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The aim of this work is the investigation of lexical interference phenomena in foreign-language word processing among multilingual Tunisian learners of German. In particular, the role of cognates is considered. In addition, cognitive theories for multilingual language processing are linked to language learning processes. The role of formal or morphological similarity (psychotypology) of the etymologically related languages French, English and German as well as Arabic and Tunisian is examined from a cognitive and psycholinguistic perspective. As a practical consequence of the study, it will be presented how a foreign language can be taught, in our case German, with the help of already known language in the sense of multilingual didactics. This learning process is based on the possibilities offered by the use of new technologies in language teaching. The work is structured as follows: Chapter two defines the concept of bilingualism or multilingualism, and presents various theoretical approaches describing bilingualism. In addition, the linguistic situation in Tunisia is presented and the role of the different languages and language varieties in Tunisia is explained, including the special situation of diglossia in North Africa and in the Arab world in general. The third chapter presents the theoretical foundations of the description of the mental lexicon, outlines the main theories dealing with the structure of the mental lexicon, and presents the main models of language processing. This introduction to the psycholinguistic foundations of the mental lexicon is followed in the fourth chapter by a discussion of the various theories of the bilingual and multilingual mental lexicon, as this study deals with the investigation of the multilingual mental lexicon of Tunisian students studying German. In the fifth chapter, the term cognates is explained in more detail psycholinguistically, distinguishing between cognates from one, the same or different script. In the sixth chapter two experiments are presented, firstly a lexical decision task with masked primes, and secondly a translation with a loud-thinking protocol. The results of the two experiments are described, analyzed, and discussed within the psycholinguistic theories of the mental lexicon. The seventh and final part is about didactical consequences for the German language class from the previously described multilingualism in the human brain. First, models of multilingual learning and the basic assumptions of multilingual didactic are presented. It also addresses the role of new technologies in multilingual foreign language teaching. Finally, there will be practical suggestions for multilingual German lessons with regard to the use of new media., Das Ziel dieser Arbeit ist die Untersuchung von lexikalischen Interferenzerscheinungen bei fremdsprachlichen Wortverarbeitungsprozessen bei mehrsprachigen tunesischen Deutschlernenden. Dabei wird insbesondere die Rolle der Kognaten betrachtet. Ferner werden kognitive Theorien zur Sprachverarbeitung von Mehrsprachigen mit Prozessen beim Fremdensprachenerwerb verknüpft. Die Rolle der formalen bzw. morphologischen Ähnlichkeit (Psychotypologie) der etymologisch verwandten Sprachen Französisch, Englisch und Deutsch sowie des Arabischen und Tunesischen wird aus kognitiver und psycholinguistischer Sicht untersucht. Als praktische Konsequenz der Untersuchung wird präsentiert, wie man im Sinne der Mehrsprachigkeitsdidaktik eine Sprache, in unserem Fall Deutsch, mit Hilfe einer schon bekannten Sprache vermitteln kann. Diese Vermittlung basiert dabei auf den Möglichkeiten, die der Einsatz von neuen Technologien im Sprachunterricht bietet. Die Arbeit gliedert sich wie folgt: Im Kapitel zwei wird der Begriff Bilingualismus bzw. Multilingualismus definiert und es werden verschiedene theoretische Ansätze zur Beschreibung von Bilingualismus dargestellt. Zudem werden die sprachliche Situation in Tunesien dargestellt und die Rolle der unterschiedlichen Sprachen und Sprachvarietäten in Tunesien erläutert, unter anderem die besondere Situation der Diglossie in Nordafrika und in der arabischen Welt im Allgemeinen. Das dritte Kapitel präsentiert die theoretischen Grundlagen der Beschreibung des mentalen Lexikons und skizziert die Haupttheorien, die sich mit der Bildung des mentalen Lexikons beschäftigen, sowie die wichtigsten Modelle der Sprachverarbeitung. Dieser Einführung in die psycholinguistischen Grundlagen des mentalen Lexikons folgt im vierten Kapitel eine Auseinandersetzung mit den verschiedenen Theorien des bi- und multilingualen mentalen Lexikons, da diese Studie die Untersuchung des multilingualen mentalen Lexikons tunesischer Germanistikstudierenden zum Inhalt hat. Im fünften Kapitel wird der Begriff Kognaten psycholinguistisch näher erläutert, dabei wird zwischen Kognaten aus ein und derselben oder aus unterschiedlichen Schriftformen unterschieden. Im sechsten Kapitel werden zwei Experimente präsentiert, zum einen eine Entscheidungsaufgabe mit maskierten Primes, zum anderen eine Übersetzung mit Laut-Denken-Protokoll. Die Ergebnisse der beiden Experimente werden beschrieben und im Rahmen der psycholinguistischen Theorien des mentalen Lexikons analysiert und diskutiert. Im siebten und letzten Teil geht es darum, Konsequenzen aus dem vorher Geschilderten für die Praxis zu ziehen und die Mehrsprachigkeit im menschlichen Gehirn im unterrichtlichen Alltag einzusetzen. Zunächst werden Modelle des multilingualen Lernens und die Grundannahmen der Mehrsprachigkeitsdidaktik präsentiert. Dabei wird auch auf die Rolle der neuen Technologien im mehrsprachigen Fremdsprachenunterricht eingegangen. Schließlich folgen praktische Anregungen für den mehrsprachigen Deutschunterricht im Hinblick auf den Einsatz der neuen Technologien.

