Month: September 2025

The most commonly used definitions of a river’s source are the stream which begins furthest from the sea; and the stream which begins at highest altitude. A third definition refers to the volume of water that the stream contributes to the river system, and so in the Chelab we wanted to examine the four sub-streams (A-D) which come together, and to establish which of those was the principle.

There are plenty of ways to calculate the volume of water in a stream, but we needed something which was simple to use, affordable, reliable, and wouldn’t cause consternation amongst customs officials or anyone else searching our baggage. In summer 2024 we’d trialled the trans velocity head rod (TVHR) in the UK and found it worked well in test conditions. But a quiet chalk stream running through Wilton is not the same thing as a glacial mountain stream. How would it fare? We’re delighted to say, it worked well.

Glacial streams vary significantly in volume over the course of a day, as the warmth of the sun melts the ice, increasing the water flow. For this reason, we needed to undertake the stream gauging at approximately the same time for each river, conducting the work over several days to allow for the time required to walk or ride between the measuring sites. Working earlier in the day, when the water volume was lower, would also be safer, so we took all the measurements between 09.00 and 10.30.

To start the process, we stretched a tape measure across each stream, from the left bank to the right. Sophie was in the water, wearing waders; and Mahmud Omar gamely kept the other end of the measuring tape in place. This gave us this width of the stream and meant we could easily see where each vertical measurement point — 20 cm apart — would be.

The TVHR is essentially a metre-long ruler made of perspex. You place it in the water vertically, side on to the flow, and raise the end of the clear gauge to the water’s surface to read the depth in centimetres. Then, you rotate the rod 90 degrees so the force of the water pushes against its flat side: there is a clear difference now between the water level on the upstream and downstream side of the rod. You slide the red gauge up to match the upstream water level, and then read off the velocity head in millimetres. Our guide, Salahuddin Esmaeli, recorded the data in a table, and we repeated the process again and again across each stream’s width, collecting all the information required to calculate the cross-section of the stream and the volume of water flowing through it.

TVHR’s inventors, INRAE, provide a spreadsheet for the calculations. Without electricity in the Chelab Valley and not wanting to risk a laptop in the harsh environment, we inputted the data later. These are the results for the four streams

A = 0.535 cumecs (535 litres/sec)

B = 0.136 cumecs (136 litres/sec)

C = 0.114 cumecs (114 litres/sec)

D = 0.490 cumecs (490 litres/sec)

Individually, A is the largest of the four streams which together comprise the Chelab. However, the other three streams have already merged upstream, so the confluence is not of A and D, but of A and the by now larger B-D stream, as the latter already holds the total volume of three streams’ flow within its course. As the mainstem of a river is the larger (by volume) of the two tributaries joining at a confluence, the mainstem of the Chelab is as follows:

A / B-D confluence: mainstem = B-D

B / C-D confluence: mainstem = C-D

C / D confluence: mainstem = D.

We first contacted Jack Wolfskin’s marketing team when the idea for the Oxus Expedition was in its infancy. Little did they (or we) know that it would take four and a half years — not the anticipated six months — to complete the expedition and have results, photos, and videos to show for it. Their generosity and patience are very much appreciated. 

Proper expedition clothing and equipment is expensive. If you cut corners on price and quality, you risk being dangerously ill equipped, so having a sponsor who both advises what you might need and provides it is invaluable. 

In the Wakhan Corridor, the greatest challenge from a clothing and equipment perspective is the range of temperatures: in August, we had scorching hot days and sub-zero nights, where ice formed on the fly sheets of the tents. Being able to add on and remove multiple layers is essential, as is having equipment with good thermal properties and which will also keep out the wind. 

Sophie’s favourite item: The item I wore most is my Pacific Green JWP t-shirt with 3/4 length sleeves. It’s an ideal base layer earlier in the morning, with a fleece and jacket on top; but once the days warmed up, I could strip everything else off and still have enough protection (at least on my body and arms!) from the intense sun. The cut, neckline, and sleeve length was also modest enough that I didn’t worry about disapproving looks. The fabric is light, doesn’t crease, and doesn’t really to show the dirt or sweat, so this short was my go-to, day in, day out. 

Kamila’s favourite item: Our tent! It was my first time camping and I was afraid of how uncomfortable and unsafe it will be, but on the contrary! Incredibly warm, safe, nearly sound proof and cozy. The views from our tent were incredible, I loved waking up early in the morning to the sun or at night to see the stars, yet the tent would keep its warmth. 

Five years on, COVID is little more than a memory but the Ishkashim border hasn’t reopened, a sign of the uneasy diplomatic relationship between the two countries. You can cross further west at Sher Khan Bandar, but for us it was more convenient to go straight from Uzbekistan to Afghanistan, saving the need for yet another Tajik visa.  

Road travel within Afghanistan is much easier and safer than it was under the previous Afghan government. The Taliban proudly advertise the improved security situation, even though one major reason for it is that they themselves are no longer planting roadside bombs or kidnapping foreigners for ransom. We could therefore drive — without a convoy or armed escort — from the Hairatan border crossing to Mazar-i Sharif, then via Kunduz to Faizabad and Ishkashim. That part of the journey, on reasonable roads, would take two days.

Once in the Wakhan Corridor, we continued east, still by car but at a much slower pace. The roads in the valley, though extended and improved in recent years, are still little more than dirt tracks, with frequent river crossings and other obstacles. As the altitude increases significantly, it is also necessary to acclimatise, so we stopped a night in the guesthouses in Qala-e Panja and in Sarhad-e Broghil. The new road from Sarhad to Bozai Gumbaz is hair raising, and although I had full trust in our driver, Abdurahmon, I could not say the same for the car, which rattled, squeaked, and generally complained, especially on precarious downhill stretches when the brakes were applied. 

In the Little Pamir, overlooking Lake Chaqmaqtin, I finally felt that the Oxus Expedition might actually conclude this year. The late, turquoise and idyllic, with peaks and glaciers either side, has often been described as the source of the Oxus, though that was one thing we were out to disprove. 

There is now a road along the northern shore of Chaqmaqtin to Tajikistan, and another through the Wakhjir Valley to China, though the latter hasn’t yet opened the border crossing. Where we were going — the Chelab Valley — there was still no road, so we left the 4×4 in the Kyrgyz winter settlement at the valley’s mouth and transferred our baggage to two horses and a donkey. Mahmud Omar and Ahmad, two young Kyrgyz men, joined us for the next four days to care for them. Bags packed, we set off on foot to establish a base camp half way along the valley, around four hours’ walk from the vehicle.