This doctoral thesis examines the history of the Iraqw’ar Da/aw area in the Mbulu Highlands of northern Tanzania. Since the late nineteenth century this area has been known for its intensive cultivation, and referred to as an “island” within a matrix of less intensive land use. The conventional explanation for its characteristics has been high population densities resulting from the prevention of expansion by hostility from surrounding pastoral groups, leading to a siegelike situation. Drawing on an intensive programme of interviews, detailed field mapping and studies of aerial photographs, early travellers’ accounts and landscape photographs, this study challenges that explanation. The study concludes that the process of agricultural intensification has largely been its own driving force, based on self-reinforcing processes of change, and not a consequence of land scarcity.

This publication summarizes the main results of the INCAProject during 2011/2012 and the contributions to the according INCA-Summer-School, which took place from September 19th – September 27th 2012 at the Technische Universität Dresden, Faculty of Environmental Sciences, Institute of International Forestry and Forest Products, Professorship of Tropical Forestry in Tharandt, Germany.

La desertificació és un problema de degradació de sòls de gran importància en regions àrides, semi-àrides i sub-humides, amb serioses conseqüències ambientals, socials i econòmiques com a resultat de l'impacte d'activitats humanes en combinació amb condicions físiques i medi ambientals desfavorables (UNEP, 1994).L'objectiu principal d'aquesta tesi va ser el desenvolupament d'una metodologia simple per tal de poder avaluar de forma precisa l'estat i l'evolució de la desertificació a escala local, a través de la creació d'un model anomenat sistema d'indicators de desertificació (DIS). En aquest mateix context, un dels dos objectius específics d'aquesta recerca es va centrar en l'estudi dels factors més importants de degradació de sòls a escala de parcel.la, comportant un extens treball de camp, analisi de laboratori i la corresponent interpretació i discussió dels resultats obtinguts. El segon objectiu específic es va basar en el desenvolupament i aplicació del DIS.L'àrea d'estudi seleccionada va ser la conca de la Serra de Rodes, un ambient típic Mediterràni inclòs en el Parc Natural del Cap de Creus, NE Espanya, el qual ha estat progressivament abandonat pels agricultors durant el segle passat. Actualment, els incendis forestals així com el canvi d'ús del sòl i especialment l'abandonament de terres són considerats els problemes ambientals més importants a l'àrea d'estudi (Dunjó et al., 2003).En primer lloc, es va realitzar l'estudi dels processos i causes de la degradació dels sòls a l'àrea d'interés. En base a aquest coneixement, es va dur a terme la identificació i selecció dels indicadors de desertificació més rellevants. Finalment, els indicadors de desertificació seleccionats a escala de conca, incloent l'erosió del sòl i l'escolament superficial, es van integrar en un model espaial de procés.Ja que el sòl és considerat el principal indicador dels processos d'erosió, segons la FAO/UNEP/UNESCO (1979), tant el paisatge original així com els dos escenaris d'ús del sòl desenvolupats, un centrat en el cas hipotétic del pas d'un incendi forestal, i l'altre un paisatge completament cultivat, poden ser ambients classificats sota baixa o moderada degradació. En comparació amb l'escenari original, els dos escenaris creats van revelar uns valors més elevats d'erosió i escolament superficial, i en particular l'escenari cultivat. Per tant, aquests dos hipotètic escenaris no semblen ser una alternativa sostenible vàlida als processos de degradació que es donen a l'àrea d'estudi. No obstant, un ampli ventall d'escenaris alternatius poden ser desenvolupats amb el DIS, tinguent en compte les polítiques d'especial interés per la regió de manera que puguin contribuir a determinar les conseqüències potencials de desertificació derivades d'aquestes polítiques aplicades en aquest escenari tan complexe espaialment.En conclusió, el model desenvolupat sembla ser un sistema força acurat per la identificació de riscs presents i futurs, així com per programar efectivament mesures per combatre la desertificació a escala de conca. No obstant, aquesta primera versió del model presenta varies limitacions i la necessitat de realitzar més recerca en cas de voler desenvolupar una versió futura i millor del DIS. / The aim of this research was to develop a simple methodology for precisely appraising the status and trends of desertification in a semi-arid Mediterranean catchment, through a so-called desertification indicator system (DIS).The assessment of land degradation processes at plot scale was conducted through the monitoring of runoff-erosion microplots. As a result, a set of variables such as soil erosion, soil organic matter and vegetation cover, were identified as the most important factors for soil quality in the target area, and some of these were applied as inputs in the DIS model, accounting for their relevance not only at the plot but also at catchment scale. Regarding the parameter sensitivity of the DIS model, the saturated hydraulic conductivity as well as the erodability factor were identified as the most sensitive variables, whereas the soil-b parameter and also the vegetation cover and the slope angle were revealed as those affecting soil erosion and overland flow the