Rainwater harvesting (RWH) is an ancient traditional technology practised in many parts of the world, especially in arid and semi-arid regions (ASARs). ASARs represent 40% of the earth’s land surface and are characterised by low average annual rainfall and uneven temporal and spatial distributions of that rainfall. In these regions an efficient use of the limited amount of rainfall available is important, e.g. by collecting and using surface runoff (water harvesting). Lately, access to water for agriculture and domestic use has become worse because of increasing population, higher levels of human activity and the impacts of climate change. The inhabitants of ASARs have developed several RWH techniques to increase the water availability, thus coping with water shortages. RWH is an important mitigation strategy to the impact of climate change on water availability in ASARs. Four main methodologies of site selection were categorised, ranging from those based only on biophysical criteria to more integrated approaches that include socioeconomic criteria. Our analysis suggests that the integration of multi-criteria analysis (MCA) with a geographic information system (GIS) is the most advanced approach. It offers high potential in data-poor regions; GIS-based hydrological modelling is always recommended for data-rich regions. The potential for RWH in wadi Horan (western desert of Iraq) was identified using a GIS-based suitability model. The method for selecting suitable sites for RWH was then further developed into an evaluation and decision support tool for assessing the overall performance of existing RWH systems by integrating engineering, biophysical and socioeconomic criteria using MCA supported by GIS. It was tested in the wadi Oum Zessar in southeastern Tunisia. A simple but generally applicable water harvesting model (WHCatch) was developed to investigate and optimise the performance of the RWH systems under various scenarios of design and management, It was tested in wadi Oum Zessar. The advantages of simulating long-term water balances at the sub-catchment level for improving our understanding of hydrological processes in an RWH system are emphasised. Several solutions for optimising RWH performance in various scenarios are provided. Finally, the impact of climate change on existing RWH systems in the Oum Zessar watershed under current and future scenarios of climate was investigated. The downscaled maximum and minimum temperatures clearly indicated an increasing trend in the mean monthly temperature and the generated precipitation tended to decrease in the future. It was shown that the combination of changing the flow direction and the spillway height had a large impact on the performance of the RWH systems under current and future conditions. Water management and structural design at the sub-catchment level plays a more important role than climate change in the performance of RWH.

The salinity problem is becoming increasingly widespread in arid countries. In semiarid Tunisia about 50% of the irrigated land is considered as highly sensitive to salinization. To avoid the risk of salinization, it is important to control the soil salinity and keep it below plant salinity tolerance thresholds. The objective of the present study was to provide farmers and rural development offices with a tool and methodology for predicting, monitoring of soil salinity for a better agronomical strategy. The experiments were carried out in the highly complex and heterogeneous semiarid Kalâat Landalous irrigated district of Tunisia. The field and laboratory measurements of soil and water properties were conducted in 1989 and 2006 at different observation scales (2900 ha, 1400 ha, 5200 m long transect, and soil profiles). Seventeen years of reclamation of a saline and waterlogged soil led to the reduction of average electrical conductivity of the soil saturated paste extract (ECe), measured at 5 soil depths (from 0 to 2 m) below the plant salt tolerance threshold and the dilution of groundwater salinity from 18.3 to 6.6 dS m−1. The variation in soil salt storage (ΔMss = Mss2006 − Mss1989) in the vadose zone was negative, equal to about −145 × 103 ton (≈−50 ton ha−1). During the same period, the salt balance (Siw–Sdw) estimated from the input dissolved salt brought by irrigation water (Siw) and output salts exported by the drainage network (Sdw) was equal to −685 × 106 kg and the Sdw was 945 × 106 kg. Under irrigation and efficient drainage, the soil salinization could be considered as a reversible process. At the transect scale, the high clay content and the exchangeable sodium percentage was negatively correlated to saturated hydraulic conductivity. The textural stratification, observed at soil profile scale, favors accumulation of salt in the soil. Based on the findings related to the multiscale assessment of soil salinity and groundwater properties, soil salinization factors were identified and a soil salinization risk map (SRU) was elaborated. The shallow groundwater constitutes the main risk of soil salinization. This map can be used by both land planners and farmers to make appropriate decisions related to crop production, and soil and water management. (Less)

This report describes a harmonized set of soil property estimates for Tunisia.

