Climate Change Of Drought And Flood In Rwanda Associated With Malaria

The global Climate is experiencing a significant change characterized by warming which profoundly affects human beings and becomes of one the major challenge facing the international community.For example,climate change is expected to increase the incidence of vector borne diseases such as malaria and create a burden to sustainable development,especially for poor countries.Recently,several extreme temperatures and precipitation,dry and wet events,sea level rise,typhoons and many other abnormal climate phenomena caused by climate change have been noted in many parts of our planet.Although,climate change trends and basic facts differ from one region to another,there are still many uncertainties in the detection of climate change trends in certain region(such as China).This study takes Rwanda in central and East Africa as an example.Using long-term sequence observations of conventional surface meteorological stations,model assimilation,reanalysis data and malaria cases in last 10 years by employing different statistical methods and techniques;The study,at first investigated the dominant atmospheric circulation patterns associated with abnormal rainfall over Rwanda from 1981 to 2010 to better understand the March-May(MAM)rainfall season.The datasets used in this part include;rainfall,wind,sea surface temperature and humidity.Correlation analysis and Composite analysis and Percent of Normal Index(PNI)were deployed in this part.Results show that the country was dominated by moisture convergence during wet years,which is in line with wind anomalies,exhibiting strong westerly winds from Atlantic Ocean and south easterly winds originated from Indian Ocean.These winds carry humid air mass passing over Congo to the study area,hence wet events.On the other hand,easterly winds were noted over the study area during dry years.Further results indicate that the dry years were noted as;1987,1988,1998 and for wet years,1984,2000,2007,and 2008 were identified.The observed wet years coincided with El Nino events,while the dry years are noted during La Nina episodes.The dry years exhibited a wide spread moisture divergence anomaly at low level and was characterized by sinking motion as opposed to wet years which depicted rising motion as exhibited by pressure vertical velocity.The anomaly fields of velocity potential/divergence further showed that the wet(dry)years were characterized by convergence(divergence)at low level over the study area.Further findings indicate that there exists a low positive correlation between mean MAM rainfall and SST over Indian Ocean,which shows minimum influence of the Ocean.On the other hand,it was noted that rainfall amount is significantly correlated at 95%confidence level to the elevation(altitude)of a given station.The results from this study will help to improve the knowledge on the occurrence of wet and dry events in Rwanda.This will further help in the future monitoring of events.Furthermore,the variations and trends of daily maximum and minimum surface air temperature(Tmax and Tmin),and diurnal temperature range(DTR)over Rwanda during the period 1961-2014 at monthly,seasonal and annual time-scales are also carried out in this study by applying various statistical methods(e.g.,ordinary least-square fitting and sequential Mann-Kendall statistical test)to data series from 54 meteorological stations.Based on the impact of topography,stations were divided into three regions;region one(R1)(1000-1500m),region two(R2)(1500-2000m)and region three(R3)(>2000m).This study reveals that both Tmax and Tmin generally increased in all regions in the past decades while DTR has slightly decreased hence minimum temperature(Tmin)increase more significantly in comparison with maximum temperature(Tmax).From the year 1984,both Tmax and Tmin have significantly increased in October to December(OND)in comparison to those in June-August(JJA)and March-May(MAM)season with abrupt and significant changes happening around the early 1990s.The warmest year of the entire series is 2010 with a Tmax of 1.16? above the mean of 1961-2014 in R1.From the year 1990 to 2014 the Tmin in all regions was above the mean of 1961-2014 except 1991,1992 and 2001,indicating warming in recent time.The observed rate of extreme Tmax is+0.2?/decade in R1,+0.01?/decade in R2 and +0.12?/decade in R3.However,DTR does not show notable annual trend.There is an increase in extreme Tmax at the rate of 47.85%in R1 while both R2 and R3 experienced almost the same rate of 31.5%for the whole period.The high rate of Extreme Tmax observed in R3(high altitude)is another approval of warming in Rwanda.Among other factors,topography was revealed to be the most influencing factor regulating Both Tmax,Tmin and DTR variation over Rwanda.This work provides convincing evidence that long-term change of Tmax,Tmin,DTR and extreme temperature events is of importance to the detection and attribution of climate change in regional difference in Rwanda.Finally,it is of great important to note that a proper Malaria control and eradication method for saving human lives and ensure sustainable development requires the understanding of relationship between climate variables and malaria.Observed malaria incidence cases covering the whole country for the period from 2010 to 2016 were considered for analyzing the correlation between malaria incidences and climate variables.Linear regression,Pearson correlation and other statistical technique analysis were employed.A high concentration of malaria cases in wet seasons than in dry season was revealed.Significant correlation between annual changes in malaria cases and annual rainfall was observed(coeff=0.72,p<0.001),whereas suitable months for malaria incidences were found to be May,June,November and December.The suitable temperature ranged between 18 to 19?.Rainfall and Topography have been revealed to have a very strong relationship with malaria cases distribution over Rwanda.Low malaria cases were found in high land.The consideration of topography and government role is very important in assessment of the effect of changes in malaria transmission patterns.The findings of this study are hoped to provide insights on effective control method and more attention is highly needed to achieve Malaria elimination stage in Rwanda.