Sekela Twisa

Dr. Sekela Twisa

UNU-FLORES
orcid

Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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8 September 2019 in Land
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Journal Article
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STSekela Twisa
Sekela Twisa
MBManfred Buchroithner
Manfred Buchroithner
Anthropogenic activities have substantially changed natural landscapes, especially in regions which are extremely affected by population growth and climate change such as East African countries. Understanding the patterns of land-use and land-cover (LULC) change is important for efficient environmental management, including effective water management practice. Using remote sensing techniques and geographic information systems (GIS), this study focused on changes in LULC patterns of the upstream and downstream Wami River Basin over 16 years. Multitemporal satellite imagery of the Landsat series was used to map LULC changes and was divided into three stages (2000–2006, 2006–2011, and 2011–2016). The results for the change-detection analysis and the change matrix table from 2000 to 2016 show the extent of LULC changes occurring in different LULC classes, while most of the grassland, bushland, and woodland were intensively changed to cultivated land both upstream and downstream. These changes indicate that the increase of cultivated land was the result of population growth, especially downstream, while the primary socioeconomic activity remains agriculture both upstream and downstream. In general, net gain and net loss were observed downstream, which indicate that it was more affected compared to upstream. Hence, proper management of the basin, including land use planning, is required to avoid resources-use conflict between upstream and downstream users.

1 October 2019 in Water
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Journal Article
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STSekela Twisa
Sekela Twisa
MBManfred Buchroithner
Manfred Buchroithner
In some parts of Africa, rainfall variability has resulted in widespread droughts and floods, thus posing a substantial challenge to water availability in rural areas, especially drinking water. Therefore, due to increasing water demands, increases in the population, and economic development, water supply systems are under constant stress. One of the critical uncertainties surrounding the effects of rainfall variability in Africa is the significant impact that it imposes on rural water supply services. The present study analyzes the trends in annual and seasonal rainfall time series in the Wami River Basin to see if there have been any significant changes in the patterns during the period 1983–2017 and how they affect the access to water supply services in rural areas. The study analyzes the trends of rainfall series of three stations using simple regression, Mann–Kendal Test and Sen’s Slope Estimator. The water point mapping datasets were analyzed considering seasonal variation. The analysis showed a statistically significant positive trend in annual rainfall at Kongwa and March–April–May (MAM) seasonal rainfall at Dakawa. The maximum increase in annual rainfall occurred at Kongwa (5.3 mm year−1) and for MAM seasonal data at Dakawa (4.1 mm year−1). Water points were found to be significantly affected by seasonal changes, both in terms of availability and quality of water. There also exists a strong relationship between rural water services and seasons.

19 March 2020 in Hydrology
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STSekela Twisa
Sekela Twisa
SKShija Kazumba
Shija Kazumba
MKMathew Kurian
Mathew Kurian
MBManfred Buchroithner
Manfred Buchroithner
Understanding the variation in the hydrological response of a basin associated with land use changes is essential for developing management strategies for water resources. The impact of hydrological changes caused by expected land use changes may be severe for the Wami river system, given its role as a crucial area for water, providing food and livelihoods. The objective of this study is to examine the influence of land use changes on various elements of the hydrological processes of the basin. Hybrid classification, which includes unsupervised and supervised classification techniques, is used to process the images (2000 and 2016), while CA–Markov chain analysis is used to forecast and simulate the 2032 land use state. In the current study, a combined approach—including a Soil and Water Assessment Tool (SWAT) model and Partial Least Squares Regression (PLSR)—is used to explore the influences of individual land use classes on fluctuations in the hydrological components. From the study, it is evident that land use has changed across the basin since 2000 (which is expected to continue in 2032), as well as that the hydrological effects caused by land use changes were observed. It has been found that the major land use changes that affected hydrology components in the basin were expansion of cultivation land, built-up area and grassland, and decline in natural forests and woodland during the study period. These findings provide baseline information for decision-makers and stakeholders concerning land and water resources for better planning and management decisions in the basin resources’ use.