Being one of the essential elements of almost any water resource system, reservoirs are indispensable in our struggle to harness, utilize and manage natural water resources. Consequently, the derivation of appropriate reservoir operating strategies draws significant attention in water resources planning and management. These operational issues become even more important with the ever increasing scale and complexity of water resource systems.In this respect, the primary obstacle in the analysis of a multiple-reservoir-multiple-user water supply system operation is the dimensionality of the problem. Namely, being a sequential decision making process, the operation of a complex reservoir system over a certain period of time can adequately be described only if all the relevant variables and parameters related to possible system state and decision realizations are taken into account. Clearly, this requirement tends to grow rapidly with the size of the system considered. The computational burden expands even more drastically if the processes involved bear unavoidable stochastic characteristics which are, in this study, assumed to be attributed only to reservoir inflows.With regard to the problem in hand, the methods proposed and analyzed in the study can be divided into three major groups. The first group of methods falls into the family of system decomposition approaches within the optimization and/or simulation of the operation of complex systems. The second one involves the assessment of the impact various simulation alternatives may have on the performance of the adopted iterative decomposition algorithms. Finally, the third part includes the application of genetic algorithms for the derivation of the best water allocation patterns within a multiple-reservoir-multiple-user water supply system.The decomposition models proposed and analyzed in this study are known as sequential decomposition methods. Essentially, to reduce the dimensionality of an optimization problem, they split up a complex system into its elementary units (i.e. reservoirs). Subsequently, the operating strategy of the system is derived in an iterative fashion by applying successive optimization, simulation and release allocation analyses to individual system elements.The optimization method employed within all the decomposition models is stochastic dynamic programming (SDP). Due to the inherent discrete nature of SDP operating policies, the iterative, decomposition-based optimization models have a certain "inaccuracy threshold" which directly affects the performance of the system. Therefore, three different simulation alternatives have been employed to assess the possibility of reducing this negative impact of discretization. It is shown that, by allowing limited policy violations within simulation, the system performance can improve significantly relative to the case when the operating policies are strictly followed.Ultimately, a method based on the theory of genetic algorithms (GA) has been employed to derive the most favourable water allocation patterns within a multiple-reservoir-multiple-user water supply system. Since GAs make use of simulation to guide their search for promising solutions, two distinct GA models have been tested: i)the first one assumes that individual reservoirs are to be operated according to the standard reservoir operating rule; and ii)the second model simulates the operation of the system according to the policies derived by a prior application of an iterative decomposition/SDP-based optimization of the system's operation.Throughout this study, particular emphasis is given to the appraisal of the system performance derived by different methods. Since all of the employed optimization and search models are essentially single-objective optimization techniques, and given the fact that the operation of a reservoir system cannot adequately be appraised on the basis of a single criterion, this study makes use of simulation to evaluate the performance of the system over a number of criteria, and thereby broaden the basis for the comparison of different models. Ultimately, it is believed that the presented results clearly exemplify the fact that performance indicators like reliability of meeting the targeted demand, resilience with regard to the system escaping from failure mode, vulnerability as a measure of the most severe failure and the likes play an essential role in comprehensive assessment of the operation of a complex reservoir system.The analyses performed in this study showed that a complex water resource system decomposition, combined with the appropriate choice of optimization and simulation approaches could provide a sound basis for a transparent, yet efficient and effective operational analysis of very large reservoir systems. In addition, the application of genetic algorithms to solve a rather large resource allocation problem of a multiple-reservoir-multiple-user water supply system proved to be both relatively uncomplicated and remarkably efficient. Furthermore, it is believed that the coupling of a genetic algorithm resource allocation model with a decomposition-based optimization model represents a potentially powerful approach for solving highly complex operational problems related to multiple-reservoir water resource systems.

Being one of the essential elements of almost any water resource system, reservoirs are indispensable in our struggle to harness, utilize and manage natural water resources. Consequently, the derivation of appropriate reservoir operating strategies draws significant attention in water resources planning and management. These operational issues become even more important with the ever increasing scale and complexity of water resource systems.In this respect, the primary obstacle in the analysis of a multiple-reservoir-multiple-user water supply system operation is the dimensionality of the problem. Namely, being a sequential decision making process, the operation of a complex reservoir system over a certain period of time can adequately be described only if all the relevant variables and parameters related to possible system state and decision realizations are taken into account. Clearly, this requirement tends to grow rapidly with the size of the system considered. The computational burden expands even more drastically if the processes involved bear unavoidable stochastic characteristics which are, in this study, assumed to be attributed only to reservoir inflows.With regard to the problem in hand, the methods proposed and analyzed in the study can be divided into three major groups. The first group of methods falls into the family of system decomposition approaches within the optimization and/or simulation of the operation of complex systems. The second one involves the assessment of the impact various simulation alternatives may have on the performance of the adopted iterative decomposition algorithms. Finally, the third part includes the application of genetic algorithms for the derivation of the best water allocation patterns within a multiple-reservoir-multiple-user water supply system.The decomposition models proposed and analyzed in this study are known as sequential decomposition methods. Essentially, to reduce the dimensionality of an optimization problem, they split up a complex system into its elementary units (i.e. reservoirs). Subsequently, the operating strategy of the system is derived in an iterative fashion by applying successive optimization, simulation and release allocation analyses to individual system elements.The optimization method employed within all the decomposition models is stochastic dynamic programming (SDP). Due to the inherent discrete nature of SDP operating policies, the iterative, decomposition-based optimization models have a certain "inaccuracy threshold" which directly affects the performance of the system. Therefore, three different simulation alternatives have been employed to assess the possibility of reducing this negative impact of discretization. It is shown that, by allowing limited policy violations within simulation, the system performance can improve significantly relative to the case when the operating policies are strictly followed.Ultimately, a method based on the theory of genetic algorithms (GA) has been employed to derive the most favourable water allocation patterns within a multiple-reservoir-multiple-user water supply system. Since GAs make use of simulation to guide their search for promising solutions, two distinct GA models have been tested: i)the first one assumes that individual reservoirs are to be operated according to the standard reservoir operating rule; and ii)the second model simulates the operation of the system according to the policies derived by a prior application of an iterative decomposition/SDP-based optimization of the system's operation.Throughout this study, particular emphasis is given to the appraisal of the system performance derived by different methods. Since all of the employed optimization and search models are essentially single-objective optimization techniques, and given the fact that the operation of a reservoir system cannot adequately be appraised on the basis of a single criterion, this study makes use of simulation to evaluate the performance of the system over a number of criteria, and thereby broaden the basis for the comparison of different models. Ultimately, it is believed that the presented results clearly exemplify the fact that performance indicators like reliability of meeting the targeted demand, resilience with regard to the system escaping from failure mode, vulnerability as a measure of the most severe failure and the likes play an essential role in comprehensive assessment of the operation of a complex reservoir system.The analyses performed in this study showed that a complex water resource system decomposition, combined with the appropriate choice of optimization and simulation approaches could provide a sound basis for a transparent, yet efficient and effective operational analysis of very large reservoir systems. In addition, the application of genetic algorithms to solve a rather large resource allocation problem of a multiple-reservoir-multiple-user water supply system proved to be both relatively uncomplicated and remarkably efficient. Furthermore, it is believed that the coupling of a genetic algorithm resource allocation model with a decomposition-based optimization model represents a potentially powerful approach for solving highly complex operational problems related to multiple-reservoir water resource systems.

