TY - JOUR A1 - Krol, Maarten A1 - Jaeger, Annekathrin A1 - Bronstert, Axel A1 - Güntner, Andreas T1 - Integrated modelling of climate, water, soil, agricultural and socio-economic processes: A general introduction of the methodology and some exemplary results from the semi-arid north-east of Brazil JF - Journal of hydrology N2 - Many semi-arid regions are characterised by water scarcity and vulnerability of natural resources, pronounced climatic variability and social stress. Integrated studies including climatotogy, hydrology, and socio-econornic studies are required both for analysing the dynamic natural conditions and to assess possible strategies to make semi-arid regions Less vulnerable to the present and changing climate. The model introduced here dynamically describes the retationships between climate forcing, water availability, agriculture and selected societal processes. The model has been tailored to simulate the rather complex situation in the semi-and north-eastern Brazil in a quantitative manner including the sensitivity to external forcing, such as climate change. The selected results presented show the general functioning of the integrated model, with a primary focus on climate change impacts. It becomes evident that due to Large differences in regional climate scenarios, it is still impossible to give quantitative values for the most probable development, e.g., to assign probabilities to the simulated results. However, it becomes clear that water is a very crucial factor, and that an efficient and ecologically sound water management is a key question for the further development of that semi-arid region. The simulation results show that, independent of the differences in climate change scenarios, rain-fed farming is more vulnerable to drought impacts compared to irrigated farming. However, the capacity of irrigation and other water infrastructure systems to enhance resilience in respect to climatic fluctuations is significantly constrained given a significant negative precipitation trend. (c) 2005 Elsevier B.V. All rights reserved. KW - integrated modelling KW - integrated river basin management KW - water resources management KW - semi-arid hydrology KW - climate change Y1 - 2006 U6 - https://doi.org/10.1016/j.jhydrol.2005.12.021 SN - 0022-1694 VL - 328 IS - 3-4 SP - 417 EP - 431 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Köchy, Martin T1 - Opposite trends in life stages of annual plants caused by daily rainfall variability BT - interaction with climate change N2 - Global Circulation Models of climate predict not only a change of annual precipitation amounts but also a shift in the daily distribution. To improve the understanding of the importance of daily rain pattern for annual plant communities, which represent a large portion of semi-natural vegetation in the Middle East, I used a detailed, spatially explicit model. The model explicitly considers water storage in the soil and has been parameterized and validated with data collected in field experiments in Israel and data from the literature. I manipulated daily rainfall variability by increasing the mean daily rain intensity on rainy days (MDI, rain volume/day) and decreasing intervals between rainy days while keeping the mean annual amount constant. In factorial combination, I also increased mean annual precipitation (MAP). I considered five climatic regions characterized by 100, 300, 450, 600, and 800 mm MAP. Increasing MDI decreased establishment when MAP was >250 mm but increased establishment at more arid sites. The negative effect of increasing MDI was compensated by increasing mortality with increasing MDI in dry and typical Mediterranean regions (c. 360–720 mm MAP). These effects were strongly tied to water availability in upper and lower soil layers and modified by competition among seedlings and adults. Increasing MAP generally increased water availability, establishment, and density. The order of magnitudes of MDI and MAP effects overlapped partially so that their combined effect is important for projections of climate change effects on annual vegetation. The effect size of MAP and MDI followed a sigmoid curve along the MAP gradient indicating that the semi-arid region (≈300 mm MAP) is the most sensitive to precipitation change with regard to annual communitie KW - Klimaänderung KW - Klimawandel KW - Einjahrespflanzen KW - Schwankung KW - tägliche Regenmenge KW - Israel KW - climate change KW - daily rainfall variability KW - annual plant KW - Israel Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14699 SP - 347 EP - 357 ER - TY - GEN A1 - Köchy, Martin T1 - Stochastic time series of daily precipitation for the interior of Israel N2 - This contribution describes a generator of stochastic time series of daily precipitation for the interior of Israel from c. 90 to 900 mm mean annual precipitation (MAP) as a tool for studies of daily rain variability. The probability of rainfall on a given day of the year is described