Browsing by Author "Kimambo, Offoro Neema"

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Analyses of past extremes precipitation– evapotranspiration indices over Sub-saharan Countries
(World Scientific Publishing Company., 2022-08-31) Mbaye, Mamadou Lamine; Bodian, Amy; Kimambo, Offoro Neema; Rouamba, Fabienne Inès; Gaveta, Elias
Extreme weather and climate events including extreme precipitation have increased in frequency, intensity, and severity due to climate change and hit vulnerable communities disproportionately hard. However, there is a gap in the understanding of the characteristics of extreme precipitation and their effects on socio-economic activities in sub-Saharan Africa societies. The study utilized climate hazards group infrared precipitation with station data (CHIRPS) to analyze the climate characteristics from 1981 to 2019 over Senegal, Burkina Faso, Tanzania, and Malawi. Standardized precipitation evapotranspiration index (SPEI) and standardized precipitation index (SPI) were used to classify the precipitation and water balance anomalies with respect to the long-term observations. It was found that Burkina Faso and Senegal have a similar climate signal with more rainfall in Burkina Faso. Malawi recorded more rainfall than Tanzania. All the four countries recorded a high rainfall variability of extreme events. Standardized hydro climatic indices have shown that these sub-Saharan countries have suffered severe droughts which have negatively affected the socio-economic activities among the rural populations.
Analysis of start, end and length of the rainfall seasons in Mbeya, southwestern highland in Tanzania
(Creative Commons CC, 2018-07) Kimambo, Offoro Neema; Ndeto, Emmanuel Lubango
Tanzania like any other developing countries is depending on uncertain rainfall for their subsistence and commercial agriculture. In this paper the start and end of rains for Mbeya Meteorological Station in Tanzania Mainland was analyzed and critically examined. Data were kindly given by Tanzania Meteorological Agency (TMA) during face to face Statistics in Applied Climatology (fSIAC) workshop which was held at Sokoine University of Agriculture (SUA) the year 2013 prior to online Course on Statistics in Applied climatology (eSIAC). In this study data were analyzed using Instat (for windows version 3.3.7) package developed by the Statistical Services Centre of the University of Reading. The analysis showed that much of rains start early December all the way to May. There is also 50 percent chance of having below and above the mean for both total annual rainfall and number of rains, in other word one in two years the total rains are below means likewise the number of rain days.
Harmful Algal Blooms in Aquaculture Systems in Ngerengere Catchment, Morogoro, Tanzania: Stakeholder’s Experiences and Perception
(MDPI, 2021) Kimambo, Offoro Neema; Gumbo, Jabulani Ray; Chikoore, Hector; Msagati, Makudali
The aquaculture sector has experienced fast growth as a result of livelihood diversification initiatives among small-scale farmers in Tanzania. Regrettably, the dynamics of harmful algal blooms (HABs) have been overlooked despite the noticeable forcing of climate variability, the interaction between social-economic activities, and domestic water supply reservoirs. This study aimed at surveying the occurrence, experiences, and perceptions of HABs in aquaculture systems from stakeholders in the Ngerengere catchment, Morogoro, Tanzania. A cross-sectional survey focus group discussion (FDG), key informant interviews, and anecdotal observation were adopted. A convenient and purposive sample population was drawn from pond owners, registered water users, and government officials in the catchment. For data analysis, descriptive statistics and constant comparison were performed. Most respondents (95%) were able to recognize the image of blooms displayed. Approximately 70% of the respondents agreed that water quality has deteriorated over time, and blooms occur during the dry season. Further, 60% of the respondents agreed that water pollution is a serious problem attributed to sources other than industrial discharge. There was no consensus regarding the health impacts associated with HABs. Raising awareness on HABs is of paramount importance as it will provide the basis for the development of HABs management framework and health risk assessment.
