Natural Discharge Research Articles

Influence of dam removal on trichopteran assemblages in the lowland Drzewiczka River, Poland

The aim of this study is to assess the response of Trichoptera in a patchy tailwater stretch of the Drzewiczka River (Poland) to dam removal as compared to the previous pulse discharge disturbance. The study was carried out in the river at the end of a whitewater slalom canoeing track located downstream of the dam reservoir called Drzewieckie Lake (area 0.84 km2). Between February and April 2002, the dam reservoir was gradually emptied before its dredging, and the Drzewiczka River recovered its natural discharge (1.7–4.5 m3 s−1) for several years (temporary renaturisation). Altogether, 120 monthly samples of macroinvertebrates and their environments were collected in two sampling cycles, S1 in 2000–2001 during high discharge fluctuations (2.1–12.0 m3 s−1 daily) and S2 in 2002–2003 during renaturisation after emptying the reservoir, from the following five habitats: HP—pool habitat, HS—stagnant habitat, HM—macrophyte habitat, HB—bank habitat and HR—riffle habitat. On the basis of trichopteran abundance, the patterns in their assemblages were recognised with use of a self-organising map that was a Kohonen artificial neural network. The obtained classification of trichopteran samples was found to be based in general on the spatial criterion, i.e. dependent on habitats, irrespective of which sampling cycle the samples originated from, which clearly showed that the habitat mosaic of the river bed was observed both in S1 and S2. In addition, a very important function was noted for riparian and land plants, which developed intensively at the bottom of the Drzewieckie Reservoir immediately after it was emptied. They restricted extensive transport of reservoir sediments to the downstream river reach, thus reducing differences between S1 and S2 in the tailwater. It is also worth noting that in S1, in comparison to S2, Cyrnus trimaculatus, Mystacides azurea and Lype reducta flowing downstream from the reservoir were observed more frequently in the river, which confirmed that impoundments can be conducive to the presence of certain species downstream of dams. Summing up, although artificial short-term flow fluctuations usually diminish the quality and quantity of benthos, the article presents a case in which they were small and short enough to allow the formation of a mosaic of bed patches and positively affected certain parameters of macrobenthic communities according to the intermediate disturbance hypothesis.

Groundwater management and coal bed methane development in the Powder River Basin of Montana

Summary Coal bed methane (CBM) development will eventually pump more than 124,000 ha-m of groundwater, or more than 40% of the recharge, from the coal seam and sandstone aquifers of the Montana portion of the Powder River Basin (PRB). This will relieve the hydrostatic pressure, by causing a drawdown in the potentiometric surface and drawing groundwater from storage and natural discharges, to release the methane gas. A numerical groundwater flow model simulated drawdown that will exceed 90 m in the middle of the CBM fields with 6-m drawdown extending up to 29 km from the fields. Simulation results indicate that river flux will decrease up to 40% and drawdown will encompass hundreds of wells and springs. Recovery requires up to 45 years for significant decreases in river flux to recover and is not complete for 200 years. CBM development impacts can be mitigated in two ways. First, reinjecting produced water into depleted coal seams would replenish the lost storage so that recovery would draw less groundwater from long distances. Second, rapid infiltration basins near potentially-affected rivers could decrease the short-term river flow depletion. Modeled artificial recharge replaced up to 4000 ha-m of deficit in the depleted coal seams and is a feasible option for mitigating some effects of CBM development. Reinjection would be more effective if the development period were lengthened.