Satellites provide the possibility to give a synoptical view of the earth surface at regular time intervals. Satellites operating in the optical wavelengths have however as disadvantage that monitoring of the surface characteristics becomes impossible as soon as clouds are present. Deserts and desert margins are for that reason much more appropriate for monitoring by optical satellites than temperate and wet tropical areas. Potential hazards, possibilities and often inaccessibility makes use of optical remote sensing very reasonable.Landsat Thematic Mapper (TM) satellites provide a much better spectral resolution than other satellites at reasonable spatial and temporal resolution. Ile presented research was hence focused on the spectral possibilities of Landsat Thematic Mapper for determining surface characteristics and their dynamics in desert areas. Field measurements of reflectance in different seasons were performed to evaluate the effect of different factors and their dynamics on reflectance. A field radiometer (MMR) with TM compatible bands was used. The study was performed in southern Tunisia in an area with large variation: footslopes, dunes and dynamical salt plains, all with few or absent vegetation cover. Dominant mineralogy is representative for many and areas and comprises gypsum, carbonate, quartz and halite.In order to compare results of field reflectance measurements with Landsat Thematic Mapper data, adequate processing of both data sets is necessary.General accepted assumptions that reference plates are ideal reflectors have to be rejected. Both wavelength and insolation angle dependant reflectance of the panel has to be determined. For large solar zenith angles also corrections have to be made for influence of diffuse irradiation (Chapter 2).Use of calibration coefficients given for Landsat Thematic Mapper data processed in Fucino will cause large errors in calculating reflectance data. It turned out that these coefficients were not updated for deterioration of the sensors during the flight and that calculations were made based on two different definitions of bandwidth. In order to achieve adequate values of reflectance these errors were evaluated and corrected (Chapter 8).The evaluation of factors affecting field reflectance can be separated in external and internal ones.The influence of external factors, solar zenith angle and atmosphere was evaluated (Chapter 3-4). Solar zenith angle dependant reflectance turned out to be limited for this area, if measurements are performed with solar zenith angles up to 65 degrees. In spring on the footslopes reflectance values at noon were about 10% higher than those at 65 degrees. Differences on the playa were even less. Both based on accuracy and applicability of the results (observations of this area at these latitudes with Landsat TM take place with angles ranging between 28 in June and 63 degrees in December), 65 degrees can be considered as a useful limit for performing adequate measurements.Influence of atmosphere on field reflectance is limited. The evaluation of the external factors leads to the conclusion that all measurements with a solar zenith angle less than 65 degrees and on clear days could be used for obtaining a field data reference set.Field measurements showed that Landsat TM-like bands are very useful in detecting the surface characteristics ( internal factors ) in this area (Chapters 5 - 7).Gypsum has absorption bands in both middle infrared bands (comparable with TM bands 6 and 7) and carbonate in TM band 7. Since on footslopes and in dunes quartz is the other important mineral, a high reflectance in these bands points to presence of quartz. Standard field reflectance measurements showed that on footslopes gypsum, quartz and carbonate dominated areas have a different spectral signature. Differences in eolian deposits are even more clear: relations between gypsum content and indices derived from spectral reflectance could be established under field conditions.Presence of halite on the playas could be detected by relatively high reflectance in the visible part of the spectrum, especially in the blue band. Field reflectance on plots showed that moisture content induces a relatively low reflectance in all bands with an extra low reflectance in the middle infrared bands. Linear relations between volumetric moisture content and reflectance in individual bands in near and middle infrared turned out to be feasible.Most dynamical parts of the area turned out to be the playas, where after storms moisture contents of the top layer were affected for a long time and halite efflorescences occurred shortly after the storms. Although dust slowly covering the surface, even in spring plots with higher halite content could be derived from the spectral signature. Field plots in dune parts showed a large variation in reflectance between November and May too due to changes by wind. Dynamics on footslopes were much less important than in other areas. Variation in vegetation appears to be relatively small, while also effect of storms was not visible for more than a few days after a storm.Results of field reflectance were extrapolated to Landsat TM satellite data (Chapter 9). It was possible to derive directly from Landsat TM data a number of useful classes for playas, footslopes and eolian material, having variation in surface mineralogy (gypsum, carbonate, quartz, halite) and variation in surface type. Also dynamics of factors like moisture and halite could be derived using multitemporal Landsat TM data.The presented methodology, implementing an extensive field reflectance measurement campaign, gives insight in possibilities of Landsat TM under a range of conditions. It corroborates that for operational application in and areas Landsat TM data will be a useful source of information in addition to other types of remote sensing as for instance aerial photography.

