This study is an attempt to identify the main causes and effect of flooding on agricultural production and the peoples living in the Lake Tana surroundings. Although floods are relatively common during the June to September rainy season in Ethiopia, the magnitude of the current flooding in 2006 is unprecedented. In year 2006 the country has experienced some of the heaviest and most intense rains on record; resulting in flash floods and/or the overflow of rivers, lakes and dams, where local residents have been advised to leave. The impact of the disaster in terms of lives, infrastructure, livelihoods, and basic coping mechanisms has yet to be assessed
The rainfall variability analysis of the Lake Tana (LT) basin in 2006 showed an on average 43% increase in wet season rainfall than the normal (mean). All rainfall gauging stations show an increase in rainfall in 2006. Similarly, the variability analysis of major rivers also showed that on average 35% increase in flood season streamflow of G/Abay, Gumara, Rib, Megech, and Koga. The trend of these rivers shows that maximum runoff for the year 2006 was higher than the mean of the long term maximum flood. Whereas Lake Tana maximum flood level of 2006 (1787.155masl) shows an increase of 16 cm only from the mean flood levels of previous records (1787 masl). The Pearson III method of the moment probability distribution is the best fit for Megech and Rib rivers. For Gumara river Pearson III probability weighted moment distribution better estimate flood quantiles with less standard error. It is also found that Gamma two probability weighted moment is the best fit for Lake Tana water surface level. In general, from rainfall and flood frequency analysis the 2006-year flooding may have a chance to occur once in six years in LTB. The 2006-year flood damage indicates that there is a high impact on agricultural production of Lake Tana surrounding plains. 107,647 peoples were actually affected by floods. At least 448, 910 quantal of food grain, 1230 domestic animals, 9634 chickens, and 1088 bee-hives were damaged by the 2006 flood. The impacts of flooding on socio-economic and environmental resource indicators were qualitatively assessed. Totally twenty-seven indicators were assessed.
Table of Contents
1 INTRODUCTION
1.1 GENERAL
1.2 STATEMENT OF THE PROBLEM
1.3 OBJECTIVE AND SCOPE OF THE STUDY
2 LITERATURE REVIEW
2.1 FLOOD DISASTER AND ITS IMPACTS
2.2 PLANT RESPONSE TO FLOODING
2.3 FLOODPLAIN MANAGEMENT
2.4 IMPACTS OF FLOOD CONTROL AND PREVENTION MEASURES
2.5 INTEGRATED FLOOD MANAGEMENT
2.5.1 Elements of Integrated Flood Management
2.6 WATERLOGGING AND DEVELOPMENT OF HIGH WATER TABLE
2.6.1 Signs of Bad Drainage
2.6.2 Harmful Effects of Excess Irrigation
2.6.3 Benefits of drainage
2.6.4 Biodrainage
3 DESCRIPTION AND METHDOLOGY
3.1 DESCRIPTION OF THE STUDY AREA
3.1.1 Administrative Location
3.1.2 Geographical Location
3.2 METHODOLOGY
3.2.1 Data Collection
3.2.2 Data Processing
3.3 BASIC FEATURES OF THE STUDY AREAS
3.3.1 Agro ecological Zones
3.3.2 Geology of Lake Tana Plains
3.3.3 Drainage
3.3.4 Soils of Lake Tana Surrounding Plains
3.3.5 Topography
3.3.6 Land Use
3.3.7 Socio-economy
4 DATA ANALYSIS AND RESULTS
4.1 FLOOD ASSESSMENT BASED ON VARIABILITY OF RAINFALL AND STREAM FLOW DATA
4.1.1 Rainfall Variability
4.1.2 Stream Flow Variability
4.1.3 Lake Tana Water Level Variation and Flood Recession
4.2 HYDROLOGIC FREQUENCY ANALYSIS
4.2.1 Flood Frequency Analysis
4.2.2 Frequency Analysis of Rainfall
4.3 SOCIO ECONOMIC IMPACT OF FLOODING ON LTSPS
4.3.1 Nature of Flooding on LTSPs
4.3.2 Flood Affected Areas
4.3.3 Causes of Flooding and Waterlogging in LTSPs
4.3.4 The Impact Flooding on Agricultural Production of LTSPs
4.4 POTENTIAL MITIGATION MEASURES
4.4.1 Flood Management Options
4.4.2 Agricultural Drainage options
5 DISCUSSION OF RESULTS
5.1 RESULTS OF THE VARIABILITY ANALYSIS OF RAINFALL AND RUNOFF
5.2 RESULT OF HYDROLOGICAL FREQUENCY ANALYSIS
5.3 RESULT OF SOCIO ECONOMIC IMPACT ASSESSMENT OF FLOODING ON AGRICULTURAL PRODUCTION OF LTSPS
5.4 RESULTS OF THE POTENTIAL MITIGATION MEASURES FOR FLOODING AND DRAINAGE PROBLEMS
6 SUMMERY, CONCLUSION AND RECOMMENDATION
6.1 SUMMERY AND CONCLUSION
6.2 RECOMMENDATIONS
6.3 LIMITATIONS
Research Objectives and Topics
The primary objective of this study is to analyze the causes and effects of flooding and waterlogging on agricultural production in the plains surrounding Lake Tana, specifically in the Fogera, Dembia, and Kunzila regions. The research evaluates meteorological and hydrological data to determine the factors driving the 2006 flood events and assesses the resulting socio-economic damage to livelihoods and infrastructure.