In situ measurements of microbially-catalyzed nitrification and nitrate reduction rates in an ephemeral drainage channel receiving water from coalbed natural gas discharge, Powder River Basin, Wyoming, USA

Nitrification and nitrate reduction were examined in an ephemeral drainage channel receiving discharge from coalbed natural gas (CBNG) production wells in the Powder River Basin, Wyoming. CBNG co-produced water typically contains dissolved inorganic nitrogen (DIN), primarily as ammonium. In this study, a substantial portion of discharged ammonium was oxidized within 50 m of downstream transport, but speciation was markedly influenced by diel fluctuations in dissolved oxygen (> 300 µM). After 300 m of transport, 60% of the initial DIN load had been removed. The effect of benthic nitrogen-cycling processes on stream water chemistry was assessed at 2 locations within the stream channel using acrylic chambers to conduct short-term (2–6 h), in-stream incubations. The highest ambient DIN removal rates (2103 µmol N m − 2 h − 1 ) were found at a location where ammonium concentrations > 350 µM. This occurred during light incubations when oxygen concentrations were highest. Nitrification was occurring at the site, however, net accumulation of nitrate and nitrite accounted for < 12% of the ammonium consumed, indicating that other ammonium-consuming processes were also occurring. In dark incubations, nitrite and nitrate consumption were dominant processes, while ammonium was produced rather than consumed. At a downstream location nitrification was not a factor and changes in DIN removal rates were controlled by nitrate reduction, diel fluctuations in oxygen concentration, and availability of electron donor. This study indicates that short-term adaptation of stream channel processes can be effective for removing CBNG DIN loads given sufficient travel distances, but the long-term potential for nitrogen remobilization and nitrogen saturation remain to be determined.

Carbon dioxide degassing and thermal energy release in the Monte Amiata volcanic-geothermal area (Italy)

Abstract The quaternary volcanic complex of Mount Amiata is located in southern Tuscany (Italy) and represents the most recent manifestation of the Tuscan Magmatic Province. The region is characterised by a large thermal anomaly and by the presence of numerous CO2-rich gas emissions and geothermal features, mainly located at the periphery of the volcanic complex. Two geothermal systems are located, at increasing depths, in the carbonate and metamorphic formations beneath the volcanic complex. The shallow volcanic aquifer is separated from the deep geothermal systems by a low permeability unit (Ligurian Unit). A measured CO2 discharge through soils of 1.8 × 109 mol a−1 shows that large amounts of CO2 move from the deep reservoir to the surface. A large range in δ13CTDIC (−21.07 to +3.65) characterises the waters circulating in the aquifers of the region and the mass and isotopic balance of TDIC allows distinguishing a discharge of 0.3 × 109 mol a−1 of deeply sourced CO2 in spring waters. The total natural CO2 discharge (2.1 × 109 mol a−1) is slightly less than minimum CO2 output estimated by an indirect method (2.8 × 109 mol a−1), but present-day release of 5.8 × 109 mol a−1 CO2 from deep geothermal wells may have reduced natural CO2 discharge. The heat transported by groundwater, computed considering the increase in temperature from the infiltration area to the discharge from springs, is of the same order of magnitude, or higher, than the regional conductive heat flow (>200 mW m−2) and reaches extremely high values (up to 2700 mW m−2) in the north-eastern part of the study area. Heat transfer occurs mainly by conductive heating in the volcanic aquifer and by uprising gas and vapor along fault zones and in those areas where low permeability cover is lacking. The comparison of CO2 flux, heat flow and geological setting shows that near surface geology and hydrogeological setting play a central role in determining CO2 degassing and heat transfer patterns.

VO2온도센서를 이용한 전원차단 PCM 구성

Most portable mobile devices employ rechargeable lithium-ion batteries. This lithium-ion battery usually suffers from the possibility of explosion due to heat generation from surrounding atmosphere or internal deficiency during charging or at overuse. To solve these problems, most rechargeable batteries have a built-in protection circuit module (PCM). The resistance of a properly processed critical temperature sensor (CTS) is changed dramatically at a critical temperature of around , which can replace some bi-metal, NTC, or PTC sensors embedded in PCM. Such CTS consumes a very small current at the level of natural discharge. Experimental results showed that this CTS could be applied to a PCM as the PCM could protect the battery while keeping its power consumption at minimum.ﶖ⨀

