Assignments in EDA in Geosciences - Chapter 2 Sharpening the Axe

Explorer

Question 1

catchment_area <- 185000 #km2
catchment_area <- catchment_area * 1000 ^ 2 # m2

Question 2

precipitation_hour <- 5 #mm / m2 h (5mm correspond to surface of 1 m2)
precipitation_day <- precipitation_hour * 24 / 1000 #m / m2 d
water_over_catchment <- precipitation_day * catchment_area #m3 / d

river_runoff <- 2900 #m3 / s
river_runoff_day <- river_runoff * 60 * 60 * 24 #m3/d

#The water that fell over the catchment in a single day is 

water_over_catchment / river_runoff_day

## [1] 88.60153

#times larger than the daily Rhine discharge

How can this number be possible?

The rate of 5 mm/h might seem negligible, but over a day it sums to 120mm, when the average annual rainfall over Rhine catchmet is approximately 800mm. In addition, it seldom rains all over the 185000 km2. However, there is also a third factor, which is demonstrated in Question 3.

Question 3

We are making two really hard assumptions here for the sake of the example.

river_length <- 1233000 #m
river_depth <- 30 #m - assumption 1
river_width <- 200 #m - assumption 2

water_velocity <- river_runoff / (river_depth * river_width) #m/s - Velocity = Flux / Area
time_to_sea <- river_length / water_velocity #s - Time = Length / Velocity

time_to_sea <- time_to_sea / (60 * 60 * 24) #days or about a month.

Thus, we should keep in mind that it might take quite significant amount of time for the rainfall hitting the ground to reach the river. And on top of that a certain amount is infiltrated to the ground, absorbed by vegetation and evaporated back to the atmosphere.

Question 4

There is a major shift of the climatic variables in the entire Rhine basin. These include mainly temperature and precipitation. Higher temperatures will reduce the amount of snow accumulation during winter and evapotranspiration in summer months. Winter precipitation is expected to increase, while it may decrease in summer months.
Assumptions around modelling of temperature in climate models, human use of water resources will be similar, CO2 emissions scenario (2.5 degrees temperature increase), percentage of precipitation increase has been evenly distributed in all months, number of days with precipitation remains unchanged (it does not rain more or less often).
The study motivation is the consequences of hydroclimatic change to: -winter sports in Alps -flood defense -inland navigation -hydropower generation -water availability for industry, agriculture and domestic use -floodplain development
Studies about Rhine:

Pfeiffer, M., & Ionita, M. (2017). Assessment of hydrologic alterations in Elbe and Rhine Rivers, Germany. Water, 9(9), 684.

Diermanse, F. L. M., Kwadijk, J. C. J., Beckers, J. V. L., & Crebas, J. I. (2010). Statistical trend analysis of annual maximum discharges of the Rhine and Meuse rivers. In BHS third international symposium, New Castle (pp. 1-5).

Impacts of Climate Change on the Seasonality of Low Flows in 134 Catchments in the River Rhine Basin Using an Ensemble of Bias-Corrected Regional Climate Simulations

L. Phil Graham “Climate Change Effects on River Flow to the Baltic Sea,” AMBIO: A Journal of the Human Environment 33(4), 235-241, (1 June 2004).

Climate Change Risk Management in Transnational River Basins: The Rhine

Studies about climate change effect in rivers:

van Vliet, Michelle TH, et al. “Global river discharge and water temperature under climate change.” Global Environmental Change 23.2 (2013): 450-464.

W. Collischonn,, C.E.M. Tucci, R.T. Clarke “Further evidence of changes in the hydrological regime of the River Paraguay: part of a wider phenomenon of climate change?,” Journal of Hydrology, 245, (1 May 2001).

Impacts of Climatic Change on Hydrological Regime in the Three-River Headwaters Region, China, 1960-2009

Impact of climate change on the hydrological regime of the Indus, Ganges and Brahmaputra river basins: a review of the literature Nigel W. Arnell, Simon N. Gosling “The impacts of climate change on river flow regimes at the global scale,” Journal of Hydrology, 486, (12 April 2013)