Assessment of Socio-Economic Impacts of the December 2011 Flood Event in Dar es Salaam, Tanzania

Floods are the most devastating hazards that have significant adverse impacts on people and their livelihoods. Their impacts can be reduced by investing on: 1) improving the forecasting skills of extreme and heavy rainfall events, 2) development of Impacts Based Flood Early Warning System (IBFEWS) and 3) effective communication of impacts from anticipated extreme or heavy rainfall event. The development of IBFEWS however, requires a complete understanding of factors that relates to the formation of extreme or heavy rainfall events and their associated socio-economic impacts. This information is crucial in the development of Impacts Based Flood Forecasting Models (IBFFMs). In this study, we assess the socio-economic impacts of the December 2011 flood event in Dar es Salaam as the preliminary stage in the development of IBFFMs for the City of Dar es Salaam. Data from household survey collected using systematic random sampling techniques and structured questionnaires are used. The survey was conducted to acquire respondent’s views on the causes of floods impacts, adaptive capacity to extreme or heavy rainfall events and adaptation options to minimize flood impact. It is found that the main causes of floods were river overflow due to heavy rainfall and blocked drainage system. Poor infrastructure such as drainage and sewage systems, and ocean surge were identified to be the causes of observed impacts of the December 2011 flood event in Dar es Salaam. Death cases analysis showed that 43 people were reported dead. The flood event damaged properties worth of 7.5 million

Floods are the most devastating hazards that have significant adverse impacts on people and their livelihoods. Their impacts can be reduced by investing on: 1) improving the forecasting skills of extreme and heavy rainfall events, 2) development of Impacts Based Flood Early Warning System (IBFEWS) and 3) effective communication of impacts from anticipated extreme or heavy rainfall event. The development of IBFEWS however, requires a complete understanding of factors that relates to the formation of extreme or heavy rainfall events and their associated socio-economic impacts. This information is crucial in the development of Impacts Based Flood Forecasting Models (IBFFMs). In this study, we assess the socio-economic impacts of the December 2011 flood event in Dar es Salaam as the preliminary stage in the development of IBFFMs for the City of Dar es Salaam. Data from household survey collected using systematic random sampling techniques and structured questionnaires are used. The survey was conducted to acquire respondent's views on the causes of floods impacts, adaptive capacity to extreme or heavy rainfall events and adaptation options to minimize flood impact. It is found that the main causes of floods were river overflow due to heavy rainfall and blocked drainage system. Poor infrastructure such as drainage and sewage systems, and ocean surge were identified to be the causes of observed impacts of the December 2011 flood event in Dar es Salaam. Death cases analysis showed that 43 people were reported dead. The flood event damaged properties worth of 7.5 million Tanzania shillings. Furthermore, the Tanzania Government spent a total amount of 1.83 billion Tanzanian shillings to rescue and relocate vulnerable communities that lived-in low-lying areas of Jagwani to high ground areas of Mabwepande in Kinondoni district.

Introduction
Floods are the most devastating hazards that have potential to cause damage to natural environment, displacement of people, destruction of infrastructure: buildings, roads, railways, bridges and power transmission lines [1]- [6]. The severity of flood impacts however, depends on a number of factors such as geographic location, topography, soil types of the area, increased human settlements and economic assets in floodplains, and reduction of the natural water retention by increased land use change [7] [8].
In recent years, due to population growth, rapid urbanization and climate change, the frequency and intensity of flood events have increased in different regions of the world. These events have posed major humanitarian concern and threaten the efforts of achieving sustainable development and the Millennium Development Goals [9] [10] [11] [12].
Several studies [13] [14] [15] indicated that, the intensity and frequency of flood events will continue to increase in future climate and their impacts are projected to severely compromise socio-economic development particularly in developing countries [16]. Adaptation is a key and only strategy to reduce the impacts of flood events.
However, before the development of adaptation strategies to floods risks, it is important to improve the forecasting skills of heavy rainfall events and develop the Impacts Based Flood Early Warning System (IBFEWS) for anticipated heavy rainfall events. This is important for effective flood risk management strategies to minimize the negative impacts of floods. The development of IBFEWS however depends on clear understanding of factors associated with a particular flood event and the associated socio-economic impacts of such event. This information is important in the development of Impacts Based Flood Forecasting Models (IBFFMs). In this study, we assess the socio-economic impacts of the December 2011 flood in Dar es Salaam as the preliminary stage in the development of IBFFMs.

