Spatial and Temporal Variation in Precipitation in Togo

Reduction in seasonal precipitation is becoming recurrent, and many countries are concerned by the concept of climate change. Global surface temperature has increased by 0.74±0.18°C from 1906 to 2005 and it is projected that annual average runoff and water availability will decrease from 10 to 30% by the middle of 21st century.1 Climate change has resulted in extreme drought condition in some parts of the world and flooding in other parts.2 Several studies have reported a drastic decrease in the principal climatic variable, precipitation, in Africa.3−7 Furthermore, it has been reported that most environmental changes in Africa are related to changes in precipitation.8,9 Observed that one of the most important contrasts in rainfall is the multi-decadal persistence of anomalies over northern Africa.10 Identified several changes in the general atmospheric circulation that have accompanied the shift to drier conditions in West African Sahel.11 Recent studies have revealed that the seasonal development of the tropical rain belt over Africa is driven by several factors of the general atmospheric circulation, which in turn, controls the location and characteristics of the inter-tropical convergence zone (ITCZ).9−14 This atmospheric circulation is believed to generate and maintain wave disturbances that modulate the precipitation field. Found the Tropical Easterly Jet (TEJ) as one of the most intense circulation features over Africa and they concluded that the TEJ may be a critical factor in the development of the rainy season and the overall climate in West Africa as opposed to the traditional belief of seasonal movements of the ITCZ.15 Suggested that the indirect effects of anthropogenic sulfate may have contributed to the drying of the Sahel in North Africa.16 A few studies in Togo revealed precipitation deficit since 1970.17‒21 Validated the hypothesis of sensible decrease in water resources in West Africa since the beginning of the 1970s.22−25 Reported that in non-Sahelian West Africa, the rainfall regime began to change around 1966 in Senegal and Guinea Bissau, and then in Guinea, Mali, Burkina Faso, and the northern part of Benin.26 The Ivory Coast, Togo, the south of Benin, Cameroon and the Central African Republic have been affected by changes in precipitation patterns to various degrees. Variability in annual rainfall is characterized by the reduction in annual total precipitation, event frequency disorganization, occurrence of in-season drought when crops are at their critical growth stage (reproductive phase) which usually coincides with the highest evapotranspiration (ET) demand and the severity of the dry period. Reported that rainfed agriculture constitutes at least 97% of agriculture in all West African countries. In Togo where staple food production is not irrigated, particular attention has to be given to precipitation patterns in time and space for better cropping season determination to optimize soil water storage and in season precipitation for crop production.27 In addition, planting date for several crops need to is (re)adjusted according to the shifting of seasonal precipitation patterns over time. Furthermore, spatial analysis of long-term trends in precipitation can help identify areas that are experiencing an increase in the magnitude and frequency of high precipitation events which can generate abundant runoff and result in flood conditions, so that appropriate water and land management practices can be adopted to mitigate these effects. It can also help identifying areas that are experiencing severe drought for resilience and adaptation to climate change strategies development. Since the majority of agriculture in Togo is rainfed, precipitation patterns and distribution need to be investigated to enhance the short and longterm sustainability of crop production as well as the economy of the country. The objective of this study was to evaluate the spatial and temporal variation of monthly and annual average precipitation across Togo for deriving eventual impact on water resources availability and water management planning in rainfed and irrigated agriculture. Volume 1 Issue 4 2017

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