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Given the following text description, write Python code to implement the functionality described below step by step
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Description:
 Orogenic landscapes modelling
In this example, we simulate landscape evolution in response to two simple climatic scenarios
Step1:  Running pyBadlands
We can run the model for a given period. The end time in the XmL input file is set to 50M years but you might want to run the model for a coupled of iterations and check the output before running the model for the entire simulation time. This is done by putting the time in the run_to_time function. 
Here we go for the full time directly... it should take less than 5 minutes on a single processor if you keep the initial setting unchanged.
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Python Code:
from pyBadlands.model import Model as badlandsModel
# Initialise model
model = badlandsModel()
# Define the XmL input file
model.load_xml('test','mountain.xml')
Explanation: Orogenic landscapes modelling
In this example, we simulate landscape evolution in response to two simple climatic scenarios: 
+ uniform and 
+ orographic precipitation. 
<div align="center">
    <img src="images/oro_rain.jpg" alt="orographic precipitation" width="450" height="200"/>
</div>
We investigate the drainage network dynamics and the steady-state fluvial patterns that emerge from an application of these climatic forcing mechanisms.
The first part of the scenario starts from a flat topography subjected to a constant and uniform rate of tectonic rock uplift (>1 mm/a) and precipitation (1 m/a). The domain is rectangular and the four edges are kept at a constant base-level elevation. The area is a 40x80 km domain. 
After 8 Ma, the second scenario is applied and consists in a linearly varying rainfall pattern corresponding to an orographic precipitation with the same uniform tectonic uplift rate. The Northern part of the domain is experiencing a 2 m/a precipitation rate and the Southern part is subject to a 0.1 m/a precipitation rate for the next 12 Ma. 
Initial settings
For this model, we use the stream power law sediment transport model which scale the incision rate $E$ as a power function of surface water discharge $A$ and slope $S=\nabla z$:
$$ E = \kappa A^m (\nabla z)^n$$
where $\kappa$ is the erodibility coefficient dependent on lithology and mean precipitation rate, channel width, flood frequency, channel hydraulics.
The values given to these parameters ($\kappa$, $m$, $n$) need to be set in the XmL input file.
For this particular setting we do not need to record any deposition as the model is purely erosive. To speed up the model we turn off the deposition computation in Badlands by setting the dep element to 0 in the input file. 
Starting pyBadlands
First we initialise the model and set the path to the XmL input file.
You can edit the XmL configuration file at /edit/volume/test/mountain/mountain.xml.
To view the complete XmL options you can follow this link to github page: complete.xml.
End of explanation
start = time.time()
model.run_to_time(10000000)
print 'time', time.time() - start
Explanation: Running pyBadlands
We can run the model for a given period. The end time in the XmL input file is set to 50M years but you might want to run the model for a coupled of iterations and check the output before running the model for the entire simulation time. This is done by putting the time in the run_to_time function. 
Here we go for the full time directly... it should take less than 5 minutes on a single processor if you keep the initial setting unchanged.
End of explanation
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