Total Water Discharge Research Articles

Changes in dissolved silicate loads to the Baltic Sea — The effects of lakes and reservoirs

We tested the hypothesis that dissolved silicate (DSi) yields [kg km − 2 yr − 1 ] of 82 major watersheds of the Baltic Sea can be expressed as a function of the hydraulic load (HL) as a measure of water residence time and the total organic carbon (TOC) concentration, both variables potentially increasing the DSi yield. Most boreal rivers fitted a linear regression model using HL as an independent variable to explain the DSi yield. Rivers with high HL, i.e., shortest residence times, showed highest DSi yields up to 2300 kg km − 2 yr − 1 . This is most likely caused by an excess supply of DSi, i.e., the geochemical sources prevail over biological sinks in these boreal watersheds. The DSi yield for regulated and unregulated larger rivers of the boreal watersheds constituting about 40% of the total water discharge and of the total DSi load to the Baltic Sea, respectively, can be expressed as: DSi yield = 190 + 49.5 HL[m yr − 1 ] + 0.346 TOC [µM] ( R 2 = 0.80). Since both HL and TOC concentrations have decreased after damming, the DSi yields have decreased significantly in the regulated boreal watersheds, for the River Luleälven we estimated more than 30%. The larger eutrophic watersheds draining cultivated landscape of the southern catchment of the Baltic Sea and representing about 50% of the annual water discharge to the Baltic Sea, deviated from this pattern and showed lower DSi yields between 60–580 kg km − 2 yr − 1 . DSi yields showed saturation curve like relationship to HL and it appears that DSi is retained in the watersheds efficiently through biogenic silica (BSi) production and subsequent sedimentation along the entire river network. The relationship between HL and DSi yields for all larger cultivated watersheds was best fitted by a Freundlich isotherm (DSi = 115.7HL 109; R 2 = 0.73), because once lake and reservoir area exceeds 10% of the watershed area, minimum DSi yields were reached. To estimate an uperturbed DSi yield for the larger eutrophic southeastern watersheds is still difficult, since no unperturbed watersheds for comparison were available. However, a rough estimate indicate that the DSi flux from the cultivated watersheds to the Baltic Sea is nowadays only half the uperturbed flux. Overall, the riverine DSi loads to the Baltic Sea might have dropped with 30–40% during the last century.

Nutrient (N, P) loads and yields at multiple scales and subbasin types in the Yukon River basin, Alaska

Loads and yields of dissolved and particulate nitrogen (N) and phosphorus (P) were measured and modeled at three locations on the Yukon River (YR) and on the Tanana and Porcupine Rivers in Alaska during 2001–2005. Total export of N and P upstream of Yukon Delta averaged 120 Gg N a−1 and 56 Gg P a−1, respectively, with 43.5% of total N (TN) as dissolved organic N, and 98% of total P (TP) as particulate phosphorus. Approximately half of the annual export of TN and TP occurred during spring. Hydrologic yields of TN (5.6–13.3 mmol N m−2 a−1) and TP (0.8–9.0 mmol P m−2 a−1) were least in the Porcupine basin and greatest in the Tanana basin and were proportional to water yield. Comparison of current and historical dissolved organic matter (DOM) export from the basin indicates decreased DON export with respect to total water discharge during summer and autumn in recent decades. Any possible climate‐related change in annual water discharge will result in proportional changes in N and P export.

AVALIAÇÃO DE ALGUMAS CARACTERÍSTICAS FÍSICO-QUÍMICAS DA ÁGUA DO RIBEIRÃO SALGADINHO, NOVA XAVANTINA-MT

As características dos ambientes aquáticos podem variar drasticamente em função da sazonalidade climática da região do cerrado, exigindo dos organismos aquáticos sua adaptação. Foram verificadas algumas características físico-químicas da água do Ribeirão Salgadinho, de 3a ordem, que se localiza na zona rural de Nova Xavantina, região sudeste de Mato Grosso. Três pontos foram escolhidos para a realização das coletas, estando um próximo a nascente, um tributário e o outro próximo à foz. As análises físico-químicas foram realizadas mensalmente no período de setembro de 2003 a setembro de 2004. Determinou-se nos pontos de coletas seis variáveis ambientais: turbidez, pH, condutividade, dureza total e vazão. As variáveis ambientais analisadas apresentaram variações entre o período de seca e o chuvoso. Verificou-se aumento no valor da turbidez, resultante do escoamento superficial das chuvas e diminuição dos valores do pH e condutividade com o aumento da vazão.