Update on subsidence at the Wairakei–Tauhara geothermal system, New Zealand

The total subsidence at the Wairakei field as a result of 50 years of geothermal fluid extraction is 15 ± 0.5 m. Subsidence rates in the center of the subsidence bowl have decreased from over 450 mm/year during the 1970s to 80–90 mm/year during 2000–2007. The location of the bowl, adjacent to the original liquid outflow zone of the field, has not changed significantly. Subsidence at the Tauhara field due to Wairakei production was not as well documented in the early years but appeared later and has been less intense than at Wairakei. Total subsidence of 2.6 ± 0.5 m has also occurred close to the original liquid outflow zone of this field, and maximum subsidence rates in this area today are in the 80–100 mm/year range. In the western part of the Wairakei field, near the area of hot upflow, subsidence rates have approximately doubled during the last 20 years to 30–50 mm/year. This increase appears to be have been caused by declining pressure in the underlying steam zone in this area, which is tapped by some production wells. At Tauhara field, two areas of subsidence have developed since the 1990s with rates of 50–65 mm/year. Although less well-determined, this subsidence may also be caused by declining pressure in shallow steam zones. The cause of the main subsidence bowls in the Wairakei–Tauhara geothermal system is locally high-compressibility rocks within the Huka Falls Formation (HFF), which are predominantly lake sediments and an intervening layer of pumice breccia. At Wairakei, casing deformation suggests the greatest compaction is at 150–200 m depth. The cause of the large compressibility is inferred to be higher clay content in the HFF due to intense hydrothermal alteration close to the natural fluid discharge areas. Future subsidence is predicted to add an additional 2–4 m to the Wairakei bowl, and 1–2 m elsewhere, but these estimates depend on the assumed production-injection scenarios.

Evaluation of the health status of a coastal ecosystem in southeast Mexico: Assessment of water quality, phytoplankton and submerged aquatic vegetation

The coastal environment of the Yucatan Peninsula (SE, Mexico) includes a wide variety of ecosystems ranging from mangroves to coral reefs, resulting in a heterogeneous landscape. Specifically, the marine system is characterized by environmental differences which respond to regional and local forcing functions such as marine currents and groundwater discharges (GD). Such functional characteristics were used here to define four subregions across the Yucatan coast and diagnose the health status of this coastal marine ecosystem. To achieve this goal, we conducted an analysis and integration of water quality variables, an eutrophic assessment, evaluated changes in submerged aquatic vegetation (SAV), and analyzed the community structure and distribution of harmful phytoplankton. The first step was to determine the reference values for each subregion based on data previously collected from 2002 to 2006 along the coast of Yucatan, 200 m offshore. The trophic index (TRIX) and Canadian index for aquatic life (CCMEWQI) were used to diagnose each subregion and then the ASSETS approach was conducted for Dzilam and Progreso, sampling localities on each end of the health status continuum (those with the best and worst conditions). Overall, results indicated that the marine coastal ecosystem of Yucatan is in good condition; however, differences were observed between subregions that can be attributed to local forcing functions and human impacts. Specifically, the central region (zone HZII, Progreso-Telchac) showed symptoms of initial eutrophication due to nutrient inputs from human activities. The eastern region (zone HZ III, Dzilam-Las Bocas) showed a meso-eutrophic condition linked to natural groundwater discharges, while the other two subregions western (zone HZI Celestun-Palmar) and caribbean (zone HZ IV Ria Lagartos-El Cuyo) exhibited symptoms of oligo-mesotrophic condition. These findings may be considered baseline information for coastal ecosystem monitoring programs in Yucatan, and the approach used could be replicated for other coastal areas.

