TY - THES A1 - Jackisch, Conrad T1 - Towards applied modeling of the human-eco-system an approach of hydrology based integrated modeling of a semi-arid sub-catchment in rural north-west India N2 - The development of rural areas concerning food security, sustainability and social-economic stability is key issue to the globalized community. Regarding the current state of climatic change, especially semi-arid regions in uenced by monsoon or El Niño are prone to extreme weather events. Droughts, ooding, erosion, degradation of soils and water quality and deserti cation are some of the common impacts. State of the art in hydrologic environmental modeling is generally operating under a reductionist paradigm (Sivapalan 2005). Even an enormous quantity of process-oriented models exists, we fail in due reproduction of complexly interacting processes in their effective scale in the space-time-continuum, as they are described through deterministic small-scale process theories (e.g. Beven 2002). Yet large amounts of parameters - with partly doubtful physical expression - and input data are needed. In contradiction to that most soft information about patterns and organizing principles cannot be employed (Seibert and McDonnell 2002). For an analysis of possible strategies on the one hand towards integrated hydrologic modeling as decision support and on the other hand for sustainable land use development the 512 km2 large catchment of the Mod river in Jhabua, Madhya Pradesh, India has been chosen. It is characterized by a setting of common problems of peripheral rural semi-arid human-eco-systems with intensive agriculture, deforestation, droughts and general hardship for the people. Scarce data and missing gauges are adding to the requirements of data acquisition and process description. The study at hand presents a methodical framework to combine eld scale data analysis and remote sensing for the setup of a database focusing plausibility over strict data accuracy. The catena-based hydrologic model WASA (Güntner 2002) employes this database. It is expanded by a routine for crop development simulation after the de Wit approach (e.g. in Bouman et al. 1996). For its application as decision support system an agentbased land use algorithm is developed which decides on base of site speci cations and certain constraints (like maximum pro t or best local adaptation) about the cropping. The new model is employed to analyze (some) land use strategies. Not anticipated and a priori de ned scenarios will account for the realization of the model but the interactions within the system. This study points out possible approaches to enhance the situation in the catchment. It also approaches central questions of ways towards due integrated hydrological modeling on catchment scale for ungauged conditions and to overcome current paradigms. N2 - Die Entwicklung ländlicher Regionen hinsichtlich von Ernährungssicherheit, Nachhaltigkeit und sozio-ökonomischer Stabilität ist eine der wichtigsten Aufgaben unserer globalisierten Gemeinschaft. In Hinblick auf den Klimawandel sind insbesondere semi-aride Gebiete im Einfluss von Monsun oder El Niño von extremen Wetterereignissen betroffen. Tockenheiten, Überschwemmungen, Erosion, Bodendegradation, Verschlechterung der Wasserqualität und Versteppung sind nur einige, oft beobachtete Folgen. Der Stand der Forschung in Sachen hydrologischer Umweltmodellierung ist insbesondere einem reduktionistischen Paradigma verhaftet (Sivapalan 2005). Obwohl eine enorme Menge verschiedenster Prozessmodelle existiert können auf Grundlage kleinskaliger Prozessapproximationen die komplex interagierenden Prozesse in ihren wirkenden Skalen im Raum-Zeit-Kontinuum nur begrenzt beschreiben werden (z.B. Beven 2002). Während die verwendeten Modelle große Mengen an Parametern und Daten benötigen, können wichtige Informationen über Muster und Organisationsprinzipien nicht in die Simulationen einfließen. Für eine Analyse möglicher Wege und Restriktionen der integrierten hydrologischen Modellierung als Mittel in der Entscheidungsunterstützung wurde das 512 km² große Einzugsgebiet des