Mercury and Drought Along the Lower Carson River, Nevada: I. Snowy Egret and Black-Crowned Night-Heron Annual Exposure to Mercury, 1997–2006

The dynamic nature of the annual volume of water discharged down the Carson River over a 10-year period, which included a century flood and drought, was examined in order to gain a better understanding of mercury movement, biological availability, and exposure to waterbirds nesting at Lahontan Reservoir. Total annual water discharge directly influenced total mercury (THg) in unfiltered water above the reservoir and downstream of a mining area, whereas methyl mercury (MeHg) at the same site was negatively related to annual discharge. Annual water storage at Lahontan Reservoir in the spring and early summer, as expected, was directly related to annual Carson River discharge. In contrast to the findings from above the reservoir, annual MeHg concentrations in water sampled below the reservoir were positively correlated with the total discharge and the amount of water stored in the reservoir on 1 July; that is, the reservoir is an important location for mercury methylation, which agrees with earlier findings. However, unfiltered water MeHg concentrations were about 10-fold higher above than below the reservoir, which indicated that much MeHg that entered as well as that produced in the reservoir settled out in the reservoir. Avian exposure to mercury at Lahontan Reservoir was evaluated in both eggs and blood of young snowy egrets (Egretta thula) and black-crowned night-herons (Nycticorax nycticorax). Annual MeHg concentrations in unfiltered water below the reservoir, during the time period (Julian Days 90-190) when birds were present, correlated significantly with mercury concentrations in night-heron blood (r(2 )= 0.461, p = 0.027), snowy egret blood (r(2 )= 0.474, p = 0.024), and night-heron eggs (r(2) = 0.447, p = 0.029), but not snowy egret eggs. A possible reason for lack of an MeHg water correlation with snowy egret eggs is discussed and relates to potential exposure differences associated with the food habits of both species. THg concentrations in water collected below the reservoir were not related to egg or blood mercury concentrations for either species.

Potential ecological effects of water extraction in small, unregulated streams

River regulation can have various effects on the natural flow regime, however the most obvious and perhaps pronounced hydrological effect is the reduction of total water discharge. Whilst there has been an increasing number of studies investigating the impacts of river regulation on lowland rivers, few studies have specifically investigated the effects of water extractions on small upland streams. In this study, we experimentally examined the effects of short-term, summer water extractions from small, unregulated streams. Five 30 m reaches were experimentally manipulated to divert a proportion of the total stream flow, and another five 30 m reaches were designated as controls, in the Yea River catchment, Victoria, Australia. The percentage of total discharge diverted from each experimental reach varied through time and between creeks (28–97%), with discharge always significantly reduced compared to control locations. All sites were monitored for available habitat, biofilm, water quality and macroinvertebrate diversity and density, fortnightly during February and March 2004. Despite the range of total stream volumes being extracted, the manipulation altered important ecological components of these unregulated creeks, including changes in physical habitat features (reduced stream wetted area and maximum stream depth) and reduced dissolved oxygen concentrations. Biofilm parameters showed a slight increase in diverted reaches, but were not statistically different from the controls. There was no statistical difference in total density of macroinvertebrates or EPT taxa; however, the density of Austrocercella mariannae (Notonemouridae) was significantly reduced in diverted reaches. Macroinvertebrate family level diversity, and the family diversity of grazers and shredders was reduced in diverted reaches. This study demonstrates that there are likely to be significant ecological impacts of extracting water in unregulated creeks. Whilst this study has demonstrated the need to consider environmental water requirements in unregulated streams, further studies are required to inform the debate about the volume, timing and predicted ecological response with improved environmental water. Copyright © 2006 John Wiley & Sons, Ltd.

