Surface Water | Trends
Summary
The Surface Water Trends webmap (link below) displays the results of statistical trend analysis over the last 30 years of streamflow measurements from surface water monitoring sites within the state of Indiana. Trends for several streamflow metrics are available for viewing through the interactive map. Descriptions of the various metrics presented in the webmap can be found at the bottom of this page.
Click Here to Open Interactive Surface Water Trends Webmap
Layers Present in Webmap
Rate of Change of Mean Flow Rate [in/yr] – The rate of change of the annual mean flow rate over the last 30 years based on the Theil-Sen trend slope estimator. The flow rates were normalized based on the drainage area of each station’s corresponding watershed. Statistically significant trends were defined based on a 10% significance level using the Mann-Kendall statistical test.
Rate of Change of Maximum Flow Rate [in/yr] – The rate of change of the annual maximum flow rate over the last 30 years based on the Theil-Sen trend slope estimator. The flow rates were normalized based on the drainage area of each station’s corresponding watershed. Statistically significant trends were defined based on a 10% significance level using the Mann-Kendall statistical test.
Rate of Change of Minimum Flow Rate [in/yr] – The rate of change of the annual minimum (7 day moving average minimum) flow rate over the last 30 years based on the Theil-Sen trend slope estimator. The flow rates were normalized based on the drainage area of each station’s corresponding watershed. Statistically significant trends were defined based on a 10% significance level using the Mann-Kendall statistical test.
Note: Discharge flow rates for trend analysis are normalized by the watershed area and presented as inches per unit area. This makes the trend magnitudes comparable between watersheds; however, those small magnitude trends can still represent substantial changes in annual water volume, especially in larger watersheds, such as along the Wabash River.