Diffuse agricultural pollution is a major contributor to poor water quality in many parts of the world. Consequently agri-environment policy promotes the use of riparian buffer strips and/or denitrifying wetlands to intercept and remove diffuse NO3--N pollution. However, these methods have the potential to cause ‘pollution swapping’: the exchange of one form of pollution as a result of measures implemented to reduce another. Thus the benefits of intercepting NO3--N could be offset by enhanced emissions of the potent greenhouse gases, nitrous oxide (N2O) and methane (CH4), from buffer strips and wetlands. This research aimed to: (1) quantify the direct N2O emissions from an irrigated buffer strip (IBS), using nitrate-rich agricultural drainage water, compared to a non-irrigated control (CP); (2) improve the understanding of N2O production and consumption within soils using controlled soil monolith experiments; (3) assess the effectiveness of a small (60 m2) instream wetland at intercepting and removing diffuse NO3--N pollution, and quantify pollution swapping in the form of CH4 and N2O emissions; (4) assess the production of CH4 and N2O within the sediment, and their emissions as well as inorganic-N concentrations in the overlying water column in response to temperature and turbulence, using intact wetland sediment and membrane inlet mass spectrometry (MIMS). The research focused on mitigating diffuse NO3--N pollution from grazed pasture at a farm in north-east England. Annual N2O-N emissions from the IBS and CP were not statistically different (P > 0.05): 509 and 263 g N2O-N ha-1, respectively, in 2007 and 375 and 500 g N2O-N ha- 1 year-1, respectively, in 2008. Irrigation of the IBS increased spatial variability in flux and generated hotspots of denitrification compared to the CP. However, these changes were short-lived. Direct N2O emission factors (EF1) calculated using the available NO3--loading data (September 2007 - December 2008) for the IBS were lower (c.0.1%) than those calculated for the CP assuming N input from biological N fixation only (<1.9%). Soil monolith experiments under a variety of irrigation and NO3--N loading regimes confirmed low direct and indirect (of dissolved N2O-N in leachate) emissions (<3.1 and <2.3% of applied NO3--N emitted as N2O-N, respectively), similar to the IPCC default emission factors. However, N loss in leachate was high, up to 82% of added NO3--N with concentrations reaching 24 mg NO3--N L-1. Therefore even though no pollution swapping occurred the high leachate losses indicate irrigation of buffer strips are not effective mitigation methods. Monitoring for 2 years of the instream wetland that received median NO3--N concentrations of c. 6 mg N L-1, but up to c. 20 mg N L-1, showed it to be ineffective at intercepting diffuse NO3- pollution: likely a result of the relatively high discharge and short water residence time, as well as the direct input of NO3--N to the wetland from secondary sources: field drains and/or overland flow. The wetland was a net source of NH4+-N in both 2007 and 2008, and a net sink of NO3--N in 2007 only. Annual wetland CH4 and N2O emissions were 713 and 237 mg CH4 m-2 year-1, and 3.5 and 1.9 mg N2O-N m-2 year-1, for 2007 and 2008, respectively and were highly variable between seasons. N pollution swapping was minimal from either direct or indirect emissions, but CH4 emissions were found to be of greater importance at a net cost of ~ £600 ha-1 over the study period (2007 to 2008), compared to N2O emissions (~ £60 ha-1) and low NO3--N interception savings (~ £24 ha-1). Incubation experiments suggest that spatially variable microsites of nitrifying, denitrifying or methanogenic activity and CH4 oxidation occur within the wetland sediment. Therefore off-line, larger wetland systems offer the best prospects of enhanced NO3--N interception and potentially reduced CH4 emissions by maintaining shallow water depths (increased CH4 oxidation) and long residence times (increased opportunity for denitrification), within the wetland or wetland cells.

No description available.

