Surface Water Changes Research Articles

Embedded implementation of image-based water-level measurement system

This paper proposes an embedded system for measuring the water level on a river using a camera. One of the main problems of using a camera in water-level measurement is that the light reflection on water surface changes rapidly. To solve this problem, this paper uses the property that variation of light reflection on the ruler showing the scale is relatively smaller than on the water surface. To emphasise this difference of light reflectance on the ruler surface and water surface, the proposed method accumulates the degree of light reflectance variation between the current image and the previous images and constructs a histogram using them. In this histogram, the boundary between the ruler and water surface is appeared as the sharpest drop point. To take into account the noise effects, the proposed algorithm finds the candidate points first and then finally select the water level among them using the reference water. The reference water level is roughly determined as the sharpest drop point in the histogram of the binary image. By installing the proposed system on actual river and testing the water-level measuring experiment in real time, its efficiency has been confirmed.

STUDIES AND ANALYSIS OF THE EFFECTIVENESS OF STORMWATER RUNOFF PURIFICATION EQUIPMENT IN VILNIUS

In order to protect the natural environment from pollution, pollutant reduction in the stormwater runoff of urban areas is a particularly relevant factor. Uneven surface water flow and changes in pollutant concentration complicate conventional matching techniques and processes as well as prolong the duration of time which requires a comprehensive study in this area. Therefore, experiments on inflow stormwater turbidity and impurity with suspended solids and petroleum products were carried out according to the prepared sample collecting methodology. The study evaluated the effectiveness of cleaning a stormwater treatment plant along the settlement chamber in the chosen points. The settling time of impurities found in stormwater was analyzed under the presence of ideal conditions in the laboratory. The conducted experiments established dependence between suspended solids and turbidity. Stormwater pollution by SS was reduced only to 21–35% after heavy rain or a snow melting period in treatment plants.

Holocene temperature and salinity variability of the Atlantic Water inflow to the Nordic seas

Piston core LINK14 from 346 m water depth on the eastern shelf of the Faroe Islands in the Faroe-Shetland Channel has been investigated in order to reconstruct temperature and salinity changes of the Atlantic surface Water during the Holocene. We have analyzed the distribution of benthic and planktic foraminifera, stable isotopes and calculated by transfer functions absolute surface, subsurface and bottom water temperatures and salinities. The summer sea surface temperature (SST) shows a stepwise decrease from an early-Holocene warm phase 10 300—8300 yr BP with temperatures around 12°C, over a mid-Holocene cooler phase 8300—4000 yr BP, to a late-Holocene relatively cool phase with SST around or slightly below 11°C. Bottom water temperatures at 346 m water depth show much less variation than the SST. The late-Holocene sea surface cooling was probably caused by increase in the influence of the polar East Icelandic Current. A distinct decrease in the subsurface salinity from about 8300 to 6800 yr BP is probably also due to a stronger East Icelandic Current. The benthic faunas indicate strong bottom current activity during the entire period. A single exceptional disturbance dated to approximately 8300 yr BP was probably caused by extraordinary high bottom current velocities. The event is marked by a significant coarsening of the sediments and a sorting by size of the foraminifera. The event is close in time to the 8.2-ka cooling event, but more likely correlates with the Storegga slide event.

Relationship between weights of planktonic foraminifer shell and surface water CO 3= concentration during the Holocene and Last Glacial Period

Shell weights of Globigerinoides sacculifer and the elemental concentration of magnesium and calcium (Mg/Ca) from Globigerinoides ruber measured from an Arabian Sea sediment core, AAS9/21, exhibit an inverse relationship with each other , which reveals that shell weights are mainly controlled by surface water [CO 3 =] rather than calcification temperature. Down core shell weight variations of Core AAS9/21 show an excellent correspondence with CO 2 concentrations in an Antarctic Ice Core, which reveals that planktic forminifera shells can trace atmospheric CO 2 due to the resultant change in surface water [CO 3 =]. Hence, shell weights of G. sacculifer can be used as a proxy to reconstruct atmospheric CO 2 concentrations in the past. Here, based on the shell weights , surface water [CO 3 =] change in the Arabian Sea is quantified and found that a [CO 3 =] variation of ∼ 8 μmol/kg occurred during the Holocene and a ∼ 36 μmol/kg variation occurred during the last glacial period.

