The influence of the mountain peatland management on the water cycle changes

Mountain landscape is not suitable for peatland development. Peat bogs originated in mountains area are characterised by small area and thin layer of organic matter therefore any artificial influence may strongly disturb the structure of a water cycle in a whole peatland basin. Wielkie Torfowisko Batorowskie is a peatland situated at the southwest part of Poland in Stołowe Mountains, which are mainly built of marls and sandstones. The peatland area covers 35ha and its catchment is 120ha when the maximum depth of the peat is 510 cm. Approximately one hundre years ago the bog was afforested by Norway spruce (Picea abies). Another artificial influence was to cross the peatland and its catchment by ditches. These caused the increased of surface runoff and lowering of groundwater table on the peatland, especially on its margin parts when peat soil became strongly mineralized and the process of the peat formation was stopped. Only a few hectares in the centre of the bog kept its natural character. The influence of the artificial drainage on the water cycle mainly concerns the stream outflow from the bog which is increased by ditches, especially during winter time. Wielkie Torfowisko Batorowskie lost some character as a reservoir of water storage contributing the water stocking in the catchment area

Origin and development of Wielkie Torfowisko Batorowskie in Stolowe Mountains

Mountain landscape is not suitable for peatland development. To access the genesis of mountain peat-bog development one should consider mainly the geological and tectonical structure of the investigating site and then respectively follow the changes in climate, which will characterise the peat accumulation during time. Nowadays plant cover shows the state of peatland in its development. Wielkie Torfowisko Batorowskie is a peatland situated at the southwest part of Poland in Stołowe Mountains, which are mainly built of marls and sandstones. The maximum depth of the peat is 520 cm in which we can distinguish about 350 cm layer of highmoor peat on the top of the profile, 20 cm of topogenous one and 140 cm of fen peat on the bottom. The bedrock is marl. Approximately one hundred years ago the bog was afforested by Norway spruce (Picea abies). Another artificial influence was to cross the peatland and its catchment by ditches. The sediment basin was formed due to land collapsing on the lines of faults. The water supply came from the springs of groundwater level in sandstones. This hydrological situation classifies the object as a bog-spring. Plant cover indicates the highmoor character of the peatland. The genesis of Wielkie Torfowisko Batorowskie strictly depended on litological and tectonic situation in the bedrock and that were main factors allowing the site for peat accumulation

The runoff structure in the Nida differential river basin

1. Alimentation of the researched system. In the years 1971-1998, an average 0.698 km³ of water alimented the researched system annually. Of this volume, merely 22 per cent originated by precipitation, while the remaining amount was the inflow from the upper course of the Nida, which therefore had a dominant influence on the regime of the researched section of the river. The temporal distribution of flow coefficient (Parde) did not change between the cross sections closing the system. The temporal distribution of both inflow variables is uneven. With regard to precipitation inflow, the privileged months are June, July and August. In case of river inflow, on the average the largest water volumes aliment the system in the spring. At the same time, the maximum flow values are reached in July and August. The inflow to the river basin is point-like, whereas the precipitation inflow is spatially varied, with the right-bank part of the basin collecting the major part of water. The distribution of precipitation is affected by such factors as the Nida valley. This is particularly well visible in June, July and August (up to 10 per cent difference in precipitation volumes), in the winter months it is an insignificant phenomenon. 2. Runoff conditions in the differential river basin subsystem The differential river basin subsystem is varied in terms of physiogeographic conditions. It is made up of three units: the Wodzisław Hummock, the Pińczów Hummock and the Solec Basin, which bears upon the runoff conditions. This is manifested by differences in the density of the drainage system, ranging from 0.36 km/km² in the Wodzisław Hummock to 0.85 km/km² within the Solec Basin. This picture is disturbed by artificial watercourses, which represent 45 per cent of the entire drainage network. If we compare the runoff conditions in the left-bank and right-bank parts of the river basin, we can observe that in the latter they are markedly worse. Measured at high water stages (in July 1999), the unit runoffs reached the values of merely 1.151 skm/skm² to 2.031 skm². In the left-bank part of the river basin, the unit runoff was definitely higher and more varied. The best runoff conditions were recorded in the gypsum karst of the Solec Basin and at the base of the Pińczów Hummock. Maximum unit runoffs measured in July 1999 reached 15.31 skm². In the years 1971-1998, the average unit runoff from the entire researched subsystem was high and amounted to 5.61 skm². In the wet years, it reached 10.711 skm², while in the dry ones it fell to 3.22 skm². The average runoff coefficient ( 1971-1998) reached 32 per cent. 3. The functioning of the Nida subsystem. The Nida valley constitutes a separate physio-geographic unit. In the early 1970s, it was strongly transformed by man owing to the regulation of the Nida channel, construction of drainage ditches and accompanying hydrotechnical facilities. All this resulted in reduced retention role of the valley in the area of Pińczów. Nonetheless, the valley's retention function was still visible in transforming high water stages. This particularly applied for summer high water stages, whose maximum flows normally diminished along with the river flow. During thaw flows, this was not as obvious, which could be associated with ice phenomena. The transformation period of the maximum flow normally lasted two to three days. In the researched section, the Nida, primarily performs a transit role. In the years 1971-1998, on the average the Nida river channel annually transported 0.546 km³ of water from the upper part of the river basin. The side tributary alimentation from the differential catchment area subsystem represented only eight to nine per cent of this volume. It was primarily water produced by the drainage of the abundant subterranean waters. The waste water discharged to the Nida represented approximately six per cent of the annual average of side tributary alimentation

