Analysis of Arid Agricultural Systems Using Quantitative Image Analysis, Modeling and Geographical Information Systems

== = = = = = = = = = = Analysis of arid agricultural systems using quantitative image analysis, modeling and geographical information systems Stefan Siebert Die vorliegende Arbeit wurde vom Fachbereich Agrarwissenschaften der Universität Kassel als Dissertation zur Erlangung des akademischen Grades eines Doktors der Agrarwissenschaften (Dr. agr.) angenommen. Erster Gutachter: Prof. Dr. Andreas Bürkert Zweiter Gutachter: Dr. Joachim Benz Tag der mündlichen Prüfung 22. Dezember 2005 Bibliografische Information Der Deutschen Bibliothek Die Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografie; detaillierte bibliografische Daten sind im Internet über http://dnb.ddb.de abrufbar Zugl.: Witzenhausen, Univ., Diss. 2005 ISBN-10: 3-89958-192-X ISBN-13: 978-3-89958-192-8 URN: urn:nbn:de:0002-1929 © 2006, kassel university press GmbH, Kassel www.upress.uni-kassel.de Umschlaggestaltung: 5 Büro für Gestaltung, Kassel Druck und Verarbeitung: Bettina Brand Grafikdesign, München Printed in Germany Dissertation S. Siebert – Table of Contents - Inhaltsverzeichnis III TABLE OF CONTENTS - INHALTSVERZEICHNIS English summary 1-18 1. Introduction 1 2. Materials, methods and research sites 2 2.1 Research sites 2 2.2 Materials and methods 5 3. Results and discussion 10 4. Conclusions 13 Acknowledgements 16 References 17 Deutsche Zusammenfassung 19-28 1. Einleitung 19 2. Material, Methoden und Untersuchungsgebiete 20 2.1 Untersuchungsgebiete 20 2.2 Material und Methoden 21 3. Ergebnisse und Diskussion 24 4. Schlußfolgerungen 26 Überblick zum eigenen Beitrag 27 Erklärung 28 Appendix (Publications 1-6) 29-180 Publication 1 29 ……………………………………………………………………. Non-destructive dry matter estimation of Alhagi sparsifolia vegetation in a desert oasis of Northwest China Publication 2 49 ……………………………………………………………………. Agricultural, architectural and archaeological evidence for the role and ecological adaptation of a scattered mountain oasis in Oman Publication 3 73 ……………………………………………………………………. Climate and irrigation water use of a mountain oasis in northern Oman IV Dissertation S. Siebert – Table of Contents - Inhaltsverzeichnis Publication 4 103 ……………………………………………………………………. Development and validation of the Global Map of Irrigation Areas Publication 5 129 ……………………………………………………………………. Nutrient cycling and field-based partial nutrient balances in two mountain oases of Oman Publication 6 153 ……………………………………………………………………. Settlement history of a mountain oasis in northern Oman – evidence from land-use and archaeological studies Dissertation S. Siebert – English summary 1 Analysis of arid agricultural systems by quantitative image analysis, modeling and geographical information systems Stefan Siebert ENGLISH SUMMARY 1. INTRODUCTION Under arid climate conditions natural ecosystems as well as man-made agro-ecological systems show a specific adaptation to limited water resources. This adaptation comprises physiological, morphological, genetic, and in the case of agricultural systems, also management-related aspects. The strong contrast between irrigated agricultural land and the sparse vegetation cover in natural ecosystems has been widely used to classify land cover and land use in arid regions by remote sensing techniques (IWMI, 2005; Leff et al., 2004; Droogers, 2002; NIRE, 2000; Ramancutty and Foley, 1998). Recently observed improvements of methodologies used in remote sensing and advancements in Geographic Information Systems (GIS) now also allow to use satellite imagery for the determination of meteorological variables such as temperature, radiation or vapor pressure and to compute net primary production of the vegetation (see for example the list of available data sets from the MODIS sensor at http://edcdaac.usgs.gov/modis/dataproducts.asp). Such applications more and more require to combine image analysis techniques and modeling. Existing remote sensing based measurements are used in models of real processes to simulate those variables that are difficult to measure. The estimate of variables that are difficult or impossible to measure (such as predictions of the future) and the reduction of costs and efforts (e.g. generation of high- resolution global data sets, calculation of evapotranspiration, climate research) are in general two of the major reasons for the development and application of models. Finally, the opportunity to use Geographic Information Systems and Global Positioning Systems (GPS) to generate, process and present geographical information in a user friendly environment led to a dynamic development of this sector and to a wide use of these methods in many disciplines. The final stage of this development are interactive map servers that even allow inexperienced users to produce individual