Assessment of the Off-season Rainfall of January to February 2020 and Its Socio Economic Implications in Tanzania: A Case Study of the Northern Coast of Tanzania

Abstract

This article examines the off season rainfall in northern coast Tanzania (NCT) including Zanzibar which occurred in January and February 2020 (JF). Like the JF rainfalls of 2001, 2004, 2010, 2016 and 2018, the JF (2020) rainfall was more unique in damages including loss of lives, properties and infrastructures. The study used the NCEP/NCAR reanalysis data to examine the cause of uniqueness of JF rainfall in 2001, 2004, 2010, 2016, 2018 and 2020 over NCT and Zanzibar. These datasets include monthly mean u, v wind at 850, 700, 500, and 200 mb; SSTs, mean sea level pressure (MSLP) anomalies, Dipole Mode Index (DMI), and monthly rainfall from NCT and Zanzibar stations. Datasets were processed and calculated into long term, seasonal, and monthly averages, indeed, Precipitation Index (PI) was calculated. Correlation analysis between the rainfall (December to January), SST, DMI and 850 mb wind vectors; and long-term percentage contribution of investigated parameters was calculated. Results revealed significant positive and negative correlations between JF rainfall, SSTs and DMI. Moreover, JFs of 2004 and 2016 had higher rainfalls of 443 mm with percentage contribution of up to 406%, while January and February, 2020 had the highest of 269.1 and 101.1mm in Zanzibar and 295 and 146.1 mm over and NCT areas, with highest January long-term rainfall contribution of 356% in Zanzibar and 526% over NCT. The DJF (2019/20) had the highest rainfall record of 649.5 mm in Zanzibar contributing up to 286%, while JF 2000 rainfall had a good spatial and temporal distribution over most NCT areas. JF, 2020 rainfall had impacts of more than 20 people died in Lindi and several infrastructures including Kiyegeya Bridge in Morogoro were damaged. Conclusively, more research works on understanding the dynamics of wet and dry JF seasons should be conducted.

The Influence of Climate Change and Variability on Spatio-Temporal Rainfall and Temperature Distribution in Zanzibar

“…Higher rainfall at Mkoani followed by Wete which indicates that Mkoani is leading compared to other regions. The impacts of the observed higher rainfall over most areas of Zanzibar is in concurrence with [24] who noted that higher rainfall in OND 2019 has resulted into a number of socioeconomic stresses including the death of people, damage to electric poles resulting in power shortage for several days (at Mwakaje and Mwera)also trees and vegetation plantation were affected. As for the climate influence on T max and T min at Unguja and Pemba, the presented results have shown that T max was increasing at the rate of 0.035 and 0.0169˚C/yr, respectively.…”

“…Annual and seasonal rainfall rates of Unguja and Pemba, wind pattern (southeast and northeast monsoon), and annual and seasonal temperature rates (maximum, minimum and daily mean). Also [24] has shown that the long-term average maximum temperature during March to May (MAM) season for Zanzibar ranged from 32.4˚C for Unguja and 31.6˚C for Pemba; while the minimum ranged from 22.7˚C and 23.1˚C for Unguja and Pemba respectively.…”

“…Additionally, frequencies of extreme and severe droughts in Pemba which experienced severe droughts in 1976, 1987 and from 1994-1997 were also detected well during both long and short growing seasons with exception of severe drought events in MAM that lead to changes in forest cover and biomass over time [21] The variability of rainfall has a great impact on agricultural planning and water resources management. For example, rain-fed agriculture has remained the dominant source of staple food production for the majority of rural poor in sub-Saharan Africa [22], for southern, heavy dependence on rain-fed agriculture in Zimbabwe and climate sensitive resources [23] and Zanzibar in particular, where the agricultural activities are rain-fed and about 85% of most of the economic activities depends on the climate-driven agricultural sector [24].…”

The Influence of Climate Variability on the Watermelon Production in Zanzibar

“…The results for the correlation between the water melon production and weather parameters shows that the MAM rainfall at Chake Chake district was high (r = 0.5) but not significant indicating that there exists little production of watermelon during MAM season as supported by anecdotal response Figure 8. Also this results in well supported by [5] who noted that the peak MAM rainfall for Pemba is during May and that of Unguja is during April indicating that the period between March and April for Pemba can be good for production of watermelon. Also results in Table 1 for Micheweni revealed a correlation of (r = 0.2 and r = 0.03), though not significant between watermelon production during MAM and OND, respectively.…”

“…composts), paste sides and farmers selfmotivation, but also climate and weather fluctuations and changes seems to be most important production deciding factor. Since most agricultural activity in East Africa and Zanzibar in particular are climate driven [5] [9] [10] and also the agricultural activities in Zanzibar are also rain fed, therefore is highly threatened by the consequences of climate change, thus the watermelon production as an adaptive measure in Zanzibar is also subjected to seasonal variability (fluctuations). The 4th IPCC report noted that by 2020 in Africa all agricultural rain fed yields would be reduced by 50% due to the climate change stress as also noted by [11].…”