988 Surface water changes in the Ryukyu Trench slope region, western margin of the North Pacific during the last 320, 000 years

988 Surface water changes in the Ryukyu Trench slope region, western margin of the North Pacific during the last 320, 000 years

Surface water dynamics in the Reykjanes Ridge area during the Holocene as revealed by coccolith assemblages

The calcareous nannofossil assemblages from sediment core DS97-2P from the Reykjanes Ridge have been investigated to document oceanographic changes in surface water during the Holocene. The recorded variations in coccolithophore species assemblages and accumulation rates indicate that the region was subjected to rapid changes of surface water masses throughout the entire Holocene. Coccolithophore assemblages generally are of low species diversity and consist mainly of Emiliania huxleyi and Coccolithus pelagicus ssp. pelagicus. Two major events occurred at 8.5–7 ka and at 4.5– 3.5 ka, showing higher coccolith accumulation rates, suggesting that the influence of relatively warm Atlantic waters via the Irminger Current was strong in the investigated area. The coccolithophore assemblages have been compared with diatom, foraminifer and sedimentological records within the same core. These data, supported by a comparison with previously published proxy records, add credit to the hypothesis that Holocene changes did not occur uniformly across the North Atlantic. The results have highlighted the Holocene pattern in the North Atlantic, as a period influenced by strong regionalism with discrepancies in the hydrographical trends and in the distribution of the planktonic proxies.

A zone-specific fish-based biotic index as a management tool for the Zeeschelde estuary (Belgium)

Fish-based indices monitor changes in surface waters and are a valuable aid in communication by summarising complex information about the environment ( Harrison and Whitfield, 2004). A zone-specific fish-based multimetric estuarine index of biotic integrity (Z-EBI) was developed based on a 13 year time series of fish surveys from the Zeeschelde estuary (Belgium). Sites were pre-classified using indicators of anthropogenic impact. Metrics showing a monotone response with pressure classes were selected for further analysis. Thresholds for the good ecological potential (GEP) were defined from references. A modified trisection was applied for the other thresholds. The Z-EBI is defined by the average of the metric scores calculated over a one year period and translated into an ecological quality ratio (EQR). The indices integrate structural and functional qualities of the estuarine fish communities. The Z-EBI performances were successfully validated for habitat degradation in the various habitat zones.

Bridge Afflux Predictions Using the Lattice Boltzmann Method

The maximum water surface change just upstream of a bridge is termed the afflux in hydraulic engineering. An initial attempt at using the lattice Boltzmann method (LBM) to study afflux has been made in this paper. The LBM representing the 2D nonlinear shallow water equations (LABSWE) is applied to both single-span and multi-span bridges with a free water surface without introducing additional empirical coefficients. For a single-span bridge, three configuration parameters, blockage ratio, skewness and eccentricity, are investigated by the LBM; for a multi-span bridge, the influence of pier shape and skewness on afflux is also tested. The results agree closely with those of traditional methods, which illustrates that LABSWE is not only able to compute average afflux but also to show the afflux distribution across the section and the flow distribution around the obstruction.

Stable oxygen isotope records of corals and a sclerosponge in the Western Pacific warm pool

High-resolution measurements of the stable oxygen isotopic signature (δ18O) of two new 10-year Porites lobata coral cores and one previously studied multi-decadal sclerosponge Acanthocheatetes wellsi from the Republic of Palau (7°16′N, 134°31′E) located in the Western Pacific warm pool were analyzed and monthly interpolated time-series records developed. Despite significant differences in collection depth and growth rates, both coral and sclerosponge faithfully recorded the interannual changes of sea surface salinity (SSS) driven by the strong influence of the El Nino Southern Oscillation (ENSO). The strong relationship of coral skeletal δ18O with SSS, but not sea surface temperature or precipitation, confirms previous findings that changes in Palau regional surface water are driven by the advection of water masses into the area over interannual timescales associated with ENSO. Opportunities exist for the expansion of short coral proxy records with longer sclerosponge records to verify the stability of ENSO-induced SSS variability over longer timescales.

