Holderness, the Vale of York, and the Vale of Pickering are three fairly typical marshland areas, and all three were originally wasteland. Medieval reclamation improved the siltlands of each area for arable and pasture, but the peatlands remained waterlogged for three-quarters of the year and were used mainly for summer pasture and as sources of fish, fowl and fuel, until the mid-eighteenth century. Between 176o and 1900 they were drained by the use of large-scale engineering methods. Improvements were greatest in Holderness, while in the other two areas much still remained to be done in the twentieth century. There are various reasons both for the similarities and differences in the drainage history of the three regions, and for the differences between these regions and the other marshland areas of England and Wales. Location, size, the existence or otherwise of a frontage on tidal water and the resulting existence of a 'Court of sewers' - farming systems, patterns of ownership, navigation interests, and the influence of settlements, as well an the physical geography, are all shown to have had an influence both on the pace of improvement and on the pattern of drains developed. The present geography of the three areas shows clear traces of the earlier stages In their history.

Indiana University-Purdue University Indianapolis (IUPUI) / Although many studies have investigated the impact of tile drainage on nitrate and pesticide export from cropland to streams, little information is known about the primary hydrological controls of tile flow response to precipitation events and its impact on N, P and C transport in artificially drained landscapes of the US Midwest. This study investigated 1) the relationship between precipitation characteristics and tile flow response at a high temporal resolution during storms; 2) the relative importance of macropore and matrix flow in tile flow and in N, P and C transport to tile drains; and 3) the impact of storm characteristics in N, P and C fluxes/export rates. The study was conducted between April and June 2008, in an agricultural tile drained soybean field, representative of agro-ecosystems of the US Midwest near Indianapolis, IN. For the 8 storms analyzed, results showed that bulk precipitation amount was the best predictor of mean and maximum tile flow, time to peak and runoff ratio. The contribution of macropore flow to total flow increased with precipitation amount, representing between 11% and 50% of total drain flow, with peak contributions between 15% and 74% of flow. For large storms (> 6 cm rainfall), cations data indicated a dilution of groundwater with new water as discharge peaked. Although no clear indication of dilution was observed for smaller storms (< 4 cm rainfall), macropore flow still contributed between 11% and 17% of total flow. For large storms, the transport of dissolved organic carbon (DOC), total phosphorous (TP) and soluble reactive phosphorus (SRP) was found to be regulated mainly by macropore flow while nitrate transport was regulated mainly by matrix flow. For smaller storms, macropore flow dominated DOC and TP transport while SRP and nitrate transport was dominated by matrix flow. These results significantly increase our understanding of the hydrological functioning of tile drained fields and its interaction with N, P and C transport in spring, which is the time of the year during which most water and N losses from tile drains occur in the Midwest.

