Gauging stations

Fig. 2 Study area, digital elevation model and subcatchments used for the hydrological simulations, along with the location of the gauging stations of precipitation, air temperature and stream-flows. Yellow polygons indicate the location of the four subcatchments selected for carrying out the hydrological simulations during the control and the future scenarios described in Sect. 6...

Fig. 5 Spatial distribution of the average annual precipitation during the control period 1961-1990, computed using ordinary kriging interpolation with cells of 1 km2 and 40 nearest neighbours. Crosses represent the location of the gauging stations...

Values computed by averaging over the corresponding gauging stations... 

Gauging stations Q063, Q071 and Q093 are only slightly disturbed [30], and therefore no withdrawals were incorporated in the simulations of their corresponding catchments. 

The Centro de Estudios Hidrograficos del Centro de Estudios y Experimentacion de Obras Publicas (CEH-CEDEX, http //hercules.cedex.es) provides the daily discharges for 275 gauging stations in the Ebro watershed. The CHEBRO website... 

There are 318 river gauging stations within the Ebro basin [80]. Around 60 of these monitor natural flow regimes and are typically located around the edges of the basin in the medium to higher reaches of the tributary rivers [8], Others are located on rivers whose streamflow has been altered by reservoirs (see [9] for a review of historical water policy in Spain). In total, 187 reservoirs impound 57% of the mean annual runoff [10]. As an example, annual discharge measured... 

Fig. 3 Measured streamflows at gauging station 027 Ebro en Tortosa during the control period 1961-1990. The upper figure shows averaged monthly streamflow where the central boxes indicate the middle 50% of data the thick horizontal line indicates the mean the whiskers show the range of data (10th to 90th percentiles) and the dots show outliers. The lower figure shows annual flow at the gauging station. Daily data provided by CHE...

Hydrologisches Zentralbiiro (2003) Water level and discharge gauging stations. Hydrological Atlas of Austria, Plate 5.1, Wien... 

In the 20th century, an appreciable rise in the water levels of the Black Sea was recorded. At the gauging stations, the sea level rise is measured with respect to the land surface hence, it is called the relative sea level rise (RSLR). 

Water object Gauging station Period Average RSLR, Refs, mm year 1 ... 

In order to assess the variability of dissolved trace elements in the Amazon River, a monthly time series covering the 1997 hydrological year was obtained at the Obidos gauging station. As previously mentioned, Obidos is the last station situated upstream the marine influence. 

Figure 7.26 shows 20-day water level records at the Wismar gauge station and, for comparison, a tidal synthesis comprising 63 tidal constituents. Although the dotted line temporarily reflects considerable wind forcing, the tidal signal nevertheless remains clearly visible. Also the semidiurnal character of the tides in Wismar is quite obvious. In Helsinki, for example, tides are diurnal. 

Consequently, Friedrich Pasc hen (1804-1873) included the culminations of the moon in his water level analyses at the Wismar gauge station (Paschen, 1856) in order to prove the existence of Baltic Sea tides. His primary goal was to clearly disprove the widespread notion that the ebb and flood tides are not noticeable in the Baltic Sea. This was also supported by the observation that, with constant wind conditions, the mouths of rivers discharging into the Baltic Sea could be observed to alternate several times a day between inflow and outflow. 

With the model approach described above, it has been possible, for the first time, to represent the tides in the entire B altic Sea, which could not be done using the measured water level data from coastal gauge stations. 

In the end of the nineteenth century the Danish Meteorological Institute (DMI) established 10 tide gauge stations scattered along the Danish coast with this only objective To calculate and define a national reference level (Chart damm). This network of stations was in the twentieth century supplemented with additional stations (more or less permanent in time and location) resulting in a present network of 15 stations. 

The German coastal gauge stations were included in the NN datum system at the end of the nineteenth century. The mean value of long-term water level records in Amsterdam was used as a basis. In 1937/1938, the gauge datum (PN) was set at 500 cm below NN in order to avoid negative values. 

Official surveys in Schleswig-Holstein (gauge stations Kiel-Holtenau, Travemiinde) are based on the Deutsches Haupthohennetz (DHHN92, German First Order Levelling Network). The damm of the Amsterdam gauge station is still used as a reference point. The formula that applies is PN = NN— 500 cm. 

Different system differences between HN and NN resulted for the individual coastal gauge stations, leading to different correction values. 3.0 cm was determined for Sassnitz, and 1.9 cm for Wamemunde. In order to obtain water levels referred to the levelling system (PN = HN 514 cm), this value has to be added to the measured values of the gauge stations, which are still referred to the NN system. 

Before the first quarter of the twentieth century the hydrological observations had not been systematic. The longest series of observations are available from the gauging stations of Kerki (1910-1920, 1925-1937, 1952-2006) and Chatli (1913-1917, 1931-1973) [6-10]. 

The mean values of annual inflow to the summit of the Amudarya delta based oti hydrologic observations of gauging stations in v. Qiatli (1931-1973), Kyzildjar (1959-1987), and Samambay (1974—1996) for particular time periods are presented in Table 8. 

Hydrological monitoring is based on data collected from 1000 gauging stations in rivers, lakes and water reservoirs. Information on the water levels is supplied in 10 minute cycles. Water level gauges used by hydrological stations are either electric sensors for hydrostatic pressure or optical sensors. The hydrological monitoring system is of key importance for flood risk evaluation and for prevention of flood effects. 

As an example, consider the calculation of concurrent absorption as applied to a gas-condensate field with low reservoir pressure and positive temperatures of gas at the entrance to the DCPG. Such thermobaric conditions make it possible to carry out intrapipe absorption even with such a low-efficient absorbent as weathered condensate. To increase the condensate recovery in the process of absorption, we can deliver the absorbent into gas flow in the pipeline before the separators at the gas gauging station. Before we start to calculate the absorption process, it is necessary to determine the composition of weathered condensate that gets collected after the first stage of separation. Denote by pB and Tb the pressure and temperature in the divider where the condensate weathering takes place. The composition of the condensate collected after the first step of separation, and also the composition of the reservoir gas are given in Table 20.3. 

Determine compositions of the gas and the condensate after their mixture before the gauging station. 

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