Regional conditionings of probable maximum Polish river flows

The purpose of this study was to obtain and prove the methods of catchment regionalization in case of annual maximum floods. Identification of Polish rivers was hold on the basis of regional frequency analyses including recognition of homogenous regions in their physical properties and river flow parameters. Results indicate the division on two regional groups: mountain and lowland catchments. Statistical tests prove the obtained regionalization and allow calculating the regional probability curves for these two catchment groups. Obtained results may be helpful in the analysis of floods in ungauged catchments and these where hydrological observations were held in a short period especially when dependency of the maximum probable flows in analysed catchments from their physico-geographical features was proved

Th e sources of moisture in the barchans of Western Sahara

The aim of the study was to determine the impact of climatic and meteorological conditions on aeolian sand transport within barchans. The study area was located at Western Sahara, around the towns of Tarfaya and Laâyoune. Particular attention was paid to the factors that increase the moisture content of the surface and subsurface layers of sand dunes. It could be one of the important factors to have an influence on threshold wind velocity. Western Sahara dune fields are situated in the zone of the dominant wind direction from the northern sector, which determines the barchan dunes shape and orientation, as well as the supply of moisture from the Atlantic Ocean. The results of investigations confirm that dunes receive quite a lot of moisture from rainfall and such phenomena as fog as well. Studies have confirmed that the water supply from the fog is comparable to, or even exceeds the amount of water from rainfall in the area. Wetted surface layer reduces the transport of aeolian material, even in case of a wind speed greater than 4-5 ms⁻¹. The presence of fog and dew does not affect the moisture of the deeper sand layers, which occurs after rainfall. Analysis of aeolian sand transport within the barchan dunes in the areas such a Western Sahara, should not be therefore limited to the measurement of wind speed and its direction. It must include the investigations on other meteorological elements, especially air temperature and humidity conditions, responsible for the amount of atmospheric deposits on the dune surface

Acoustic testing and response prediction of the CASSIOPE spacecraft

A high intensity acoustic test in a reverberant chamber was conducted on the CASSIOPE spacecraft in the final stages of integration and test campaign to ensure that it would survive the acoustic loads during launch. This paper describes the acoustic test methodology, the details of the model used for analytical prediction of the structural response for acoustic excitation and discussion of the predicted response comparison with test results that provided confidence in the spacecraft structural design for acoustic loads. The objective of the spacecraft acoustic test was to demonstrate the ability of the structure and avionics to withstand the broadband random acoustic environment experienced within the launch vehicle payload fairing. The CASSIOPE spacecraft was tested in the reverberant chamber at overall sound pressure level up to 142.1 dB. The automatic spectral control system of the acoustic test facility, which used six control microphones, was able to achieve and the maintain target spectrum levels around the spacecraft within tolerances without manual adjustments to the noise generators' controls. The dynamic response of the CASSIOPE spacecraft during the test was measured using a large number of accelerometers installed on critical locations of the structure. Low level pre-test and post-test structural response signatures as well as electrical integrity checks performed after the exposure to the proto-flight acoustic environment demonstrated the ability of the spacecraft to survive the launch. The acoustic response of the spacecraft was also predicted based on a finite element model analysis to identify the critical components, evaluate structural margins and assess the risks in proceeding with a proto-flight acoustic test based on the specified launch vehicle spectrum. The analysis method used to predict the responses combines the NX/NASTRAN solver and RAYON, a vibro-acoustic simulation software. The RAYON software functionality is based on a boundary element model that enables the creation of an accurate fluid loading on the structure, with consideration of fluid mass and damping effects. The study used a finite element model of the structure that was correlated through an experimental modal survey test and actual spectrum levels achieved during the acoustic test. Responses of most locations compared favourably with the predictions in critical locations such as the solar arrays. Due to the limited availability of the satellite as well as time and cost constraints in a spacecraft development program, it is important to perform both qualification tests as well as analytical predictions in an efficient and timely manner to validate structural designs of spacecraft.Peer reviewed: YesNRC publication: Ye