Climate Variability and Its Impacts in Tanzania: Climatology of Tanzania

Copyright © 2021 by Ladislaus Chang’a.

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Rev. date: 10/04/2021

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CONTENTS

Dedication

Preface

Acknowledgments

Chapter 1: The Climate of Tanzania

1.1 Physical-Geographical Features

1.2 Main Climatic Drivers in Tanzania

1.1.1 Intertropical Convergence Zone (ITCZ)

1.1.2 East African Monsoon

1.1.3 Tropical Cyclone

1.1.4 El Niño-Southern Oscillation

1.1.5 Congo Air Mass (Westerlies)

1.1.6 The Role of Subtropical High-Pressure System

1.1.7 The Role of Local (Mesoscale) Features

1.3 Brief Description of the Rainfall Patterns

Chapter 2: Spatial and Temporal Variability of Main Climatic Elements

2.1 Mean Monthly Rainfall and Temperature Distribution

2.2 Spatial and Temporal Variability of Rainfall

2.3 Spatial and Temporal Variability of Temperature

2.3.1 Spatial and Temporal Distribution of Maximum Temperature

2.3.2 Trends in Maximum Temperature

2.3.3 Spatial and Temporal Variability of Minimum Temperature

2.3.4 Trends in Minimum Temperature

2.3.5 Trends in Rainfall

2.4 Spatial and Temporal Variability of Relative Humidity

2.5 Spatial and Temporal Variability of Evaporation

2.6 Wind Patterns

2.7 Extreme Weather and Climate Events

Chapter 3: Drought Patterns and Evolution

3.1 Drought Definition

3.2 Drought Indices

3.1.1 Percent Normal

3.1.2 Palmer Drought Index

3.1.3 Standardized Precipitation Index

3.1.4 Bhalme-Mooley Drought Index

3.1.5 Pedya Drought Index

3.2 Spatial and Temporal Distribution of Droughts and Floods in Tanzania

3.3 Spatial Patterns and Distribution of Rainfall During Severe Droughts and Extreme Wet Years

Chapter 4: Socioeconomic Impacts of Droughts and Floods in Tanzania

4.1. Socioeconomic Impacts of Droughts

4.2. Socioeconomic Impacts of Floods

4.3. Environmental and Ecological Impacts of Droughts and Floods

4.4. Political Implication of Droughts and Floods

Chapter 5: Drought Coping and Adaptation Strategies

5.1 Global and Regional Initiatives in Drought Monitoring and Prediction

5.2 The role of National Meteorological and Hydrological Services

5.3 The Role of Indigenous Knowledge in Weather and Climate Prediction

5.3.1 Indigenous Climate Forecast Information

5.3.2 Indicators from Plant Phenology

5.3.3 Indicators from Animals, Birds, and Insects

5.3.4 Indicators from Air Temperature and Wind

5.4 Forecast of 2009/2010 Rainfall Season Over Southwestern Highland Using Indigenous Knowledge

5.5 Drought-Tolerant and Early Maturing Crops

5.5.1 Indigenous Granaries and Food Preserving Techniques

5.5.2 Ngitiri

5.6 Rainfall Enhancement

5.6.1 Global Experience of rainfall nhancement activities

5.6.2 Rainfall Enhancement Experience in East Africa

Chapter 6: Summary

Glossary

References

Endorsement

DEDICATION

To my humble and loving wife, Shukuru, for making our home and our family a conducive place and environment for creativity, innovation, and maximizing our potential. Your love, care, and prayers are sources of inspirational and motivation to my desire and commitment to achieve excellence in my professional career and in leadership.

To my daughter, Joannah, and my sons, Jeremiah, Jonathan, and Joseph, your presence, obedients, and desire for excellency and prayers enhances my commitment to be hardworking and to be a role model for you, the nation, and the world.

To my PhD supervisor, the late Raisa Petrovna, may your soul rest in eternal peace. Your great mentorship, the time and energy that you invested in me will always be remembered and always push me to go extra mile searching and seeking knowledge and sharing it to the world and particularly my prospective students.

PREFACE

All aspects of human life and all socioeconomic activities are affected and influenced by climate and its variability in space and time. Our mobility, diet, and dressing are closely linked and affected by the nature and characteristics of climate in our area. All socioeconomic sectors, particularly agriculture, water, health, transport, energy, sports, and tourism, are largely affected by climate and its variability.

The influence and impacts of climate on livelihoods and all socioeconomic sectors are magnified by the observed and projected climate change. Therefore, a thorough understanding of the nature and characteristics of climate and its associated variability is prerequisite for effective planning and success in all sectors, particularly in the context of climate change.

It is through clear and thorough understanding of the climate and particularly the extent of its variability that effective decision on planning and implementation of various socioeconomic activities, including what, where, and when to plant, can be made. These are three critical and pertinent questions for most of the developing countries, including Tanzania, where agriculture is a major source of livelihoods for majority of the people. This book aims at equipping readers with a basic understanding of the nature and characteristics of climate of East Africa, focusing on Tanzania.

The motivation for writing this book is also driven by my experience and lessons learned in running climate and climate change awareness for secondary school students, and for teaching various climate-related courses, including climatology, climate monitoring and prediction, and the science of climate change at the University of Dar es Salaam and Sokoine University of Agriculture since 2008. The need for a textbook on basics or introduction to climate variability and specifically on the climatology of Tanzania has been greatly underscored by lack of such textbook and by numerous requests from students.