Alternating low frequency stimulation of medial septal and commissural fibers induces NMDA‐dependent, long‐lasting potentiation of hippocampal synapses in urethane‐anesthetized rats

Recent evidence indicates that some synapses exhibit long-lasting synaptic potentiation in response to low frequency (1 Hz) stimulation, similar to long-term potentiation (LTP) following high frequency induction protocols. Here, the authors characterize a form of long-lasting synaptic potentiation in the hippocampal CA1 area following alternating, single pulse stimulation of the medial septum (MS) and hippocampal CA3 commissural fibers (MS-H LTP). In urethane-anesthetized rats, alternating single pulse stimulation of the MS and CA3 (50 pulses each at 0.5 Hz, 1,000 ms interstimulus interval [ISI]) produced gradual increases of field excitatory postsynaptic potential (fEPSP) amplitude in CA1 ( approximately 123% of baseline), while MS or CA3 stimulation alone was ineffective. The fEPSP enhancement was long-lasting (>4h) and repeated episodes of alternating MS-CA3 stimulation tended to result in greater levels of potentiation than those elicited by a single episode. Surprisingly, ISIs of 500, 750, and 1,500 ms did not result in significant changes in fEPSP amplitude, while an ISI of 100 ms produced synaptic depression. MS-H LTP was resistant to systemic administration of nicotinic and muscarinic receptor antagonists (scopolamine, mecamylamine), but abolished by systemic MK-801 (0.5 mg/kg, i.p.) or local CA1 application of AP-V (10 mM), indicative of a critical role of hippocampal NMDA receptors in this effect. Paired-pulse facilitation experiments revealed a gradually developing, significant inverse correlation between fEPSP enhancement and decrease in paired-pulse facilitation ratio, suggesting a role of changes in presynaptic transmitter release. Together, these data demonstrate a novel form of long-lasting synaptic enhancement in CA1 neurons in response to low frequency activity in separate afferent systems, an activity that might mimic some aspects of natural discharge patterns during the acquisition or consolidation of memory processes in hippocampal circuits.

Circolazione idrica sotterranea nelle torbiditi dell’Appennino Settentrionale (Italia): deflusso naturale e drenaggio dei tunnel ferroviari Alta Velocità

Turbidites crop out extensively in the Northern Apennine mountains (Italy). The huge amounts of groundwater drained by tunnels, built for the high speed railway connection between Bologna and Florence, demonstrate the aquifer-like behaviour of these units, up to now considered as aquitards. A conceptual model of groundwater flow systems (GFS) in fractured aquifers of turbidites is proposed, taking into account both system natural state and the perturbation induced by tunnel drainage. Analysis of hydrological data (springs, streams and tunnel discharge), collected over 10 years, was integrated with analysis of hydrochemical and isotopic data and a stream-tunnel tracer test. Hydrologic recession analysis of undisturbed conditions is a key tool in studying turbiditic aquifer hydrogeology, permitting the discrimination of GFS, the estimation of recharge relative to the upstream reach portion and the identification of springs most vulnerable to tunnel drainage impacts. The groundwater budgeting analysis provides evidence that the natural aquifer discharge was stream-focused through GFS, developed downslope or connected to main extensional tectonic lineaments intersecting stream beds; now tunnels drain mainly active recharge groundwater and so cause a relevant stream baseflow deplenishment (approximately two-thirds of the natural value), possibly resulting in adverse effects on local ecosystems.

Monitoring of Energetic and Exergetic Performance Analysis of Salihli Geothermal District Heating System

This study deals with a monitoring and assessment of energetic and exergetic analysis of Salihli Geothermal District Heating System (SGDHS) in Manisa, Turkey. In the analysis, actual system yearly average data of latest heating season are used to assess the district heating system exergetic performance. New exergetic model is improved and compared with old exergetic model results throughout the SGDHS. The new exergy losses occur particularly due to the fluid flow, taking place in the reinjection of thermal water (e.g., geothermal fluid), pumps, and the heat exchanger, as well as the natural direct discharge of the system.

