About retention and land reclamation, or where is our water?

Improve or meliorate?

Few today remember that, according to Latin etymology, the word “land reclamation” means “improvement.” The origins of land reclamation activities in our country date back to the 12th century, when part of the fertile lands in the Vistula delta were embanked, initiating a high agricultural culture in the Zulawy Wislane area. Around the same time, monks of the Joannite and Cistercian orders, who specialized in draining swamps, began operating in the western part of Poland’s current territory – primarily in Silesia and today’s Lubuskie Voivodeship. Traces of their work can still be found today – for example. Ośno Lubuskie is a town built by the Joannites on marshes in the valley of the Łęczy River. Another example of floodplain management, which was able to combine land reclamation work with an understanding of the cycles of floods on rivers and the use of floodplains, is the Ollander settlement. Olenders were settlers from Friesland and the Netherlands who, in the 16th and 17th centuries, established villages in Royal Prussia, along the Vistula and its tributaries, in Kujawy, Mazovia and Greater Poland. They often settled on floodplains where locals were unable to farm. They built their houses on hills, known as terps, which they piled up from soil obtained when digging canals. They planted poplars and willows in the vicinity of their homes – in case of spring floods, they protected them from the flooding of rivers. The Olenders meliorated the floodplains in a way that allowed for grazing or farming, leaving the rivers unregulated.

Żuławy Gdańskie, okolice Steblewa -Autor: Bogdan_Groth

After World War II, the goal of introducing a system of land reclamation in Poland was to rapidly increase the acreage under agricultural production. After 1945, they began to be implemented on a large scale – at the forefront was the need to ensure security and growth based on efficient agriculture.

Drainage of wetlands, regulation of rivers, year-round use of land that had previously been flooded at certain times of the year – all this was supposed to make it possible to increase farmland and, consequently, food production. Land reclamation – a system of ditches and canals that collect excess water in agricultural and forest areas – was not intended to result in the drainage of these areas, but rather to regulate water levels.

Rowy odwadniające zostały wyposażone w systemy zastawek i jazów, które powinny pomóc w oszczędzaniu wody w krajobrazie po odprowadzeniu nadmiaru wody ze śniegu lub z obfitych opadów deszczu. Such use of them would help prevent land drying leading to drought, thereby delaying its onset. In practice, however, these systems are rarely operational today. In addition, the water administration has shifted from maintenance work to natural waters, where all activities are geared toward decongestion, mowing vegetation on banks and de-silting of watercourses, resulting in accelerated runoff.

Ditch dam
Ditch dam – source: Wikimedia Commons


The situation was not improved by Poland’s accession to the EU in 2004.

The Water Framework Directive (from 2000, introduced in Poland in 2004) obliges member states to achieve good water status by 2027 and emphasizes the need to move away from technical measures in water maintenance as a significant factor in the lack of good ecological status, further significantly increasing the risk of flooding. While Poland has succeeded in improving the physicochemical parameters of its waters (mainly due to the implementation of the National Urban Wastewater Treatment Program), the hydromorphological conditions and natural resources of rivers continue to be degraded on a large scale, primarily through the implementation of poorly understood water maintenance, generally in the form of hydraulic engineering projects. The situation was further exacerbated by the pressure to spend EU funds quickly and efficiently, often by means of hydrotechnical investments, subsequent land reclamation, regulation and carrying out “maintenance work,” which often meant re-regulation of self-renatured watercourses. The Common Agricultural Policy’s subsidy system has not helped either: for example, in the case of permanent grasslands (meadows), mowing them is a condition for receiving payments. To be sure, farmers start draining them as early as spring, which significantly reduces the water retention capacity of the catchment area.

