Kilder og klima i Roskilde Projektrapport, Geografi, Roskilde Universitet. Rapporten er udarbejdet af: Efterårssemester - 2018 Anders Heindorff Lin Sigrid Hall Sveinbjørnsson Vejleder: Magnus Kjersgaard Stig Roar Svenningsen Mikael Gamborg Lauridsen Antal anslag: 215.068 Roskilde Universitet Kandidatprojekt i Geografi - efterår 2018 Indholdsfortegnelse Titelblad ......................................................................................................................................................................................................... 5 1.0 Introduktion......................................................................................................................................................................... 6 1.1 Abstract ................................................................................................................................................................................................... 6 1.2 Indledning .............................................................................................................................................................................................. 7 1.3 Motivation .............................................................................................................................................................................................. 8 1.4 Indkredsning af problemfelt ........................................................................................................................................................... 9 1.5 Hypoteser ............................................................................................................................................................................................. 10 1.6 Problemformulering ........................................................................................................................................................................ 11 1.6.1 Underspørgsmål for problemformulering .................................................................................................................. 11 1.7 Afgrænsning ........................................................................................................................................................................................ 11 1.8 Læsevejledning ................................................................................................................................................................................... 12 2.0 Metode ................................................................................................................................................................................. 14 2.1 At studere naturen i geografien .................................................................................................................................................. 14 2.1 Historisk indblik i casestudiet i naturgeografien ................................................................................................................. 15 2.2 Den hypotetisk-deduktive metode .............................................................................................................................................. 17 2.3 Geografiske Informationssystemer (GIS) - Metode .............................................................................................................. 18 2.3.1 GIS - metode .............................................................................................................................................................................. 18 2.3.2 Kort over afstrømningsforhold i Roskilde .................................................................................................................. 19 2.3.3 Data og bearbejdning............................................................................................................................................................ 19 2.3.4 Forbedringsforslag til modellering ................................................................................................................................ 21 2.4 Metodiske overvejelser før feltarbejdet .................................................................................................................................... 22 3.0 Teori ..................................................................................................................................................................................... 23 3.1 Hydrologi i Roskilde ......................................................................................................................................................................... 23 3.1.1 Hydrologiske kredsløb og vandbalanceligningen i Roskilde .............................................................................. 23 3.1.2 Vandbalancen sat på formel .............................................................................................................................................. 24 3.1.3 Grundvandets karakteristika ............................................................................................................................................ 30 3.1.4 Det primære - og sekundære grundvandsmagasin i Roskilde ........................................................................... 30 3.1.5 Grundvandets bevægelse .................................................................................................................................................... 31 3.1.6 Darcy's lov og grundvands-hydrauliske parametre ............................................................................................... 35 3.1.7 Grundvandets strømningshastighed ............................................................................................................................. 36 3.1.8 Tidsperspektiver for dannelse af grundvand i det sekundære grundvandsmagasin .............................. 38 3.1.9 Grundvandsdannelse i fremtiden med scenarie A1B ............................................................................................. 39 3.1.10 Vandkvalitet ........................................................................................................................................................................... 40 3.2 Kildernes dannelse ............................................................................................................................................................................ 41 3.2.1 Kilder ........................................................................................................................................................................................... 41 3.2.2 Kilder i Roskilde ...................................................................................................................................................................... 42 3.3 Geologien og geomorfologien omkring Roskilde. ................................................................................................................. 44 Side 2 af 147 Roskilde Universitet Kandidatprojekt i Geografi - efterår 2018 3.3.1 Kridt og Palæogen .................................................................................................................................................................. 44 3.3.2 Kvartær ....................................................................................................................................................................................... 46 3.4 Påvirkning af klimaforandringer................................................................................................................................................ 52 3.5 LAR - Lokal Afledning af Regnvand............................................................................................................................................ 56 3.5.1 Roskilde Ring ........................................................................................................................................................................... 57 3.5.2 Den nordlige del af Roskilde by: ...................................................................................................................................... 60 3.6 Opsummering: .................................................................................................................................................................................... 62 4.0 Casebeskrivelse ....................................................................................................................................................... 65 4.1 Lokalitet ................................................................................................................................................................................................ 65 4.2 Interessenter og kildevæld............................................................................................................................................................. 66 4.3 Kildernes historiske betydning og udvikling: ......................................................................................................................... 68 4.3.1 Roskildes vandforsyning ..................................................................................................................................................... 69 4.3.2 Vandforsyningens betydning for kilderne: ................................................................................................................