Mod Flusses in Jhabua, Madhya Pradesh, Indien ausgewählt. Es ist gekennzeichnet von charakteristischen Problemen der Neuen Peripherie (z.B. Scholz 2004) (im human-geographischen Kontext) und intensiv anthropogen beeinflusster Agrar-Öko-Systeme der semi-ariden Tropen. Die dünne Datengrundlage des nicht-bepegelten Einzugsgebiets stellt dabei eine besondere Anforderung an die Datenakquise. In der vorliegenden Arbeit wird ein methodischer Ansatz vorgestellt, der Feld- und Fernerkundungstechniken zur Landschaftsanalyse verbindet. Mit dem Fokus auf Plausibilität statt strenger "Datengenauigkeit" wird eine Datenbank zur hydrologischen Modellierung des Gebiets entwickelt. Das Catena-basierte hydrologische Prozessmodell WASA (Güntner 2002) wird um eine Routine zur Simulation der Entwicklung von Nutzpflanzen nach de Wit (z.B. in Bouman et al. 1996) erweitert. Zur Anwendung des Modells als Entscheidungsunterstützungssystem ist ein agentenbasierter Landnutzungsalgorithmus entwickelt worden, welcher auf Grundlage von Standorteigenschaften und politischen Vorgaben wie Profitmaximierung oder Standortanpassung über die Landnutzung entscheidet. Das neue Modellsystem wird zur Untersuchung von einigen Landnutzungstrategien so verwendet, dass nicht antizipierte Szenarien sondern die Wechselwirkung des Systems selbst die Realisation des Modells bestimmen. Die Umsetzung zeigt einerseits mögliche Ansätze zur Verbesserung der Situation im Untersuchungsgebiet auf. Anderseits gibt sie konkrete Vorschläge zu zentralen Fragen hydrologischer Umweltmodellierung und zur Überwindung bestehender Paradigmen. KW - Hydrologische Modellierung KW - Semi-arid KW - Agrarökosystem KW - Indien KW - Jhabua KW - Madhya Pradesh KW - Agent KW - Modellierung KW - WASA KW - SWAP KW - WOFOST KW - Hydrologic Modeling KW - Human-Eco-System KW - India KW - Agent Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13513 ER - TY - JOUR A1 - Bronstert, Axel A1 - de Araujo, Jose-Carlos A1 - Batalla Villanueva, Ramon J. A1 - Costa, Alexandre Cunha A1 - Delgado, José Miguel Martins A1 - Francke, Till A1 - Förster, Saskia A1 - Guentner, Andreas A1 - Lopez-Tarazon, José Andrés A1 - Mamede, George Leite A1 - Medeiros, Pedro Henrique Augusto A1 - Mueller, Eva A1 - Vericat, Damia T1 - Process-based modelling of erosion, sediment transport and reservoir siltation in mesoscale semi-arid catchments JF - Journal of soils and sediments : protection, risk assessment and remediation N2 - To support scientifically sound water management in dryland environments a modelling system has been developed for the quantitative assessment of water and sediment fluxes in catchments, transport in the river system, and retention in reservoirs. The spatial scale of interest is the mesoscale because this is the scale most relevant for management of water and land resources. This modelling system comprises process-oriented hydrological components tailored for dryland characteristics coupled with components comprising hillslope erosion, sediment transport and reservoir deposition processes. The spatial discretization is hierarchically designed according to a multi-scale concept to account for particular relevant process scales. The non-linear and partly intermittent run-off generation and sediment dynamics are dealt with by accounting for connectivity phenomena at the intersections of landscape compartments. The modelling system has been developed by means of data from nested research catchments in NE-Spain and in NE-Brazil. In the semi-arid NE of Brazil sediment retention along the topography is the main process for sediment retention at all scales, i.e. the sediment delivery is transport limited. This kind of deposition retains roughly 50 to 60 % of eroded sediment, maintaining a similar deposition proportion in all spatial scales investigated. On the other hand, the sediment retained in reservoirs is clearly related to the scale, increasing with catchment area. With increasing area, there are more reservoirs, increasing the possibility of deposition. Furthermore, the area increase also promotes an increase in flow volume, favouring the