Sedimentation and Climate Change on reservoirs in northern Peru

Juan Walter Cabrera Cabrera, Julio Isaac Montenegro Gambini

Wednesday 1 july 2015

9:15 - 9:30h at North America (level 0)

Themes: (T) Extreme events, natural variability and climate change, (ST) Hydrological extremes: floods and droughts

Parallel session: 8I. Extreme events - Flood Drought

Peru is a climatology complex country located in South America. Its Coast is characterized by flat surfaces, a semi arid climate, and a few rivers which drain to Pacific Ocean. In northern Peru, the rivers are characterized by high flows however, in the southern rivers have low flows; for this reason, an important number of irrigation projects have been planned and developed in northern and the most important reservoirs are located over there. The river dynamic produces sediment which will be deposited in the reservoir and will reduce its life. Poechos reservoir represents the most critical case. This is the largest dam in Peru and it was designed to store 885 MCM of water but its volume has been reduced to 418MMC due to heavy sedimentation processes to which it is exposed. Recent studies suggest that could be completely silted by 2035, a process that could be accelerated if we consider the effects of global warming. In this article the potential effects of climate change on the storage capacity of reservoirs in northern Peru is discussed. These reservoirs are part of important irrigation projects like Chira-Piura and Olmos-Tinajones Project. First, an empirical correlation between monthly discharges and sediment volume is calibrated to every reservoir. After that, the abc rainfall–runoff model is calibrated to every basin. Then, the projected changes in precipitation and temperature are used to generate projected series which are input to the calibrated R-R model to estimate projected discharges and new sediment loads that will affect the life of the reservoir. The analysis was performed using the projected changes by ECHAM 4, HadCM3 and NCAR DOE PCM models, which have higher spatial resolution. The results show an important reduction in the life of the reservoir as a result of increased volumes and the resulting increases in sedimentation and silting.