Climate sensitivity of spring snowpack in the Sierra Nevada

California's spring snowpack provides a critical water resource that may be greatly reduced by greenhouse warming. However, warming over the past half century has had little effect on total summer water discharge. The region's snowpack may therefore be less sensitive to temperature change than predicted by numerical models. In this study, 53 years of 1 April snow course measurements of snow‐water equivalent (SWE) from the Sierra Nevada are used in a spatially distributed covariance model of SWE sensitivity to temperature and precipitation. This model is applied at a 2.5 arc min resolution using a multivariate parameter‐surface interpolation scheme and Parameter‐elevation Regressions on Independent Slopes (PRISM) climate grids. Total modeled SWE volume has a greater covariance to precipitation than to temperature. Increasing precipitation and temperature from 1950 to 2002 has led to an increase in SWE at high elevations and a loss at low elevations, resulting in little or no overall change in SWE volume. The covariance model predicts a 6–10% decrease in total SWE volume per °C. However, sensitivity is both highly dependent on concurrent change in precipitation and spatially variable, with the lower‐elevation watersheds in the north being the most sensitive to warming. Overall, climate sensitivity is much less than that predicted by numerical models. This difference may result from inadequate treatment of elevation and precipitation in climate models.

ISOTOPE HYDROGRAPH SEPARATION FOR MODELING OF RUNOFF MECHANISMS OF ATMOSPHERICALLY DERIVED CHEMICAL AND RADIOACTIVE POLLUTANTS

In a tributary watershed of the Kuji River of Japan, the hydrological components of runoff associated with a precipitation event were investigated using isotope tracers of hydrogen (2H) and oxygen (18O) in precipitations and stream water. The runoff was separated into “old water” (pre-existing in the ground before the precipitation event) and “new water”(from the precipitation). It was found that the discharge of several hazardous trace elements (Sb, Cu, Cr) was largely (24-54%) attributable to that of the new water in spite of its small contribution to the total water discharge. These investigations suggest that the new water may play an important role in the migration of atmospherically derived, hazardous trace elements to streams during precipitation events. The present findings will contribute to current necessity of assessment of a risk of long-term exposure to pollutants at low concentrations by providing information on their transport among different environmental media.

Enhanced Submarine Ground Water Discharge from Mixing of Pore Water and Estuarine Water

AbstractSubmarine ground water discharge is suggested to be an important pathway for contaminants from continents to coastal zones, but its significance depends on the volume of water and concentrations of contaminants that originate in continental aquifers. Ground water discharge to the Banana River Lagoon, Florida, was estimated by analyzing the temporal and spatial variations of Cl− concentration profiles in the upper 230 cm of pore waters and was measured directly by seepage meters. Total submarine ground water discharge consists of slow discharge at depths > ∼70 cm below seafloor (cmbsf) of largely marine water combined with rapid discharge of mixed pore water and estuarine water above ∼70 cmbsf. Cl− profiles indicate average linear velocities of ∼0.014 cm/d at depths > ∼70 cmbsf. In contrast, seepage meters indicate water discharges across the sediment‐water interface at rates between 3.6 and 6.9 cm/d. The discrepancy appears to be caused by mixing in the shallow sediment, which may result from a combination of bioirrigation, wave and tidal pumping, and convection. Wave and tidal pumping and convection would be minor because the tidal range is small, the short fetch of the lagoon limits wave heights, and large density contacts are lacking between lagoon and pore water. Mixing occurs to ∼70 cmbsf, which represents depths greater than previously reported. Mixing of oxygenated water to these depths could be important for remineralization of organic matter.

PARÂMETROS HIDROGEOLÓGICOS DO SISTEMA AQÜÍFERO BAURU NA REGIÃO DE ARAGUARI/MG: FUNDAMENTOS PARA A GESTÃO DO SISTEMA DE ABASTECIMENTO DE ÁGUA

The paper presents hydrogeologic parameters for the Bauru Aquifer System in the area of Araguari, state of Minas Gerais, Brazil. The public water supply system is based on groundwater exploration. It operates 96 deep wells responsible for a total water discharge up to 1900 m 3 /h, resulting in average yield of 19.5 m 3 /h. The Bauru Aquifer System shows the following values for the dimensional parameters: the saturated thickness is 33 meters, the thickness of the vadose zone varies from 7 up to 36 meters, the effective porosity of the conglomerate facies is 19.5%, the effective porosity of the sandy facies is 12.7%, the hydraulic conductivity ranges from 5 x 10 -6 to 1.6 x 10 -4 m/s, with an average of 3.1 x 10 -5 m/s, the average transmissivity is 9.6 x 10- 4 m 2 /s, the average well discharge is 19.5 m 3 /h, and the average specific capacity is 1.3 m 3 h/m. The wide variation of values results from the bad conditions of construction of the wells.