Sustainable water resource management requires understanding how hydrologic processes are impacted by environmental management and land-use decisions across multiple spatial and temporal scales. A key concept in this respect is hydrologic ecosystem services (HES), which are the water related ‘goods’ produced by the environment which are valuable to humans. This dissertation assesses a range of topics concerning HES in the Vouga basin (north-central Portugal), and their connection with land-cover and land-use practices. Specifically, the relationship between changes in forest and agricultural land-cover and management practices, and associated changes in HES were examined using a range of statistical and modeling approaches. To quantify the effects of different agricultural scenarios on both HES and potential stakeholders, the ‘Soil and Water Assessment Tool’ (SWAT) was utilized, in conjunction with economic assessment methods. The first research section (Section 6) of the dissertation assesses the trends in streamflow quantity and yield in the Águeda watershed (a sub-basin of the Vouga) over a 75-yr period which coincided with large-scale afforestation of Pinus pinaster and (later) Eucalyptus globulus. Counter to the findings from meta-analysis studies of the effect of forest change on water availability, this study did not detect statistically significant trends in streamflow. By contrast, these findings support the view that there are prerequisite climatic, pedological, and eco-physiological watershed conditions that are necessary to observe hydrologic impacts at the watershed scale (which are not present in the Águeda watershed). By contrast, the significant changes which were detected are related to baseflow, which correspond with different periods of afforestation, and may be attributable to the promotion of soil water repellency under the mature pine and eucalypt stands. In the second research section (Section 7), an assessment is carried out on the hydrologic and nitrate dynamics at the whole basin scale, using the SWAT model. This assessment indicated that there is a high degree of variability in nitrate export from the different parts of the basin, with the highest rates coming from the lower (agriculturally dominated portion) of the basin. The main flow pathways for nitrate export were found to be leaching from agricultural land-cover types, which consistently had the highest export for all land-use and pathways. These findings indicate that the water bodies at the highest risk of nitrate pollution in the Vouga basin are the groundwater aquifers. The final research section (Section 8) utilizes the SWAT model to examine how reduced rates of fertilizer inputs would affect nitrate leaching, crop yields, and agricultural profitability in the lower Vouga basin. This research found that reduced rates of fertilization would reduce the amount of leached nitrate substantially, but that this would also lead to a large decrease in crop yield and profitability. A large difference in the inefficiency (i.e. crop production vs. nitrate export) between different HRUs was found, which could provide a focus for potential management action. This research strongly indicates that such actions may be needed to reduce the negative impacts of this pollution on the value of the groundwater aquifers, and to avoid associated costs which are otherwise passed on to local water users (e.g. through higher water treatment costs). The overall findings of the dissertation highlight the importance of the upper (forested) basin as a drinking water supply area, given the prevalence of nitrate pollution in the lower basin. However, the historic afforestation in the Vouga basin has resulted in a reduction in baseflow, which is negative from a drinking water supply perspective. Therefore, while the forested uplands are beneficial from water quality standpoint (compared to intensive agriculture), they also have altered flow patterns in a manner which will reduce available supply. The findings from the upper basin contrast sharply with the lower basin, where there are potentially large negative HES impacts due to current agricultural practices. These practices will primarily impact groundwater aquifers, and therefore the water quality within the lower basin receive little benefit from the relatively high-quality water from the upper basin. This highlights the importance of considering the interconnectivity of HES across spatial scales, which will depend on the specific site characteristics of the river basin.

Η περιοχή μελέτης εκτείνεται στο βόρειο και παραλιακό τμήμα του νομού Κορινθίας μεταξύ των πόλεων Κιάτου και Κορίνθου και καταλαμβάνει έκταση 65km2. Η νέα εθνική οδός Κορίνθου – Πατρών αποτελεί το νότιο όριο της περιοχής ενώ προς βορρά περιορίζεται από τον Κορινθιακό κόλπο. Το τοπογραφικό ανάγλυφο είναι ήπιο με το υψόμετρο να κυμαίνεται από 0 – 50 μέτρα. Ο ποταμός Ασσωπός και οι χείμαρροι Ραχιάνης και Ζαπάντης δομούν το υδρογραφικό δίκτυο της περιοχής. Το γεωλογικό υπόβαθρο της περιοχής αποτελείται από ανθρακικά ιζήματα των ζωνών Τρίπολης και Πίνδου, των οποίων υπέρκεινται μετα-ορογεντικά ιζήματα Πλειο-πλειστοκαινικής ηλικίας. Ο υδροφόρος ορίζοντας που μελετήθηκε αναπτύσσεται σε αλλουβιακά ιζήματα, κυρίως άμμους, κροκάλες, λατύπες, και λεπτομερή αργιλοαμμώδη και πηλοαμμώδη ιζήματα που εμφανίζουν υψηλό βαθμό ετερογένειας. Το πάχος του υδροφόρου κυμαίνεται από λίγα μέτρα έως 60 m και χαρακτηρίζεται ως ελεύθερος. Η ρηξιγενής ζώνη που εμφανίζεται κατά μήκος της Ν.Ε.