Satellites provide the possibility to give a synoptical view of the earth surface at regular time intervals. Satellites operating in the optical wavelengths have however as disadvantage that monitoring of the surface characteristics becomes impossible as soon as clouds are present. Deserts and desert margins are for that reason much more appropriate for monitoring by optical satellites than temperate and wet tropical areas. Potential hazards, possibilities and often inaccessibility makes use of optical remote sensing very reasonable.Landsat Thematic Mapper (TM) satellites provide a much better spectral resolution than other satellites at reasonable spatial and temporal resolution. Ile presented research was hence focused on the spectral possibilities of Landsat Thematic Mapper for determining surface characteristics and their dynamics in desert areas. Field measurements of reflectance in different seasons were performed to evaluate the effect of different factors and their dynamics on reflectance. A field radiometer (MMR) with TM compatible bands was used. The study was performed in southern Tunisia in an area with large variation: footslopes, dunes and dynamical salt plains, all with few or absent vegetation cover. Dominant mineralogy is representative for many and areas and comprises gypsum, carbonate, quartz and halite.In order to compare results of field reflectance measurements with Landsat Thematic Mapper data, adequate processing of both data sets is necessary.General accepted assumptions that reference plates are ideal reflectors have to be rejected. Both wavelength and insolation angle dependant reflectance of the panel has to be determined. For large solar zenith angles also corrections have to be made for influence of diffuse irradiation (Chapter 2).Use of calibration coefficients given for Landsat Thematic Mapper data processed in Fucino will cause large errors in calculating reflectance data. It turned out that these coefficients were not updated for deterioration of the sensors during the flight and that calculations were made based on two different definitions of bandwidth. In order to achieve adequate values of reflectance these errors were evaluated and corrected (Chapter 8).The evaluation of factors affecting field reflectance can be separated in external and internal ones.The influence of external factors, solar zenith angle and atmosphere was evaluated (Chapter 3-4). Solar zenith angle dependant reflectance turned out to be limited for this area, if measurements are performed with solar zenith angles up to 65 degrees. In spring on the footslopes reflectance values at noon were about 10% higher than those at 65 degrees. Differences on the playa were even less. Both based on accuracy and applicability of the results (observations of this area at these latitudes with Landsat TM take place with angles ranging between 28 in June and 63 degrees in December), 65 degrees can be considered as a useful limit for performing adequate measurements.Influence of atmosphere on field reflectance is limited. The evaluation of the external factors leads to the conclusion that all measurements with a solar zenith angle less than 65 degrees and on clear days could be used for obtaining a field data reference set.Field measurements showed that Landsat TM-like bands are very useful in detecting the surface characteristics ( internal factors ) in this area (Chapters 5 - 7).Gypsum has absorption bands in both middle infrared bands (comparable with TM bands 6 and 7) and carbonate in TM band 7. Since on footslopes and in dunes quartz is the other important mineral, a high reflectance in these bands points to presence of quartz. Standard field reflectance measurements showed that on footslopes gypsum, quartz and carbonate dominated areas have a different spectral signature. Differences in eolian deposits are even more clear: relations between gypsum content and indices derived from spectral reflectance could be established under field conditions.Presence of halite on the playas could be detected by relatively high reflectance in the visible part of the spectrum, especially in the blue band. Field reflectance on plots showed that moisture content induces a relatively low reflectance in all bands with an extra low reflectance in the middle infrared bands. Linear relations between volumetric moisture content and reflectance in individual bands in near and middle infrared turned out to be feasible.Most dynamical parts of the area turned out to be the playas, where after storms moisture contents of the top layer were affected for a long time and halite efflorescences occurred shortly after the storms. Although dust slowly covering the surface, even in spring plots with higher halite content could be derived from the spectral signature. Field plots in dune parts showed a large variation in reflectance between November and May too due to changes by wind. Dynamics on footslopes were much less important than in other areas. Variation in vegetation appears to be relatively small, while also effect of storms was not visible for more than a few days after a storm.Results of field reflectance were extrapolated to Landsat TM satellite data (Chapter 9). It was possible to derive directly from Landsat TM data a number of useful classes for playas, footslopes and eolian material, having variation in surface mineralogy (gypsum, carbonate, quartz, halite) and variation in surface type. Also dynamics of factors like moisture and halite could be derived using multitemporal Landsat TM data.The presented methodology, implementing an extensive field reflectance measurement campaign, gives insight in possibilities of Landsat TM under a range of conditions. It corroborates that for operational application in and areas Landsat TM data will be a useful source of information in addition to other types of remote sensing as for instance aerial photography.

