Deformations occurred in natural and regulated stream change beds lateral and longitudinal profiles. This is particularly evident in regulation furrows, where their initial state is known. Research showed that landslips of the upper slopes in regulated watercourses is the most common deformation (72.8% of studied cases), and the largest deformation occurs in the lower part of the slope (63.4%), where the accumulation of the moved silt and soil is. It was found that the deformation changes the bed plan as well. 59.1% of regulated streams distort furrows and make meanders due to deformation effects. The analysis of river beds widths and depths ratio relationship with discharge of channel running flow observed that ratio B/H increases with increasing flow evenly in regulated beds, while the above-mentioned ratio varies unevenly in the natural watercourse. Cross-sectional shape also varies in regulated and natural beds: heterogeneous form beds dominated in natural beds, while parabolic cross section shape is approaching during the deformation in regulated beds, what is more favourable for the living environment.

The change from large scale agriculture to private small scale farming has resulted in a severe lack of plant protection means. Fields of Latvia have become more weedy for last four years. This fact shows the necessity for a change in the strategy of weed control. The effect of inexpensive and wide-spread herbicides 2.4-D and MCPA is insignificant in weed control. From 1994 Latvian State Centre of Plant Protection has been studying the occurance of weed species in the Central part of Latvia (Vidzeme), to make use schedules of necessary herbicides. The research was carried out jointly with the Latvia University of Agriculture. During the research carried out from 1997 to 2000, 60 weed species were established, but in all the crop sowings 10 species were predominant. The number of Elymus repens, Myosotis arvensis and Viola arvensis has increased during last four years. In Vidzeme region, from 1997 to 2000, it was stated that soil infestation of weed seeds varies from 4.5 to 11.1 thousand seeds per square metre on the average. Perennial dicot-weeds have shown the lowest variation coefficient, compaered with other weed groups.