Estimating ground water discharge by hydrograph separation.

Iron Mountain is located in the West Shasta Mining District in California. An investigation of the generation of acid rock drainage and metals loading to Boulder Creek at Iron Mountain was conducted. As part of that investigation, a hydrograph separation technique was used to determine the contribution of ground water to total flow in Boulder Creek. During high-flow storm events in the winter months, peak flow in Boulder Creek can exceed 22.7 m3/sec, and comprises surface runoff, interflow, and ground water discharge. A hydrograph separation technique was used to estimate ground water discharge into Boulder Creek during high-flow conditions. Total ground water discharge to the creek approaches 0.31 m3/sec during the high-flow season. The hydrograph separation technique combined with an extensive field data set provided reasonable estimates of ground water discharge. These estimates are useful for other investigations, such as determining a corresponding metals load from the metal-rich ground water found at Iron Mountain and thus contributing to remedial alternatives.

The geochemical characteristics of the Paraná River suspended sediment load: an initial assessment

AbstractMost water in the Paraná River drainage basin is supplied by the tropical Upper Paraná (over 60% of the total annual water discharge, 550 km3). The total suspended solids (TSS) load (c. 80 × 106 t year−1), however, is essentially furnished (50–70%) by the mountainous, arid and mostly sediment‐mantled upper Bermejo River drainage basin. This characteristic suggests that the Paraná River solid load (TSS, 600 km upstream from the mouth) is largely recycled sedimentary material, whose discharge‐weighted mean chemical index of alteration is c. 71. The extended UCC‐normalized multi‐elemental diagrams are similar to those of other world rivers. Nevertheless, the detailed inspection of UCC‐normalized rare earth element (REE) ‘spidergrams’ reveals a lithological source for the Paraná River TSS that might be compatible with either tholeiitic flood basalts (widespread in the upper drainage) or with young Andean intermediate volcanic rocks. In view of the Bermejo River's dominant role as a sediment contributor, we feel that the signature preserved in the Paraná's TSS is the latter. Conversely, the Uruguay River TSS REE signature is certainly determined by the extensive weathering products of Jurassic–Cretaceous tholeiitic basalts. Copyright © 2003 John Wiley & Sons, Ltd.

The transport of Cu and Zn from agricultural soils to surface water in a small catchment

Long-term manure-borne copper and zinc inputs (18–324 mg Cu m −2 yr −1 and 100–800 mg Zn m −2 yr −1) to grassland soils resulted in their catchment in water concentrations that often exceeded the surface water quality criteria (2 μg Cu l −1 and 5 μg Zn l −1). This paper compares retention and release of Cu and Zn by two types of soil, a mineral soil (MS) and a dark colored soil rich in organic matter (OS). On the basis of dry soil mass, the OS has a higher retention/affinity for Cu and Zn than the MS, but much less Zn accumulated in the MS when compared on an areal basis. This is largely because of the much smaller bulk OS density and larger dissolved metal concentrations in the OS drainage than that for the MS. However, because of the greater water retention capacity of the OS, elevated metal concentrations in the soil solution do not necessarily cause greater loss to water. It is concluded that artificially drained OS can contribute significantly to the observed elevated Cu and Zn concentrations of the river, especially during relatively dry weather conditions when the contribution of water seeping from OS to the total river water discharge becomes increasingly important.

Herbicide and insecticide loadings from the Susquehanna River to the northern Chesapeake Bay.

