GIS Blog

Come On Up For The Rising

With props to Bruce Springsteen, another post looking at elevation profiles.

We had a tramping related post not long ago and here’s another one.  Sometimes tramping is just idyllic with fantastic views, good mates and serene moments.  Other times, well it’s just a plain, hard out slog of putting one foot in front of the other and hoping you’ll get the saddle soon.  Sometimes, all you can see it’s what’s right in front of you:

Credit: R. Kane

Case in point: the Cascade Track to Angelus Hut in Nelson Lakes National Park, which I briefly hit on this in that earlier post.  DOC describes the track as such: “From the Cascade Track junction it’s a steady climb for 4 hr alongside the Hukere Stream. The track ends at the bush edge. Climb the steep poled route to Angelus Hut.”  They also state that it is an “Advanced: Tramping Track” and “Expert: Route”.  (Ed. What does that mean?)

Don’t get me wrong, I look back it on with great fondness, but there were a few hours of steep ascent where I wasn’t sure I was going to make it another step, my pack feeling heavier with each small rise.  Here’s good mate Blair making his way up – it doesn’t look nearly as steep in this picture as it felt on the day, but I an assure you, it was:

Credit: R. Kane

The thing is I shouldn’t have been at all surprised by this.  I had plenty of warning, but then it’s often the case that all the prep in the world wouldn’t quite have prepared me.  I had, in fact, been anticipating this part of the walk from the time we stepped off the water taxi at Coldwater Hut near the head of Lake Rotoiti.  How did I know?  The topo map told me so.  Here’s the track, as a reminder:

Most of this looks pretty reasonably (and gorgeous), but it’s the last leg up to the hut that had me worried:

See how all those seemingly benign contour lines bunch up angrily together?  That would strike fear into even the most hearty trampers – it means nothing but steep.  From the 1200 m contour line at the lower right of the blue box, the track ascends 450 vertical meters over a distance of just over 900 horizontal meters, a slope of (gulp) 50% or about 26 degrees.  In some places, it gets closer to 45 degrees (or more), which is almost hand over hand.  Try that next time you’re on the StairMaster!  The more closely the contour lines bunch together, the steeper the slope:

Erin eyes up her approach.  Credit: R. Kane

For most people, thinking about things in terms of percent slopes and angles isn’t very intuitive, so let’s try another way – our old friend elevation profiles.  Here’s the whole track; I’ve done my best to match the x- and y-axes to the same scale:

This makes it not look so bad, but it certainly felt like a challenge on the day.  I’d say the slope for the last bit was close to double what it had been coming up the valley.  To their cautious credit, DOC seem to be recognising that some of these slopes may be challenging.  We came across some warning signs that advised us to be sure we were happy to move on,

Credit: R. Kane

(That’s not a real DOC worker, it’s part of the sign, but daughter Islay is quite real, I can assure you.)  This one has its own elevation profile:

It might seem like this post has focused a bit too much on the steep stuff, and it has, to be fair.  And like many difficult things to get through, one can often look back with fondness – after the fact.  What does this have to do with GIS?  Well, to be honest, it was just another nice opportunity to demonstrate elevation profiles, but I can assure you that there were many vertical moments where I cursed the very letters of G, and I, and S many time over.

C

 

• 16/08/2022


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