Irrigation Pumping Plant Efficiency in Wells in Eastern Valley of Mexico

摘要

Where there is no surface water for crops, irrigation water is obtained from groundwater sources through deep wells. Over extraction of aquifers has depleted static and dynamic levels and, consequently, pumping from greater depths is necessary. In eastern Valley of Mexico the water table declines from 1 to 1.5 m per year, making it necessary to modify the original design of the wells with a performance curve that differs from that for which the pumps were selected. This causes low overall pumping plant efficiency (EEP). Poor maintenance of the well and the electromechanical equipment have also contributed to reducing efficiency. Another cause could be loss of interest in agriculture since it is no longer profitable and farmers have turned to other activities. Variables for calculating EEP in eastern Valley of Mexico were diagnosed and measured, following the Mexican Standard (NOM - 006-ENER, 1995), recommendations of the Trust for Energy Savings (FIDE) of the Federal Electricity Commission (CFE) and those of CONAGUA for efficient water use. EEP is the relationship in percentage of the energy (hydraulic) obtained over the energy (electric) supplied. The calculation variables were measured in more than 40 wells, although only eight that could be adequately measured are reported. Levels were measured with an electric HGE probe, flow with an ultrasonic PT878 GE Parametrics meter, and electric variables with a 435 FLUKE analyzer. The results showed that pump efficiency varied from 23 to 56%. Rehabilitation of wells and electromechanical parts with efficiency below 40% was recommended to obtain reasonable pumping costs and contribute to efficient water and energy use.