Water scientists engaged in field work don't get to wait for pleasant weather to go out and do their tasks, such as streamgaging (measuring how much water is flowing at a certain time). These tasks go on all year long and often during periods of the worst weather, such as when flooding is occuring.
Most streams in winter still have water flowing below a frozen surface, as it is relatively difficult for moving water to freeze solid. This hardy hydrologist is conducting a routine stream measurement that involves measuring the velocity of water flowing at numerous locations across the stream. At each location he also measures velocities at a number of vertical points, too. From these velocities, the total amount of water per second flowing by can be calculated.
What if it was your job to stand by a river all night during a rainstorm and take a water sample every 30 minutes, hour after hour? Some water-quality projects require this kind of sampling (especially during rainstorms), so one way to automate the task is to employ automated stream samples, as you see here.
This picture shows an automatic water sampler that has some smarts to it. It has tubes going into the water and a pump to pull water through the tubes into the sampling bottles. It is programmed to take a sample at intervals during a storm when the river is first rising and again later, where it's falling. During a storm a river tends to rise quickly at the beginning of the storm, reach a peak, and then slowly fall back to pre-storm levels. It is most important to get water samples at the beginning of the river's rise, as that is when substances are first flushed into the river.
So, this particular sampler is programmed to take water samples maybe every 30 minutes when the river is rising quickly, every hour or so when it is peaking, and every four hours when it is falling back to normal levels. After the storm a hydrologist will visit the sampler, remove the samples, and prepare the sampler for the next storm.
Here, a U.S. Geological Survey (USGS) hydrographer is collecting a suspended-sediment water sample from the Little Colorado River, a kilometer upstream from the Colorado River, Grand Canyon, Arizona, USA. To gain knowledge of the suspended-sediment characteristics of the entire river (water quality can vary greatly across a river), suspended-sediment water samples have to be collected in multiple cross-section intervals (notice the string going horizontally across the picture, which allows the hydrographer to sample in a straight line across the river).
Suspended-sediment concentrations also vary vertically with depth, so the sampler must also sample vertically by moving the sample bottle up and down at a constant speed, being careful not to hit the stream bed, which could cause bottom sediment to rise into the water column.
The hydrographer carries numerous glass bottles, using one bottle for each cross-sectional location. The bottle is secured in the metal sampler and there is a tube in the front of the sampler to allow water to enter the bottle at a controlled rate, while letting out air from inside the bottle. The very brown water here indicates the presence of a lot of fine dirt particles and the turbidity of this water is very high.
A staff gage to measure river height and crest gage to measure peak height
The metal pipe and pole with a scale marked on it are some very simple, yet valuable, means by which the U.S. Geological Survey (USGS) gauges both the current gage height (river stage) and the peak gage height during the last high water. It is a widely used low-tech piece of equipment that provides valuable information about how high water in streams get during storms.
There are holes drilled in the bottom of the pipe to allow water to enter. Inside the pipe is a wooden rod with markings in feet and inches. The technician puts some ground cork in the pipe and when it rains both the creek water and the water in the pipe rises, thus floating the cork in the pipe. When the water stops rising, and then falls, the cork sticks to the wooden rod at the highest point the water level rose.
The staff gage allows a hydrologist to quickly look at the creek and see the current gage height.