Interpretation of pumping tests in a mixed flow karst system

A long‐duration pumping test performed in the conduit of a mixed flow karst system (MFKS) is analyzed and interpreted. It constitutes a unique experiment of catchment wide response of a karst system, with drawdowns measured both in the pumped conduit and in the matrix. A modeling approach is proposed for this interpretation. The developed double continuum model consists of two reservoirs ‐ karst conduits and the surrounding carbonate rocks ‐ between which flow exchange is modeled using the superposition principle and the hypothesis of Darcian flow in the matrix considered as an equivalent porous media. The karst conduits are assumed to have an infinite hydraulic conductivity. Model calibration results in a very good match (relative root mean square [rRMS] = 2.3 %) with drawdown measured at the pumping well (karst conduit). It shows that the matrix hydrodynamic parameters (hydraulic conductivity and storativity) have a greater influence on the drawdown than the storage capacity of the conduit network. The accuracy of the model relies mostly on a very good knowledge of both pumping rate and natural discharge at the spring (with and without pumping). This type of approach represents an advance in double continuum modeling of karst systems. It also provides a methodology for the management of water resources from karst aquifers.

Nutrient and suspended matter discharge by tributaries into the Berre Lagoon (France): The contribution of flood events to the matter budget

The Berre Lagoon receives freshwater from three rivers and a hydroelectric plant. The latter has become the main tributary since the beginning of its functioning in 1966. In a recent juridical context of the plant's discharge restriction, this study focussed on rivers’ implication in the lagoon's eutrophication, with a strategy particularly adapted to floods. Rivers carry an annual mean load of 27,100 tons of suspended matter (SM) into the lagoon, 275 tons N–NO 3, 36 tons P–PO 4, 680 tons total N and 130 tons total P. Depending on the river, floods are responsible for up to 99% of SM annual input, 33% nitrate, 53% phosphate, 44% total nitrogen, and 72% total phosphorus. Respecting the quotas given, the power plant remains the main tributary of the lagoon: at least doubling the annual natural discharge of SM and nutrients. Nevertheless, global discharges are lower than those measured 20 to 30 years ago were due to the restrictions applied to the power plant, to dryer conditions and better treatment of sewage waters along the catchment basin.

Groundwater resources in the Jabal Al Hass region, northwest Syria: an assessment of past use and future potential

In many cases, the development of groundwater resources to boost agricultural production in dry areas has led to a continuous decline in groundwater levels; this has called into question the sustainability of such exploitation. In developing countries, limited budgets and scarce hydrological data often do not allow groundwater resources to be assessed through groundwater modeling. A case study is presented of a low-cost water-balance approach to groundwater resource assessments in a 1,550 km2 semi-arid region in northwestern Syria. The past development of irrigated agriculture and its effect on the groundwater system were studied by analysis of Landsat images and long-term groundwater level changes, respectively. All components of the groundwater balance were determined. Groundwater recharge was estimated using the chloride mass balance method. Over the past three decades, groundwater levels have declined, on average, 23 m, coinciding with a two-fold increase in the groundwater-irrigated area. Groundwater resources are currently depleted by a value that lies between 9.5×106 and 118×106 m3 year−1, which is larger than can be compensated for by a future decrease in natural discharge or changes in boundary conditions. However, groundwater resources are likely to be sufficient to supply domestic and livestock needs in the area.

Impacto do Uso de Vazões Naturais em Estudos Hidrológicos

A major effort has been dedicated to the reconstitution of natural discharges. The natural discharge is the sum of the consumed discharges and the observed ones. The effect of anthropic actions in the Paracatu basin increased water consumption about 11 times in the last 27 years. This study was undertaken to evaluate the impact of the use of natural discharges to substitute the observed ones in different sections of Paracatu basin. The data of the observed and natural discharges of 21 rivergaging stations from 1976 to 2000 were analyzed. The impact of the use of the natural discharges was estimated to the maximum (Qmax), the medium of long duration (Qmld) and the minimums discharges (Q7,10; Q95 and Q90) by using an index, characterized in this study as ∆ (delta). The correlation between the drainage area of each section and its respective delta was calculated. The delta behavior was analyzed using a graphic, according to the values of the natural discharges. The statistical analysis used the Student t test (α = 5%). The mean value of the ∆ for Qmax, Qmld ,Q90, Q95 and Q7,10 was, respectively, 0.01%, 0.66%, 4.26%, 5.45% and 5.76%. All these deltas were considered significant (α = 5%). The highest values of discharges led to the lowest values of delta. The deltas of the maximum, medium of long duration and minimums discharges were statistically different. The correlation between the drainage area and the delta was not significant. The delta behavior according to the values of the natural discharges followed a potential model with negative declivity at a high R2 (0.9842). For the purpose of hydrologic studies of the Paracatu basin, the use of natural discharges in the case of the maximum and medium of long duration is not a concern, but in the case of the minimums discharges, it is recommended to take some precautions

