HYDROLOGIC STUDIES FOR THE LA LECHE DAM AND RESERVOIR

SCOPE OF WORK

Dr. Victor M. Ponce, Consultant

July 11, 2007

This document details the hydrologic studies to be performed in relation to the La Leche river dam and reservoir project, in Lambayeque, Peru. The focus of the study is the determination of peak discharges for the design of the emergency spillway. The study will accomplish the following tasks:

  1. Review of existing studies. The Consultant will review the existing hydrologic and hydraulic studies, dated 1992, with aim to use this knowledge in the formulation of the hydrologic study.

  2. Visit to the site. The Consultant will perform a visit to the dam and reservoir site, with aim to gather field data required for hydrologic modeling. Data on soils, vegetation, and typical channel cross sections, will be gathered in the field as needed to support detailed hydrologic modeling. Maps and aerial photos will be used to support modeling. The Consultant will discuss project needs with the local staff.

  3. Gathering of relevant hydrologic data. The Consultant will gather climatological and hydrologic data in the SENAMHI offices in Chiclayo and Lima. The Consultant will purchase the existing precipitation and flow data that will support hydrologic modeling.

  4. Basin hydrologic modeling. The Consultant will perform basin hydrologic modeling using a HEC-HMS type model, with the objective of determining the flood discharges for 2-, 5-, 10-, 25-, 50, and 100-yr frequency. In addition, the Consultant will extend the flood series to 10,000-yr flood using the Gumbel method. The 10,000-yr flood is akin to the Probable Maximum Precipitation.

  5. Climate Change. The Consultant will make an assessment of how impending climate change may affect the flood hydrology of the region, and will take into account the climate change factor in the hydrologic modeling. The El Niño (ENSO) effect will be considered.

  6. Yield hydrology. The Consultant will work closely with the dam designer to ensure that the amount of water stored in the reservoir is sufficient to irrigate 15,000 hectares and provide water to eight communities of 50,000 people each.

  7. Project Coordination. The Consultant will work in close coordination with the Project Manager in order to ensure the success of the overall project.

  8. Recommendations. The Consultant will provide recommendations for the hydraulic design of the overflow spillway. Specifically, the Consultant will provide the design hydrograph for the emergency spillway. The Consultant will also provide the freeboard hydrograph, which is applicable for the Probable Maximum Flood.
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