Nivel 9 20 where is my water

Cazenave, J. Gregory, S. Jevrejeva, A. Levermann, M. Merrifield, G. Milne, R. Nerem, P. Nunn, A. Payne, W. Pfeffer, D. Stammer and A. Sea Level Change. Qin, G. Plattner, M. Tignor, S. Allen, J. Boschung, A.

Nauels, Y. Xia, V. Bex and P. Midgley eds. Surveys in Geophysics, 32 , — Domingues, R. East Coast During —?

Geophysical Research Letters , 45 24 , 13,, Summary for Policymakers. Accessed November 2, Leuliette, E. The budget of recent global sea level rise: Published by the National Oceanic and Atmospheric Administration. Accessed November 18, Sea level trends.

Parris, A. Bromirski, V. Burkett, D. Cayan, M. Culver, J. Hall, R. Horton, K. Knuuti, R. Moss, J. Obeysekera, A. Sallenger, and J. Accessed November 18 Pelto, M. Alpine glaciers: Another decade of loss. Sweet, W. NOAA Tech.

Sweet W. Park, J. Marra, C. Zervas and S. Therefore, the actual discharge for a given water level will be greater than the "normal" discharge taken from the simple rating curve when the water level rises and the actual discharge will be lower than the "normal" discharge when the water level decreases.

In all these cases, in which the free surface of the water and its gradient are variable and there is no simple relationship between the levels and the discharges, complex rating curves must be developed.

A calibration loop can be plotted by joining the consecutive discharge data during a flood. If the complex rating curve has already been established, the loop for each flood can be obtained without discharge measurements by joining the successive points of instantaneous levels and the corresponding calculated discharge of that curve.

Generally, two types of auxiliary curves are used in the determination of the rating curve: i H vs. This last method was not applied in the La Balsa station, because there is no auxiliary topographic stadia rod near the station that allows determining the slope of the free surface of the water. The main components in this method are a Level - Discharge curve for steady regime and a storage curve.

The actual discharge is calculated by adding a correction per storage to the discharge obtained from the Level - Discharge curve for steady regime. The storage correction is the value obtained from the storage curve multiplied by the rate of change in the water level. The equation to determine the discharge in non-steady regime is the following:.

The method of variation rate of water level does a correction of the discharge in the river in accordance with the storage that occurs during a flood. The rating curve is obtained by trial and error, starting with a curve plotted very close to the measurements made during the condition of steady or quasi- steady regime.

The storage curve represents the storage correction due to the variation rate over time of the water level and is based on these plotted points. Each measured discharge is adjusted to steady regime conditions corrected by storage effect using the storage curve. The process is repeated until refinement of the rating curve or storage curve is not possible.

Those points based on measured flows, whose rates of variation in water levels during gauging J are high have a greater weight and, therefore, the storage curve should be plotted close to those points. The curve should be as gradual or smooth as the data allow.

Prepare the field data and tabulate the following information: indicator or number of the gauging Column 1 , measured water level H, Column 2 , gauged discharge Qm, Column 3 and hourly change rate of the water level during the gauging J, Column 4. Plot a first curve Level - Discharge: the curve must be plotted very close to the points corresponding to the steady regime, to the left of the gaugings carried out during the ascending water levels and to the right of the descending water levels.

Then skip to step 6 for the first calculation or trial. Plot the curve Level Vs. Adjusted Discharge: this curve must average the points plotted in point 4, as much as possible. Read the discharges values of the curve plotted in step 3 first trial or in step 5 subsequent trials. These discharges are recorded in Column 5 Qr. Plot the Storage Curve, i. If an additional trial is required, return to step 4. Calculate and record in column 11 the relative difference Rel. Between the adjusted discharge Qaj and the read discharges Qr according to the expression:.

If the relative differences are acceptable, continue with step 16; otherwise, perform a new test by returning to step 4. Final test: With the data of the measured water levels during a flood in the river, calculate the corresponding discharges. Otherwise, a new trial must be carried out by returning to step 4. Calculation of discharge based on the complex rating curve water level variation rate method.

Tabulate the hourly water level data, including date and time. Calculate the value of the variation rate of levels J for each water level data. It must be taken into account that:. For each level value read the corresponding discharge value Qr of the rating curve plotted for steady regime. Figure 2 shows the simple rating curve obtained for the La Balsa station.

It is observed that the slope of the line, which represents the exponent of H-H 0 , is less than 2. Figure 2 Water level variation in La Balsa station. Period 1 to 5 January In order to generate the rating curves, the existing gaugings from to in the different hydrometric stations were considered.

In La Balsa station there are gaugings records carried out during the ascending and descending phases of floods, as well as in steady state conditions; this allowed calculating the corresponding complex rating curve.

Generally, the fluctuation of the water level during gaugings is important. Table 1 shows the calculations made to determine the complex rating curve in La Balsa station through the Water Levels Variation Rate Method.

As shown in this table, the number of field records available for the ascending and descending phases of floods is limited. Table 2 shows the calculated discharges for the moderate flood of January 01 of To illustrate the differences that can occur in the estimated discharges, the two rating curves found simple and complex were applied for the moderate flood of January 01, In the hydrographs obtained Figure 4 , it is observed that when the simple curve steady state is used during the ascending phase of the flood the discharges are underestimated with respect to the real situation, i.

For more intense floods the differences could be greater. Station: The: La Balsa. Figure 3 Rating curve Level - Discharge in steady state condition. Figure 4 Determination of the discharges of a flood in the Cauca River from simple and complex rating curves. Station: La Balsa Date: January 1, An important first step to obtain the rating curve in a station of a river is the analysis of the available information for the selection of the gauging data to be included in the procedure and, especially, the evaluation of the dynamics of the river to establish the type of dominant regime and the characteristics of the stretch and the natural conditions discharge of a tributary, for example and artificial conditions a reservoir, a derivation, etc.

The analysis of the variation of parameters, such as the hydraulic factor and the discharge as a function of the water level, the levels of the bed, the rates of variation of the water levels and the gradient of the free surface of water during the gauging, allows defining the characteristics of the gauging section, the type of the Stage - Discharge relationship and the procedures more appropriated to determine it.

It also helps to establish the validity time of the curve. To determine the simple rating curve in the La Balsa station, the logarithmic method was implemented because it allows identifying the type or types of control section or channel that determine the Stage - Discharge relationship and, therefore, extrapolate with less uncertainty the rating curve; in addition, it is easier to establish if there are changes in the type of control and, therefore, to determine with better precision the shape, curvature and tendency of the rating curve, for the different ranges of levels and in the transitions between two controls.

From the computed along-track water levels, outliers are rejected by Standard Deviation test and an average water level is computed. Final selection step ensures consistency of the most recently computed water level value with the existing water level time series.

Calmant, S. Advances in Space Research , 51 , - DOI Cretaux, J. Abarca; Cazenave, A. Advances in Space Research , 47 , - Water Level products are validated in absolute terms, by checking the dispersion of consecutive measurements of the same targets and within the same basin in relative terms by correlating to in situ observations, that may or may not be co-located in time and space, and comparing water level with water surface area for lakes by comparison between satellite missions, in particular Jason-2 and Jason-3 The dispersion of the water level estimates over rivers was computed for each major basin with respect to the number of measurements and the seasonality, analysing high- and low-water separately.

Number of colocations Correlation median value Correlation mean value 10 km 5 0. Main application domains:. The Water Level products are commonly used for applications using transboundary water level observations, such as climatological studies at basin, continental or global scales. Main users:. Water management authorities University and Research institutions. Projection and grid:. Temporal information:. File format:. Data file content:. Product Version File s Size Available since 2.

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