maps. Examples are map servers of the United States Geological Survey (USGS) at http://seamless.usgs.gov/website/seamless/viewer.php or the Australian Natural Resources Atlas at http://audit.ea.gov.au/ANRA/atlas_home.cfm. In the context of this dissertation methods and tools of quantitative image analysis, modeling and GIS were developed and applied for: - the non-destructive dry matter estimation of Alhagi sparsifolia vegetation in the foreland of the Qira oasis in Northwest China (publication 1), - mapping of land cover and land use at global, regional or local scale (publications 1, 2, 4 and 6), - the classification of mountain oases in northern Oman according to land use, water resources and settlement type, 2 Dissertation S. Siebert – English summary - the establishment of water- and nutrient balances in mountain oases of the Sultanate of Oman (publications 3 and 5), - the calculation of the carrying capacity of two mountain oases in northern Oman to assess the sustainability of the current resource use (publications 2 and 6) and to - establish settlement hypotheses for two mountain oases in northern Oman (publications 2 and 6). In the following section the materials and methods used to reach these goals are described and the research sites are introduced. The main results are presented and discussed in section 3 and conclusions are given in section 4. The six already mentioned publications are part of this thesis and were placed in its appendix. 2. MATERIALS, METHODS AND RESEARCH SITES With the exception of the work published within the Global Map of Irrigation Areas, the research summarized in this thesis was carried out on arid sites in the Northwest of the Peoples Republic of China (publication 1) and in the North of Oman (publications 2, 3, 5 and 6). In the following section these research sites are introduced. 2.1 Research sites Sultanate of Oman All work was conducted at the eastern edge of the Arabian Peninsula along the Hajar mountain range in the northern part of the Sultanate of Oman (Fig. 1). With an average annual precipitation of 55 mm and a potential evapotranspiration of more than 2000 mm yr-1 the Sultanate is effected by extremely arid climate conditions. Thus the country's agriculture depends completely on irrigation. The area equipped for irrigation was reported to be 61 550 ha in 1993, equivalent to about 0.2% of Oman's total land surface. Almost 57% of it, or 34 930 ha, is located in the Al Batinah coastal plain in the North of the country. The total area harvested was 70 930 ha in the same year. The most important crops were perennial date palm (Phoenix dactylifera L.) and banana (Musa ssp) on 43 000 ha as well as alfalfa (Medicago sativa L.) on 17 330 ha, vegetables (5700 ha) and cereals (4900 ha; FAO, 1997). There are different figures for the irrigation techniques used. While some reports indicate only 3730 ha to be equipped with modern sprinkler and drip irrigation techniques (FAO, 1997), other authors claim about 74% of the irrigated area to be equipped with modern techniques (Ibrahim, 1999). Although agriculture and fisheries employed about 37 % of the total labour force in 1993, they accounted for only 3.3% of the country’s GDP (FAO, 1997). The predominant suppliers to Oman's economic well-being are the oil industry, trade and services. Funded by the Deutsche Forschungsgemeinschaft (DFG), the two oasis settlements of Balad Seet (57.39° E, 23.19° N, 996 m a.s.l.) and Maqta (59.00° E, 22.83° N, 1050 m a.s.l.) and the settlements in Wadi Tiwi with Tiwi as main village (59.25° E, 22.83° N, 32 m a.s.l.) have been studied within the framework of an interdisciplinary project entitled 'Transformation Processes in Oasis Settlements of Oman'. The oasis of Balad Seet (Fig. 2a) is situated at the upper end of the Wadi Bani Awf, a watershed on the northern side of the Hajar range of the Jabal Akhdar mountains at the foot of a 1000 m high cliff and surrounded by mountains consisting of carbonates and clay-stones. The houses of today’s 650 inhabitants, which are located on a rocky outcrop in the center of the oasis, are surrounded by 385 agricultural fields covering 4.6 ha and by 8.8 ha of palm groves. A large part of the agricultural land is cultivated and irrigated year-round. The inhabitants own about 200 small ruminants (sheep and goats) and about 30 cattle. Five irrigation water supply systems, called Dissertation S. Siebert – English summary 3 Tiwi Maqta Fig. 1. Relief map of northern Oman showing the major mountain ranges, important towns and villages and the research sites of Balad Seet, Maqta and Tiwi (Fig. 1 of publication 6, modified). aini-Aflaj, provide spring water from the surrounding mountains to the villagers (publication 6). In contrast to the compact settlement structure found at Balad Seet, houses

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