Impacts of climate variability and hydrological modifications on cyanobacteria potentials in aquaculture systems in the ngerengere catchment, Morogoro, Tanzania
(University of Venda, 2021-04) Kimambo, Offoro Neema
The scientific consensus is that the global increase in cyanobacterial harmful algal blooms (CyanoHABs) is attributed to eutrophication, hydrological variations, and anthropogenic activities compounded by climate change. Cyanobacteria are known to produce a wide range of toxins (cyanotoxins) and hypoxia conditions that can alter the food web. Besides the fact that Tanzania is rich in water resources such as the ocean, lakes, rivers, dams, and ponds and shreds of evidence of environmental constraints, climate and hydrological variations (episodic events and altered river flows), on HABs, much is yet to be done. Their growth is not spatially homogenous, and that there is an information gap on their dynamics. CyanoHABs have registered impacts on food security, tourism, water resources, fishery, and human health. The only recorded incidences (recurrence) are the mass fatalities of Lesser flamingo in Lake Manyara, Arusha. Some recent reports, for instance, gauged the rapid growth of the aquaculture sector as a result of livelihood diversification, but the sector is facing management and environmental constraints. Since the aquaculture farms/fishponds are hydrologically connected with the domestic water reservoirs in the Ngerengere catchment, there is a need for a thorough analysis. The study explored the impacts of climate variability and hydrological modification on cyanobacteria potentials in aquaculture systems in the Ngerengere catchment in Morogoro, in the United Republic of Tanzania. In this study, a review of the literature (i.e., historical reconstruction) on CyanoHABs occurrences in Tanzania and their link with climate and hydrological variation was conducted. A stakeholders’ perception and experience (questionnaire, focus group discussions, and key informant interviews) and anecdotal observations were also conducted and examined. Water samples were collected and analyzed for the identification and characterization of common species of cyanobacteria and in-situ measurements of physicochemical characteristics. Also, case studies were also diagnosed to examined how CyanoHABs link with other key environmental observations. The study also involved obtaining online data for chlorophyll-a to analyze their trends and how they are teleconnected with climate and hydrological variation in Mindu, Dam situated in the Ngerengere catchment. The methods and procedures followed in the study are detailed under the specific chapters. The study found that on HABs, the field is still at its nascent stage in Tanzania, and research iiin the field is lagging. Most studies are events driven, for example, post-mortem analysis and that there is no limnological data to perform time series analysis. Regarding the survey on stakeholders’ perception of CyanoHABs in the Ngerengere catchment, 95% of the respondents could recognize blooms as displayed to them, with 70% noting that algal blooms proliferate more during the dry season. On the other hand, respondents were uncertain about any health effects associated with blooms. During the survey, farmers revealed that they sometimes feel itching during and after fishing, which is linked to toxic effects from CyanoHABs. The morphological assessment shows the occurrences of common species of CyanoHABs in the Ngerengere catchment, such as Microcystis, Cylindrospermopsis, Anabaena, Lyngbya, as well as other species such as diatoms and Euglenophytes, which at times might be a nuisance to the environment. It was further observed that colony-forming cyanobacteria dominated the fishponds while filamentous species were dominant in Mindu Dam (a domestic water supply in the catchment). However, the eutrophic state of the sampling points varied from eutrophic to hypereutrophic state for all the sampling schedules. Moreover, Mindu Dam was eutrophic, becoming hypereutrophic toward the end of sampling (September 2018, usually the dry season). During the study period, two unique cases, namely, heavy rainfall, which caused flash flood (in this study defined as an episodic hydrological event) and unusual observation of reddish colouration (red algae) fishponds at Kingolwira National Fish Farming Centre were gauged and examined. The heavy rainfall event happened between the first (October 2017) and the second (February 2018) sampling phases, which showed to be affecting the equivalent spherical diameter (ESD) and area-based diameter (ABD) of the community structure. The heavy rain phenomenon was localized (enhanced by the orographic nature of the place) but also steered by the presence of the Intertropical Convergence Zone (ITCZ) and the tropical cyclone Berguitta (which was the dominant weather over the Indian Ocean). Regarding the unusual observation of reddish bloom in the fishpond, the associated physicochemical characteristics during the event were also studied. To the best of our knowledge, the observed red algae is the first to be reported in fishponds in Tanzania. These results show that the fishponds were significantly (p<0.05) different from each other except for water temperatures. Microcystis and euglenophytes species respectively dominated non-reddish and reddish fishponds. The study findings demonstrate the dynamics of harmful cyanobacterial blooms in iiithe study area. The use of case studies and observations synergistically can be utilized in understanding the local context hence studying the dynamics of CyanoHABs. A retrospective analysis of chlorophyll-a was conducted in Mindu Dam, which demonstrated increasing Chlorophyll-a trends (defined as a chlorophyll-a index and a ratio between bands characteristics using Landsat 7 surface reflectances), minimum and maximum temperatures, and solar radiation. While rainfall trends were neutral, wind speed and directions and water levels for the Mindu Dam showed a significant decreasing trend with time. However, there was a strong correlation between wind speed and maximum temperature but weak with minimum temperature. There was also a significant weak correlation between Nino-3.4 monthly rainfall as well as water levels. The study area is to the leeward side of the Uluguru mountains. The patterns suggest links and causality between the CyanoHABs variations and meteorological parameters such as temperatures, solar radiations, and water levels. Findings in this study contribute to the understanding of CyanoHABs with climate and hydrological variation in a region in the face of data paucity. The study further provides an insight into state of the art, cause of CyanoHABs, and their link with climate and hydrological variation hence informing policies and practices and professional development. The findings also provide a basis for the development of the CyanoHABs management framework and health risk assessment.
