Amelioration

Importance of amelioration in Latvia

While some regions suffer from such unfavorable climatic conditions as draught, other regions, as Latvia, are facing another problem, floods, endangering agricultural and forestry production and indirectly influencing other sectors of national economy and even safety of people.

One of the most important factors having impact on soil productiveness is regulation of soil wetness regime. Latvia, Estonia, Lithuania, Belarus, Poland, Russia and partly Finland are situated in a zone characteristic for humid continental climate. This means that the annual amount of precipitations, particularly in vegetation period, in these countries exceeds evaporation capacity.

In conditions of Latvia’s nature and climate, the amount of precipitations exceeds the annual summary evaporation in average by 250 mm but in the years with abundant precipitations – even up to 500 mm and more. Thus, in Latvia about 90% of agricultural land suffers from excessive moisture. Of the total area of agricultural land, 2/3 have been subjected to soil wetness regulation measures – construction of water discharges and drainage, including 37 thousand ha of flood endangered land where safety of population and the moisture necessary for economic activities are ensured by Latvia’s polder system.

In Latvia, amelioration systems also ensure a safe exploitation and maintaining of other infrastructure – roads, railway, air ports and communications proving their invaluable significance in the overall development of Latvia’s national economy.

Therefore, it is important for Latvia to pay attention to amelioration measures and to support a productive, economically beneficial use of land and nature resources, creating a safe living environment for people and ensuring the necessary water regime by building new amelioration systems or restoring the existing ones.

Geographic specificity of Latvia

Latvia’s climate is also influenced by large format relief objects. Elevations, particularly elevations in Vidzeme, unlike plains, are characteristic for lower temperatures, higher humidity and cloudiness, more durable snow cover. The amount of precipitations reaches 700-800 mm per annum, but on western slope of Vidzeme elevation– even up to 850 mm. On plains, even on the coast of the Baltic Sea and the Gulf of Riga, there is less precipitations – in average 550-600 mm per annum because the flat ground does not facilitate rising of masses of air and formation of precipitations. Whereas, Zemgale plain, protected from masses of air coming from the Sea by Kurzeme elevation, is the driest and warmest region in Latvia.

Taking into account the relief of Latvia, more and more attention must be paid to anti-flood measures because nature processes do not anymore occur evenly and foreseeably due to climate changes, but they are more connected with devastating storms, rainfalls, long periods of bitter frost, and other extreme nature phenomena. Timely adaptation measures are necessary to lessen negative impacts. They could be the measures, regulating soil humidity regime: improving operations of draining systems in warm autumns in winters with frequent thaws but particularly in springs.

Effectiveness of amelioration in Latvia:

• It is possible to increase yield/productivity on ameliorated agricultural and forest land in average by 20-40%;

• In Latvia’s conditions, it is not possible to grow winter crows without an optimum regulation of wetness that can be achieved only by means of amelioration;

• Durability, stability and normal exploitation of engineering buildings is dependent not only on characteristics of construction but also on soil properties as well as on interrelation of the building and the base;

• It is particularly important to drain the bases of motor roads. By means of draining bases of motor roads, the length of service of motor roads can be considerably extended and construction, maintenance and exploitation expenses can also be significantly reduced.