least. Likewise, the model showed greater sensitivity to the dry than to the normal or wet rainfall scenarios. From the results of a plot scale model validation exercise it may be concluded that the behaviour of runoff and erosion at plot scale is somewhat different to that at the landscape scale: a scaling problem. At the plot scale, soil erosion was greatly overestimated by the model in the least vegetated environments and especially under cultivated olive trees, whilst it was slightly underestimated in the most vegetated ones (e.g. dense cork trees). The same pattern was found for overland flow, although measured and modelled runoff data were in the same order of magnitude and so errors were smaller than for erosion. Nevertheless, results may be considered significant in terms of which land uses are the most and least potentially degraded and in this way, the model fulfils its objective as a desertification support tool as it identifies the patterns of change expected, if not the magnitudes. The model would need to be more complex, have better and more input data and a regional scale validation if the magnitudes were to be predicted reliably.Since soil loss is considered the main indicator of soil erosion processes, according to FAO/UNEP/UNESCO (1979), the original landscape as well as the two developed scenarios, one related to a hypothetical landscape after a wildfire and another to a completely cultivated landscape, may be classified as being under low to moderate land degradation. In comparison to the original scenario, both developed scenarios were revealed to have higher soil erosion and runoff rates, especially the cultivated scenario. Hence, these two scenarios seem not to be a sustainable alternative to land degradation processes in the study area. However, a wide range of alternative scenarios may be developed with the DIS model, based on policies of particular relevance to the region and which help to determine the potential desertification consequences of these policies in this spatially complex landscape.

Changes in land use and water use can greatly impact the cycling of water and water-borne substances. Increased redistribution of river water to irrigated fields can cause enhanced evapotranspiration and decreased river discharge. Additionally, the water quality can be affected by the external input of fertilisers and pesticides, and by changed pollutant transport pathways in expansive irrigation canal systems. This thesis examines basin-scale changes in water use, river discharge, water quality and nitrogen (N) loading under conditions of intensified irrigated agriculture, using the Aral Sea drainage basin (ASDB) with its two large rivers Syr Darya and Amu Darya in Central Asia as study area. Results show that more efficient irrigation techniques could reduce outtake of river water to the cotton fields in the ASDB by about 10 km3/year, while the corresponding river water saving at the outlet would be 60% lower. The result illustrates the importance of accounting for return flows of irrigation water in basin-scale water saving assessments. Moreover, a decrease in riverine N concentrations at the outlet of the Amu Darya River Basin (ADRB) was observed during a 40-year period of increasing N fertiliser input. The decrease was identified to be primarily caused by increased recirculation of river water in the irrigation system, leading to increased flow-path lengths and enhanced N attenuation. Decreasing N loads were shown to be primarily related to reduced discharge. N export from the basin may further decrease due to projected discharge reductions related to climate change. Furthermore, nutrients and metals were occasionally found at concentrations above drinking water guideline values in surface waters in the ADRB. However, metal concentrations in groundwater in the lower ADRB were subject to orders of magnitude higher health hazards. Projected decrease in downstream surface water availability would thus imply decreased access to water suitable for drinking. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript.</p>

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Wald weist gegenüber anderen Landnutzungen meist die günstigeren Wasserrückhalteigenschaften auf. Diese sind jedoch begrenzt. Ob zusätzlicher Wald in einem Einzugsgebiet zur Reduktion eines Hochwassers führt, hängt ab von der Vorwitterung, den Eigenschaften des Bodens, auf dem die Aufforstung etabliert wurde, Dauer und Intensität des hochwasserauslösenden Niederschlagsereignisses und Lage und Größe der Aufforstungsfläche im betrachteten Einzugsgebiet. Weiterhin spielt das Waldmanagement, welches in dieser Arbeit nur am Rande diskutiert wurde, eine bedeutende Rolle. Bei der Umwandlung einer anderen Landnutzung in Wald sind noch nicht alle Prozesse, die den Wasserrückhalt betreffen, ausreichend untersucht und beschrieben. Dies gilt besonders für die Änderungen in der hydraulischen Architektur der Böden. Es wurde dargestellt, dass aufwachsende Wälder schon nach wenigen Jahren die Porenverteilung besonders in den oberen Bodenhorizonten verändern. Obwohl experimentelle Felduntersuchungen besonders durch die Suche nach geeigneten Teststandorten schwierig sind, wären weitere Messergebnisse von anderen Böden mit anderen Baumarten hier wünschenswert. Eine modellhafte Beschreibung einer Landnutzungsänderung hin zu Wald in Bezug auf den Hochwasserrückhalt ist demnach mit hohen Unsicherheiten behaftet. Modelle bleiben dennoch die