NE Atlantic surface water mass changes over the last 15 kyr

Planktic foraminiferal faunas (> 150 µm) and stable isotopes from the last 15 kyr were studied in kasten core 13078#16 from the Porcupine Abyssal Plain, NE Atlantic (48°49.91 N, 16°29.94 W, water depth 4844 m) in order to document changes in surface waters. The faunas were dominated (> 80%) by four species: Neogloboquadrina incompta (= N. pachyderma dextral), Globigerina bulloides, N. pachyderma (= N. pachyderma sinistral) and Globorotalia inflata and their abundances fluctuated strongly over the last 15 kyr. Other species, G. truncatulinoides (right and left-coiling forms) and Globigerinoides ruber (white), had low abundances (typically < 6%). The polar species N. pachyderma dominated (~ 60%) the terminal glacial interval when surface conditions were cold, decreased to 25–35% during the deglaciation and remained low (< 2%) throughout the Holocene. The relative abundance of N. incompta increased over the last 15 kyr and shows an inverse relationship with N. pachyderma. The increase in δ 13C values of G. bulloides, G. inflata and G. truncatulinoides over the last 15 kyr is consistent with the whole ocean shift due to the expansion of the terrestrial biosphere, indicating that the upper oceanic δ 13C values did not change significantly during this time. Between the deglaciation and the Holocene, the negative shift (~ 1.0‰) in δ 18O values of G. inflata and G. truncatulinoides equates to the global ice volume shift suggesting that there was no significant warming of the deeper surface waters or that the species migrated to occupy a similar temperature water mass during this time. In contrast, the negative shift (~ 1.7‰) in δ 18O values of G. bulloides corresponds to a local shift of 0.7‰, equivalent to a ~ 3 °C warming of surface waters. Between 10 kyr and 5 kyr, the positive δ 18O increases in G. inflata and G. truncatulinoides suggest a decrease in deeper surface water temperatures in the order of 1.0–1.5 °C, a change not evident in the shallow surface water δ 18O record of G. bulloides. Water mass stratification changes, revealed by the Δ δ 18O G. inflata – G. bulloides and Δ δ 18O G. truncatulinoides – G. bulloides records, suggest that the waters of the upper water column were more mixed during the last deglaciation than during the Holocene, and that there was a trend towards increasing water stratification over the last 15 kyr with a peak at ~ 4 kyr. Intervals of enhanced carbonate dissolution at ~ 12–8.5 kyr and ~ 4 kyr previously reported are not clearly reflected in changes in solution-susceptible planktic foraminiferal species, such as G. ruber.

Environmental degradation related to mining, urbanization and pollutant sources: Poços de Caldas, Brazil

The paper considers the environmental problems associated with development within a volcanic depression at Pocos de Caldas, Brazil, which was undertaken without appropriate investigation and planning. Engineering geological mapping was carried out to characterize the area and identify the main environmental problems. The results allowed the division of the region into geological and geotechnical zones. Decommissioned and abandoned mines, agricultural uses, point and non-point pollutant sources and urban land use were identified as the main causes of erosion, siltation, soil and surface water pollution and changes in geomorphology, infiltration rates, groundwater recharge conditions, groundwater pollution, runoff and channel density.

Spatial and temporal variability of biogenic gases during the Southern Ocean spring bloom

The Southern Ocean exerts a strong influence on global biogeochemical cycles and air‐sea gas fluxes. Significant progress has been made towards understanding the general patterns of circulation and biological productivity in this region, but the small‐scale dynamics of surface water gases remain poorly resolved. Here we present new data documenting unprecedented spatial and temporal variability of Southern Ocean biogenic gases during the spring phytoplankton bloom. Using real‐time underway mass spectrometry, we observed significant changes in surface water O2/Ar, pCO2, and dimethylsulfide (DMS) concentrations over time scales of days to weeks and sub‐km spatial scales. Our results demonstrate a tight coupling between physical and biological processes controlling Southern Ocean gas distributions, and highlight the distinct biogeochemical dynamics governing gas cycling in open water and ice‐covered regions.

The dynamics of climate elements and land drainage impact on hydrologic conditions in a lakeland blind drainage area