2 April 2020 in Resources
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Journal Article
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STSekela Twisa
Sekela Twisa
MMMohamed Mwabumba
Mohamed Mwabumba
MKMathew Kurian
Mathew Kurian
MBManfred Buchroithner
Manfred Buchroithner
Land-use/land-cover changes are considered the dominant form of anthropogenic pressure on the environment, causing changes in ecosystem service patterns and affecting water supply services. Using the spatial econometric technique, we analysed the impact of land-use/land-cover change on water ecosystem services for domestic use upstream and downstream of the Wami River Basin. The results in terms of land-use/land-cover classes during the study period (2011–2016) indicate that cultivated land showed maximum positive changes in both sub-catchments, while bushland and woodland showed maximum negative changes upstream and downstream. The results showed that bushland, woodland, cultivated land, and grassland were significantly correlated with water point characteristics in both sub-catchments. For functionality characteristics, a significant effect was observed in bushland and grassland upstream and downstream, respectively, while sufficient water was found in woodland upstream and grassland downstream. Moreover, bushland was observed to have a significant number of water points with poor quality of water upstream, and a substantial number of water points with good quality of water were found in grassland downstream. We found that all measured land-use/land-cover changes and water point characteristic correlations were statistically significant; therefore, we concluded that land-use/land-cover change affects the water ecosystem in the basin. These results could facilitate decision-making and development of related policies and might support finding sustainable strategies for water ecosystem services for domestic use.

2 February 2024 in Water
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OSOnesmo Zakaria Sigalla
Onesmo Zakaria Sigalla
STSekela Twisa
Sekela Twisa
NCNyemo Chilagane
Nyemo Chilagane
MMMohamed Mwabumba
Mohamed Mwabumba
JSJuma Selemani
Juma Selemani
PVPatrick Valimba
Patrick Valimba
Global croplands, pastures, and human settlements have expanded in recent decades. This is accompanied by large increases in energy, water, and fertilizer consumption, along with considerable losses of biodiversity. In sub-Saharan Africa, policies are implemented without critical consideration; e.g., agricultural expansions impair ecosystem services. We studied land use/cover and the associated rate of change for four time epochs, i.e., 1991, 2001, 2011, and 2021. This employed remote sensing and GIS techniques for analysis, while future projections were modeled using cellular automata and the Markov chain. The kappa coefficient statistics were used to assess the accuracy of the final classified image, while reference images for accuracy assessment were developed based on ground truthing. Overall change between 1991 and 2021 showed that major percentage losses were experienced by water, forest, woodland, and wetland, which decreased by 8222 Ha (44.11%), 426,161 Ha (35.72%), 399,584 Ha (35.01%), and 105,186 Ha (34.82%), respectively. On the other hand, a percentage increase during the same period was experienced in cultivated land, built-up areas, and grasslands, which increased by 659,346 Ha (205.28%), 11,894 Ha (159.93%), and 33,547 Ha (98.47%), respectively. However, this expansion of thirsty sectors has not reversed the increasing amount of water discharged out of the Kilombero River catchment. We recommend the promotion of agroforests along with participatory law enforcement and capacity building of local communities’ institutions.

22 June 2026 in Journal of Water, Sanitation and Hygiene for Development
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Journal Article
Open access
GBGeorge Bennett
George Bennett
MTMalugu Maduhu Tembo
Malugu Maduhu Tembo
MMMinza Mboje
Minza Mboje
SLSamwel Lupyana
Samwel Lupyana
LKLulu Tunu Kaaya
Lulu Tunu Kaaya
STSekela Twisa
Sekela Twisa
Climate change, driven by increased rainfall variability and rising temperatures, exacerbates water scarcity and significantly affects household water, sanitation, and hygiene practices. In response, households often adopt coping mechanisms that, while intended to conserve water, may result in reduced hygiene and sanitation practices, thereby increasing exposure to health risks. In the Bahi Swamp sub-basin of Tanzania, acute water scarcity prevails due to semi-arid climate conditions, climate change, and inadequate water management, posing significant threats to local livelihoods. To assess household water scarcity, coping strategies, challenges, and measures for sustainable water management, a semi-structured questionnaire was administered to 260 households. The results indicate that most households experience persistent water shortages, causing conflicts over water use. Most households (92%) adopted coping strategies such as purchasing water, storing water, reducing daily consumption, rainwater harvesting, and switching water sources; however, some of these strategies may increase the risk of water-borne diseases and negatively affect overall wellbeing. Rainwater harvesting could serve as an effective strategy for addressing domestic water scarcity. Lack of knowledge and training, and financial constraints are key challenges to sustainable water resource management. Crucial measures include improved access to training and resources, along with financial support or subsidies.