by a regular Gaussian peak curve function. The amount of rain is drawn randomly from an exponential distribution whose mean is the daily mean rain amount (averaged across years for each day of the year) described by a flattened Gaussian peak curve. Parameters for the curves have been calculated from monthly aggregated, long-term rain records from seven meteorological stations. Parameters for arbitrary points on the MAP gradient are calculated from a regression equation with MAP as the only independent variable. The simple structure of the generator allows it to produce time series with daily rain patterns that are projected under climate change scenarios and simultaneously control MAP. Increasing within-year variability of daily precipitation amounts also increases among-year variability of MAP as predicted by global circulation models. Thus, the time series incorporate important characteristics for climate change research and represent a flexible tool for simulations of daily vegetation or surface hydrology dynamics. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 029 KW - stochastische Zeitreihen KW - täglicher Niederschlag KW - Israel KW - Klimawandel KW - stochastic time series KW - daily precipitation KW - Israel KW - climate change Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-13155 ER - TY - THES A1 - Post, Joachim T1 - Integrated process-based simulation of soil carbon dynamics in river basins under present, recent past and future environmental conditions T1 - Prozessbasierte Modellierung der Bodenkohlenstoffdynamik in Flusseinzugsgebieten unter heutigen und zukünftigen Umweltbedingungen N2 - Soils contain a large amount of carbon (C) that is a critical regulator of the global C budget. Already small changes in the processes governing soil C cycling have the potential to release considerable amounts of CO2, a greenhouse gas (GHG), adding additional radiative forcing to the atmosphere and hence to changing climate. Increased temperatures will probably create a feedback, causing soils to release more GHGs. Furthermore changes in soil C balance impact soil fertility and soil quality, potentially degrading soils and reducing soils function as important resource. Consequently the assessment of soil C dynamics under present, recent past and future environmental conditions is not only of scientific interest and requires an integrated consideration of main factors and processes governing soil C dynamics. To perform this assessment an eco-hydrological modelling tool was used and extended by a process-based description of coupled soil carbon and nitrogen turnover. The extended model aims at delivering sound information on soil C storage changes beside changes in water quality, quantity and vegetation growth under global change impacts in meso- to macro-scale river basins, exemplary demonstrated for a Central European river basin (the Elbe). As a result this study: ▪ Provides information on joint effects of land-use (land cover and land management) and climate changes on croplands soil C balance in the Elbe river basin (Central Europe) presently and in the future. ▪ Evaluates which processes, and at what level of process detail, have to be considered to perform an integrated simulation of soil C dynamics at the meso- to macro-scale and demonstrates the model’s capability to simulate these processes compared to observations. ▪ Proposes a process description relating soil C pools and turnover properties to readily measurable quantities. This reduces the number of model parameters, enhances the comparability of model results to observations, and delivers same performance simulating long-term soil C dynamics as other models. ▪ Presents an extensive assessment of the parameter and input data uncertainty and their importance both temporally and spatially on modelling soil C dynamics. For the basin scale assessments it is estimated that croplands in the Elbe basin currently act as a net source of carbon (net annual C flux of 11 g C m-2 yr-1, 1.57 106 tons CO2 yr-1 entire croplands on average). Although this highly depends on the amount of harvest by-products remaining on the field. Future anticipated climate change and observed climate change in the basin already accelerates soil C loss and increases source strengths (additional 3.2 g C m-2 yr-1, 0.48 106 tons CO2 yr-1 entire croplands). But anticipated changes of agro-economic conditions, translating to altered crop share distributions, display stronger effects on soil C storage than climate change. Depending on future use of land expected to fall out of agricultural use in the future (~ 30 % of croplands area as “surplus” land), the basin either considerably looses soil C and the net annual C flux to the atmosphere increases (surplus used as black fallow) or the basin converts to a net sink of C (sequestering 0.44 106 tons CO2 yr-1 under extensified use as ley-arable) or reacts with decrease in source strength when using bioenergy crops. Bioenergy crops