH (Fluorescent in situ hybridization) with an 18S rDNA probe. Four 5S rDNA clusters were identified using FISH methodology. C-banding revealed a great amount of heterochromatin blocks, present in most chromosomes, preferentially located in subter-minal and interstitial regions. Four GC-rich regions were identified by chromomycin A3 staining. The data are di...

Assessment of water protection targets for agricultural nutrient loading in Finland

Temporal changes in observed P and N losses were studied in agricultural catchments in order to evaluate the achievement of water protection targets in Finland. Agriculture comprises the largest single source of nutrients into surface waters in Finland. Today, the main goal of water protection policy is controlling agricultural nutrient losses. In 1998, the Finnish Council of State issued a Decision-in-Principle on the water protection targets to 2005. By the year 2005, P and N loads from field cultivation should be reduced by 50% from the estimated loads at the beginning of the 1990s. The Finnish Agri-Environmental Programme (FAEP) forms the most important policy measure. It was implemented when Finland joined the European Union in 1995. The implementation of the Water Framework Directive will be reflected in the future environmental support scheme. The aim of this study was to investigate whether the water protection measures have decreased P and N losses in two small, intensively monitored agricultural catchments and in four coastal river basins in southern Finland. Due to high annual variability in observed losses, long-term monitoring data (years 1981–2000) of water quality were used in the analysis. Five year mean values of annual total P and total N loads were calculated for each of the catchments. The results showed that little or no reduction of loads was achieved during the first period (years 1995–1999) of the FAEP in the studied catchments. The results suggest that water protection measures for agricultural production need to be further intensified if the eutrophication tendency of Finnish lakes, rivers and coastal waters is soon to be reversed. The delayed response of water quality must be taken into account in the implementation of the Water Framework Directive.

Integrated coastal zone and river basin management: a review of the literature, concepts and trends for decision makers

River management has frequently been associated with water supply and resource management, whereas coastal zone management has been more concerned with marine resource management and physical planning. Recognizing the close connection between the river and its catchment area has led to a more integrated approach to river basin management, taking into account water quality along with quantity. Similarly, recognition of the importance of integrated management of the coastal zone as a move towards achieving sustainable development, has led to integrated coastal zone management, with expansion of the domain in both landward and seaward directions. Considering the intrinsic link through physical and ecological structure as well as related physical and biological processes, any modification in a river basin will ultimately affect the coastal zone. Land-based activities, rivers, estuaries, coastal zones and marine environments are all inherently interlinked. As such, an integrated approach to the concomitant management of coastal zones and river basins is crucial. This paper provides an overview of various concepts, approaches and strategies to integrated coastal zone and river basin management. It points out lessons that could be learned from previous and ongoing projects. The paper provides a starting point for investigating how changes in land use and management of river basins might have an impact on the quality of river water and the corresponding coastal zone through scrutinization of management tools and implementation instruments. The paper identifies a requirement further to develop tools which will assist in evaluating current and future environmental conditions at a river/estuary/sea interface within a rigorous framework.