Ο. Κορίνθου – Πατρών αποτελεί υδρογεωλογικό όριο προς νότο για τον υπό μελέτη υδροφόρο. Η εμφάνιση μαργών στην περιοχή του Κιάτου είναι το δυτικό υδρογεωλογικό όριο, ενώ ανατολικά περιορίζεται από την επέκταση των Τυρρήνιων αναβαθμίδων στη θάλασσα. Η κύρια τροφοδοσία του υδροφόρου προέρχεται από τη διήθηση των επιφανειακών υδάτων του ποταμού Ασωπού και των παρακείμενων χειμάρρων, ενώ κατά δεύτερο λόγω από την απευθείας κατείσδυση των ατμοσφαιρικών κατακρημνισμάτων. Για την προσομοίωση της υπόγειας ροής του αλλουβιακού υδροφόρου έγινε χρήση του κώδικα MODFLOW της USGS. Από την εφαρμογή του μοντέλου εξήχθησαν ικανοποιητικά αποτελέσματα που έδωσαν τη δυνατότητα υπολογισμού ενός αξιόπιστου ισοζυγίου, το οποίο μπορεί να αποτελέσει ένα εργαλείο στην εφαρμογή ενός σχεδίου ορθολογικής διαχείρισης των υδατικών πόρων της Κορινθίας. Για την υδροχημική έρευνα χρησιμοποιήθηκε πυκνό δίκτυο δειγματοληψίας νερού σε 35 υδροσημεία της περιοχής μελέτης. Ο υδροφόρος έχει επηρεαστεί από φαινόμενα υφαλμύρινσης και ανταλλαγής ιόντων κυρίως στις βόρειες παράκτιες ζώνες. Οι συγκεντρώσεις των NO3-, NH4+ και των SO4-2 ιόντων παρουσιάζονται υψηλότερες από τα ανώτατα επιτρεπόμενα όρια ποσιμότητας. Η εφαρμογή της παραγοντικής ανάλυσης ανέδειξε τις παραπάνω υδροχημικές διεργασίες. / The study area forms the northern coastal part of Corinth’s prefecture, between the towns of Kiato and Corinth and has an area extend of 65 km2. To the south it is bounded by Athens - Patras National road, whilst to the north it is bounded by Corinthian Gulf. The topographic relief is quite gentle and varies from 0 to 50 m. A considerable hydrographic network develops across the studied region and is represented mainly by the river Asopos and the less important torrents Rachianis and Zapantis. The region can be characterized as an agro tourism center. The land is used mainly for the cultivation and of citrus fruits, olives, apricots and vineyards. Regional environment is subject to numerous pressures most important of which are intensified uses of land and water resources. Water demands have considerably increased over the last 15 years and mainly are covered by groundwater abstract from the alluvial aquifer system. The geological bedrock of the study area consists of the carbonate sediments of Tripolis and Pindos isopics zones and a transitional zone between Pindos and Pelagonial Zone. The plain north of the national zone is covered by post orogenetic sediments of Pliocene to Holocene age which unconformably overlay the bedrock formations. The studied aquifer is formed of recent unconsolidated material consisting of sands, pebbles, breccias and fine clay to silty sand deposits, characterized by high degree of heterogeneity and anisotropy. The thickness of the aquifer varies from a few meters to 40 m. From a hydrogeological point of view the system consists of an unconfined phreatic aquifer. A fault zone along the national highway delineates the southern edge of aquifer system, which is bounded by the Gulf of Corinth to the north. To the east, the system is bounded by the Tyrrhenian deposits extended to the sea. The marl series which, as an entity, is considered an aquitard, slopes to the north and forms the bedrock of the studied coastal alluvial aquifer system. The basic recharge of the phreatic aquifer is from the fluviotorrential deposits, especially those of the Asopos River and also from the Tyrrhenian deposits across the southern edge of the basin. In addition to that the aquifer recharged from direct infiltration of precipitation and river bed indirect infiltration. The simulation of ground water flow of the alluvial aquifer is based on the MODFLOW model of the USGS. The application of the mathematical model had very satisfactory results which is a reliable hydrogeological balance. Estimation of hydraulic conductivity distribution was optimized by using trial and error inverse method. The ground water hydrochemical study was carried out, by an extensive network of 35 samples. The use of inorganic fertilizers in cultivations has a great pollution effect in ground water. The coastal aquifer has been affected, by sea water intrusion and as a result catio-exchange phenomena took plase along the coastline mainly at Lechaio area. The concentration of NO3- , NH4+, and SO4- ions are higher than the maximum allowed drinking limits. The application of R-mode factor analysis helped to delineate the major hydrochemical process of the area.

The cumulative dissertation at hand addresses the question of how promising the successful implementation of the WFD is. Since research on implementation deficits has so far mainly considered national and sub-national levels, regional and local scales are taken centre stage within the dissertation. The Hase river catchment, which is located in one of Germany s most intensive livestock areas, serves as an example. The thesis shows that the procedural character of the WFD and regulative uncertainties give way to interpretation and action leeway, which will be pivotal to judgement on implementation success at lower levels. Moreover, the consistent operationalisation of nitrate limits in particular has led to major difficulties during implementation in Germany from which restraints can be expected for the preparation of river basin management plans and the program of measures. As to the regional level, implementation restraints also upraise due to socio-economic dependencies from agriculture and a high identification of the regional population with this economic sector have placed agriculture in a powerful position. In conclusion, one can state that various implementation restraints occur and the cause of these can be found at all scales European, sub-national and regional. The results of this dissertation concerning the multi-level system reveal that the relationship and interaction of the various scales will be given increased attention during the implementation process of European environmental policy. Besides the national and sub-national scale, the regional and local levels will be of equal importance. The question of suitable scales for implementation decisions and measures also offers pivotal approaches to undertake future research. Further research needs occur with new regional studies at national and international scales, with regard to the future of water protection in the course of the reform of German federalism and the current debate on climate change.