additionally offer a considerable potential for fossil fuel substitution (~37 PJ, 1015 J per year), whereas the basin wide use of harvest by-products for energy generation has to be seen critically although offering an annual energy potential of approximately 125 PJ. Harvest by-products play a central role in soil C reproduction and a percentage between 50 and 80 % should remain on the fields in order to maintain soil quality and fertility. The established modelling tool allows quantifying climate, land use and major land management impacts on soil C balance. New is that the SOM turnover description is embedded in an eco-hydrological river basin model, allowing an integrated consideration of water quantity, water quality, vegetation growth, agricultural productivity and soil carbon changes under different environmental conditions. The methodology and assessment presented here demonstrates the potential for integrated assessment of soil C dynamics alongside with other ecosystem services under global change impacts and provides information on the potentials of soils for climate change mitigation (soil C sequestration) and on their soil fertility status. N2 - Böden speichern große Mengen Kohlenstoff (C) und beeinflussen wesentlich den globalen C Haushalt. Schon geringe Änderungen der Steuergrößen des Bodenkohlenstoffs können dazu führen, dass beträchtliche Mengen CO2, ein Treibhausgas, in die Atmosphäre gelangen und zur globalen Erwärmung und dem Klimawandel beitragen. Der globale Temperaturanstieg verursacht dabei höchstwahrscheinlich eine Rückwirkung auf den Bodenkohlenstoffhaushalt mit einem einhergehenden erhöhten CO2 Fluss der Böden in die Atmosphäre. Weiterhin wirken sich Änderungen im Bodenkohlenstoffhaushalt auf die Bodenfruchtbarkeit und Bodenqualität aus, wobei eine Minderung der Bodenkohlenstoffvorräte wichtige Funtionen des Bodens beeinträchtigt und folglich den Boden als wichtige Ressource nachhaltig beinflusst. Demzufolge ist die Quantifizierung der Bodenkohlenstoffdynamik unter heutigen und zukünftigen Bedingungen von hohem Interesse und erfordert eine integrierte Betrachtung der wesentlichen Faktoren und Prozesse. Zur Quantifizierung wurde ein ökohydrologisches Flusseinzugsgebietsmodell erweitert. Ziel des erweiterten Modells ist es fundierte Informationen zu Veränderungen des Bodenkohlenstoffhaushaltes, neben Veränderungen der Wasserqualität, der Wasserverfügbarkeit und des Vegetationswachstums unter Globalem Wandel in meso- bis makroskaligen Flusseinzugsgebieten bereitzustellen. Dies wird am Beispiel eines zentraleuropäischen Flusseinzugsgebietes (der Elbe) demonstriert. Zusammenfassend ergibt diese Arbeit: ▪ eine Quantifizierung der heutigen und zukünftigen Auswirkungen des Klimawandels sowie von Änderungen der Landnutzung (Bodenbedeckung und Bodenbearbeitung) auf den Bodenkohlenstoffhaushalt agrarisch genutzter Räume im Einzugsgebiet der Elbe. ▪ eine Beurteilung welche Prozesse, und zu welchem Prozessdetail, zur integrierten Simulation der Bodenkohlenstoffdynamik in der meso- bis makroskala zu berücksichtigen sind. Weiterhin wird die Eignung der Modellerweiterung zur Simulation dieser Prozesse unter der Zuhilfenahme von Messwerten dargelegt. ▪ darauf begründet wird eine Prozessbeschreibung vorgeschlagen die die Eigenschaften der Bodenkohlenstoffspeicher und deren Umsetzungsrate mit in der betrachteten Skala zur Verfügung stehenden Messdaten und Geoinformationen verbindet. Die vorgeschlagene Prozessbeschreibung kann als robust hinsichtlich der Parametrisierung angesehen werden, da sie mit vergleichsweise wenigen Modelparametern eine ähnliche Güte wie andere Bodenkohlenstoffmodelle ergibt. ▪ eine umfassende Betrachtung der Modell- und Eingangsdatenunsicherheiten von Modellergebnissen in ihrer räumlichen und zeitlichen Ausprägung. Das in dieser Arbeit vorgestellte Modellsystem erlaubt eine Quantifizierung der Auswirkungen des Klima- und Landnutzungswandels auf den Bodenkohlenstoffhaushalt. Neu dabei ist, dass neben Auswirkungen auf den Bodenkohlenstoffhaushalt auch Auswirkungen auf Wasserverfügbarkeit, Wasserqualität, Vegetationswachstum und landwirtschaftlicher Produktivität erfasst werden können. Die im Rahmen dieser Arbeit dargelegten Ergebnisse erlauben eine integrierte Betrachtung der Auswirkungen des Globalen Wandels auf wichtige Ökosystemfunktionen in meso- bis makro-skaligen Flusseinzugsgebieten. Weiterhin können hier gewonnene Informationen zur Potentialabschätzung der Böden zur Linderung des Klimawandels (durch C Festlegung) und zum Erhalt ihrer Fruchtbarkeit genutzt werden. KW - Kohlenstoff KW - Stickstoff KW - Anthropogene Klimaänderung KW - Bioenergie KW - Unsicherheit KW - Ökohydrologie KW - Ökosystemmodellierung KW - Landnutzungsänderung KW - Modellsensitivität KW - eco-hydrology KW - Ecosystem modelling KW - Carbon KW - Nitrogen KW - land use change KW - climate change KW - terrestrial carbon balance KW - model uncertainty Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-11507 ER -