Numerical modeling of the electrical breakdown and discharge properties of laser-generated plasma channels

An extensive nonequilibrium steady-state kinetics model incorporating collisional and radiative processes is developed to study the electrical breakdown and discharge maintenance of laser-induced atmospheric plasma channels formed in externally applied electric fields. The model is based upon a self-consistent numerical solution of the Boltzmann equation for the electron energy distribution function coupled with the electron energy balance equation and the population balance equations for electrons and air species. Using the electron energy distribution function, the ionization and electron attachment rates as a function of the reduced applied electric field at different degrees of ionization are calculated. We find that the ionization rate as a function of applied electric field in a laser-induced plasma channel is orders of magnitude larger than that obtained for a natural atmospheric air discharge. Therefore, the electrical breakdown of these plasma channels may occur at significantly lower applied electric fields. The present model predicts a breakdown electric field of 10kVcm , while the experimentally determined breakdown field strength is approximately 5.7kVcm [A. P. Baronavski, NRL Memorandum Report No. NRL/MR/6110-02-8642, 2002 (unpublished)], a reduction of about a factor of 5 from the natural Paschen electrical breakdown field of approximately 30kVcm .

Hydrogeological characteristics of a groundwater‐dependent ecosystem (La Lantejuela, Spain)

AbstractBy means of a simple water balance model, together with hydrogeochemical and morphological interpretation, the hydrogeological characteristics of a series of playa lakes forming an endorheic complex within the Guadalquivir river basin in Southern Spain (La Lantejuela) have been evaluated. The lakes are demonstrated to be groundwater‐dependent ecosystems. The main source of groundwater input to the lakes is from an unconfined detritic aquifer, the playa lakes being the natural discharge points from the aquifer within the endorheic complex. High rates of evaporation from the lakes induce a centripetal groundwater flow pattern. This water body has been disturbed by a combination of extensive drainage works and intensive groundwater abstraction. There is a need for a sustainable water management strategy for the whole catchment area. It is hoped this will be an issue addressed within the Guadalquivir river basin management plan in accordance with the requirements of the European Water Framework Directive (WFD).

Environmental flows for the Yangtze Estuary based on salinity objectives

Environmental flows based on the salinity objectives for China’s Yangtze Estuary were quantified to assess the impacts of changing freshwater inflow on the estuarine ecosystem. The salinity objectives for three benthos habitats in the Yangtze Estuary were studied to determine their requirements during the most critical period of the year. The temporal variation in the natural monthly river discharge represented the temporal variation of the ecological objectives used to maintain natural flow regimes. A numerical model, coupled a hydrodynamic processes model with a salinity model and validated using field data of tidal height, current velocity, and salinity at different stations, was developed to simulate the spatial distribution of salinity as a function of the variation in freshwater inflows. The prediction results of the proposed model agreed well with the field data. Considering the salinity objectives for the different habitats, the environmental flow requirements for the Yangtze Estuary were determined. Annual environmental flows should be 9.63×1011, 6.32×1011, and 4.70×1011m3 for the high, medium, and minimum objectives, which are equivalent to 104%, 68%, and 50% of the annual river discharge, respectively. The periods from September to November should be considered as the critical seasons to maintain the minimum environmental flows in the Yangtze Estuary.

