52 / 2023-12-25 14:51:20

Evaluating Operation of Pao-Cachinche Water Reservoir in Period 1983-2009

water reservoir,water management,operation evaluation

This study evaluates the performance of the operation of the Pao-Cachinche Water Reservoir (PC-WR) during the period 1983-2009 through the application of stochastic technique (ARIMA: Autoregressive Integrated Moving Average), deterministic technique and artificial intelligence (i.e. ANN: Artificial Neural Network) modeling techniques using reservoir operation variables. This study was carried out in five stages: Stage 1: Data collection. Data was collected from public institutions. Stage 2: Characterization of Central Regional Aqueduct System (CRAS). CRAS was divided into three subsystems: (a) Subsystem 1: Pao River Basin, (b) Subsystem 2: PC-WR and (c) Subsystem 3: Entrance to the Alejo Zuloaga Treatment Plant. This study was focused on Subsystem 2. Stage 3: Diagnosis of the reservoir operation during the period 1983-2009. In this stage, the behavior of the daily historical series, during the period 1983-2009, of the net contribution, pumping flow, ecological expenditure, evaporation and relief in the reservoir were analyzed. Stage 4: Data processing Forecasting, artificial neural network and systems models are applied. Stage 5: Evaluation of the results. The monthly inflows were graphed against the monthly discharges (outflows) corresponding to the annual water balance in the reservoir, during the period 1983-2009. The long-term trend of the historical records of contribution and extraction during the period 1983-2003 was cyclical and irregular, due to the occurrence of dry and rainy seasons; with a decreasing trend of 30%. With the diversion of the Cabriales River in 1999 and the transfer of Valencia Lake in 2004. Since 2005, PC-WR had operated at capacity, showing a condition of permanent relief, even in the dry season, due to the increase in inflow volumes. The pumping extraction flow between 1983 and 2003 maintained a linear trend (1,020 L/s). Since 2005, the flow of water extraction by pumping in PC-WR showed a gradual trend towards increase, with an increase of approximately 5% annually, due to the transfer of Valencia Lake. If this trend continues, it could reduce the useful volume of the reservoir and compromise the water supply. Ecological spending showed a linear trend between 1983 and 2003. With the transfer of Valencia Lake in 2004, the flow discharged into the Pao River bed increased by 25%. If this trend continues, it might cause, in the long term, an alteration of the Pao River ecosystem.