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Modern Geomatics Technologies and Applications




           rate  of  subsidence  for  the  years  2008  to  2013  obtained  from  settlement  gauge
           observations is 129 mm/yr, whereas rate of subsidence is 105 mm/ yr based on precise
           leveling. This small difference is concerned to date of precise leveling observations,

           because the 7th and 8th epochs of leveling observations have been done in November
           2007 and November 2009, respectively and due to the relatively large subsidence that
           has occurred in the interval between the 7th and 8th periods (Figure 2), if the 8th epoch

           of leveling observations was performed in 2008, it certainly had a very good agreement
           with settlement gauge measurements.

                          28-Feb-08  1-May-08  3-Jul-08  4-Sep-08  6-Nov-08  8-Jan-09  12-Mar-09  14-May-09  16-Jul-09  17-Sep-09  19-Nov-09  21-Jan-10  25-Mar-10  27-May-10  29-Jul-10  30-Sep-10  2-Dec-10  3-Feb-11  7-Apr-11  9-Jun-11  11-Aug-11  13-Oct-11  15-Dec-11  16-Feb-12  19-Apr-12  21-Jun-12  23-Aug-12  25-Oct-12  27-Dec-12  28-Feb-13

                      -1.00                                                 384.00
                      -1.50                Settlement Rate (SM-33)          383.50
                    Settelment (m)  -2.50                                   382.50  Embankment
                                                                            383.00
                      -2.00
                      -3.00
                                                                            382.00
                      -3.50
                                                                            381.50
                                                                            381.00
                      -4.00
                      -4.50
                                                                            380.00
                      -5.00                                                 380.50
                                                 Date
                        SM-3308 318     SM-3309 328    SM-3310 338     SM-3311 349
                        SM-3312 359     SM-3313 369    SM-3314 379     EMBANKEMENT
                                Figure 12: Observation of settlement gauge SM33

           Figure 13 shows the settlement occurred in the crest of dam through the years 2003 to
           2013  (4th  epoch  to  13th  epoch)  obtained  from  precise  leveling  observations.  As
           expected, the  subsidence in  the  middle  part  of  dam  is  significantly  more  than  the
           corners and exceeds 2 meters during this time interval. Approximately, in most periods

           of measurements, subsidence has the same pattern, except in the interval between the
           6th and 7th steps of microgeodesy measurements that an abruptly subsidence has been
           occurred. This really is a result of the long time interval between the  6th and 7th

           measurements, since the sixth and seventh epochs of observation have been done in
           June 2004 and Oct. 2007, respectively. Average level of reservoir has been 369.7 and
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