Geography
The city of Dar es Salaam is located between latitudes 6.36˚S and 7˚S and between longitudes 33.33˚S and 39˚E, at an altitude of 53 m above the sea level ( Figure 1). The city is found along coastline of western Indian Ocean and has tropical type of climate modulated by the warm tropical Indian Ocean. Dar es Salaam experience two distinct seasonal rainfall-the short rainfall season (Vuli)

Data
This study uses primary data of socio-economic implication of the flood event

Methodology
Primary data were collected through personal interview using a structured questionnaire written in English, translated into Swahili and administered in Swahili.
It is important to note that before implementation of the main data collection from the sampled households, the structured questionnaire was subjected to pre-testing on a randomly selected sample of 59 households displaced to Mabwepande. The pre-testing of the questionnaire intended to: 1) assess the time needed to conduct the household survey; 2) assess whether the designed questions can be understood by the respondents and testing the effects of question formulation (appropriateness of questions in terms of socio-cultural standard, lifestyles, etc.).
After conducting the pre-testing of the structured questionnaire, expert meeting of interviewers was conducted to analyze the tested questionnaire and to have common understanding of each question in the structured questionnaire. This meeting resulted into modification of the questionnaire by adding some question in order to acquire more information and irrelevant questions were removed from the structured questionnaire. The modified questionnaire was used in this study to collect primary data.

Sampling Techniques
The sampling unit for this study was a household. The study aimed at completing a total of 59 Households questionnaires to obtain sufficient information to draw valid conclusions from the sample for the population of interest. Of the total sampled, were females and males head of household. Accordingly, a sample of households selected was proportionate to the number of households in the area. Thus, the number of households interviewed/questionnaires analyzed was 59 (out of 500) which represents 11.8 per cent of the total population size. This percentage has been used in other studies such as [19].

Data Collection Techniques
Data collection in the household's surveys was carried out through face-to-face interviews using a structured questionnaire consisting of both closed and open-ended questions formulated to capture information in the three areas of major focus of the study: (causes of flood, impacts, adaption option).
Systematic random sampling technique was used to draw respondents from affected community. This was done by using a registered book of all household given a piece of land at Mabwepande. A size of population of households was 500.
This study aimed to sample 10% of the entire population for meaningful analysis. One household was drawn in every 10 households, making a total number of 59 households (11.8% out of 500).
The interviews were conducted by two people (one man and one lady) who were recruited based on several criteria, including previous experience in data collection and educational backgrounds. The objective of the survey was made clear to the respondent through a consent seeking statement, which was read out at the first contact with each respondent. The interviews were conducted in Swahili, thus the interview technique adopted in the survey was to read the ques-

The Major Factors That Led to Flood in December 2011
Results from the survey indicate that the flood in December 2011 over the city of Dar es Salaam was mainly caused by river overflow due to heavy rainfall and  Table 1 below.  Based on the analysis from the survey it indicates that rainfall is not the only source of flood over the city of Dar es Salaam, other factors such as the topography and infrastructures can lead to flood events. All areas indicated in Table 1 above are flood prone due to fact that is at the low altitude from the sea level. In these areas there is small rivers pass through and discharge water to the Indian Ocean. Therefore, if there is rainfall due to poor infrastructure the rivers overflow and results to floods. However, the areas that are close to the Indian Ocean Coastline experience floods due to rise of sea level which results to ocean surge. This was identified by respondents to be among of the cause of flooding in those areas. The findings from this study correspond to what [24] found after analysing Dar es Salaam's vulnerability to sea level rise. They estimate that at present 8% of the city currently lies in a low elevation zone below the 10-meter contour line.
Studies by [25], identified the flood prone areas in Dar es Salaam to include Msasani bonde la mpunga. This area has mixed residential, commercial and institutional settlements; and has the fastest growing settlements in Kinondoni municipality. Other areas include Msimbazi valley, Jangwani. This is a slum area characterized by floods during rainy season almost every year.
Areas such as (Magomeni Mapipa, Jangwani Valley adjacent Muhimbili and Hannanasif) are found in Kinondoni district and have an informal settlement. These areas are located in low altitude from the sea level therefore, communities living in those areas suffers flooding during the rainy season nearly every year. The Msimbazi river, joined by the Ubungo river which flows across Tandale Mkunduge and Mtogole influence flooding event over low laying area during heavy rainfall events. It is important to note that the Ubungo River which is baptized as Ng'ombe River, literally meaning "Cow Dung Carrying River" and the Msimbazi river influence flooding events over Jangwani areas (respondent's location before evacuate).

