Exercise 3 – Hydrograph Separation
In the most simplified case, the surface water flow from a catchment may comprise only baseflow (groundwater discharge to the river). One notch of added complexity is that the surface water may comprise a mixture of baseflow and precipitation. For this scenario in Yongan watershed in Zhejiang, eastern China, estimate the fractions of groundwater and precipitation contributing to surface water flow using the data from Hu and others (2020) provided in the table below. Comment on the significance of the errors (as shown in the table) to the estimated proportions.
Stable isotope data for key flows in Yongan, Zhejiang, China
|
Sample Type |
δ2H (‰) |
δ18O (‰) |
|
Precipitation |
-33.9 ± 24.1 |
-6.4 ± 2.9 |
|
River water |
-42.8 ± 6.1 |
-6.9 ± 1.1 |
|
Groundwater |
-44.7 ± 3.3 |
-7.2 ± 0.9 |
Click for solution to Exercise 3