einzige Möglichkeit, Auswirkungen von Landnutzungsänderungen mit vertretbarem Aufwand quantifizierend abzuschätzen. Allgemein gilt bei der Anwendung hydrologischer Modelle zur Prognose von Auswirkungen veränderter Landnutzungen, dass bislang wenig quantitativ verwertbares Wissen über Änderungen im Boden besteht. Weder der Zielzustand noch der Verlauf der Transformation können hier sicher prognostiziert werden. Vernachlässigt man aber solche Prozesse, dürfen bei einer Ergebnisdiskussion auch nur die berücksichtigten Prozesse angeführt werden. Die Weiterentwicklung der Modelle mit gezielter paralleler Datenerhebung ist hier unabdingbar. Die zunehmenden Fragestellungen hinsichtlich veränderter Landnutzungssysteme erfordern auch innovative Formen der Parametrisierung und Kalibrierung der Modelle. Der zunehmende Grad an Prozessabbildungen in den Modellen darf die Parametrisierbarkeit nicht unmöglich machen. Eine adäquate Prozessabbildung ist jedoch der Schlüssel für die szenarienfähige Modellierung. Die Kommunikation der Ergebnisse muss deshalb eine hohe Transparenz mit der Benennung aller bekannten Unsicherheiten aufweisen, da Entscheidungen in der Landnutzung Konsequenzen über sehr lange Zeiträume hinweg nach sich ziehen. Die qualifizierte Prognose von Landnutzungsänderungen ist eine disziplinübergreifende Aufgabe. Hier wirken soziologische, ökonomische und ökologische Prozesse zusammen, deren Resultat die zukünftige Landnutzung ist. Eine weitere wichtige Schlussfolgerung der vorliegenden Arbeit ist daher, dass für die Umsetzung von Maßnahmen, zur Erhöhung des Wasserrückhaltes, wie hier der Aufforstung, ein breiter wissenschaftlicher und gesellschaftlicher Konsens herrschen muss. Es braucht integrierte Ansätze zur disziplinübergreifenden Beschreibung von Auswirkungen veränderter Landnutzung. Trotz aller Unsicherheiten bei der wissenschaftlichen Beweisführung wird erwartet, dass bis zur Umsetzung der Hochwasserrisiko-Managementpläne „nachhaltige Flächennutzungen“ zur „Verbesserung des Wasserrückhaltes“ definiert sind. Besonders für die politischen Entscheidungsträger ist zur Entwicklung geeigneter Steuerelemente festzuhalten, das Hochwasserschutzmaßnahmen in der Fläche ihre hauptsächliche Wirkung nicht am Punkt der Implementierung entfalten, sondern erst weiter flussabwärts. Daher sind die bisherigen Förderinstrumente der EU-Agrarflächenförderung für den Hochwasserschutz in der Fläche nahezu nicht anwendbar. Es gilt hier sektorales Denken zu überwinden. Unterschiedliche Ansprüche an Landnutzungssysteme sind durch Lösungsansätze auszubalancieren, die die unterschiedlichen Landschaftsfunktionen berücksichtigen, von denen Wasserrückhalt ein Teil sein kann. Andere Schutzziele wie Naturschutz, Bodenschutz, Ziele der Wasserrahmenrichtlinie, Fragen eines ästhetischen Landschaftsbildes und nicht zuletzt Fragen der wirtschaftlichen Ansprüche an die einzelnen Flächen spielen hier eine wichtige Rolle. Bei der Entwicklung begründeter Zukunftsszenarien ist diese transdisziplinäre Herangehensweise unbedingt zu empfehlen. Hochwasserschutz kann aber nicht die Aufgabe haben, Hochwasserereignisse vollkommen auszuschließen. Schon heute ist bekannt, dass das Ausbleiben kleiner und mittlerer Hochwässer ökologische Konsequenzen hat. Vielmehr könnte in Gebieten, wie dem hier untersuchten, eine Erhöhung des Waldanteils dazu beitragen, die anthropogenen Störungen zu reduzieren und den Wasserrückhalt dahingehend zu erhöhen, dass hochwasserverschärfende Eingriffe in den Einzugsgebieten zurückgebaut werden. / Forests show, compared to other land uses, in many cases good water retention potential. This is however limited. Whether additional forest area in a catchment leads to a reduction of flooding depends on the pre-event atmospheric conditions, the soil characteristics at the afforested site, the duration and intensity of the rain storm event, and location and size of the afforested area. Further, the forest management, which is only briefly discussed in this thesis, plays an important role. Many water retention related processes occurring during the transformation of a landuse into forest are not yet sufficiently investigated an described. This applies especially to the changes in the hydraulic architecture of the soil. It was shown that after a few years growing forests have already changed the pore distribution, especially in the upper soil horizons. However, further research under different soil and tree type would be desirable. Therefore, a model-based description of land use change towards forest with regard to flood retention comprises uncertainties which should be taken into consideration. Nevertheless, models are the only possibility to assess land use change effects with justifiable expenditure. In general, the application of hydrological models comprised sparse useful information about changes in the soil due to a changed land use. Neither the target state nor the progression of the transformation can be predicted with certainty. Further development of models with parallel observations and data gathering is essential. With increasing number of questions regarding modified land use systems, a need arises for innovative forms of parameterisation and model calibration. The increasing degree of process mapping in models may make parameterability difficult, however, adequate process mapping is the key to scenario capable modelling. The communication of results must therefore include a high degree of transparency in the definition of