construction of larger reservoirs, which generally overflow less frequently and retain higher sediment fractions. The second example comprises a highly dynamic Mediterranean catchment in NE-Spain with nested sub-catchments and reveals the full dynamics of hydrological, erosion and deposition features. The run-off modelling performed well with only some overestimation during low-flow periods due to the neglect of water losses along the river. The simulated peaks in sediment flux are reproduced well, while low-flow sediment transport is less well captured, due to the disregard of sediment remobilization in the riverbed during low flow. This combined observation and modelling study deepened the understanding of hydro-sedimentological systems characterized by flashy run-off generation and by erosion and sediment transport pulses through the different landscape compartments. The connectivity between the different landscape compartments plays a very relevant role, regarding both the total mass of water and sediment transport and the transport time through the catchment. KW - Connectivity KW - Deposition KW - Erosion KW - Modelling KW - Sediment transfer KW - Semi-arid Y1 - 2014 U6 - https://doi.org/10.1007/s11368-014-0994-1 SN - 1439-0108 SN - 1614-7480 VL - 14 IS - 12 SP - 2001 EP - 2018 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Schulz, Katharina A1 - Voigt, Karsten A1 - Beusch, Christine A1 - Almeida-Cortez, Jarcilene S. A1 - Kowarik, Ingo A1 - Walz, Ariane A1 - Cierjacks, Arne T1 - Grazing deteriorates the soil carbon stocks of Caatinga forest ecosystems in Brazil JF - Forest ecology and management N2 - Grazing by domestic ungulates can have substantial impacts on forests in arid and semi-arid regions, possibly including severe loss of carbon from the soil. Predicting net livestock impacts on soil organic carbon stocks remains challenging, however, due to the dependence on animal loads and on soil and environmental parameters. The objective of this study was to better understand grazing effects on soil organic carbon in seasonal tropical dry forests of north-eastern Brazil (Caatinga) by quantifying carbon stocks of the upper soil profile (0–5 cm depth) and greater soil depths (>5 cm depth down to bedrock) along a gradient of grazing intensity while accounting for other influencing factors such as soil texture, vegetation, landscape topography, and water availability. We analysed soil organic carbon, soil clay content, altitude above sea level, soil depth to bedrock, distance to the nearest permanent water body, species diversity of perennial plants and aboveground biomass on 45 study plots located in the vicinity of the Itaparica Reservoir, Pernambuco, Brazil. Livestock (mainly goats and cattle) are unevenly distributed in the studied ecosystem, thus grazing intensity was accounted for based on the weight of livestock droppings per square metre and classified as no or light, intermediate, or heavy grazing. The mean soil organic carbon in the area was 16.86 ± 1.28 Mg ha−1 C with approximately one-quarter found in the upper 5 cm of the soil profile (4.14 ± 0.43 Mg ha−1 C) and the remainder (12.57 ± 0.97 Mg ha−1 C) in greater soil depths (>5 cm). Heavy grazing led to significantly lower soil organic carbon stocks in the upper 5 cm, whereas no effect on soil organic carbon of the soil overall or in greater soil depths was detectable. The soil’s clay content and the altitude proved to be the most relevant factors influencing overall soil organic carbon stocks and those in greater soil depths (>5 cm). Our findings suggest that grazing causes substantial release of carbon from Brazilian dry forest soils, which should be addressed through improved grazing management via a legally compulsory rotation system. This would ultimately contribute to the conservation of a unique forest system and associated ecosystem services. KW - Carbon cycle KW - Degradation KW - Desertification KW - Livestock KW - Semi-arid KW - Soil Y1 - 2016 U6 - https://doi.org/10.1016/j.foreco.2016.02.011 SN - 0378-1127 SN - 1872-7042 VL - 367 SP - 62 EP - 70 PB - Elsevier CY - Amsterdam ER -