AN ABSTRACT OF THE THESIS OF Carlos Valdes-Casillas for the degreeof Doctor of Philosophy in Geography presentedon June 28 1996. Title:DEVELOPMENT AND TESTING OF APROCEDURAL MODEL FOR THE ASSESSMENT OF HUMAN/WETLANDINTERACTION IN THE TOBARI SYSTEM ON THE SONORANCOAST, MEXICO Abstract approved: Dr. James R. Pease Coastal wetlands provide basic linkagesbetween productive estuarine and freshwater ecosystems. Throughoutthe Mexican coast, rates of wetland loss andchange are unknown. This project developed wetlandinventories for 1973 and 1991, including ecological functions and values, andhuman activities in and around the wetlands.Data was integrated by use of a geographic informationsystem. Identification of changes in wetlands and human activitieswas completed, as well as analyses of relationships between wetland change and changes in humanactivities. The model also identified andevaluated Mexican governmental policiesaffecting wetland changes. Results include descriptions,maps, and analyses of wetlands conditions and human activities, changes overan 18 year period, and interactions supported bycorrelation analyses Wetlands functionswere summarized for the Tobari system. Human activities showed an increase in aquaculture, salt mining, agriculture, and fisheries.Changes by spatial distribution are shown inan intensity map. The federal government haspromoted policies focusedon development of irrigation districts, including self-sufficiency in grains and openingagricultural land. Economic incentives includesubsidies, infrastructure financing,price controls, and compensation for international marketfluctuations. Federalgovernment policies did have important impactson wetland change. The emphasis of this modelwas on correlation between changes in wetland functions and values, and changes in human activities. Whilewetland distribution, classes, and interactions are essential information, assigning valueto them requires knowledge of their functions. Since valuesoften depend upon local cultural andeconomic conditions, local perception of wetland valuesemerge from people's awareness of them. Some values are recognized by local people in the Tobari system, especially those related to their economic system. Others, such as those relatedto water quality and climatic regulation, are not recognized yet. Results indicate that statistical analysis resulted in moderateto high correlation between changes in wetland types and changes in landuse patterns. This research contributes to understanding wetland functions and their relationships with humanlife styles. ©Copyright by Carlos Valdes-Casillas June 28, 1996 All Rights Reserved DEVELOPMENT AND TESTING OF A PROCEDURAL MODEL FOR THE ASSESSMENT OF HUMAN/WETLAND INTERACTION IN THE TOBARI SYSTEM ON THE SONORAN COAST, MEXICO by Carlos Valdes-Casillas A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Completed June 28, 1996 Commencement June, 1997 Doctor of Philosophy thesis of Carlos Valdes-Casillas presented on June28, 1996 APPROVED: Major Professor, representing Geography Head of Department of Geo sciences Dean of the Gradte School I understand that my thesis will become part of the permanent collectionof Oregon State University libraries. My signature below authorizes release of my thesis to anyreader upon request. Carlos Valdes-Casillas, Author ACKNOWLEDGMENTS ...It all began when my wife Elena and I discussed a dream while our first months of marriage, fifteen years ago. Then, a few months later, Dr. Enrique Carrillo Barrios- GOmez augured Elena and me a "very fulfilling life" while getting our Masters at Oregon State University. His suggestion led to fiveyears of much more than just studies at Corvallis, and now this thesis; and with it, a full array of opportunities. The initial encouragement and friendship of Enrique and his wife, Socorro, is unswerving. For guiding and criticizing my Ph.D.program and dissertation, I thank the Geography program in the Department of Geo sciences. I especially appreciate Dr. James R. Pease's assistance and friendship in cultivatingmy interests in Geography, sharing with me his valuable expertise, guiding me into the geography science, and helping me to structure a critical mind, always leading me into research perspective. Members of my committee, including Dr. Gordon E. Matzke, Dr. A. Jon Kimerling, Dr. Frederick Smith, and graduate representative Dr. Steven C. Rubert, each made contributionsto my program and thesis. The National Council of Science and Technology (CONACYT) for the full economic support through my studies. Thanks to Dr. Guillermo Soberon-Chavez, Director of the Instituto Tecnologicoy de Estudios Superiores de Monterrey-Campus Guaymas for hisencouragement, extending my employment, and providing continuous support for my research. The North American Wetland Conservation Council, for their support and assistance in the conservation efforts of Southern Sonora Wetlands. In Oregon, Ram6n and Carmen Simbeck who shared withme their experience and guided me to value each hour of work, they also provideus with day to day support and friendship