River catchment?coastal sea interaction and human dimensions

The regional or local perspective of coastal change becomes increasingly important when coastal people are recognised as an integral part of the system. As pointed out in this journal (Cramer 2002), the key to improved interdisciplinary science of global change is not only to provide answers to the crucial Earth-system questions at a global scale. We also need to identify meaningful ways to look at the human environment and its changes at scales that are appropriate to identify choke and switch points for system functions, and where institutional settings enable action to be taken as a societal and policy response. For coastal zones, three major challenges need to be met by an appropriate and flexible scientific approach to this problem (cf. Kremer et al. 2002). First, the time delay between changes in land-based material flows (due to socioeconomic activities, morphological changes or regulatory measures) and their impact on the coastal zone system must be determined. Second, the complexity of the coastal sea environments needs to be investigated in order to derive assessments of ‘critical loads’. Third, multiple interests and stakeholder needs must be studied, as they are affected by transboundary issues, particularly when local, regional, national and multinational governmental bodies have conflicting interests. The Land-Ocean Interactions in the Coastal Zone (LOICZ) core project of the International Geosphere and Biosphere Program (IGBP), after 10 years of collaborative global research, has made an effort to follow this direction. Its ‘Basins project’ (http://w3g.gkss.de/projects/loicz_basins/) has, since 1999, tried to provide a first-order global assessment of key land-based processes that affect coastal zones. Regional scientific networks have been established to look at the drivers, pressures, state changes and the impact on coastal systems by applying a scale that considers the catchments and coasts as a single interrelated system: the water continuum. The relevance of this scale had been highlighted by Meybeck (1998, 2003) to emphasise the multiple boundaries and processes through which land-based drivers affect the water cycle and the global coastal ocean. However, regional expert typologies of this ‘river dimension’ of coastal change and subsequent upscaling to subregional and continental scales, as performed in the Basins project, had been lacking. Recently, policy and global assessment efforts hosted by, for example, UN Programmes such as UNEP and UNESCO, have adopted this approach to programs such as the Integrated Coastal Area and River basin Management (ICARM) initiative under the Global Program of Action for the Protection of the Marine Environment from Landbased Activities (GPA), and to efforts that deal with global monitoring in coastal zones, e.g., Coastal GOOS (Global Oceans Observing System). Coastal themes are under development for initiatives that deal with regular Earth Observation such as IGOS, and practical management has recognized the catchment scale of coastal change in some of the most recently launched regional ‘institutions’, i.e. the European Water Framework Directive (Directive 2000/ 60/EC, L 327/1 Brussels, 23 Oct. 2000 and Ledoux et al. 2004) and the EU recommendations concerning the implementation of Integrated Coastal Zone Management in Europe (2002/413/EC, L 148/24, Brussels 30 May 2002). Recent research reflects the relevance of the water-continuum scale for integrated modeling and forecasting, and also for policy advice. Examples are projects such as the EU-funded EuroCat (http://www.iia-cnr.unical.it/EUROCAT/project.htm), daNUbs (http://danubs.tuwien.ac.at/) and Catchment2Coast (http://www.catchment2coast.org/), which study coastal change in a regional perspective in Europe and Africa. The ‘New’ LOICZ, mandated to provide an integrated view on coastal systems and human-initiated-change issues to the Earth System Sciences in the coming decade (2003–2012), has given the water-continuum scale of coastal change a priority position among the themes that will guide its scientific agendas in the future (see the ‘New’ LOICZ draft Science Plan and Implementation Strategy and subsequent information under http:// www.loicz.org). Its ‘‘Anthropogenic influences on river basin and coastal zone interactions’’ theme, as well as the other three themes (Fig. 1), will contribute to the key question on ‘‘what determines the vulnerability of coastal systems and human safety’’ all of them being embedded in Published online: 17 February 2004 a Springer-Verlag 2004

The influence of hatchery coho salmon (Oncorhynchus kisutch) on the productivity of wild coho salmon populations in Oregon coastal basins

To aid in the recovery of depressed wild salmon populations, the operation of hatcheries must be changed to reduce interactions of juvenile hatchery fish with wild fish. Evidence suggests that productivity of wild populations can be reduced by the presence of large numbers of hatchery smolts in lower rivers and estuaries that attract predators. An index of productivity based on the density-independent rate of reproduction of wild coho salmon (Oncorhynchus kisutch) in 12 Oregon coastal river basins and two lake basins was negatively correlated with the average number of hatchery coho salmon smolts released in each basin. The index of productivity was not significantly correlated with the average proportion of hatchery coho salmon in each naturally spawning population or with habitat quality. Alterations to hatchery programs that could encourage recovery of wild populations include (i) avoiding release of large numbers of smolts in areas with high concentrations of wild fish, (ii) decreasing the number of smolts released, and (iii) using a volitional release strategy or a strategy that employs smaller release groups spread temporally.