L'aménagement des versants méditerranéens en terrasses et en fossés avait pour but d'augmenter la surface agricole et de permettre une meilleure gestion de l'eau. La dégradation des terrasses et des drains peut conduire à une augmentation des risques d'inondation, d'érosion et de maintien des cultures. Pour améliorer la connaissance de l'impact réel sur la réponse hydrologique des versants, cette thèse suit différentes approches de modélisation. D'abord la réponse hydrologique d'un bassin versant méditerranéen (0.91 km2) avec des terrasses et des fossés aménagés est simulée à l'aide d'un modèle distribué, événementiel, à base physique, adapté aux bassins versants agricoles. La performance est très satisfaisante pour certains événements simulés, même si le modèle ne tient pas compte des terrasses. Afin de modéliser l'impact des terrasses agricoles et de l'écoulement artificiel, nous avons conçu un nouveau modèle distribué et parcimonieux qui utilise une distribution linéaire du temps de réponse, combiné avec l'hydrogramme unitaire instantané géomorphologique. Les simulations sur des versants et bassins virtuels avec un réseau non-optimal de drainage (non-OCN) montrent que (i) pour de longues interfaces entre une parcelle et un cours d'eau la réponse hydrologique est plus rapide et le débit de pointe plus élevé; (ii) la vitesse du ruissellement de surface a un plus grand impact sur le débit de pointe que la vitesse d'écoulement dans les fossés; et (iii) la densité de drainage accrue combinée avec la création de terrasses résulte en un débit de pointe plus élevé en aval et moins élevé en amont. / Terrace cultivation and artificial drainage were implemented on Mediterranean hillslopes for multiple reasons: agricultural terraces increase arable land surface and artificial drainage allows for better water management. Degradation of terraces and channels inevitably leads to an increase in flood risk, erosion and, eventually, crop damage. Little is known about their effect on hillslope hydrologic response, and therefore this thesis presents an integrated method where we compare different modelling approaches. We first simulated the hydrologic response of a Mediterranean catchment (0.91 km2) with terrace cultivation and artificial drainage using a physically-based, fully distributed storm flow model for agricultural catchments. Simulation performance is impressive for some storms, even though the model does not account for terraces. In order to model the effects of terrace cultivation and artificial drainage on hillslope hydrologic response explicitly, we subsequently developed a new distributed model with only geometric and flow velocity parameters, using a linear response time distribution combined with the hillslope geomorphologic instantaneous unit hydrograph. Simulations on virtual hillslopes and catchments with a non-optimal channel network suggest that (i) drainage is faster and attains higher peak flows for longer interface lengths between agricultural fields and drainage channels; (ii) overland flow velocity has greater influence on peak flow than channel flow velocity; and (iii) the combined effect of increased drainage density and introduction of terrace cultivation is enhanced peak flow at the outlet, and a reduction of peak flow from upstream terraces.

An integrating approach, including knowledge about whole systems of processes, is essential in order to reach both development and environmental protection goals. In this thesis Geographical Information Systems (GIS) are suggested as a tool to realise such integrated models. The main hypothesis in this work is that several natural technical and social systems that share a time-space can be compared and analysed in a GIS. My first objective was to analyze how GIS can support research, planning, and, more specifically, bring a broad scattering of competence together in an interdisciplinary process. In this process GIS was ivestigated as a tool to achieve models that give us a better overview of a problem, a better understanding for the processes involved, aid in foreseeing conflicts between interests, find ecological limits and assist in choosing countermeasures and monitor the result of different programs. The second objective concerns the requirement that models should be comparable and possible to include in other models and that they can be communicated to planners, politicians and the public. For this reason the possibilities to communicate the result and model components of multidimensional and multi-temporal data are investigated. Four examples on the possibilities and problems when using GIS in interdisciplinary studies are presented. In the examples, water plays a central role as a component in questions about development, management and environmental impact. The first articles focus on non-point source pollutants as a problem under growing attention when the big industrial and municipal point sources are brought under control. To manage non-point source pollutants, detailed knowledge about local conditions is required to facilitate precise advices on land use. To estimate the flow of metals and N(itrogen) in an area it is important to identify the soil moisture. Soil moisture changes over time but also significantly in the landscape according to several factors. Here a method is presented that calculate soil moisture over large areas. Man as a hydrologie factor has to be assessed to also understand the relative importance of anthropogen processes. To offer a supplement to direct measurements and add anthropogen factors, a GIS model is presented that takes soil-type, topography, vegetation, land-use, agricultural drainage and relative position in the watershed into account. A method to analyse and visualise development over time and space in the same model is presented in the last empirical study. The development of agricultural drainage can be discussed as a product of several forces here analyzed together and visualized with help of colour coded "Hyper pixels" and maps. Finally a discussion concerning the physiological and psychological possibilities to communicate multidimensional phenomena with the help of pictures and maps is held. The main conclusions in this theses are that GIS offer the possibilities to develop distributed models, e.g., models that calculate effects from a vide range of factors in larger areas and with a much higher spatial resolution than has been possible earlier. GIS also offer a possibility to integrate and communicate information from different disciplines to scientists, decision makers and the public. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 6 uppsatser.</p> / digitalisering@umu