Photo: N. Doscher-Ozanne

Last weekend was a glorious, bluebird weekend and I was lucky enough to head out on an early season tramp with daughter number 1 (number 1 in terms of birth order; they’re both number 1 in my book). What could possibly go wrong? Only that I’m getting to be an old man and my knees begin to ache when I think about our last trip to Carroll Hut (Ed. Really? Maybe you should model yourself off of Hugh Wilson. Get a grip.) (Pipipi Ed. Thanks for the nod! And we recognise that imitation is the sincerest form of flattery.) I found that a number of useful lessons were relearnt on this muddy trip.

We set out for Mt Oxford on a crisp Saturday morning with a plan – from Cooper’s Creek carpark up to Mt Oxford, down to Wharfedale Hut for the night and then back along the Wharfedale Track, something like this:

Our first view of Mt Oxford from the Old West Coast Highway gave us an immediate rethink – there was a lot of snow up there, so on arrival, we switched things up – first we’d go up the Wharfedale and on day 2, we’d take the Mt Oxford Route and make a decision about going all the way to the top or taking the Route back down to the Wharfedale Track:

So feeling reasonably happy with this plan, off we went. Lots of time for map work on the way:

Both my daughters are good with maps (excuse me while I wipe away a tear, sorry) and seven long hours later…much longer than we had anticipated, we arrived at the hut, tired, hungry and muddy. At times it seemed like the track was more mud than solid ground, but I only exaggerate slightly – students of ERST202 and 606 might be thinking that a bit of track maintenance is needed – and it was.

We shouldn’t have been surprised that it took this long. After all, looking on the map, we see the Wharfedale squiggle in around nooks and crannies on its long, slow climb. The data tell us that it’s roughly 16 km from the carpark to the hut and it’s not at all a straight line. Our aim was still to hopefully get to the top of Mt Oxford on day 2 (sidenote: while looking over the topo map, one of our hutmates asked why were we using a paper map? Why not use the maps on your phone? I’m a firm believer in relying on map and compass – batteries die, and I’ve never quite trusted those compass apps. I’ve found the earth’s magnetic field to be very reliable). The Mt Oxford Route ascends from the hut to a point where we could make the next decision. Which leads us to the first lesson relearnt on this trip.

Beware of Straight Lines

One of the considerations with taking the route is that it looked to be a bit shorter on the map; it would at least allow us to bypass all the twists and turns of the Wharfedale. But that came at a cost – taking a close look at the first part:

We see a nice straight line going up the hill towards peak 945. Paying close attention to the contour lines, we can also see that it’s veeeery steep – from the hut up to peak 945 the slope was around 20 degrees, 25 in some places. This makes for very exhausting walking (not helped by a bad night’s sleep due to someone snoring in the hut…jeez). Throw a bit of snow in there and it becomes even more challenging.

By the time we got to our decision point, the snow was about shin deep and very hard going, so we chose to leave the peak for another day (a good decision, methinks). The route down was not quite as steep, but still a challenge.

We should have remembered that DOC calls this a “route” for a reason. They classify walks into six classes: of them, routes are “challenging”, suitable for “people with high-level fitness” (not so much me these days) and “may be rough, muddy and very steep”. We got all of those on the Mt Oxford Route though I’m sure other routes can be more difficult.

So this served as a reminder that when looking at nice straight tracks on the map, one should also be looking at the contours – the closer together they are, the steeper that land is – and steeper means harder, whether your going up or down. It’s just different muscles that end up sore. And that brings up to the next lesson relearnt

Straighter Isn’t Always Shorter

By taking the route, we knew we were reducing the total distance back to the car park by about 5.5 km. But that didn’t make it any shorter time-wise. Because we were in steeper terrain, and particularly because we were trudging through sometimes knee deep snow, we took just as long to get back to the carpark as we had the day before. It was just slower going. This brings up an important GIS concept. There was extra effort imposed on us given our route choice – effort due to both terrain and the snow. You could think about these as “costs” of moving through the landscape. Not $$ costs, but costs nonetheless. It “cost” us more in energy (and time) on those steeper slopes than on nice, flat(ish), clear ones. If we were seeking to minimise those costs, we certainly wouldn’t have chosen to go that way – but there were other considerations in our minds.

With GIS, we can use some modelling tools to find paths through landscapes based on the cost of different factors, which we refer to as impedance. High impedance means more “cost”. For instance, if you were wanting to identify some wildlife corridors, you might have some factors that make some areas better for a corridor than others. Maybe one of them is landcover. It might be preferable that animals move through areas of native bush rather than cropland or dairy pastures. We might also prefer that the corridors be a certain distance away from roads, or populated areas. To do this in GIS we can use a set of raster-based modelling tools under the general umbrella of least-cost path mapping. We’d have a raster layer for each important factor, reclassified with impedance values. The point of least-cost path mapping is that the route will follow the path of least cost, so with landcover, we’d assign a high impedance value to cropland and dairy pastures, and a lower cost to native bush, directing the corridor through the bush. Within a given distance of a road, the impedance value could be set higher, to shoo the animals away. When combined with other factor layers, they can all be taken into account to find the overall least-cost path. Sunday was definitely a high impedance day due to our highest-cost path mapping.

Back to the Carpark

Once off the route we had a good seven km to go. As always, those last few kms are usually quiet and one has lots of time to think. Maybe about the first song we’ll put on when we get to the car (my choice) or what we’re going to have for tea (pizza!), or that stupid thing you said to person A the other day, or how you want to do something different next week. I find I have a bit of a love-hate relationship with tramping at these times. After another seven hour day I was feeling like it might be a while before I want to get out again, like maybe, oh, next weekend, but we’ll see.

Getting out in the bush is always a great refresher, especially over a weekend like that – there’s something rejuvenating about seeing blue sky through green trees. A lot of tramping is about making decisions and I think we made a number of good ones, but the best one was to go in the first place. It’s a great way to get you head out of your…er…Aspect and refocus.

To be fair, it wasn’t the muddy boots that re-taught me these lessons, but it was putting the boots on in the first place that did. Though it may not be that accurate, that title was one of the things I was thinking about on the way back to the carpark.

C