Rio Grande Nature Center

1. Rio Grande Nature Center Virtual Tour: Fall 2011

2. Objectives • During the tour we will discuss the following questions: • How have flood control measures affected the floodplain? • How have invasive species effected the ecosystem? • How does water chemistry differ between the Rio Grande and the floodplain groundwater?

3. Stop 1: Old Floodplain • Water measurements will be made once we reach the river, and again when we arrive at the nature center – groundwater will be pumped from a well inside. • Observe changes in vegetation as we approach the river – note the cottonwoods in particular. The cottonwood forest is commonly referred to as the bosque. • Open forest structure; mainly large cottonwoods; few mid-hight trees • Keep in mind that the Rio Grande was originally a shallow, braided sand bed river with lots of channel switching and relatively frequent floods.

4. Stop 1: Old Floodplain • Water measurements will be made once we reach the river, and again when we arrive at the nature center – groundwater will be pumped from a well inside. • Observe changes in vegetation as we approach the river – note the cottonwoods in particular. The cottonwood forest is commonly referred to as the bosque. • Open forest structure; mainly large cottonwoods; few mid-hight trees • Keep in mind that the Rio Grande was originally a shallow, braided sand bed river with lots of channel switching and relatively frequent floods.

5. Near Stop 2 Is this the Rio Grande? How can you tell? What is the earthen structure on the right?

6. Stop 2 • What are these metal structures and why are they here? • Why is the levee here? • Which side is higher and why?

7. Stop 3: Young Floodplain • Just past the Jetty Jacks we start to notice a difference in the cottonwoods. Compare the photos below. What differences do you see? • Cottonwoods need floods to germinate and to flourish. We’ve discussed several flood control methods, but not the largest one. • Cochiti Dam was built in 1972, 50 miles upstream of ABQ. The Rio Grande waters used to flow at ~ 25000 ft3/sec, now it is between 5000 – 7000 25000 ft3/sec. This won’t move water out of the river banks. Older, near the parking lot germinated in the 30’s – 40’s younger: germinated in the 60s

8. Stop 4: Forest Structure • As we get closer to the Rio Grande, dense undergrowth has accumulated over time. • Three main species compete for resources: Cottonwood, Salt Cedar and Russian Olive • Salt Cedar (invasive, tap root, exudes salt, germinates at any time, burns easily) • Russian Olive (invasive, tap root, germinates at any time, burns easily) • Cottonwood (native, branching roots, germinates after a flood, fire resistant bark)

9. Stop 5: Rio Grande Note the effects of Cochiti Dam, in particular the river width. In the 50s, the river channel was a half mile across – now it is only 500 ft across. Here we will analyze water chemistry: Nitrogen – Zero currently, but not always. Why? DO– Dissolved oxygen. How does this relate to conditions promoting life? Hydrogen– measured to find pH. Why is this important? Conductivity – an indication of the relative amount of dissolved elements and compounds. Where do these dissolved compounds come from? • Open forest structure; mainly large cottonwoods; few mid-hight trees • Keep in mind that the Rio Grande was originally a shallow, braided sand bed river with lots of channel switching and relatively frequent floods. “rip-rap”, a structure used to reduce bank erosion Russian Olive, originally planted along RG to reduce bank erosion

10. Stop 6: Duck Pond • A pond is a place where water from runoff stagnates and is connected to groundwater flowing beneath towards the river. • The duck pond has a high level of nitrates. Why? • If this water table was higher it might pond in a depression before it reaches the river http://www.whoi.edu/seagrant/page.do?pid=52039

11. Stop 6: Groundwater • In the Nature Center we take a sample of the groundwater from a spigot and take measurements. • Why are the pH and DO lower? • What accounts for higher conductivity?