Water sources to the Ciénega include agricultural return water from the U.S. delivered through the Main Outlet Drain Extension (MODE) to the Bypass Drain in Mexico and agricultural return water from Mexico’s irrigation district through the Riito-Santa Clara drain.

The research team is measuring flows in the bypass drain and the Riito-Santa Clara drain near the discharge point to the Ciénega. We are manually measuring water flows into the Ciénega with a FlowTracker Handheld ADV device made by SonTek/YSI Inc. The FlowTracker Handheld ADV is a single-point Doppler current meter designed for field velocity measurements and it uses the proven Doppler technology of the SonTek/YSI Acoustic Doppler Velocimeter (ADV). This discharge measurement device has one of the highest qualities in the market. It has been tested by the USGS under different conditions and was found to perform well in many stream environments (USGS, 2004).

We are taking the discharge measurements at two locations. The measurement at the Bypass drain is taken on the upstream side of the access bridge (see figure)ear the end of the lined portion of the drian, while at the Riito drain is taken at a culvert located where the drain intersects with the road to the Ejido Luis Encinas Johnson.

Flow measuring point at the Bypass drain.

Flow measuring point at the Riito drain.

In both locations we have installed a water gauge and a pressure-based water level logger. The logger at Riito is an YSI 600 LS logger that measures water level, specific conductivity and temperature and the logger at the Bypass drain is a HOBO that measures water level and temperature. The data loggers take a measurement every hour, and data is download and processed once a month.

The measurements of water level at the water gauges allow us to verify the actual elevation measured by the loggers and to convert them into actual levels referenced to mean sea level.

The UABC and the Sonoran Institute are measuring flow discharge with the Flow Tracker every two weeks. We expect that the combination of direct discharge measurements and the water level measured by the sensors will allow us to develop a calibration curve and be able to estimate a daily average flow at each location.

Data Available

Table I. Inflows into the Ciénega in cubic meters per second.

** Value modified after verification * Preliminary value.

We are measuring flow discharge at the Riito Drain and Bypass Drain just before discharging into the Ciénega. We have measured flows at least every two weeks. The following figure shows a graph for these measurements.    

Figure with Flows at Bypass drain and Riito drain through December 2010. Bypass flows at SIB are preliminary and have been provided by the US. Bureau of Reclamation.