Managing Sediment in Peru's Pativilca River Basin

摘要

In view of the high content of solids in the Pativilca River, a number of activities have been undertaken, resulting in a reduction of aggregate unit downtime, increased working hours of turbines and a recovery of generation revenues, primarily due to the installation of new turbines and a new way of operating the intake, gates and desander bays. The payback period is expected to be about seven years, with the profits from recovered production from each runner equaling more than $101,300 per year. Gauging and solid analyses were performed to know the properties of the sediments, and with these results, the following improvements were made: 1. A system that includes a small laboratory was installed for measuring suspended solids entering the desanders and headrace tunnel; 2. Turbines were installed that can work with 10 g/l of material in suspension; and 3. The operation of gates and sand traps was optimized. The improvements achieved to date have resulted in a reduction in down time to seven to 15 days per year, longer working hours for the turbines and the recovery of revenue generation. While sediment control has seen a significant improvement, the solid management can still be optimized to increase revenues at Cahua through: 4. Arrangements in the desander bays, which are currently under review; and 5. An early warning system to operational decision making, using conceptual rainfall-flows-suspended solids modeling guidelines presented in this article. In addition, tributaries in the Pativilca River Basin with higher solids were identified, and to further improve sediment management at the Cahua project, a digital rainfall station with remote signal is planned to be installed in September in these tributaries to give early warning (two to three hours in advance) of the presence of suspended solids in the intake for making operating decisions. For this, a new model of rainfall-flow-suspended solids will be developed. Once the model is calibrated and according to the results obtained, the implementation of an early warning network will be planned. This system can then be replicated in other basins with behaviors similar to the Pativilca River.