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- Delin, Anders
(författare)
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Naturvärden vid VOXNAN : Från Klucksjön till Vallhaga
- 1988
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Länsstyrelsen gav ifebruari 1984 Gävleborgs Botaniska Sällskap i uppdrag att inventera den 12 millånga outbyggda delen av VOXNAN mellan klucksjön och Vallhagaforsens kraftverk.Inventeringen skulle omfatta naturvärdena i stort, och framför allt debotaniska. Inventeringen utfördes under maj-september av fyrauniversitetsstuderande i botanik och åtta medlemmar i sällskapet, under ledningav Anders Delin. Denna rapport redogör för resultaten.
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| 2. |
- Grip, Harald
(författare)
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Water chemistry and runoff in forest streams at Kloten
- 1982
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Natural variability of stream water composition and discharge was studied in the Kloten area, Central Sweden, by means of statistical methods and simulation technique. The effects of Urea (155 kgN ha-1) and ammonium nitrate (AN, 160 kgN ha-1) fertilization and clear-cutting were studied by comparing treated and reference streams before and after management.The concentrations of the chemical constituents and runoff were mostly inhomogeneous in space and time and the coefficients of variation were considerable.Urea fertilization had a more prolonged nitrogen leaching and a total of 750 kgN km-2 compared with AN treated areas (500 kgN km-2). The difference was due to higher nitrate leaching. Base cation leaching was larger and pH increased after Urea fertilization. pH decreased after AN fertilization.Runoff increased 180 mm year-1 after clear-cutting, while no significant change was found after fertilization. The immediate effect of clear-cutting on stream water chemistry was an increase in dissolved organic matter, followed by increased leaching of ammonia (10x), nitrate (9x) and potassium (4.8x). The total excess leaching of nitrogen was 1 040 kgN km-2 during the first three years after clear-cutting.A Norwegian hydrochemical model, that explained stream water composition, was modified and parameterized (40 parameters) for two catchments to analyse differences between them.The differences in parameters between the catchments were interpreted as differences in slopes close to the drainage net, dilution due to different evaporation, differences in standing biomass and current annual increment and slightly different mineral composition of the soils. pH at high flows could be deduced from stand characteristics.
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| 5. |
- Lyngfelt, Sven, 1947
(författare)
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Sediment i avloppssystem - ett nygammalt bekymmer inom ledningsteknikområdet
- 1987
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Ingår i: Bygg & terknik. - 0281-658X. ; 79:5, s. 27-31
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Avloppsnätens viktiga och självklara uppgift är att föra förbrukat vatten och överskottsvatten till reningsverk och recipient. Minst lika viktig men ibland ändå förbisedd är uppgiften att transportera det material som följer med vattnet in i ledningarna. En dålig funktion i det här avseendet resulterar i mer eller mindre permanenta avsättningar. Dessa ger ledningarna en nedsatt kapacitet med risk för översvämmningar som följd.
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| 7. |
- Berndtsson, Ronny, et al.
(författare)
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Spatial and temporal scales in rainfall analysis : Some aspects and future perspectives
- 1988
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 100:1-3, s. 293-313
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Tidskriftsartikel (refereegranskat)abstract
- Aspects of spatial and temporal rainfall variability and rainfall analysis in relation to some water management problems are surveyed and discussed. It is concluded that relevant modelling of hydrological processes in which the rainfall is a driving force is vital with respect to possibilities of finding solutions to increasing environmental problems following urbanization and industrialization. However, modern computer methods and our knowledge of the spatial and dynamic properties of rainfall fields are seldom used in practical engineering applications. This causes errors and uncertainties in the calculated output. Bridging the gaps between researchers and engineers may overcome some of these problems. It is also argued that experimental studies in a variety of climates and physiographical conditions using an interdisciplinary approach are needed in order to further investigate the scale and dynamics of spatial rainfall variability.
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| 8. |
- Berndtsson, R., et al.
(författare)
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The effects of storm water on Lake Vaxjosjon
- 1989
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; 45:2, s. 167-173
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present study was to determine the pollution load originating from storm water on Lake Vaxjosjon. Each year about 1,050,000 m3 of storm water are discharged into the lake. Storm water represents a substantial pollution source for the lake and therefore also a main reason for the hypertrophic conditions in the lake. In order to evaluate the effects of the discharged storm water on the ecological conditions in the lake, an investigation was carried out using available information on storm water quality together with complementary sampling and flow measurements. Two different time scales were considered to be important: a short time scale for evaluating effects on the receiving waters due to shock loads of toxic substances (hours and days) and a long time scale for evaluating the effects of nutrients (years). In order to investigate effects concerning the short time scale, a computer-based runoff model was used. For the long time scale a daily precipitation series from 1970 to 1983 was used. The results showed that approximately 37% of the annual load of total phosphorus and 70% of the annual load of total nitrogen originate from storm water. Also a considerable portion of the annual heavy metal load originates from storm water (zink 51%, copper 55%). The annual total phosphorus load on Lake Vaxjosjon is 0.63 g/m2 lake area and year. The storm water part represents a phosphorus load equal to 0.23 g/m2 lake area and year. The acceptable load of phosphorus, for mesotrophic conditions in the lake, is about 0.2 g/m2 lake area and year. In order to improve the water quality in Lake Vaxjosjon sediment dredging of the bottom sediments needs to be undertaken. The sediments consists of an organic rich, phosphorus and nitrogen accumulated, black, anaerobic deposit, causing internal nutrient loading during summer periods.
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