n Q ©yro 30 A management plan for thé Acelhuate catchment/ El Salvador: soil conservation, river stabi Iisation « - - ' o and water pollution control QdEGDäßtesaias^G^^ Scanned from original by ISRIC - World Soil Information, as ICSU World Data Centre for Soils. The purpose is to make a safe depository for endangered documents and to make the accrued information available for consultation, following Fair Use Guidelines. Every effort is taken to respect Copyright of the materials within the archives where the identification of the Copyright holder is clear and, where feasible, to contact the originators. For questions please contact [email protected] indicating the item reference number concerned. A management plan for the Acelhuate River catchment, El Salvador: soil conservation, river stabilisation and water pollution control ISSN 0305-6554 ISBN 0 902409 95 6 it-yTl ^»-rutfe- *•*••• "Mz~*- ^ ;•• •*-*<&;'% '-' -A**?"' "?$$"»* ' *~« wo- •QC^ftjfK •*£:^ •-J^*. ^ "2^**, San Salvador visto del Cerro San Jacinto. En frente se pueden ver cultivos anuales en tierras muy inclinadas. View of San Salvador from Cerro San Jacinto. Annual crops are grown on the steep slopes in the foreground. Land Resources Development Centre A management plan for the Acelhuate River catchment. El Salvador: soil conservation, river stabilisation and water pollution control Editor: J R D Wall Land Resource Study 30 Land Resources Development Centre, Overseas Development Administration, Tolworth Tower, Surbiton, Surrey, England KT6 7DY 1981 LAND RESOURCES DEVELOPMENT CENTRE The Land Resources Development Centre, one of the scientific units of the Overseas Development Administration, assists developing countries in mapping, investigating and assessing land resources, and makes recommendations on the use of these resources for the development of agriculture, livestock husbandry and forestry; it also gives advice on related subjects to overseas governments and organisations, makes scientific personnel available for appointment abroad and provides lectures and training courses in the basic techniques of resource appraisal and development. The Centre works in close cooperation with government departments, research institutes, universities and international organisations concerned with land resources assessment and development planning. CENTRE DE DEVELOPPEMENT DES RESSOURCES DE LA TERRE Le Centre de Développement des Ressources de la Terre (Tun des organismes scientif iques du Département britannique de Développement Outremer) apporte son aide aux pays en voie de développement en matière de cartographie, recherche et evaluation des ressources de la terre et fournit des recommandations quant ä l'exploitation de ces ressources pour le développement de l'agriculture, l'élevage et la sylviculture. Le Centre offre également des conseiis techniques aux gouvernements et organismes outremer, se charge de trouver du personnel scientif ique pour les postes ä pourvoir ä I'étranger et organise des conférences et des stages de formation sur les techniques de base relatives ä 1'évaluation et a' la mise en valeur des ressources. Le Centre travaille en étroite cooperation avec services gouvernementaux, institutsde recherche, universités et organismes internationaux s'occupant d'evaluation des ressources de la terre et de plans de développement. ELCENTRO DE DESARROLLO DE RECURSOSTERRESTRES El Centro de Desarrollo de Recursos Terrestres del Departamento de Desarrollo de Ultramar ayuda a pafses en vfas de desarrollo a hacer mapas, investigar y evaluar recursos de la tierra, y da recomendaciones sobre el uso de estos recursos para el desarrollo de la agricultura, la ganaderfa y la silvicultura. También presta su asesoramiento sobre temas vinculados a gobiernos y organizaciones de ultramar, ofrece personal cientifico para puestos en el exterior y suministra conferencias y cursosde capacitaciön sobre las técnicas bäsicas de evaluación y desarrollo de los recursos. El Centro trabaja en estrecha colaboración con departamentos gubernamentales, institutes de investigación, universidades y organizaciones intemacionales vinculadas a la evaluación de recursos de la tieraa y a la planificación del desarrollo. IV Contents LIST OF FIGURES ix LIST OF PLATES ix LIST OF MAPS x ABSTRACTS AND KEYWORDS xi SUMARIO, RECOMENDACIONES Y ENMENDACIONES AL REPORTE BORRADOR xiii AMENDMENTS TO DRAFT TEXT xxi GLOSSARY AND LIST OF ABBREVIATIONS xxiii PART 1 INTRODUCTION AND SUMMARY 1 1.1 Preface 1 1.1.1 The structure of the report 1 1.1.2 Background and origin of the project 2 1.1.3 Reasons for choice of Acelhuate catchment, and project objectives 4 1.1.4 Main fields of study and the composition of the study team 