This book is therefore intended for undergraduate and postgraduate students majoring in meteorology, climatology, environmental management, and other climate- and environmental-related courses. The book will also be useful to researchers, MSc, and PhD students doing research related to climate variability and change.

The book is organized into six chapters.

Chapter 1 provides a brief description of the climate of Tanzania, its spatial and temporal patterns, and the main climate drivers, including the role of Intertropical Convergence Zone (ITCZ), East African monsoon, El Niño-Southern Oscillation (ENSO), and tropical cyclone in modulating spatial and temporal distribution of rainfall in Tanzania. This chapter could also be very useful for teachers and secondary school students studying geography.

Chapter 2 describes the spatial and temporal distribution of key climate elements including rainfall, maximum temperature, minimum temperature, and relative humidity. The analysis of climatological statistics of these climate elements is provided using measures of central tendency (mean) and measures of variability (standard deviation and variance). Trend analysis of rainfall and temperature is also provided. This chapter could be very useful for those involved in climate change studies and dealing with designing climate change adaptation strategies.

Chapter 3 provides a basic understanding of drought concepts, including different types of droughts and approaches (indices) used in drought monitoring. Historical assessment of recent droughts, including frequency and magnitude of severe droughts, is also provided. This chapter could also be very useful for those dealing with Disaster Risk Reduction.

Chapter 4 describes a brief overview of the impacts of climate variability in Tanzania. Some cases of fatalities and infrastructural destruction caused by strong winds, heavy rainfall, and flooding are described. Quantification of the socioeconomic impacts of some of the historical severe droughts is also given.

Chapter 5 addresses some of the options used by local communities and institutions for coping with the challenges of climate variability. These include the climate services provided by National Meteorological and Hydrological Services, indigenous knowledge in weather, and climate prediction and rainfall enhancement.

Chapter 6 provides a brief and a concise summary of the climate variability issues discussed and some potential practical applications of some of the information discussed, including the potential application of the wind patterns and wind rose for exploitation of wind energy potential and in construction of a runway. Potential application of the generated highest rainfall and temperature extremes in planning and designing is also discussed. For research and development purposes, the summary also captures the potential application of each of the ten questions reflected in each of the five chapters.

ACKNOWLEDGMENTS

This book is a result of many years of learning and development through working, teaching, mentoring, and participation in national and international seminars, workshops, and meetings related to climate variability and change. It is also the results of the knowledge, experience, and skills gained through my sustained interactions with my family, friends, and mentors who have invested a lot in my life and in my professional career. The successfully completion of this book is therefore a product of inputs from many people, whom I am very grateful.

To the Lord God Almighty, I am grateful for the purpose and vision you have put in my heart and for the knowledge, wisdom, and strengths you have bestowed unto me to successfully complete this book. Groly and honor belong to you.

To my wife, Shukuru, for your unconditional love, continuous and sustained insistence, and support, pushing me to be what God intended me to be, to demonstrate excellency in science, research, and leadership.

To Dr. Buruhani Nyenzi, for your mentorship and continuous encouragement and support in my professional career and in the process of writing this book.

To Dr. Agnes Kijazi, Director General of Tanzania Meteorological Authority (TMA), for giving me opportunities to teach at different universities, attend meetings and seminars, and exercise my leadership potentials at TMA, in national and international levels. These have strongly contributed to enhancing my capacity, knowledge, and skills and enabled me to successfully complete writing this book.

To my coworkers at TMA, especially those from division of Research and Applied Meteorology, I thank you for the teamwork spirit and also for the constructive discussion over the years on different scientific matters related to weather and climate. Your presence, desire for excellency, hard work, and teamwork spirit has been the catalyst to my success. I thank you all.

1

The Climate of Tanzania

In this chapter, the physical-geographical features, main climatic drivers, and the current climatological status of Tanzania are described. In the discussion of the climate of Tanzania, more emphasis is put on rainfall patterns, since rainfall is the most variable climatic element both in space and time. Furthermore, the productivity and development of most socioeconomic sectors, particularly agriculture, water, health, and energy (the generation of hydroelectricity) are strongly influenced by the spatial and temporal distribution of rainfall. Therefore, a thorough understanding of the climate of a specific area, particularly rainfall and temperature dynamics, is prerequisite for effective planning and implementation of all socioeconomic activities.

1.1 Physical-Geographical Features

The United Republic of Tanzania is one of the East African countries lying in south of the Equator between 1–12°S and 29–41°E. It is constituted by Tanzania mainland and Zanzibar with a total area of 945,087 km² of which 883,749 km² is covered by land area, and 59,050 km² is covered by inland water bodies and part of the Indian Ocean. The country is characterized by diverse and complex topographical features extending from a narrow coastal belt of the Western Indian Ocean with sandy beaches to an extensive plateau with altitude ranging from 1,000 to 2,000 meters above sea level. The plateau is fringed by narrow belts of highlands, including Mount Meru (4,566 m); Mount Kilimanjaro (5,895 m), the highest mountain in Africa; and other mountain ranges such as Livingstone, Kipengere, Udzungwa, Uluguru, Nguu, Usambara, and Pare. Tanzania has several freshwater bodies, including Lake Victoria, the largest in Africa; Lake Tanganyika, the longest and deepest in Africa; and Lake Nyasa. The country also