- Hydrological assessment of rainfall and stream flow variability.
- Flood frequency analysis for major rivers and Lake Tana water levels.
- Evaluation of the socio-economic impacts of flooding on agricultural production.
- Development of potential flood mitigation and drainage management strategies.
Excerpt from the Book
2.1 Flood Disaster and Its Impacts
Natural disasters cause much misery, especially in developing countries where low-income economies are greatly stressed by their recurrence. Statistics show that around 70 per cent of all global disasters are linked to hydro-meteorological events. Flooding is one of the greatest natural disasters known to humankind. Flood losses reduce the asset base of households, communities and societies by destroying standing crops, dwellings, infrastructure, machinery and buildings. In some cases, the effect of flooding is dramatic, not only at the individual household level but on the nation as a whole. The 1982 floods in Bolivia are reported to have resulted in a loss equivalent to 19.8 per cent of the country’s GDP. It may, however, be argued that looking at the impact of floods on a piecemeal basis, rather than making holistic appraisals, has too narrowly assessed their impact (APFM,2003).
As it is also indicated by APFM (2003) technical document, Absolute protection from flooding is neither technically feasible nor economically or environmentally viable. Thinking in terms of setting a design standard of protection is both a trap and a delusion: such a standard conflicts with the principle of managing all floods and not just some. It is also a delusion because estimates of the magnitude of extreme floods are very inaccurate and, due to climate change, likely to get modified over time.
Although living on a flood plain exposes its occupants to one set of disturbance – i.e. flooding – it also offers enormous advantages. The deep, fertile alluvial soil of flood plains – the result of aeons of flooding – is ideal for higher crop yields and helps reduce vulnerability of the flood plain occupant to a wide range of other disturbances.
Summary of Chapters
1 INTRODUCTION: This chapter introduces the nature of floods in the Lake Tana basin, defines the problem statement regarding recurrent flooding and its impact on agriculture, and sets out the study objectives.
2 LITERATURE REVIEW: This chapter reviews concepts of flood disasters, plant responses to waterlogging, integrated flood management, and the impacts of drainage and flood control measures.
3 DESCRIPTION AND METHDOLOGY: This chapter describes the study area's administrative and geographical location, climate, and topography, while detailing the data collection and processing methods used.
4 DATA ANALYSIS AND RESULTS: This chapter presents the analysis of rainfall and runoff data, hydrological frequency analysis for major rivers, and an assessment of the socio-economic impacts of flooding, including potential mitigation measures.
5 DISCUSSION OF RESULTS: This chapter interprets the findings from the rainfall and runoff variability analysis and discusses the socio-economic impacts alongside proposed flood control strategies.
6 SUMMERY, CONCLUSION AND RECOMMENDATION: This chapter concludes the study with a summary of key findings, recommendations for future development, and an acknowledgement of the study's limitations.
Keywords
Lake Tana, Flooding, Agricultural Production, Hydrological Analysis, Rainfall Variability, Runoff, Waterlogging, Drainage, Flood Management, Flood Frequency Analysis, Socio-economic Impact, Fogera, Dembia, Kunzila, Mitigation Measures.
Frequently Asked Questions
What is the core focus of this research?
The research focuses on assessing the causes and impacts of flooding on the agricultural output of the plains surrounding Lake Tana, particularly following the severe 2006 flood event.
What are the primary thematic areas covered?
Key themes include hydrological data analysis (rainfall and stream flow), flood frequency estimation, assessment of socio-economic damage to agriculture and infrastructure, and identification of appropriate flood management and drainage technologies.
What is the research goal?
The main goal is to identify why flooding occurs, measure its impact on rural livelihoods, and recommend sustainable mitigation strategies to enhance agricultural productivity in the region.
Which scientific methodology is employed?
The methodology combines the analysis of long-term meteorological and hydrological data with field surveys, including semi-structured questionnaires conducted with local farmers and experts to assess impact and gather local knowledge.
What topics are discussed in the main body?
The main body examines the physical characteristics of the study area, analyzes the 2006 flood hazard via rainfall and runoff trends, and explores various structural and non-structural flood mitigation options, such as levee construction and watershed management.
Which keywords best describe the paper?
The research is best characterized by terms like Lake Tana flooding, agricultural impact, hydrological variability, drainage management, and socio-economic assessment.
How did the 2006 flood affect Lake Tana's backwater levels?
The study found that the Lake Tana backwater effect in 2006 was minimal and did not significantly contribute to the flooding, as the lake level rise was relatively low compared to previous record years.
Why are the local farmers reluctant to leave flood-prone areas?
Farmers remain in these areas despite flood risks because the plains are highly fertile and provide essential agricultural opportunities, and the economic benefits of the land often outweigh the occasional risks posed by flooding.
- Quote paper
- Yirga Alemu Azene (Author), 2007, Assessment of Causes and Impacts Of Flooding On Agricultural Production of Plains Surrounding Lake Tana, Ethiopia, Munich, GRIN Verlag, https://www.grin.com/document/945382