Optimal Crop Planning and Conjunctive Use of Water Resources in a Coastal River Basin

Due to increasing trend of intensive rice cultivation in a coastal river basin, crop planning and groundwater management are imperative for the sustainable agriculture. For effective management, two models have been developed viz. groundwater balance model and optimum cropping and groundwater management model to determine optimum cropping pattern and groundwater allocation from private and government tubewells according to different soil types (saline and non-saline), type of agriculture (rainfed and irrigated) and seasons (monsoon and winter). A groundwater balance model has been developed considering mass balance approach. The components of the groundwater balance considered are recharge from rainfall, irrigated rice and non-rice fields, base flow from rivers and seepage flow from surface drains. In the second phase, a linear programming optimization model is developed for optimal cropping and groundwater management for maximizing the economic returns. The models developed were applied to a portion of coastal river basin in Orissa State, India and optimal cropping pattern for various scenarios of river flow and groundwater availability was obtained.

Losses of nitrogen and phosphorus from agricultural and forest areas in Finland during the 1980s and 1990s.

The temporal changes and spatial variability of phosphorus and nitrogen losses and concentrations in Finland during the period 1981-1997 were studied in 15 small agricultural and forested catchments. In addition, four coastal river basins with high agricultural land use located in southern Finland were included in the study in order to assess the representativeness of agricultural loss estimates from small agricultural catchments. The mean annual loss specific for agricultural land was estimated to be on average 110 kg km(-2) a(-1) for total phosphorus and 1500 kg km(-2) a(-1) for total nitrogen. The results from small agricultural catchments were in agreement with the corresponding loss estimates from rivers, with an average of 137 kg km(-2) a(-1) for total phosphorus and 1800 kg km(-2) a(-1) for total nitrogen. The results from the studied agricultural catchments and rivers during the period 1981-1997 suggest that weather-driven fluctuation in discharge was usually the main reason for changes in nutrient losses, and little or no impact of changes in agricultural production or management practises can be observed. In forested areas the total phosphorus loss (average 9 kg km(-2) a(-1)) and total nitrogen loss (average 250 kg km(-2) a(-1)) were lower than in agricultural areas. In forested catchments the impact of forestry operations, such as clear-cutting and fertilization, and the impact of atmospheric nitrogen deposition can be seen in changes in nutrient losses.

Aspidoras depinnai(Siluriformes: Callichthyidae): A New Species from Northeastern Brazil

Abstract A new species of the corydoradine catfish genus Aspidoras is described from an isolated coastal river basin in northeastern Brazil. The new species is the first record of a member of the subfamily Corydoradinae from the intervening region between the rio Jaguaribe and rio Sao Francisco basins. Aspidoras depinnai, new species, is distinguished from all congeners by the presence of distal bifid serrations on the ossified portion of pectoral-spine posterior border and an irregular arclike blotch on the caudal peduncle. It differs from the remaining Aspidoras species examined in the present study by the presence of an irregular row of minute pores on the head and a small cartilage between the upper principal and procurrent caudal fin rays.

Soil Erosion in a Coastal River Basin: A Case Study from the Philippines

Soil Erosion in a Coastal River Basin: A Case Study from the Philippines

Ecological and geographical characteristics of the coastal zone of the Black Sea

The coastal zone of the Black Sea is viewed as marine terrestrial geosystem. Its sea and land parts are interconnected by intensive flows of matter, such as water run-off, aerial transfer of water vapour and salts, ingressions of sea water, mining of mineral resources and extraction of biotic resources, transportation of goods, etc. The zone includes the shelf and a belt of land within the boundaries of small coastal river basins. Specific combinations of various branches of the economy are typical for the coastal area in the whole and for its regional sections as well.