The Susquehanna River watershed has a large drainage area (71200 km(2)) containing heavy agricultural land usage. The river provides approximately half the total freshwater input to the Chesapeake Bay. Water samples were collected at Conowingo Dam near the mouth of the river every 9 days from February 1997 through March 1998. Atrazine, its transformation product 6-amino-2-chloro-4-(isopropylamino)-s-triazine (CIAT), and metolachlor were found in the highest concentrations with maximums of 500, 150, and 330 ng/L, respectively. The annual mass loads for atrazine, CIAT, metolachlor, simazine, and 6-amino-2-chloro-4-(ethylamino)-s-triazine (CEAT) from the Susquehanna River to the Chesapeake Bay were 1600, 1600, 1100, 820, and 720 kg/year, respectively. Annual loadings of insecticides and organochlorine compounds ranged from 2.8 kg/year for alpha-HCH to 34 kg/year for diazinon. Strong correlations between loading data from this and previous studies and total annual water discharge through the dam were used to estimate total metolachlor and atrazine loads (12400 and 9950 kg, respectively) to the northern Chesapeake Bay from 1992 to 1997.

Short-term hydrothermal scheduling through evolutionary programming technique

Abstract An efficient short-term hydrothermal scheduling algorithm based on the evolutionary programming (EP) technique is proposed. In the algorithm, the thermal generating units in the system are represented by an equivalent unit. The power balance constraints, total water discharge constraint, reservoir volume constraints and the constraints on the operation limits of the equivalent thermal and hydro units are fully taken into account. The effectiveness of the proposed algorithm is demonstrated through an example system and the results are compared with those obtained by the classical gradient search and simulated annealing (SA) approaches. Numerical results show that the proposed EP approach provides a cheaper schedule even than the SA approach and hence, has more powerful ability to achieve the global optimum solution than the SA approach.

Deep-seated., complex tunnel systems — a hydrological study in a semi-arid catchment, Loess Plateau, China

During 1989–1990, delailed monitoring of deep-seated, complex tunnel systems was conducted in Yangdaogou, a subbasin in the Hilly Loess Region, Shanxi, which has a catchment area of 0.203 km2. It was found that tunnel flow hydrological processes were characterized by a quick response to rainfall, an early flow peak, and a short duration. All the tunnel discharge was derived from overland flow entering via inlets. However, discharge is not significantly related to rainfall parameters in some tunnels, which is contrary to observations on surface plots. Field surveys show frequent blockages of tunnels caused by collapses inside the tunnels which could be reopened in subsequent events, as well as the occasional abrupt opening of new inlets. As a result, tunnel discharge was highly erratic in some of the monitored events. Partial damming within the tunnel systems may also be involved. Hence, instability in the tunnel systems is one of the key factors affecting their hydrologic response. During the period of monitoring, fifteen events occurred and on average at least 43% (ranging from 0 to 78%) of the total basin water discharge was routed through four major tunnel systems which account for 90% of the catchment area of all tunnel systems in the basin. The deep-seated tunnel systems in this area seem not to be developed from the micro-pipes close to the surface. Instead, they are most likely formed in some catastrophic storms and expanded in subsequent storms. 1997 Elsevier Science B.V.

Determining water use by trees and forests from isotopic, energy balance and transpiration analyses: the roles of tree size and hydraulic lift.

Use of soil water and groundwater by open-grown Acer saccharum Marsh. (sugar maple) tree canopies and forests was estimated by measuring transpiration (E) rates using porometry, sap flow methods, and the Bowen ratio method. The Bowen ratio and sap flow methods showed the best agreement; porometer measurements scaled to whole canopies always underestimated E by 15-50%. Trees of different sizes showed very different rates of E. I hypothesized that these differences were due to the differential access of large and small trees to groundwater and soil water, respectively. Transpirational flux was partitioned between soil water and groundwater by tracing the water sources based on their hydrogen stable isotopic composition (deltaD). Soil water deltaD varied between -41 and -16 per thousand seasonally (May to September), whereas groundwater deltaD was -79 +/- 5 per thousand during the entire growing season. Daily transpiration rates of large (9-14 m tall) trees were significantly higher than those of small (3-5 m tall) trees (2.46-6.99 +/- 1.02-2.50 versus 0.69-1.80 +/- 0.39-0.67 mm day(-1)). Small trees also showed greater variation in E during the growing season than large trees. In addition, compared to the large trees, small trees demonstrated greater sensitivity to environmental factors that influence E, such as soil water deficits and increased evaporative demand. Over the entire growing season, large trees and forest stands composed of trees > 10 m tall transpired only groundwater. The high rates of water loss from large trees and older forests were likely a result of the influence of an enhanced "pool" of transpirational water in the upper soil layers caused by hydraulic lift (see Dawson 1993b). The hydraulically lifted water reservoir enabled large trees to use more potential transpirational water during daylight hours than small trees, leading to a greater total water flux. In contrast, small trees and forest stands composed of younger trees almost exclusively used soil water, except during two dry periods when their transpirational water was composed of between 7 and 17% groundwater. Thus groundwater discharge from sugar maple trees and forest stands of different sizes (ages) differs significantly, and large trees and older forest stands have a greater impact on the hydrologic balance of groundwater than small trees and younger forest stands. However, mixed stands (small and large trees) may have a greater overall impact on the regional hydrologic balance than old stands, because trees in mixed stands draw on both soil water and groundwater reservoirs and thus can substantially increase total water discharge on scales from tens to hundreds of hectares.

