**3. Method**

To evaluate the impact of the operation of the PHLC in the lagoon and MaNas zones, a flash flood period for an average historical year from September 19th to October 6th, 2010 was analyzed. Two conditions were applied: without the dam using the hydrograph measured during the mentioned period, and with the dam using the turbine hydrograph plus the contributions of its own basin. **Figure 4** shows the two hydrographs considering these scenarios.

The operation of the PHLC in the lagoon and MaNas zones shows that the two hydrographs, with and without the dam are practically the same, so one can conclude that the alteration of the flow in flash floods due to the presence of the PHLC would be minimal, without any important consequence for the downstream areas. Another fundamental aspect to consider is the sedimentation sites and granulometric characteristics of the material. For that, Gracia-Sánchez et al. [27] applied physical models looking for a reliable representation of the reservoir entrance. Thus, sites with materials between 1.0 and 0.1 mm were identified for their possible extraction and, consequently, to refine or adjust the model results. With this information a numerical model was developed founding that only four sites required an adjustment (**Figure 5**), these sites are the mouths of Camichín (SEC1) and Palapares (SEC11), the Toluca Lagoon (SEC25), and the Mexcaltitlán lagoon (SEC85). However, even though the numerical model represents well the deposit of sediment at the entrance of the reservoir, there is no interpretation of the granulometric distribution that occurs in the deposit, particularly in the case of the PHLC, which is crucial to define the future transport downstream the curtain.

*Interconnection among River Flow Levels, Sediments Loads and Tides Conditions and Its Effect… DOI: http://dx.doi.org/10.5772/intechopen.109175*

*Hydrographs for the simulation scenarios in the flash flood season.*

**223 Figure 5.** *Flash flood analysis sites.*