Klerksdorp Tornado on March 4, 2007, in South Africa: a synoptic overview
(World Scientific Publishing Company., 2024-06-22) Kimambo, Offoro Neema
This research delves into the factors contributing to tornado formation in South Africa, with a specific focus on the Klerksdorp tornado that occurred on March 4, 2007, in Northwest Province. Despite their recurrent occurrence and significant potential for damage, tornadoes have received relatively little attention. Between 1990 and 2014, these weather phenomena incurred estimated costs exceeding half a billion American dollars in addition to other weather-related disasters. In this study, data from multiple observation systems, including the National Oceanic and Atmospheric Administration (NOAA), the National Centers for Environmental Prediction (NCEP), the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) in Germany, and the South African Weather Service (SAWS), were thoroughly analyzed. The findings reveal that the Klerksdorp tor- nado was linked to a cold front and a cut-off low, which were the dominant weather systems on the day of the tornado. This case study enhances our comprehension of tornado dynamics in South Africa, aiding in improving short-term forecasts and potentially early warning systems. Future research should concentrate on the recurring nature of tornadoes in association with tropical weather systems and locally-driven factors.
The occurrence of cyanobacteria blooms in freshwater ecosystems and their link with hydro-meteorological and environmental variations in Tanzania
(Elsevier, 2019-03-07) Kimambo, Offoro Neema; Gumbo, Jabulani Ray; Chikoore, Hector
Understanding the Effects of Changing Weather: A Case of Flash Flood in Morogoro on January 11, 2018
(Hindawi, 2019) Kimambo, Offoro Neema; Chikoore, Hector; Gumbo, Jabulani Ray
Floods are the leading cause of hydrometeorological disasters in East Africa. Regardless of where, when, and how the event has happened, floods affect social security as well as environmental damages. Understanding floods dynamics, their impacts, and management is thus critical, especially in climate risk assessment. In the present study, a flash flood (a case of an episodic hydrological event) which happened on January 11, 2018, in Morogoro, Tanzania, is examined and synthesized. Data were courtesy of the National Oceanic and Atmospheric Administration Global Forecasting System (NOAA GFS) (forecast data), Tanzania Meteorological Agency (TMA), and Sokoine University of Agriculture (for the automatic weather data). With the help of ZyGRIB-grib file visualization software (version 8.01, under General Public License (GNU GPL v3)), the forecast data and patterns of the observation from the automatic weather station (temperatures, wind speed and directions, rainfall, humidity, and pressure) and the long-term rainfall data analysis in the study area made it possible. This study contributes to the knowledge of un- derstanding the changing weather for planning and management purposes. Both forecasts and the observations captured the flash flood event. The rain was in the category of heavy rainfall (more than 50 mm per day) as per the regional guidelines. The synergy between the forecasts and the 30-minute weather observation interval captured the fundamental weather patterns that describe the event. For studying the nature and impacts of flash floods in the region, the integration of automatic weather observation into the systems of national meteorological centers is inevitable. Additionally, as part of an integrated disaster risk reduction effort, there is a need for a review on catchment management strategies.