all known uncertainties, because decisions have long lasting consequences. A qualified prediction of land use changes is a cross-disciplinary task. Ecological, economical, and sociological processes together form the future land use distribution. An important conclusion from this thesis is that the implementation of measures targeting increased water retention requires must result in a consensus with society and economics. Integrated approaches and transdisciplinary assessment of impacts of land use modifications are needed. Although, the uncertainties in model-based land use change assessment are high, there is a need for the definition of “sustainable land use” and “increase of water retention” for the flood risk management plans. Adapted land use as a component of integrated flood risk management has a major constraint: the benefits of water retention in the landscape are mostly not directly noticeable at the place where a measure is implemented. This is highly important for stakeholders and decision makers. However, given that most of the land available for afforestation is a private property, it may be necessary to provide subsidies to encourage landowners to increase the percentage of forested land. Competitive land use system requirements need to be balanced with approaches dealing with different landscape functions. Water retention is part of this functioning. Other protection aims like nature protection, soil protection, aims of the Water Framework Directive, aesthetic land use pattern but also the agrar-economic production play an important role. Well-founded future land use scenarios should use this transdisciplinary view. Finally, it is also important to keep in mind that floods belong to a healthy river runoff regime. Floods are an important part of the natural hydrological cycle, and therefore the goal of watershed management should not be to eliminate them entirely. Additional forest can help to re-establish the natural water retention potential in anthropogenically disturbed river basins and to decrease the human-made contribution to flood generation.

A coastal lagoon is a landform that is influenced by natural processes and human activities. All human activities at the upstream, particularly agriculture and cultivation bring soil, waste, and other materials to the downstream area through the river drains into the lagoon. Even though its position is inland of water bodies, the lagoon is still affected by waves and winds from the sea. Additionally, coastal lagoon will be the depository place for sedimentation from the upland area. Segara Anakan (SA), which is located in Indonesia, is an example of a coastal lagoon area, which has a unique biophysical characteristic. The region has a great natural ability to ensure the sustainability of the interrelationships between terrestrial, estuarine and marine ecosystems in harmony and balance as a habitat for flora and fauna. The region is an area of migration of various types of protected animals and it is a place of breeding for diverse species of the shrimp and fish, which have a highly economical value. Segara Anakan lagoon (SAL), currently experiencing acceleration narrowed on its area due to a very intensive sedimentation from the mainland. The research aims to answer the question of how ecological dynamic occurs in the SAL area due to sedimentation. Achieving the objectives of this study required examining the morphology and land use changes with multitemporal remote sensing approaches. While, to assess the role of community participation and planning management strategies is using qualitative descriptive methods and SWOT analyze. The using of multitemporal remote sensing Landsat images is possible to analyze the morphological and land use changes with different time and sensors. These Landsat has image accuracy about 92.66%. It can be used for image interpretations resulting 13 classes of land use. The morphodynamics of SAL indicated by the changes of area of lagoon and accreted land and also the distance of coastlines during the periods 1979-2013. In addition, the land use or land cover also changes during that time. The bigger portions of land use changes are in the tropical and mangrove\'s forests. There are distinctive forms of participation in conservation efforts. The upstream community involvement in conservation tends to be different participating in the way of ideas, money, materials, properties, skills and expertise or social activities. In addition, the community at downstream area has a sufficiently high level of participation in environmental conservation. There are also strong relationships between the level of education and level of income and basic knowledge in conservation with the participation of SA conservation. The ecological dynamics of the SAL area are described with a historical time line. It is divided into three time periods: the 1970s - 1980s, the 1990s and from 2000 onwards. Each of these has occurrences that can lead to changes in the environment. The implementation of appropriate conservation technique can reduce the sedimentation rate. Hence, the synergic coordination measures between upstream and downstream regions are necessary in the future. Increasing community awareness and participation in the conservation by improving educational sector, providing information, and applying sustainable development land use are the ways to match human activities with the temporal and spatial dynamics of the coastal resources.

