This paper offers an overview of the history, the present state and the outlook for the future of tile drainage on agricultural lands of the Czech Republic. Being located in a zone of moderate climate, the country does not need drainage as a corrective measure after irrigation. Draining of agricultural mineral soils took place on a large scale over almost the whole of the twentieth century. Today, virtually no drainage systems are being either built anew or rehabilitated, but most of them are still working. Negative and positive impacts of land drainage on catchment runoff, water balance, groundwater hydrology, nitrate leaching and local climate are described. The future of land drainage depends on the prospects of agriculture. At present, the doing-nothing option prevails. In future, some of the existing drainage systems may be rebuilt as controlled systems combining drainage, retention and irrigation. Studies on the impact of land drainage and land use changes on nitrate leaching and microclimate indicate the need for corrective measures.

Abstract:Tile drainage water temperatures and discharge rates were measured in five highland watersheds of which most are underlain by acid crystalline rock. One of them, Dehtáře in the Bohemo-Moravian highland (Czech Republic), was studied in greater detail. The aim was to evaluate water temperature monitoring as a means of determining the source and pathway of drainage runoff during high-flow events. Rapid increase in drainage discharge was accompanied by rapid change in water temperature. In winter, the rising limb of the hydrograph was accompanied by a decrease in temperature, and the falling limb was associated with a corresponding temperature increase. In summer, the trends were reversed. These data suggest that the water temperature changes are caused by the fastest component of drainage runoff, water from a precipitation event or snowmelt, which can be separated from the remainder of the hydrograph. Measurements of hydraulic conductivity, soil moisture content, soil temperature, and groundwater table level indicate that the major portion of the event water causing this effect infiltrates in the watershed recharge zone where soils are permeable, enters the weathered bedrock, flows preferentially and rapidly down the slope along disjoint fissures in the bedrock, finally emerging as ascending springs, and is, for the most part, intercepted by the tile drainage systems.

Agricultural drainage systems have traditionally served the optimization of soil water balance for crop production and soil management. In the Czech Republic (CR), installation of drainage systems started in the second half of the 19 th century [1]. At that time, an exact engineering approach was applied, which proposed principles for drain spacing and depths in mineral agricultural soils based on foreign and domestic experience. However, the majority of Czech agricultural drainage systems was built in the 20 th century, during three discrete periods. The first period came shortly before World War I, the second boom took place between the World Wars, and the third wave-and by far the largest

No abstract

The paper presents basic facts and knowledge of special survey focused on detection and evaluation methods of subsurface drainage systems by means of remote sensing. It is aimed at the complex analysis of applied processes in spatial localization, classifi cation or assessment of subsurface drainage systems' actual condition by means of distance research methods. Data collection, their analysis and interpretation have been shown in seven experimental areas in the Czech Republic. Mainly it means determination of potential, application principles and limits of pracical use of diff erent technologies and image data obtained by remote sensing in solving questions.

Non-point sources of water pollution caused by agricultural crop production are a serious problem in Czechia, at present. This paper describes a new approach for the mutual delineation and assessment of different pollution sources where the critical points method is used to identify the origin of contamination and the source areas. The critical points, i.e., sites presenting the entry of quick surface and drainage runoff into waters, are classified into three (for surface pollution sources using a WaTEM/SEDEM model) or four (subsurface = drainage sources via the catchment-measures need index) categories, respectively. This enabled us to prioritize the most endangered areas at different scales, ranging from the third-order catchments to very small subcatchments, and to design the appropriate combination of control measures to mitigate surface and drainage water runoff, with these being the main drivers of associated pollution. This methodology was applied to a study conducted in the Czech Republic within the entire Vltava River basin, with a total area of 27,578 km2, and utilized in depth to assess a 543 km2 catchment of the Vlašimská Blanice River. When the effect of the designed surface runoff control measures system had been assessed for sediment transport through outlet profiles of the fourth-order catchments, the average reduction reached 43%. The total reduction in the subsurface transport of nitrogen within the fourth-order catchments was 24%. The approach and results are planned to be projected into river basin management plans for the Vltava River basin. Nevertheless, a thorough reassessment of current legislations and strategies is needed to enable the broader adoption of mitigation measures and sustainable management patterns within agricultural landscapes.

<p>The continuous rain simulator used with very precise dosing enables both simulation of characteristic rainfall as well as accurate determination of infiltration rate and automatic calculation of hydraulic conductivity of soils under natural conditions. As a part of the research of infiltration processes induced by characteristic rainfalls, the effects of stormy rainfalls were verified in the described project stage. Stormy rain with constant intensity was applied by rain simulator in a single ring infiltrometer. Samples were tested in the laboratory (soils and kaolinite) and directly in the field. During rain infiltration was measured ponding time. Theoretical base of the research comes from non-steady state unsuturated vertical infiltration, which process (in one-dimensional flow conditions) can be described by Richard´s equation. Final simplified solution is provided by Philip´s simplified infiltration equtions. Hydraulic conductivity K was approximated from the analysis of time series of the process of vertical non-steady cumulative infiltration, going after ponding time. Sorptivity S was calculated by the numerical experiment with known values of stormy rain intensity, ponding time and hydraulic conductivity. Compared to traditional methods (single or double ring infiltrometer), soil hydro-physical characteristic (K, S) determined by this method is more reliable, informative and verified by ponding time.</p>