5.   LAND IMPROVEMENT

In Estonia the amount of precipitation exceeds that of evaporation by 30 %. It the water regime is not regulated, about two thirds of cultivated area would suffer from surplus humidity. The first land improvement constructions were built in the 17th century, but in the 2nd half of the 19th century the attention to these activities grew considerably. In the 2nd half of the 20th century, especially in the sixties and seventies the volume of land improvement operations was especially impressive. In Estonia, 735,000 hectares of cultivated land have been drained and 650,000 hectares of this area have been drained using tile drains. At present, the most important task is to maintain the existing land improvement systems and recipients in good condition so that reclaimed lands would remain suitable for crop cultivation also in future.

The Land Improvement Act (RT I 1994, 34, 534) states that land improvement consists of the following procedures: drainage, irrigation, using both these methods for regulating water balance and implementing other methods of land improvement. The two most important methods of drainage are drainage with open ditches and drainage with underground pipe drains. Methods for land improvement are as follows:

In addition to these operations it is necessary to construct field roads and build bridges, culverts and footbridges.

5.1. Building of land improvement systems

The need for drainage arises due to floods caused by melting waters in spring and surplus humidity in soil caused by heavy rains in late summer and autumn. Because of these two reasons groundwater may rise and reach the layers near the surface. As it hinders land cultivation, sowing and harvesting, it becomes necessary to construct drainage systems. Depending on the porosity of soil and conditions of runoff some soils suffer from over moisture temporarily while others are constantly over moist. The only way to get rid of surplus humidity is to construct drainage systems. In Estonian conditions drainage with underground pipe drains will guarantee the best water regime for soil.

Land improvement system is a complex of constructions for draining or irrigating cultivated areas or regulating water regime by using both these methods. This system of constructions forms an essential part of the plot of land and belongs to the owner of the land. The land improvement system for a piece of land, which suffers from over moisture consists of open water conduits (ditches) and subsurface water conduits (drains and collectors) and constructions, which are necessary for the functioning of the water conduits (drain outfalls, drain wells, culverts), sometimes also various water constructions (water reservoirs, pumping stations, etc.).

Recipients are necessary for the proper functioning of the land improvement systems. Recipient is a water body to which the water removed from farmland will be discharged. For a smaller land improvement system also collectors with a diameter of at least 20 cm may serve as the recipient. In accordance with the Land Improvement Act building of new land improvement systems or reconstruction of the existing ones is permitted on the basis of the design criteria issued by the regional land improvement office. In case the system is smaller and not so complicated, e.g. when a drainage system is being built within the boundaries of one immovable occupying an area of 2 ha or when an open ditch drainage occupying an area of up to 5 ha is being constructed, the procedure is more simple. The building design documentation, building permits and construction supervision are not needed, it is only necessary to obtain a written permission from the land improvement office.

In case of a land improvement system, building design documentation is necessary. In such cases the regional land improvement office will issue the building permit. Before the system is taken into use, it will be inspected and if it meets all the requirements, it will be registered in the Register of Land Improvement Systems.

The Water Act establishes the water protection requirements for building and using the land improvement systems. Building and using land improvement systems must not cause water pollution, release of garbage into water, excessive decrease of water resources and soil erosion.

When land improvement systems are built or used in the protective zones of some other constructions (railway, power or communication lines, roads, gas lines), requirements established by corresponding laws must be met.

5.2. Maintaining and renovating of land improvement systems

All the elements of a land improvement system must be in good order to make it possible to use the system in an appropriate way. To maintain the elements in working order, it is obligatory to carry out repairs in time and to make necessary renovations. Maintenance and repairing are the activities, which guarantee the operations of land improvement systems.