永續發展的概念現今已被運用於都市，其中，都市綠地在環境、生態、景觀、社會各層面之機能皆可提升都市永續性，在快速的都市化下，都市內綠地減少，土地利用變遷帶來之環境衝擊影響已自個體單元累積到全球。然而，過去研究中未有關注在綠地的變化趨勢與其他土地利用間的互動關係，以及在不同區域下的變化差異。因此，本研究採用GIS和景觀指數看在1995年至2006年間台北都會區綠地變遷趨勢，並分區探討土地利用間的互動關係，最後藉由二元羅吉斯迴歸分析綠地變化可能原因。 研究結果顯示，在1995年至2006年間，台北都會區整體發展是建地增加，林地也呈上升趨勢，而草地是土地利用轉移下被犧牲掉最多的土地，綠地轉移成其他土地利用情形以都會邊緣地區最嚴重。不同綠地型態在1995年至2006年間的變遷仍有差異，林地在整個台北都會區屬於景觀中的基質，主導性未受動搖，僅在都會中心減少並受破壞；而農地面積略微下降，呈破碎化發展，尤其以都會中心外圍區農地被破壞情形最明顯；草地面積亦下降，破碎化情形較農地更嚴重，在都會郊區、次中心之草地被破壞嚴重，草地各方面機能降低。透過二元羅吉斯迴歸分析發現自然環境、社會經濟與計畫環境皆影響台北都會區的綠地變遷。根據研究結果，建議未來政府於都市計畫上應將綠地空間納入考量，對於不同綠地型態應有不同管制措施，考量各區域綠地型態之差異性，以及自然環境、社會經濟和計畫環境對於綠地變遷的影響，以促進都市朝向永續發展。 / The concept of sustainable development has been applied in cities. Urban green space plays an important role in enhancing the sustainability of the city in regards to the environment, ecology, landscape and society aspects. Under rapid urbanization, green space has greatly declined in cities. Environmental impact resulting from land use change has grown from local to global proportions. However, researches did not pay attention to interactions between green spaces and other land-use change trends or different types of change in different areas. This research used GIS and landscape metrics to investigate the green space change trend and interactions among different land use types in the Taipei metropolitan area from 1995 to 2006. Furthermore, this research analyzed possible reasons that may have caused green space change through logistic regression. The results showed that, from 1995 to 2006, the built up area and the forest increased in Taipei Metropolitan Area; however, the grass decreased because of land use change. Urban fringe was the place that green space changed to other land-use most. There were differences of land use change for different types of green space. Forest was the matrix in the landscape of Taipei metropolitan area. It still kept the predominant role, only decreased and was destroyed in the center of metropolitan area. Farmland slightly decreased and became fragmented, especially in the periphery of the urban center. Grassland area decreased and became fragmented much more than farmland. In suburb and sub-center, grassland was destroyed seriously and became less functional. Through binary logistic regression, the study found that natural environment, socio-economic and government planning do have influence on green space changes in the Taipei metropolitan area. According to the result of the study, the recommendation was that government should take green space into consideration when doing urban planning. For different types of green space and different areas, the government needs to have different measures and needs to consider the impact factors of green space change in order to accelerate sustainable development in cities.