Planning of the agricultural sector has been neglected in development economies. On this level between macro and project planning, there has been no evident progress either in methodology or in policy-supporting activities of a planning administration. This study aims at demonstrating for a concrete situation in a developing country, Tunisia, how the agricultural sector as a whole should be planned so that there is a talk of usefullness for policy makers. The Tunisian agricultural sector is social economically analysed. The most important problem resulting from this analysis is the poverty and unemployment in rural areas. Then agricultural policy options in the long term, translated into concrete actions. measures and projects are indentified, employment and income distribution taking a central place. Implications of the formulated long-term agricultural development plan for short-term policy and organization of the Tunisian planning administration are indicated. Conclusions on the applicability of the agricultural planning methodology in other developing countries are postulated.

Dit boek richt zich tot allen die op een of andere wijze betrokken zijn bij de problematiek van de planning in ontwikkelingslanden: internationale organisaties, instituten voor onderzoek en onderwijs, hulpverlenende instanties en de planners in de ontwikkelingslanden zelf.Het doel van de studie is bij te dragen tot de verbetering van methoden van planning die in praktijk in ontwikkelingslanden worden of kunnen worden toegepast. Tot dat doel wordt het begrip efficiency van de planning in zijn componenten ontleed en toegepast op een speciaal geval, nl. de landbouwplanning in Tunesië. Onidat de Franse samenvatting de inhoud van het boek per hoofdstuk weergeeft zullen wij ons hier beperken tot de algemene kenmerken van deze studie.In de litteratuur over ontwikkelingsplanning wordt voornamelijk aandacht besteed aan de inhoudelijke kant van de ontwikkelingsproblematiek. Te weinig wordt benadrukt dat de planning zelf een instrument voor ontwikkeling is dat gepland kan en moet worden. Immers, in een ontwikkelingsstrategie is de strateeg, d.w.z. de overheid, zelf betrokken. Planning van de sociaal-economische ontwikkeling vereist ontwikkeling van de planning, inhoudelijk en bestuurlijk. Een belangrijk uitgangspunt van het onderzoek is dan ook dat verbetering van methoden van planning niet alleen betrekking dient te hebben op verbetering van de methoden van informatieverzameling en van sociaal-economische analyse. Zulke pogingen kunnen nutteloos zijn indien men niet ook rekening houdt met de bestuurlijke en politieke context waarin de planningfunctioneert.De efficiency van de planning kan alleen begrepen worden in het totale cybernetische planproces, dat globaal in de volgende cycli verloopt: informatieverzameling ->planopstelling ->planuitvoering ->evaluatie en bijsturing. De evaluatie van de resultaten van het planproces dient op drie niveaux te geschieden:1. de evaluatie van de mate waarin de voorgenomen maatregelen en projekten daadwerkelijk zijn uitgevoerd;2. de evaluatie van de invloed van de uitgevoerde maatregelen en projekten op de sociaal-economische ontwikkelingen en3. de evaluatie van de invloed van onbeheersbare externe faktoren zoals het klimaat, de wereldmarktprijzen en het autonome gedrag van het publiek waar de overheidsplanning zich op richt.Deze drie typen invloeden vormen de verklarende faktoren van de verschillen tussen de voorspellingen en de realisaties van sociaal-economische plannen.De efficiency van de planning dient echter niet alleen afgemeten te worden aan de uitkomst van zijn voorspellingen. In ieder geval dient de werkelijke invloed van het overheidsingrijpen op de eindresultaten te worden onderscheiden van toevallige faktoren die in gunstige of ongunstige zin aan de eindresultaten hebben bijgedragen. Bovendien kan de efficiency van de planning alleen geappreciterd worden in het licht van de reikwijdte van de planning, waaronder wij verstaan de omvang van de te plannen probleemgebieden, het detail waarin deze gepland worden en de in de beschouwing betrokken samenhangen. Het onderscheid tussen trefzekerheid en reikwijdte komt voort uit twee mogelijke benaderingen van de evaluatie van de efficiency van de planning, te weten respectievelijk: de immanente kritiek, die uitgaat van de veronderstellingen van het planningsysteem zelf en de transcendente kritiek, die uitgaat van veronderstellingen die aan criteria van buiten het planningsysteem ontleend zijn.Ieder efficiency-onderzoek komt neer op een doeleinden-middelen analyse. Terwijl trefzekerheid en reikwijdte tot de doeleinden van een planningsysteem gerekend kunnen worden, behoren tot de middelen: de tijd, de mankracht en het geld nodig voor het opstellen en evalueren van plannen en de overheadkosten van het uitvoerende apparaat. Wij hebben niet getracht tot een nauwkeurige kwantitatieve berekening van deze middelen te kornen, hoewel zij in ontwikkelingslanden vaak een reële beperking op de planning en dus op de ontwikkeling in het algemeen vormen. Wij menen echter dat in de beginfase, waarin dit type onderzoek zich nog bevindt, een kwantitatieve benadering niet relevant is. Een kwalitatieve benadering ter besparing van de kosten van de planning is vooralstiog vruchtbaarder. Deze houdt o.a. in: een goede definiëring van de