Fort Smith Indicators of Hydrologic Alteration
This is an example of the data collection, manipulation, analysis and graphing for IHA variables for a station on the Slave River.
Indicators of Hydrologic Alteration (IHA) variables are a series of ecologically relevant calculations that can be used to understand changes in river hydrology over time.
This data is from the Water Survey of Canada database, and has historical and current hydrometric data from hundreds of stations across Canada.
Here we have tidied, cleaned, calculated IHA variables, and graphed a few of them to show hydrometric variables before and after the installation of the Bennett Dam.
Map of Station 07NB001
We chose this station because it’s near Fort Smith along the Slave River.
IHA ANALYSES
To calculate the IHA variables, we used the IHA package from the Nature Conservancy.
This is what some of the output variables look like:
## Year October November December January February March April May June July
## 1 1960 3650 2365 1950 1990 1020 688 749 4250 6625 7450
## 2 1961 4530 2795 1970 2140 2240 1950 1895 3940 7050 5860
## August September 1 Day Min 1 Day Max 3 Day Min 3 Day Max 7 Day Min 7 Day Max
## 1 5550 5270 544 8100 547.3333 8043.333 552.5714 8021.429
## 2 4360 3740 1650 7420 1670.0000 7353.333 1682.8571 7221.429
## 30 Day Min 30 Day Max 90 Day Min 90 Day Max Zero flow days Base index Min Max
## 1 596.6667 7572 892.6333 6667.667 0 0.1591389 90 190
## 2 1766.3333 6965 2037.1111 5928.667 0 0.4702986 88 163
## Low pulse number Low pulse length High pulse number High pulse length
## 1 3 3.0 2 40.5
## 2 2 13.5 1 56.0
## Rise rate Fall rate Reversals Time_Period
## 1 58 -40 97 Pre Dam
## 2 50 -60 105 Pre DamFlow Reversals, pre and post dam
All other IHA variables can be graphed this way.
Minimum flows
Maximum flows
Monthly flows