Abstract: The assessment of climate dynamics and the impact of land drainage systems on lakeland blind drainage area was the problem studied in the paper. The research area was located based on relative stability of non-climatic physiographic characteristics and water management practices over a longer time-scale. Thus, the influence of non-climatic factors on water storage could be omitted. The study site was situated in Warmia region in the Doplyw spod Nowej Wsi catchment (27.53 km). One of local seepage ponds called Bagna Ramuckie within the aforementioned catchment was investigated. The study covered the time period since the first half of the 19 century to the year 2005. The decisive factors affecting processes of increase and decrease of pond water surface area in considered spatial units were the trends of air temperature over the long time scale. It was indicated that natural enlargement of water surface area in the pond occurred after 40-years long period of air temperature decrease and the decline followed 20-year-long period of air temperature rise. Precipitation did not show any trends for long periods but typical cyclic changes of precipitation over a short time-scale. These pluvial cycles stimulated or destimulated processes of water surface changes additionally over short periods. The first episode of water surface decrease in the seepage pond occurred when air temperature rise trend coincided with intensive land drainage and changes in some land management patterns (the 2 half of the 19 century). Nevertheless, during the 20 century water management practices were rather stable and did not have any impact on rise or decline of seepage pond water surface area.

Development of Fluid-Elastoplastic Hybrid Particle Method for Tsunami Simulation due to Slope Failure

In order to simulate an occurrence process of tsunami induced by a slope failure due to an earthquake, it is required to treat an elastoplastic analysis for slope failure, fluid analysis and fluid-elastoplastic interaction in the numerical model. Therefore, in this study, by using the particle method which is suitable for an analysis on large deformation of soil and complicated water surface change, the fluid-elastoplastic hybrid model is developed to simulate a complicated process of a slope failure induced tsunami. In this model, an elastoplastic analysis including large deformation of soil and a fluid analysis are unified.

Impact of changing climate and land use on the hydrogeology of southeast Australia*

Anthropogenic climate change is the Earth's most serious large-scale environmental concern. While the projected changes of global temperatures, rainfall and surface water have been modelled in a sophisticated manner, the impact on groundwater resources is much less well constrained. In southeast Australia, the decrease in rainfall amount and an increase in temperature that are predicted by climate models are generally assumed to reduce the amount of recharge to the groundwater systems. However, the increase in recharge that has resulted from clearing of the native vegetation will almost certainly produce a greater impact on the groundwater system, increasing quantity and potentially improving quality. Additionally, the impact on recharge of changes to rainfall frequency rather than just total amount is not well documented. Overall our understanding of the impacts of climate change on groundwater systems is insufficiently advanced to make firm predictions. Indirect impacts of climate change, particularly the projected increased demand for groundwater or surface water to supplement surface water supplies also will have a major impact that may be greater than the direct effect of climate change.

Interannual variations of river water storage from a multiple satellite approach: A case study for the Rio Negro River basin

Spatiotemporal variations of water volume over inundated areas located in a large river basin have been determined using combined observations from a multisatellite inundation data set, the TOPEX/POSEIDON (T/P) altimetry satellite, and in situ hydrographic stations for the water levels over rivers and floodplains. We computed maps of monthly surface water volume change over the period of common availability of T/P and the multisatellite data (1993–2000). The basin of the Negro River, the largest tributary in terms of discharge to the Amazon River, was selected as a test site. A strong seasonal signal is observed with minima in October and maxima in June. A strong interannual component is also present, particularly important during ENSO years. The surface water change was estimated to be 167 ± 39 km3 between October 1995 (low water) and June 1996 (high water). This result is consistent with previous estimates obtained for the 1995–1996 hydrological cycle over the same area using the JERS mosaic data. The surface water volume change is then compared to the total water volume change inferred from the GRACE satellite for an average annual cycle. The difference between the surface storage change and the total storage change derived from GRACE was computed to estimate the contribution of the soil moisture and groundwater to the total storage change. Our study supports the hypothesis that total water storage is almost equally partitioned between surface water and the combination of soil moisture and groundwater for the Negro River basin. The water volume changes are also evaluated using in situ discharge measurements and the GPCP precipitation product (correlation of 0.61). The results show the high potential for the new technique to provide valuable information to improve our understanding of large river basin hydrologic processes.

The effect of hydrodynamic flow regimes on the algal bloom in a monomictic reservoir

The effectiveness of a proposed curtain weir to be installed in the transitional zone of a eutrophic reservoir located in monsoon areas on the control of algal blooms in the lacustrine zone where drinking water withdrawals occur was assessed with various hydrodynamic flow regimes. A two-dimensional hydrodynamic and eutrophication model that can accommodate vertical displacement of the weir following the water surface changes was developed and validated using field data obtained from two distinctive hydrological years; drought (2001) and wet (2004). The model adequately reproduced the temporal and spatial variations of temperature, nutrients and phytoplankton concentrations in the reservoir. The efficacy of the curtain weir method found to be diverse for different hydrological conditions and dependent on the inflow densimetric Froude number (Fr(i)). Algal blooming was considerably mitigated by curtailing the transport of nutrients and algae from riverine zone to lacustrine epilimnion zone during the drought year as long as Fr(i) < 1.0. However, some flood events with Fr(i) > 1.0 transported nutrients and algae built upstream of the weir into the downstream euphotic zone by strong entrainments in 2004. Numerical experiments revealed that the efficiency of the weir on the control of algal blooming becomes marginal if the Fr(i) > 3.0.