since the first day we arrived to Oregon. Thanks to Jim and Janet Good,Peter and Kathryn Howd, Paul and Mary Richards, Jay and Bonnie Lorenz, Scott and Jane Splean, and Antonio Martinez Cob. Their interest and unconditionalsupport went beyond friendship. In Corvallis, Pat, Jocey and Murphy Pease, Alice Hackenshmith, Enrique, Dolores and Daphne Riquelme, and Gaby Rosales for helpingme in my last stage.. Jan Meranda's suggestions and company, Joanne and Theresa in the main office, and all the Geosciences friends, thanks..To Bob and Karen Streeter, for her friendship and intensive guidance. A number of individuals made special contributions toward assembling the database, and producing this thesis. In Guaymas, the Biogeographic Information Unit personnel, with friendship and patience,saw me through the process of getting my attention back to this research, thanks to Manuel and Gloria Murioz, who sendme the information from Mexico City since the development of the original proposal and lateron collaborated with me at ITESM. Thanks to Luis Bowillon and Maiisol Tordesillas, Jose Campoy and Jorge Sereno, for their contributions in getting materials ready, sharing their knowledge and the support while the development of research and fieldtrips for wetland assessment. To Ma. de Jests and Liliana for their help in digitizing and map editing. Mariana, Diana and Raquel, for all those little details in adjustment of thereport. For Assistance with research design and statistical analysis I thank Ernesto Bravo Nunez at the Metropolitan Autonomous University UAM-Ixtapalapa in Mexico City, and Gaby Rosales from Oregon State University. The Dr. Idelfonso de la Pena, form the National Water Commission in the State of Sonora, Dr. Christopher Watts at CIDESON, Pedro Rosales from ITMAR, The Prof. Hector Araiza form the Autonomous University of Sinaloa (UAS), andmany local institutions for facilitating reports and publications and share their experience in the field. To "El Coffee" for his help and hospitality during the field trips. To Hugo Rodriguez, that patiently asked me day by day if I finished, finally Hugo, yes I did. To Alberto Oriza and Irene Gamio, for being continuously editing maps and text, helping me in the GIS processing of the aerial photos, maps and databases, sure life in the last stage of this dissertation would havea different history if they had not been there. Because of the time it took me to finish this research, the list of individuals and organizations would be very long, in different stages and differentways many people made it possible, thanks to all of them. I was fortunate to have Bruce and Loren Bechtel, being lucky enough of having them in Oregon, then in Guaymas, then in Tucson and lateron, back in Oregon. They were beside me all along, thanks. Embarking on my Ph.D. program was made possible by encouragement frommy family to follow my dreams. To my parents, Rodrigo and Marcela, they helpme talking to government officials in Mexico City, sending me materials and always a warm confident support; my sisters: Maria Marcela, who was responsible for helping me several times in my trips to Corvallis, and also spending long nights getting the literature ready; La Chachineca, always ready to help; To Rodrigo, Anita, Rodri, Diego and Eduardo, always living in me. Adri, Claudia and Loren, andmy father-in-law, (Paco) Dionisio Chavarria and Marcela, thanks to all. To my wonderful Cachorros, el Carlitosy la Ita. Their cheerful smiles and love helped keep my work in perspective Lsaben?, thanks for all the time of absence and remainders of....iya acaba! Finally, to Elena my wife, who has always provided totalencouragement and support. She would never imagined how far an answer to: where is the classroom? might take; I am sure this thesis would finally be the only Birthday and Christmaspresent she has ever asked me. For her faith and patience, this is your dissertation, and the degree goes on to you, iGracias! trilyat. To Elena, Ma. Teresa, Rosa Estela, Tartaleta, Mirmicine and Tat! To Carlitos and Elenita To my brother Rodrigo TABLE OF CONTENTS INTRODUCTION 1 1.1. Need for the Project 3 1.2. Research Problem and Research Hypotheses 4 1.3. The Proposed Procedural Model for Wetland Assessment 6 1.4. Organization of the Document 8 LITERATURE REVIEW AND BACKGROUND 9 2.1. Assessment of Land Resources 9 2.1.1. Land Use 9 2.1.2. Land Use Change 10 2.1.3. Land Use Classification 11 2.1.4. Monitoring of Land Use Change and the Process of Land Use Planning 13 2.1.5. Changes of Coastal Wetlands in Sonora and Land Use 14 2.2. Wetland Assessment 15 2.2.1. Wetlands as Critical Habitat 15 2.2.2. International Importance 16 2.2.3. Wetlands' Functions and Values: from Inventories to Wetland Management 18 2.2.4. Wetlands in Mexico 20 2.3. The Sonoran Coastal Zone 22 2.3.1. Development of Southern Sonora Coast and the Water Dilemma 23 2.4. The Tobari System, a Geographic Setting 25 2.4.1. Climate 29 2.4.2 Hydrology 29 2.4.3. Geology, Geomorphology and Soils 31 2.4.4. Human Activities 31 2.4.4.1 Mining 32 2.4.4.2. Tourism and Hunting 32 2.4.4.3.