The basin’s water management system has worked better or worse for many years, but for the past several seasons the drought has regularly worsened and has not abated even in wetter years. Water is in short supply, although rainfall, from which renewable water resources are derived, is still the same. Their distribution has changed – it snows less often, which used to replenish water resources better, while most of the rain falls at a time when evaporation is higher, and thus more than half of the precipitation returns to the atmosphere. The chemization of agriculture, which changes the structure of soils and causes water to run off them, the “drainage” model of water management, maintenance work on watercourses, and the consistent sealing of catchments (concrete “revitalization” of cities, regulation of rivers, often from the very sources) mean that less and less of the precipitation has a chance to infiltrate deep into the soil profile to recharge and replenish groundwater. Their level has been steadily declining – in recent years by as much as 2 meters. This causes water shortages in water supply systems, wells drying up, unavailability of water in the ground for plants in crops and forests, and finally – drought.


Today, no one doubts it: water must be retained, that is, it must be retained and its outflow slowed down so that it is available to plants longer and better feeds groundwater resources before it escapes through the main rivers to the sea.

However, that’s where the consensus of opinion ends. There are as many ideas for implementing retention as there are opinions, interests and dependencies. While some prefer to talk about natural retention – landscape, catchment, soil – others focus on artificial retention – the retention of water in reservoirs, dams, riverbeds – associated with large investments.

There is also a division into small and large retention, where large retention is called reservoirs in which more than 1 million m3 of water is stored.

Most often these are artificial reservoirs, created by building a dam on a river. Such solutions, while they may seem impressive, have their drawbacks. They are a gigantic intrusion into the landscape, disrupt the balance of the entire ecosystem, adversely affect water ecology, and destabilize water relations throughout the area. In addition, it is important to remember that any artificial hole in the ground, even if we call it a retention basin, will cause a lowering of the water table in the ground. Large reservoirs also always require significant financial resources and come with social costs – displacement and compensation. However, from the point of view of water management, their biggest drawback is that water once drained from the landscape – rural areas, fields or forests – is extremely difficult to return to it. Such activities involve significant energy consumption, limit access to a shared resource such as water, and even risk monetizing it.

Advocates of small-scale retention stress that the most important thing is to keep the water as close as possible to where it fell in the form of rain or snow. The more it can be preserved in the upper parts of the catchment area, the greater will be the resistance of the entire system to deviations from the norm – too little or too much rainfall.

Small-scale retention fits into a model that is compatible with landscape retention: thanks to the varied terrain, water has somewhere to stay, instead of flowing quickly down a system of watercourses. Natural depressions, ditches, rangelands, wetlands, swamps, bogs and depressions are places where water can accumulate, which translates into ensuring that the water level in the surrounding land is close to natural. In Poland, where precipitation in the mountains in the south is almost twice as high as the average for the whole country – more than 1,000 mm per year compared to an average of about 630 mm – this is particularly important. Mountains, and especially forested areas in southern Poland, should act like a sponge that collects water and then slowly gives it back to the lower parts of the catchment area. The retention capacity of natural forest complexes, especially those above 500 meters above sea level, should allow them to accumulate abundant precipitation and then slowly release it by supplying water to lower-lying areas, providing both drought and flood protection. However, if these areas are heavily transformed – natural forests have been replaced by commercial ones and cut by a dense network of roads that exacerbate soil erosion, and streams have been regulated and concreted over – forests do not perform this function. Water is not retained, which, in the absence of rainfall, results in drought, and the rains quickly cause flood waves in the lower parts of the catchment area. The problem starts at the source.

There are two species that consciously transform the ecosystem to suit their needs – humans and beavers. But while the former may be guided by different motives and interests when designing retention, the goal of beavers is always to retain water in the landscape. The more the drought intensifies, the more active the beavers become. It is estimated that several million cubic meters of water are stored in the spillways they have created throughout the country. Beaver retention, while it may be associated with generating losses, has many advantages: it is scaled to fit the landscape and the capacity of the ecosystem, and above all, beavers perform and operate it completely free of charge. All they expect to get us out of the mess of water shortages is compensation for owners of flooded land or felled trees. This is the low price of good retention.

Author: Joanna Perzyna

The text is based on the Expert Report „Woda w rolnictwie”, Koalicja Żywa Ziemia

The text was written as part of the project „Hydrozagadka – how to win against drought?”