If we want to have a better understanding for a stream, or even have the abilities to manage a stream and water resources, we need a quantitative analysis. The data from stream gages will definitely help us to figure out how much flow/stream water we have.
U.S. Geophysical Survey (USGS) has 7 gages in Mānoa-Pālolo watershed (as the map below, including 4 in Mānoa, 2 in Pālolo, and one at the confluence of both). Since we’re going to focus on the Mānoa watershed first, three USGS gages have been selected:
- Waihi Stream gage: the confluence of ‘Aihualama, Lua’alaea and Waihi streams
- Waiakeakua Stream gage: the confluence of Wa’aloa, Naniuapo and Waiakeakua streams
- Manoa Stream at Woodlawn Drive gage: the confluence of Waihī and Waiakeakua streams
- (We don’t include the Manoa Stream at Kanewai Field gage because of it only have data for few days)
Gage Data Ability
The data ability of streamflow (discharge) data and water quality of 3 gages are listed below (current: 15-min interval discharge; daily: daily discharge; water quality data only provides few days in years):
The stream summary from the USGS, and I converted the unit here. According to the drainage areas of each stream are very small comparing to the drainage areas in the Continental U.S. (CONUS). Besides, the maxima and minima of the streams also show the extreme streamflow condition, which may impact on the niches or habitat of the stream shrimps, fishes, and other. Baseflow indicates the permanent flow contributing to the total streamflow, and quick flow indicates the stormflow contributing to the total streamflow. The Waiakeakua stream has higher baseflow contribution than quick flow contribution may because it has groundwater discharge into the stream.