Seasonal variation in chemical distributions in the Amazon (Solimões) River: A multiyear time series

The results of a 10‐year time series study of the chemistry of the Amazon River mainstem near Manaus, Brazil, are presented. All variables measured showed distinct seasonal patterns linked to the discharge hydrograph except respiration rate and PO4−3 concentration. Stepwise multiple regression analysis showed that alkalinity, calcium, fine suspended sediment, and sulfate were correlated, primarily, with the percentage of the total water discharge that was derived from Andean drainages. Silicate, potassium, and the weight percentages of carbon and nitrogen in the coarse suspended sediment were correlated with the percentage of water attributable to local lowland drainages. These correlations suggest that seasonal cycles of these variables were controlled by their source strength. Coarse suspended sediment and the concentration all of the particulate carbon, nitrogen, and phosphorus species were correlated with river surface slope, suggesting that the seasonal cycles of these variables were controlled by river turbulence. The biogeochemically active elements O2, CO2, NO3− and SO4=, along with pH, Na, and Cl were all highly correlated with river discharge. The shapes of the seasonal cycles of O2 and CO2 and much of their amplitude could be reproduced by a quasi steady state model in which respiration was balanced by air‐water gas exchange. In the model, increases in river depth during the annual cycle result in increased depth‐integrated respiration rates. This produces a drawdown of O2 concentration, which increases air‐water gas exchange, until the two processes are in balance. Thus the model produces seasonal cycles in which minimum dissolved O2 and maximum dissolved CO2 coincide with high water and the converse at low water, in agreement with the observations. The remainder of the amplitude signal was probably either advected in from upstream or produced by lateral exchange with the fringing floodplain.

Fragmentation and Flow Regulation of River Systems in the Northern Third of the World

Seventy-seven percent of the total water discharge of the 139 largest river systems in North America north of Mexico, in Europe, and in the republics of the former Soviet Union is strongly or moderately affected by fragmentation of the river channels by dams and by water regulation resulting from reservoir operation, interbasin diversion, and irrigation. The remaining free-flowing large river systems are relatively small and nearly all situated in the far north, as are the 59 medium-sized river systems of Norway, Sweden, Finland, and Denmark. These conditions indicate that many types of river ecosystems have been lost and that the populations of many riverine species have become highly fragmented. To improve the conservation of biodiversity and the sustainable use of biological resources, immediate action is called for to create an international preservation network of free-flowing river systems and to rehabilitate exploited rivers in areas that lack unaffected watercourses.

Short-term hydrothermal scheduling part. I. Simulated annealing approach

The paper develops a short-term hydrothermal scheduling algorithm based on the simulated annealing technique. In the algorithm, the power balance constraint, total water discharge constraint, reservoir volume limits and constraints on the operation limits of the hydrothermal generator and the thermal generator are fully accounted for. The relative operation capacities of the hydroplant and the thermal plant are also considered. A relaxation method for checking the limits is proposed and included in the algorithm. The performance of the algorithm is demonstrated through a test example.

Well Design and Influence of Ground Water Level on Pump Performance.(Dept.C)

A deep water well of 600 m depth was designed and drilled in the farm, college of agriculture Al-Qassim, fourteen stages turbine pump was selected. to be installed on this well, according to the total head and water discharge required for irrigation. A severe decline of ground water level will not provide the required water discharge and total head even if the pump works under its maximum speed. This could make a trouble shooting or damage to the pump unless its column pipe length will be increased to deal with the existing water level.