Source of Livelihood
The communities living in flood prone areas to a large extent are marginalized and characterized by inadequate adaptive capacity to respond to impacts. Socio-economic analysis of the flood victims showed that the majority, especially women, depend on small scale business as the main source of income ( Figure 6). During the survey most of women and men did not have work due to the effect of the displacement and because they lost most of the resources they had before the flood. Few respondents had small business in the area where they have been allocated after displacement because the area is far away from town city and the development of the area is still in low conditions resulting in every individual seeking for small amount of income for survival of their families. There are no good facilities such as transport for easy trade of goods from one place to another and these results to community living there depend only on small income getting from small businesses which have least cost compared to larger businesses which requires high financial capacity in coordination. Most of these small businesses involve use of their own hands to make some goods and sell to the surround community such as food stuffs especially for women and most of other women they remained housewives. For agriculture case is specifically for domestic purpose of getting food for survival for the family hence there Hence there is no easy access of means of transport such as buses from where they are staying to the main road results to more financial challenges. Option taken to arrive to main road is to walk a long distance and spend longer time or use motorcycle for transport which needs more money to spend. The fact is they cannot afford using of motorcycle every day because majority they spend money in the process of building good houses on the plotted lands government provided for them. For now, a lot of building constructions are taking place to demolish tent which are in poor condition. Hence there is more job for building constructors and non-permanent job for the other respondent such as carrying of blocks and supply of water in building areas. For retired respondents they only depend on the pension government provide for retired people.

Overall Loss of Life and Property
The respondents were asked by how much their property and lives were affected by the flood. The analysis indicated that 80% of the respondents had some property damage and 10% had all property damaged. Death cases were reported and the analysis showed that 6 families lost a total of 15 family members that is equivalent to 10% of families to have lost at least 2 family members, Figure 7 showed the details. Most of respondents lost some of their properties include houses, land, money, livestock, household items such as furniture, electronic devices example television, radio, Iron boxes and so on. Due to this more of social as a result of the flooding event, see Figure 7 above. Figure 7 shows that more than 50% of the respondents lost more than two million which is more evidence that they were in good term of living compare to where they are now. Flood caused respondents be poor because no income they depend on the government. The Figures shows other respondents lost above 30 million TSH means that they were already stabilized in term of the basic needs for the family like house and everything which required for a simple home but due to floods all was lost. These had results other who are well good condition of earns income to start building good houses in the plot lands government gave to them. But is worse for others respondent such as elders who cannot do anything than to wait for support from any organization to help them get a better place because they are still on tents which anytime when rain fall down or the presence of strong winds, they will have no place to sleep. Some of the photos taken when questionnaires were administered are shown in Figure 8 below. Figure 8 below shows the conditions where the respondents were living. They are very poor compared to the life standard of ordinary person. These made majority of respondents feel like not to participate in answering the questionnaire because they need more help of acquiring good houses and nice living condition. Others they were angry at the condition they are living now and they tried to remember what they own before the flood occurred and made them  Table 2 indicates the distribution of money for every support government provides to the affected group.  were spent to provide basic needs such as mattresses, bucket, bed sheets, building of tents and toilets, preparing camps, renovation of classes, buying of desks for students, paying of the hired temporary toilets, preparing title deeds for plot of land and the whole process of move people from dangerous area to safer place at Mabwepande. The total amount is equivalent to 1,099,086.91 USD which is a lot of money. If this disaster did not occur means that the money would be used for other purpose of strengthen economic of the country. But due to that flood government had no option than putting an eye to the affected people in order to reduce the risk of more people lost their life. The impact could have been minimized if proper education on disaster preparedness were given prior to the flood event. Results of socio-economic impacts indicate that the main causes of floods were river overflow due to heavy rainfall and blocked drainage system. Poor infrastructure such as drainage and sewage systems, and ocean surge were identified to be the causes of observed impacts of the December 2011 flood event in Dar es Salaam. Death cases analysis showed that 43 people were reported dead. The flood event damaged properties worth of 7.5 million Tanzania shillings. Furthermore, the Tanzania Government spent a total amount of 1.83 billion Tanzanian shillings to rescue and relocate vulnerable communities that lived-in low-lying areas of Jagwani to high ground areas of Mabwepande in Kinondoni district.