Centennial‐scale evolution of Dansgaard‐Oeschger events in the northeast Atlantic Ocean between 39.5 and 56.5 ka B.P.

There is much uncertainty surrounding the mechanisms that forced the abrupt climate fluctuations found in many palaeoclimate records during Marine Isotope Stage (MIS)‐3. One of the processes thought to be involved in these events is the Atlantic Meridional Overturning Circulation (MOC), which exhibited large changes in its dominant mode throughout the last glacial period. Giant piston core MD95‐2006 from the northeast Atlantic Ocean records a suite of palaeoceanographic proxies related to the activity of both surface and deep water masses through a period of MIS‐3 when abrupt climate fluctuations were extremely pronounced. A two‐stage progression of surface water warming during interstadial warm events is proposed, with initial warming related to the northward advection of a thin warm surface layer within the North Atlantic Current, which only extended into deeper surface layers as the interstadial progressed. Benthic foraminifera isotope data also show millennial‐scale oscillations but of a different structure to the abrupt surface water changes. These changes are argued to partly be related to the influence of low‐salinity deepwater brines. The influence of deepwater brines over the site of MD95‐2006 reached a maximum at times of rapid warming of surface waters. This observation supports the suggestion that brine formation may have helped to destabilize the accumulation of warm, saline surface waters at low latitudes, helping to force the MOC into a warm mode of operation. The contribution of deepwater brines relative to other mechanisms proposed to alter the state of the MOC needs to be examined further in future studies.

Holocene millennial‐scale productivity variations in the Sicily Channel (Mediterranean Sea)

The calcareous nannofossil assemblages of Ocean Drilling Program Hole 963D from the central Mediterranean Sea have been investigated to document oceanographic changes in surface waters. The studied site is located in an area sensitive to large‐scale atmospheric and climatic systems and to high‐ and low‐latitude climate connection. It is characterized by a high sedimentation rate (the achieved mean sampling resolution is &lt;70 years) that allowed the Sicily Channel environmental changes to be examined in great detail over the last 12 ka BP. We focused on the species Florisphaera profunda that lives in the lower photic zone. Its distribution pattern shows repeated abundance fluctuations of about 10–15%. Such variations could be related to different primary production levels, given that the study of the distribution of this species on the Sicily Channel seafloor demonstrates the significant correlation to productivity changes as provided by satellite imagery. Productivity variations were quantitatively estimated and were interpreted on the basis of the relocation of the nutricline within the photic zone, led by the dynamics of the summer thermocline. Productivity changes were compared with oceanographic, atmospheric, and cosmogenic nuclide proxies. The good match with Holocene master records, as with ice‐rafted detritus in the subpolar North Atlantic, and the near‐1500‐year periodicity suggest that the Sicily Channel environment responded to worldwide climate anomalies. Enhanced Northern Hemisphere atmospheric circulation, which has been reported as one of the most important forcing mechanisms for Holocene coolings in previous Mediterranean studies, had a remarkable impact on the water column dynamics of the Sicily Channel.

Assessment of possible mechanisms of decreasing 137Cs concentrations in river waters affected by the Chernobyl NPP accident

The analysis of possible mechanisms of 137Cs concentration changes in surface waters was performed in the process of preparation of reliable long-range forecasts of radioactive river contamination after the Chernobyl accident. The following mechanisms were considered: (1) radioactive decay; (2) advective transport with river waters; (3) irreversible sorption; (4) vertical migration deep into bottom sediments due to diffusion; (5) burial in clean bottom sediments. The data published on 137Cs monitoring at Dobrush, on the Iput’ River in Belarus were used in the analysis. It is shown that the best agreement with the experimental results is achieved when the second, third, and fifth mechanisms are used in calculations. However, a dominating mechanism still cannot be chosen at the present stage of our study. Most probably, all of these mechanisms act simultaneously.