1. Characterization of Surface Waters, Wetlands and Groundwater
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1. Characterization of surface waters, wetlands and groundwater 1.1 River basin 1.1.1 Landscape and soil types Figure 1.1.1 Topography of Odense Odense River Basin encompasses an area of ap- River Basin. prox. 1 046 km2 and includes approx. 1 100 km Source: National Sur- of open watercourse and 2 600 lakes and ponds vey and Cadastre and (>100 m 2). The present landscape of Fyn was Fyn County. primarily created during the last Glacial Period Height above Danish Zero 11.500 to 100 000 years ago (Figure 1.1.1). The 0-10 m most common landscape feature is moraine plains covered by moraine clay that was depos- 10-20 m ited by the base of the ice during its advance. The 20-30 m meltwater that fl owed away from the ice formed 30-40 m meltwater valleys. An example is the Odense fl oodplain, which was formed by a meltwater 40-50 m river that had largely the same overall course as 50-60 m today’s river. The clay soil types are slightly dominant and 60-70 m encompass approx. 51% of the basin, while the 70-80 m sandy soil types cover approx. 49% (Figure 80-90 m 1.1.2). The moraine soils of Fyn are particu- larly well suited to the cultivation of agricultural 90-100 m crops. Agriculture has therefore left clear traces 100-110 m in the landscape. Deep ploughing, liming and 0 5 10 km the suchlike have thus rendered the surface soils Over 110 m more homogeneous. Watercourse Figure 1.1.2 1.1.2 Land use, population and Soil conditions in wastewater Odense River Basin. The dominant soil Just as elsewhere in Denmark, land use in types at a depth of 1 m Odense River Basin is dominated by agricultural are shown. Mapping exploitation (Figure 1.1.3). Farmland thus ac- carried out by Danish counts for 68% of the basin. Of the remainder, Institute of Agricultur- approx. 16% is accounted for by urban areas, 10% al Sciences 1975–79. by woodland, and 6% by natural/seminatural ar- Coarse sandy and eas (meadows, mires, dry grasslands, lakes and fine sandy soil wetlands, which are protected by Section 3 of the Clayey sand soil Protection of Nature Act). The corresponding Sandy clay soil fi gures for farmland, woodland and natural/sem- inatural areas for Denmark as a whole are 62%, Clay soil 11% and just over 9%, respectively. Special soil type The population of Odense River Basin num- bers approx. 246 000, of which approx. 182 000 Humic soil inhabit Odense, which is Denmark’s third largest Unclassified: city. Approx. 90% of the population in the basin discharge their wastewater to a municipal waste- Urban areas water treatment plant. The remaining 10% of the Woodland population live outside the towns in areas with- Inland waters (lakes, out access to sewerage. There are a total of 6 900 0 5 10 km watercourses residential buildings in these sparsely built-up Residual areas areas outside the sewerage system catchments. Odense PRB Odense Pilot River Basin 11 1.1 River basin Figure 1.1.3 seepage. Many of the dairies and abattoirs were Land use in Odense subsequently closed down due to centralization, River Basin. and serious efforts were initiated to treat urban Source: Areal Infor- mation System (AIS). wastewater. Measures of change were not made Ministry of the Envi- until the 1980s and early 1990s when treatment ronment. of urban and industrial wastewater was consid- erably improved, and unlawful discharges of Urban areas silage juice etc. by the agricultural sector were Cultivated land Woodland stopped. Inland waters (lakes, watercourses) Natural contryside (mires, meadows, etc.) 1.1.3 Agricultural conditions In 2000, there were approx. 1 870 registered farms in Odense River Basin, of which approx. 960 were livestock farms. Livestock production in the basin amounts to approx. 60 000 livestock units (LU) (1999–2002), consisting of 59% pigs, 37% cattle and 4% other livestock. Livestock den- sity averages 0.9 LU/ha farmland, corresponding to the national average, but varies to some extent within the individual catchments that comprise 0 5 10 km Odense River Basin (Figure 1.1.4). Overall, live- stock production in the basin has increased in re- cent years. This masks a production decrease in Figure 1.1.4 dairy farming and a marked increase in pig farm- Livestock density in ing. Based on the applications for permission to the river basins and increase herd size submitted to Fyn County (EIA local water body catch- screening) it is concluded that livestock produc- ments of Fyn County tion will continue to increase in the coming in 2002 expressed in years. Thus in the period from 2000 to mid 2003, relation to the area of permits have been granted to increase livestock farmland in the catch- ments (LU/ha). production in the basin by 17%. Source: Central Live- The dominant crop in Odense River Basin is stock Register under cereals (2/3 winter cereals), while only 10% is ac- the Ministry of Food, counted for by grass/green fodder (Figure 1.1.5). Agriculture and Fish- The concentration of market gardens in the basin eries. is relatively high, occupying approx. 