03/04/2026
The Upper Daugava Ancient Valley
Within Latvia, the Daugava River valley can be divided into five main sections: Koškovci–Piedruja, Piedruja–Daugavpils, Daugavpils–Pļaviņas, Pļaviņas–Salaspils, and the lower reach downstream of Salaspils. Each section has its own distinct characteristics. One of the most remarkable and least altered by human activity is the stretch between Piedruja and Daugavpils, which includes the scenic Upper Daugava ancient valley.
In the river section from Krāslava to the village of Krauja, the valley separates the Latgale Upland from the Augšzeme Upland and reaches depths of up to 45 metres.
The width of the valley varies considerably. Downstream of Krāslava, it is about 2 km wide, while near Naujene it expands to approximately 4.5 km. However, in the central part—near the mouths of the Borne and Rudņa tributaries—over a stretch of about 5 km where the river crosses a glacial marginal formation known as the Borne zone, the valley narrows to just 0.7–1.2 km. An even more pronounced narrowing occurs southwest of Slutiški village. This section is known as the “Daugava Gates,” where the valley width decreases sharply from 2.7 km to 0.5–0.6 km, framed by steep valley sides rising more than 40 metres high.
The stretch of the Daugava between Krāslava and Krauja is also the most recognisable, thanks to the nine large meanders formed by the river—five to the north and four to the south of the valley’s central axis. Each meander has its own name, derived from nearby settlements, farms, or tributaries: Priedaine, Skerškāni (also known as Adamova), Zvejnieki, Rudņa (or Tartaks), Daugavsargi, Ververi, Rozališki, Butiški, and Elerne.
These meanders give the valley a distinctly asymmetrical cross-section. On one side, broad and gently sloping terraces dominate, while on the opposite side, steep and often dramatic valley walls rise sharply. Moving from the outer bank toward the inner part of a meander, a sequence of progressively lower and younger terraces appears, along with the floodplain. In total, seven to eight terrace levels can be distinguished, resembling a series of giant steps.
Thanks to its depth, sweeping bends, terraced slopes, and steep valley sides, this stretch of the river offers some of the most visually striking landscapes not only within the Upper Daugava valley but potentially in all of Latvia.
Scientific research indicates that the formation of this natural gem began around 16,000–18,000 years ago, which is relatively recent in geological terms. At the end of the last Ice Age, as the climate warmed, the Fennoscandian ice sheet began to melt and retreat. At that time, meltwater flow towards the west and northwest—roughly the direction in which the Daugava flows today—was blocked by remaining ice masses. As a result, water flowed instead eastwards and southeastwards across what is now Belarus, eventually reaching the Black Sea. In other words, in its early stages, the river flowed in the opposite direction to what we see today.
Evidence of these processes can be observed in the highest terraces, for example in the Skerškāni meander, where the slope of the terrace surfaces reflects the direction of ancient water flow. This area is also significant because it was among the first in Latvia to become ice-free after the last glaciation, marking the beginnings of river network development in the region. The Upper Daugava ancient valley is therefore considered one of the oldest river valleys in Latvia.
As the ice sheet continued to retreat, drainage towards the east ceased, and the watershed between the Baltic Sea basin and the Black Sea basin was re-established. Meltwater accumulated in ice-dammed lakes, first in the Disna basin and later in the Polotsk basin. When the ice margin retreated further to the west and northwest, large volumes of water were suddenly released westward from these lakes. These powerful flows significantly widened and deepened the Upper Daugava valley, transporting not only sand but also gravel, pebbles, and even small stones. Evidence of this can be seen in the gravel and sand deposits that form the terraces, many of which are still extracted today.
At the same time, distinctive funnel-shaped depressions formed in the landscape. In places, sediments carried by strong meltwater flows buried blocks of stagnant ice. As these buried ice blocks gradually melted, the ground above subsided, creating depressions. Such features can be observed in several meanders, including Skerškāni, Zvejnieki, and Daugavsargi, but they are most pronounced in the Rudņa meander, where local people have given them the evocative name “devil’s pits.”
As glacial melting continued across the rest of Latvia, other ice-dammed lakes formed, and during the late glacial and post-glacial periods, the Baltic Sea basin developed. These changes repeatedly altered the position of the river mouth, while the Daugava gradually deepened its channel. Over time, lower terraces and the modern floodplain were formed.
The valley sides and terraced slopes along the entire Krāslava–Krauja stretch are deeply dissected by ravines, gullies, meltwater channels, and tributary valleys. A combination of natural processes and human activity has intensified erosion, resulting in a particularly dense network of ravines. This area represents the second most extensive zone of gully erosion in Latvia, after the Gauja erosion belt.
Today, the flow of the Daugava is much calmer compared to the powerful meltwater streams that once shaped the valley. In summer, the current averages 0.3–0.4 m/s, while in faster-flowing sections—such as near Užinkalns or Kaplava—it may be slightly higher. In spring, during peak flow, the current reaches 1.3–1.5 m/s. Although this is no longer strong enough to move pebbles or stones along the riverbed, it is still sufficient to transport sand and gravel. The results of this process can often be seen as sandy shallows along the banks or as sandbars and islands within the river.
Although the Daugava is no longer as powerful as it was in the past, it remains the most water-rich river in Latvia. In the Upper Daugava, between Krāslava and Daugavpils, during low-water summer periods, 75 to 100 cubic metres of water pass through the river cross-section every second—equivalent to 75 to 100 tonnes of water flowing past each second. During spring floods, however, discharge increases significantly. For example, during the major floods of 2013—the largest in the past decade—the flow reached as much as 3,660 cubic metres per second.
Seasonal flooding has played a crucial role in shaping settlement patterns in the Upper Daugava valley. Each spring, water levels rise rapidly before gradually receding. Typically, water levels increase by 5 to 6 metres, but during extreme floods—such as those in 2013 near Krāslava—they can rise by as much as 9.5 metres or more. As a result, floodplains and low-lying areas are regularly inundated, and in some cases even the first terrace above the floodplain is affected. For this reason, people traditionally built their homes on higher terraces, where experience showed the water would not reach.
Finally, it is worth noting that in the 1980s, the Upper Daugava valley faced a serious threat. Plans were made to construct the Daugavpils hydroelectric power plant, which would have flooded the valley. However, public opposition—led by the Latvian intelligentsia—sparked a broader national awakening. In 1987, a decision was made to halt the construction of the Daugavpils hydroelectric power station. In 1990, the nature park “Daugavas Loki” was established to preserve the unique landscape of the Upper Daugava valley, its valuable ecosystems, biodiversity, and cultural heritage.