ontwilekelingsproblernatiek, waarvoor de planning gesteld is, het toepassen van arbeids- en tijdsbeparende methoden van informatieverzameling en analyse (b.v. het toezien op de benodigde precisie van gegevens), het bewust kiezen van de beslissingsprocedures, een adekwate verdeling van de expertise over de planningsorganen, een juiste keuze van de expertise in functie van de op te lossen problemen, het zo goed mogelijk verdelen van de planningactiviteiten in de tijd, enz... .Grote nadruk valt in dit onderzoek op de case-study van de landbouwplanning in Tunesië. Daarmee is aangegeven dat dit soort onderzoek zich nog in een empirisch stadium bevindt. Na een reeks van dergelijke deelstudies kan later tot systematisering van de kennis worden gekomen. Wij menen, dat in de litteratuur nog een groot gebrek is aan nauwkeurige, concrete beschrijvingen van totale planprocessen. Uiteraard zijn met de case-study ook de beperkingen van dit onderzoek gegeven. In feite is de problematiek van ieder land specifiek en vraagt daarom om aarigepaste methoden van planning. De kenmerken van Tunesië zijn: het is een klein, al relatief ontwikkeld land, dat sterk in de economische en politieke invloedssfeer van Europa ligt. Naar Europese standaarden gemeten zijn de problemen van armoede en werkloosheid er echter nog zeer groot en zullen dat op lange termijn nog blijven. De planning in Tunesië kan bogen op een vrij lange traditie en staat relatief op een hoog peil. (Dit maakt van de Tunesische planning overigens een geschikt objekt van evaluatie). Een bijzondere omstandigheid in Tunesië is de overgang van de politiek van collectivisatie van de jaren 60 naar een meer liberale gemengde economie. Dit schept de gelegenheid twee totaal verschillende planningsystemen binnen de context van één land te vergelijken. De behandeling van de landbouwplanning in het bijzonder geeft ook een specifiek karakter aan deze case-study. De landbouwsector kenmerkt zich immers door zijn heterogeniteit als een zeer omvangrijk gebied van planning, waarvan de trefzekerheid echter gering is. Men kan dan ook constateren dat de landbouwplanning zich vaak eenzijdig richt op de makkelijk grijpbare aspekten van de landbouwontwikkeling: infrastrukturele werken, de technische aspecten van de produktie, de grote landbouwbedrijven, de regio's met grote potenties. De sociale problematiek van de landbouw in ontwikkelingslanden (de lage inkomens en de werkloosheid) wordt relatief verwaarloosd.Tenslotte moet worden opgemerkt dat de koers, die een klein land als Tunesië in de toekomst gaat varen, in hoge mate bepaald wordt door de internationale politieke situatie (relatie tot de EEG en tot Frankrijk in het bijzonder, relatie tot de andere Arabische landen, invloed van de V.S. en de Sowjet-Unie in het Middellandse zeegebied). Wij hebben deze randvoorwaarden niet in de beschouwing betrokken, in de eerste plaats orndat wij niet competent zijn hierover een wetenschappelijk oordeel te vellen, in de tweede plaats orndat wij menen dat de interne ontwikkeling, ook van kleine landen, niet uitsluitend door externe faktoren wordt bepaald. Er blijft een ruime marge voor een eigen ontwikkelingspolitiek, waarin het probleem van de efficiency van de planning zeer relevant is.

Dit boek richt zich tot allen die op een of andere wijze betrokken zijn bij de problematiek van de planning in ontwikkelingslanden: internationale organisaties, instituten voor onderzoek en onderwijs, hulpverlenende instanties en de planners in de ontwikkelingslanden zelf.Het doel van de studie is bij te dragen tot de verbetering van methoden van planning die in praktijk in ontwikkelingslanden worden of kunnen worden toegepast. Tot dat doel wordt het begrip efficiency van de planning in zijn componenten ontleed en toegepast op een speciaal geval, nl. de landbouwplanning in Tunesië. Onidat de Franse samenvatting de inhoud van het boek per hoofdstuk weergeeft zullen wij ons hier beperken tot de algemene kenmerken van deze studie.In de litteratuur over ontwikkelingsplanning wordt voornamelijk aandacht besteed aan de inhoudelijke kant van de ontwikkelingsproblematiek. Te weinig wordt benadrukt dat de planning zelf een instrument voor ontwikkeling is dat gepland kan en moet worden. Immers, in een ontwikkelingsstrategie is de strateeg, d.w.z. de overheid, zelf betrokken. Planning van de sociaal-economische ontwikkeling vereist ontwikkeling van de planning, inhoudelijk en bestuurlijk. Een belangrijk uitgangspunt van het onderzoek is dan ook dat verbetering van methoden van planning niet alleen betrekking dient te hebben op verbetering van de methoden van informatieverzameling en van sociaal-economische analyse. Zulke pogingen kunnen nutteloos zijn indien men niet ook rekening houdt met de bestuurlijke en politieke context waarin de planningfunctioneert.De efficiency van de planning kan alleen begrepen worden in het totale cybernetische planproces, dat globaal in de volgende cycli verloopt: informatieverzameling ->planopstelling ->planuitvoering ->evaluatie en bijsturing. De evaluatie van de resultaten van het planproces dient op drie niveaux te geschieden:1. de evaluatie van de mate waarin de voorgenomen maatregelen en projekten daadwerkelijk zijn uitgevoerd;2. de evaluatie van de invloed van de uitgevoerde maatregelen en projekten op de sociaal-economische ontwikkelingen en3. de evaluatie van de invloed van