3% of the 1.4 and above farmland. 1.2-1.4 1-1.2 0.8-1 Historical development – Artifi cial drainage 0.6-0.8 and land reclamation in Odense River Basin 0.4-0.6 0-0.4 Over the past 50–100 years, artifi cial drainage no information has been established on an estimated 55% of the cultivated land in Odense River Basin. The aim has been to ensure rapid drainage of the arable 0 5 10 km land and to optimize the possibilities for cultiva- tion. In addition, mires, meadows, watercourses Due to increasing industrialization and the and shallow lakes and areas of the fjord have spread of fl ushing toilets, poorly treated waste- undergone major physical changes or have been water from towns, dairies, abattoirs etc. started erased from the map due to reclamation of the to be discharged into the water bodies of Fyn at land for cultivation. Thus 72% of the major ar- the beginning of the 20th Century. In the 1950s, eas of meadow and mire have disappeared from the agricultural sector also started to cause seri- Odense River Basin over the past 100 years ous pollution of the aquatic environment by dis- (Figure 1.1.6). Much of this has been turned into charging silage juice, liquid manure and manure farmland through regulation of watercourses Odense 12 PRB Odense Pilot River Basin 1.1 River basin Root crops Market gardens Figure 1.1.5 and regular watercourse maintenance. Moreover, 3% Permanent grass 5% Crop distribution on many watercourses and ditches have been piped, 4% and many watercourses have been straightened. Spring cereals farmland in Odense Grass/green fodder 23% River Basin (2000). 10% A corresponding reduction has taken place in Source: Danish Plant the number of minor lakes and ponds. All in all, Pulses Directorate. decades of land reclamation and drainage of wet- 2% lands and farmland have considerably reduced the natural self-cleansing ability of Odense River Seed crops Basin. Specifi c knowledge of currently drained 8% farmland in Odense River Basin is lacking. This knowledge is important for determining the pressure placed on the environment by the individual agricultural areas, and is necessary for Winter cereals future prioritization of environmental initiatives 45% in the agricultural areas. Historical development – farming in Fyn County Figure 1.1.6 Danish agriculture has undergone considerable Distribution of fresh- structural development since the 1950s. Among water meadows, salt other things, holding structure has become more marshes and mires in specialized, and livestock herds have become Odense River Basin concentrated. Since the 1950s, the number of in 1890 and 1992. Pre- pared by Fyn County holdings in Fyn County has decreased by 75%, on the basis of maps while their average size has increased by 250%. from 1890 (1:20 000) Diversifi ed farming with mixed livestock and and the National Sur- crop production has increasingly been replaced vey and Cadastre map by specialized cattle or pig holdings or exclu- from 1992 (1:25 000). sively crop holdings. Watercourses are not Crop distribution in the agriculture of the indicated on the map. 1950s refl ected the diversifi ed holding structure, with mixed livestock and crop production. At Distribution in that time, up to half of the farmland was cultivat- 1890 ed with grass, green fodder and root crops, while 1992 the other half was cultivated with cereal crops, primarily spring cereals. Among other things, agricultural development has entailed a more than 50% reduction in the area of grass, green fodder and root crops since the 1950s, while the area of cereals has increased. At present, only ap- 0 5 10 km proximately 18% of farmland is cultivated with grass, green fodder and root crops, while more than 60% is under cereals (Figure 1.1.7). The reduction in the area under grass, green fodder to an increase in the pig herd, while the cattle and root crops to the benefi t of cereal crops has herd continues to decrease in size. increased leaching of nitrogen due to the fact Due to the great specialization the livestock that the long growing season for grass and green herd – in contrast to previously – is much more fodder crops renders them better able to retain unevenly distributed between the individual the nitrogen than cereals. Since the 1980s, the holdings. The pig herd in particular has become proportion of the land under winter cereals has concentrated in holdings with very large herds.