Soil erosion in a coastal river basin: a case study from the Philippines

Soil erosion in a coastal river basin: a case study from the Philippines

Serious problems in using equations to estimate bedload yields for coastal rivers in NSW

SUMMARY Bedload yields have been calculated using eight bedload equations at a total of 11 gauging sites in four coastal river basins in New South Wales. Comparisons of yields calculated by each equation at each site show enormous variations. Furthermore, on the Manning River, where calculations could be made on the four main tributaries and compared to those from the trunk channel below their combined confluence, there was no recognisable continuity of results. For the following reasons, the use of bedload formulae on these rivers appears to be a futile exercise. Firstly, the formulae appear to be inherently unstable under natural field conditions. Secondly, application of the formulae must rely on extrapolated flow data, as actual flow measurements are rarely conducted at discharges that are more than a small fraction of largest discharges recorded at any site. Thirdly, formulae must be applied assuming an unlimited availability of bed material; yet the rivers studied here behave as ‘conveyor belts’ of ...

A sediment budget and an analysis of geomorphic process in the Van Duzen River basin, north coastal California, 1941–1975: Summary

The coastal river basins of the northern California Coast Ranges have the highest sediment discharge of basins of comparable size with the United States (Judson and Ritter, 1964; Brown and Ritter, 1971; Knott, 1971; Janda, 1975; Brown, 1975). The high erosion rates in this region are caused by the unique combination of tectonic setting, geology, land use, and climate. This rapidly eroding region is located adjacent to the seismically active triple junction of three crustal plates near Cape Mendocino, California; late Tertiary and Quaternary underthrusting along the continental margin has caused recent (post-mid-Miocene) uplift (Silver, 1971). The area is underlain by the Mesozoic and early Cenozoic Franciscan assemblage, which is a deformed, faulted, locally sheared, and in part metamorphosed accumulation of continental-margin deposits. These deposits consist of intermixed units of melange and more coherent sandstones. The melange consists of an intensely sheared matrix of siltstone or sandy siltstone in which are dispersed large blocks and smaller boulders of sandstone, metasandstone, greenstone, chert, blueschist, and greenschist. Before European settlement, the area was vegetated with redwood (Sequoia sempervirens) , Douglas fir (Pseudotsuga menziesii) , and interior expanses of grassland and grass-oak woodland. Since 1870, the region has undergone progressively more intensive land use. Cattle and sheep grazing on the prairies became widespread by the 18709s, and harvesting of redwood in the lower basin started in the late 18809s. Extensive harvesting of Douglas fir commenced on private lands in the middle and upper portions of the basin after World War II and continued until the mid-sixties. The region has high annual rainfall (125 to 300 cm) that occurs almost entirely between October and April. Between two and six intense rainstorms each winter furnish the streamflows that transport the majority of the annual sediment yield. An important climatic feature is the occurrence at intervals of 100 to 500 yr of storms of extreme intensity and duration that may be responsible for much of the erosion in the region. One such storm occurred in December of 1964. All of the above features, the climate, tectonic setting, geology, vegetation, and land-use history, probably contribute to the high erosion rate of the region. In order to reach some understanding of the relative contributions of these factors and of how sediment moves through the watershed in this region, a detailed analysis was undertaken of the processes and distribution of erosion and deposition in the upper 575 km 2 of the 1,111-km 2 Van Duzen River basin (Kelsey, 1977). The Van Duzen is the northernmost tributary of the Eel River in north coastal California, and flows into the Eel 22 km upstream of its mouth (Fig. 1). Field work for the study took place in 1973–1976. In addition, six sets of aerial photos covering the basin from 1941 through 1975 are available, and stream-gaging records for a U.S. Geological Survey gaging station at the downstream end of the study area near Bridgeville, California, have been available since 1951. A study of changes recognizable in the aerial photographs and interpretation of stream-gaging data for 1940–1975 and sediment discharge data for the periods 1956–1967 and 1975–1976 make possible an analysis of erosion and sedimentation for the 35-yr period, 1941–1975. Surveying records going back to 1869, plus datable trees buried by flood deposits, make it possible to extend some aspects of the record to the last century.