Critical Environmental Flows to Support Integrated Ecological Objectives for the Yellow River Estuary, China

The volume of inflowing water needed to meet multiple demands in the Yellow River Estuary of China was examined and quantified. Pressure on available environmental flows comes from varied ecological objectives, including maintenance of freshwater habitat for hundreds of plant and animal species, salinity balance, sediment transport and general equilibrium of the hydrologic cycle. Temporal fluctuations of flow input and output were considered and the amount of water needed for both consumptive and non-consumptive uses was evaluated. The rule of summation was used to calculate consumptive water requirements and the rule of compatibility (i.e., maximum principle) was adapted to estimate the non-consumptive ones. It was determined that the minimum, medium and high levels of annual environmental flows are 134.22 × 108, 162.73 × 108 and 274.9 × 108 m3, respectively, in the Yellow River Estuary, which represent 23.7, 28.7 and 48.5% of the natural river discharge. Water requirements differ across months. The months of May through June, August and October were identified as the most critical periods for maintaining the environmental flows. The basic purpose of water entering the system is to compensate for water losses due to evaporation and to maintain an acceptable level of salinity in the estuary. Sediment transport into and through the estuary area are likely to be directly impacted by variations in river discharge. Improved efficiency in the sediment transport regime of the Yellow River could potentially reduce environmental flow requirements of the estuary, thus freeing water resources for other beneficial uses.

Runoff variations in the Luanhe River Basin during 1956–2002

The decrease of runoff in the Luanhe river basin, which caused water crisis in Tianjin for several times, was investigated using discharge data covering the period 1956–2002. The data from the differential integral curves of the annual runoff indicate that the decreasing point began in 1979 in the six sub-basins. The decrease of runoff in the Luanhe river basin resulted from the combination of climate effects and human activities, in which the latter plays an important role. This can be illustrated by noting that after 1979 the runoff generated by similar precipitation decreased under the condition that the total precipitation did not decrease in the entire basin. As a result, the annual runoff of the Luanhe river basin after 1979 decreased by about 6.46 × 108 m3 each year. To analyze the runoff characteristics, it is inadequate to seek the runoff trends only and the identification of cyclical component of the runoff as accurate as possible is necessary. From the natural annual runoff discharge time series, we can see the annual runoff fluctuates around the long-term average. Analyzed by VRL (Variable Record Length) method, the main periods of 3, 5–6, 7, 9, 16–20 and 37–39 years were found. The last decade causing water crisis was the driest period in the history, and this condition will last several years from trend analysis and power spectrum analysis. So finding new water sources is urgent to solve water crisis in Tianjin city, and the South-North Water Transfer is a feasible option.

Test methodology for determining the incendiary nature and electrostatic discharge characteristics of plastic surfaces

This experimental study was originally designed to quantify the electrostatic characteristics of offshore grade fiberglass reinforced plastic (FRP) pipes [Dastidar, A. G., Dahn, C. J., Cole, B. W., & Lo, K. H. (2005a). Electrostatic characteristics of FRP pipes. In Fourth international conference on composite materials for offshore operation, Houston, TX, Oct 4–6, 2005]. Discharge energies were measured from the sample surfaces for each test condition after an aggressive corona charging of up to −40 kV. While the measured values of total discharge energy were relatively high for some samples, the energy in the first peak was significantly lower. The first peak energy is thought to be the most significant measure in establishing the potential for incendive events. To further quantify the incendive potential of discharges from FRP pipes, a unique test method was developed [Dastidar, A. G., Dahn, C. J., Cole, B. W., & Lo, K. H., (2005b). Incendiary nature and electrostatic discharge characteristics of FRP pipes. In Fourth international conference on composite materials for offshore operation, Houston, TX, Oct 4–6, 2005]. The methodology has been expanded to include other FRP components. This paper describes the test method and the test results obtained for testing several FRP structures and materials (pipes, grill work, railing etc.). The significance of the experimental results to industry is also discussed.