6 1.2 Summary and recommendations 8 1.2.1 Background: the project area and its development 8 1.2.2 Soil erosion 8 1.2.3 River erosion 9 1.2.4 Water contamination g 1.2.5 Land use planning 10 1.2.6 Recommendations 10 1.3 Acknowledgements 13 v PART 2 THE ENVIRONMENTAL, HUMAN AND INSTITUTIONAL FRAMEWORK 15 2.1 Physical environment 15 2.1.1 Introduction 15 2.1.2 Geology 15 2.1.3 Climate 18 2.1.4 Hydrology 20 2.1.5 Geomorphology 29 2.1.6 Soils 33 2.1.7 Vegetation 41 2.2 Human environmenenvironmentt 42 2.2.1 Population 42 2.2.2 Agriculture 43 2.2.3 Land use pattern 48 2.2.4 Land tenure 50 2.2.5 Social conditions 55 2.2.6 Industry 57 2.3 Institutional frameworframeworkk 59 2.3.1 General 59 2.3.2 Government orga rtionswith overall responsibility for environmental matters 59 2.3.3 Government organisations most concerned with the environment in the Acelhuate basin 59 2.3.4 Other government agencies concerned with the environment in the Acelhuate basin 63 2.3.5 Interested non-governmental agencies 64 2.3.6 Legal aspects 64 PART 3 ANALYSIS OF THE MAIN PROBLEMS, SOLUTIONS AND COSTS 67 3.1 Introduction 67 3.2 Soil erosion and erosion control measures on agricultural and urban land 67 3.2.1 The erosion problems on agricultural land 67 3.2.2 Possible physical and agronomic conservation methods 70 3.2.3 A comparison of the costs of conservation schemes 76 3.2.4 Erosion and rural roads 80 3.2.5 Erosion problems on urban land 81 3.3 River erosion problems and solutions 83 3.3.1 General 83 3.3.2 Upper Tomayate and Acelhuate Rivers 84 3.3.3 Middle Tomayate and Acelhuate Rivers 85 3.3.4 Lower Acelhuate River to the confluence with Guazapa River 86 3.3.5 Lower Acelhuate below confluence with Guazapa River 86 3.3.6 Guazapa River 87 3.3.7 Las Canas River 87 3.3.8 Proposed works 90 3.3.9 Urban drainage 94 3.3.10 Hydro meteorological considerations 95 VI 3.4 Water contamination problems, solutions and costs 96 3.4.1 General 96 3.4.2 The 1974 and 1979 study results compared 96 3.4.3 The problems 103 3.4.4 Possible solutions and alleviatory measures 105 3.4.5 Cost of pollution reduction 113 3.5 Institutional and legal requirements 116 3.5.1 Introduction 116 3.5.2 Limitations of the present framework 116 3.5.3 Possible improvements 118 PART 4 LAND USE PLANNING 121 4.1 Introduction 121 4.2 Land capability 121 4.2.1 General 121 4.2.2 The capability classes: description and recommended land use 122 4.3 Recommended land use: discussion 125 4.4 Management zones 125 4.4.1 General 125 4.4.2 The management zones (ZMs): description and recommended land use 128 4.4.3 The critical management areas (ACMs) 131 PART 5 PROPOSED WORK PROGRAMMES IN THE MANAGEMENT PLAN AND RECOMMENDATIONS FOR THEIR IMPLEMENTATION 135 5.1 Introduction 135 5.2 Soil conservation 135 5.2.1 Choice of soil conservation works 135 5.2.2 Recommended short-term actions 135 5.2.3 Legislation and associated measures 139 5.2.4 Soil erosion from construction sites 140 5.2.5 Summary of principal recommendations 140 5.3 River stabilisation 141 5.3.1 Review of problems and solutions 141 5.3.2 Recommended short-term actions 141 5.3.3 Longer-term measures 144 5.3.4 Legislation and associated measures 144 5.3.5 Summary of principal recommendations 144 5.4 Reduction of water pollution 144 5.4.1 Review of problems and solutions 144 5.4.2 Options for improving river water quality 146 5.4.3 Strategies for improving water quality in urban reaches 147 vii 5.4.4 Short-term programme: investigation/preliminary planning, 1980-3 148 5.4.5 Long-term programme, 1983-94 150 5.4.6 Industrial effluent control 152 5.4.7 Legislation and associated measures 153 5.4.8 Summary of principal recommendations for water pollution control 154 PART 6 REFERENCES 157 APPENDIXES (reproduced as microfiches inside the rear cover) A. General, economic and social A.1 Terms of reference A.2 Problems of land tenure, pollution and conservation in the Acelhuate Basin, El Salvador. (Document ELSAL-01-12). D A Preston A.3 Sociological studies in the Acelhuate River catchment. A M Uribe 3.1 Attitudes and forms of organisation of smallholders 3.2 Health and water pollution 3.3 Population A.4 Cost-benefit analysis of soil conservation. (Document ELSAL-01-20/REP-104). S L Wiggins & O G Palma A.5 A note on the value of protecting urban construction sites from soil erosion. S L Wiggins & O G Palma B. Environmental B.1 Soil and land capability data. U P Velasco & P M Nunez B.2 Agricultural data. M D Holland & M S Valdamez B.3 Report on agricultural/horticultural aspects. (Document ELSAL-01-6/REP-64). B W Eavis B.4 Soil erosion in El Salvador. (Document ELSAL-01-11). N W Hudson B.5 Hydro meteorological data and proposed designs for river erosion control.