onbeheersbare externe faktoren zoals het klimaat, de wereldmarktprijzen en het autonome gedrag van het publiek waar de overheidsplanning zich op richt.Deze drie typen invloeden vormen de verklarende faktoren van de verschillen tussen de voorspellingen en de realisaties van sociaal-economische plannen.De efficiency van de planning dient echter niet alleen afgemeten te worden aan de uitkomst van zijn voorspellingen. In ieder geval dient de werkelijke invloed van het overheidsingrijpen op de eindresultaten te worden onderscheiden van toevallige faktoren die in gunstige of ongunstige zin aan de eindresultaten hebben bijgedragen. Bovendien kan de efficiency van de planning alleen geappreciterd worden in het licht van de reikwijdte van de planning, waaronder wij verstaan de omvang van de te plannen probleemgebieden, het detail waarin deze gepland worden en de in de beschouwing betrokken samenhangen. Het onderscheid tussen trefzekerheid en reikwijdte komt voort uit twee mogelijke benaderingen van de evaluatie van de efficiency van de planning, te weten respectievelijk: de immanente kritiek, die uitgaat van de veronderstellingen van het planningsysteem zelf en de transcendente kritiek, die uitgaat van veronderstellingen die aan criteria van buiten het planningsysteem ontleend zijn.Ieder efficiency-onderzoek komt neer op een doeleinden-middelen analyse. Terwijl trefzekerheid en reikwijdte tot de doeleinden van een planningsysteem gerekend kunnen worden, behoren tot de middelen: de tijd, de mankracht en het geld nodig voor het opstellen en evalueren van plannen en de overheadkosten van het uitvoerende apparaat. Wij hebben niet getracht tot een nauwkeurige kwantitatieve berekening van deze middelen te kornen, hoewel zij in ontwikkelingslanden vaak een reële beperking op de planning en dus op de ontwikkeling in het algemeen vormen. Wij menen echter dat in de beginfase, waarin dit type onderzoek zich nog bevindt, een kwantitatieve benadering niet relevant is. Een kwalitatieve benadering ter besparing van de kosten van de planning is vooralstiog vruchtbaarder. Deze houdt o.a. in: een goede definiëring van de ontwilekelingsproblernatiek, waarvoor de planning gesteld is, het toepassen van arbeids- en tijdsbeparende methoden van informatieverzameling en analyse (b.v. het toezien op de benodigde precisie van gegevens), het bewust kiezen van de beslissingsprocedures, een adekwate verdeling van de expertise over de planningsorganen, een juiste keuze van de expertise in functie van de op te lossen problemen, het zo goed mogelijk verdelen van de planningactiviteiten in de tijd, enz... .Grote nadruk valt in dit onderzoek op de case-study van de landbouwplanning in Tunesië. Daarmee is aangegeven dat dit soort onderzoek zich nog in een empirisch stadium bevindt. Na een reeks van dergelijke deelstudies kan later tot systematisering van de kennis worden gekomen. Wij menen, dat in de litteratuur nog een groot gebrek is aan nauwkeurige, concrete beschrijvingen van totale planprocessen. Uiteraard zijn met de case-study ook de beperkingen van dit onderzoek gegeven. In feite is de problematiek van ieder land specifiek en vraagt daarom om aarigepaste methoden van planning. De kenmerken van Tunesië zijn: het is een klein, al relatief ontwikkeld land, dat sterk in de economische en politieke invloedssfeer van Europa ligt. Naar Europese standaarden gemeten zijn de problemen van armoede en werkloosheid er echter nog zeer groot en zullen dat op lange termijn nog blijven. De planning in Tunesië kan bogen op een vrij lange traditie en staat relatief op een hoog peil. (Dit maakt van de Tunesische planning overigens een geschikt objekt van evaluatie). Een bijzondere omstandigheid in Tunesië is de overgang van de politiek van collectivisatie van de jaren 60 naar een meer liberale gemengde economie. Dit schept de gelegenheid twee totaal verschillende planningsystemen binnen de context van één land te vergelijken. De behandeling van de landbouwplanning in het bijzonder geeft ook een specifiek karakter aan deze case-study. De landbouwsector kenmerkt zich immers door zijn heterogeniteit als een zeer omvangrijk gebied van planning, waarvan de trefzekerheid echter gering is. Men kan dan ook constateren dat de landbouwplanning zich vaak eenzijdig richt op de makkelijk grijpbare aspekten van de landbouwontwikkeling: infrastrukturele werken, de technische aspecten van de produktie, de grote landbouwbedrijven, de regio's met grote potenties. De sociale problematiek van de landbouw in ontwikkelingslanden (de lage inkomens en de werkloosheid) wordt relatief verwaarloosd.Tenslotte moet worden opgemerkt dat de koers, die een klein land als Tunesië in de toekomst gaat varen, in hoge mate bepaald wordt door de internationale politieke situatie (relatie tot de EEG en tot Frankrijk in het bijzonder, relatie tot de andere Arabische landen, invloed van de V.S. en de Sowjet-Unie in het Middellandse zeegebied). Wij hebben deze randvoorwaarden niet in de beschouwing betrokken, in de eerste plaats orndat wij niet competent zijn hierover een wetenschappelijk oordeel te vellen, in de tweede plaats orndat wij menen dat de interne ontwikkeling, ook van kleine landen, niet uitsluitend door externe faktoren wordt bepaald. Er blijft een ruime marge voor een eigen ontwikkelingspolitiek, waarin het probleem van de efficiency van de planning zeer relevant is.