Valleys – formed by streams – are important features in the mountain geography for the alpine style hiker. Valleys can be clearly identified on topographic maps using contour lines. During my winter 20/21 ultra journey across the entire breadth (East-West) of Uttarakhand I crossed some 15 major valleys flowing down (North-South) from the high ranges above. Neighboring valleys are separated by ridgelines and connected by trails through passes across these ridgelines.
Valleys are deeper eroded into the landscape / topography and carry major rivers from high ranges to the plains. Lower altitude and abundance of water means that most human settlements are located inside the (lower) valleys providing useful stop-overs for the alpine style hiker to resupply food and recharge his electronics. Roads (and paths) are usually laid along the lower slopes of the valleys connecting neighboring villages.
Survey of India (and Open Street Maps) shows names for hundreds of rivers and thousands of streams across the Western Himalayas. These names are a useful reference for alpine hikers to identify valleys.
Rivers, streams, gullies
There are roughly three categorizations of water flows in increasing volume. The initial birth canals of water flow from the upper ridgelines are called gullies. These are usually steep as there is less water insufficient to cut deeper into the landscape. As multiple gullies join forces in the upper valley a stream is formed carrying more water flow. As the volume of water increases down the valley or multiple smaller side-valleys join a major river is formed.
Each type of water flow forms a different challenge for the alpine hiker. Gullies are usually steep and impossible to climb up / down periodically dropping as waterfalls. A trail crossing a gully horizontally can be difficult (landslides or frozen snow / slippery). The streams in the upper valleys carry medium water flow and are usually gentler sloped and easier to traverse / cross (unless during monsoon rains or summer peak snow melt). One might encounter makeshift bridges to cross these streams made by shepherds who graze the meadows in the upper valleys.
Once the water volume increases further down the valley and smaller streams become larger rivers other challenges appear. Water currents are stronger / water level is deeper and it becomes more difficult to cross without a proper bridge. More water cuts deeper into the surrounding landscape forming steeper valleys, less easy to traverse without a proper trail.
SOI maps usually refer to streams as Nal / Nalla / Khad (Himachal, JK) or Gad (Uttarakhand) or Tokpo / Phu / Lungpa (Ladakh)
Springs
In addition to gullies and streams water can also originate from a spring, a place where groundwater flows out of the ground. A spring may flow the whole year or only sometimes. Survey of India maps mark many springs (blue cross) across the Himalayas
Hopping Valleys
Below map shows my 2000km trans Uttarakhand ultra journey during winter 20/21. I crisscrossed UK East-2-West several times (red trails) crossing numerous valleys (major rivers, blue – flowing down from high ranges, purple) hopping across in-between ridgelines using passes (X, pink).
Why valley hopping? (as compared to just contouring within a valley) The effort involved in constantly hopping across passes (high) between valleys (low) is significant – elevation gain is huge (I climbed 1.6 lakh meters vertical ~ 18x height of Everest). Benefits are multi-fold: one touches villages in every valley and can resupply food regularly (reduce weight). Climbing up from valley to pass we pass through a variety of terrain: forest -> meadows -> rocks -> moraines -> glaciers -> and reverse order on the other side of the pass into the next valley, all in a single day.
Within the valley
Instead of hopping / connecting neighboring valleys, one can also hike within a single valley from base to top / source. This usually follows a similar pattern – from lower altitude forest / villages (sub 2500m) to medium altitude meadows (3000m) to rock and ice (moraines and glaciers, 4000m). The stream originates from glacial melt or rain / snow melt through gullies from surrounding ridgelines.
Major ranges like for example the Pir Panjal separating Chamba (Ravi river) from Lahaul (Chenab river) form several major side-valleys or streams flowing down from the high ranges into the main valleys below. Many of these side-valleys lead to passes crossing over between Chamba and Lahaul and can be hiked through beautiful ancient shepherd routes.
Lakes
Natural lakes form (naturally) along a stream when the water flow gets blocked due to landslides or moraines, mostly at higher altitudes (also called alpine lakes). More than 2000 lakes across the Western Himalayas are mapped in Open Street Maps and form beautiful hiking destinations, mostly located higher up in the valleys (alpine or high altitude lakes). Many lakes are considered holy and target of an annual pilgrimage by locals accessible through well laid rock paths. Lakes are usually called “Dal” (Himachal) or “Sar” (J&K)
Canyons, Gorges
As the volume (force) of the water increases or the landscape is more erosive (higher Himalayas, Ladakh, Zanskar) streams cut deeper into the surrounding landscape forming steep canyons (larger) and gorges (smaller). Canyons and gorges are walled by near vertical rock formations which can form significant obstacles for the alpine hiker to cross
Assignment
Acknowledge your understanding of valleys and streams in the mountains
