Vallegrande Climate Hazards
Monthly Precipitation Average in the Vallegrande Region (1971-2001)
The meso-thermal sub-humid dry climate is predominant in the region with low levels of water in the rainy season and water shortages during the dry season. Due to the different geographic characteristics of the region, the climate varies for the different localities within the area. In general terms, the average minimum temperature ranges between 6.8 and 15.5 °C and extends from April to August (winter). The maximum temperature average ranges between 21.1 and 26.2 °C and is applicable from October to March (summer) .
The rainy season in the Vallegrande region begins in October and can last until April. During this period, and in particular between January and March in the past two decades, some areas such as Postervalle and Masicuri present occasional flooding problems. The average monthly precipitation (1997 to 2001) is presented in Figure 6. The relative humidity average in the region varies between 60 and 70%, presenting significant differences between the months of winter (low level of humidity) and summer (high level of humidity).
The predominant winds in the region come from the north with an average velocity that ranges between 5 and 15km/h. During the dry season (winter) wind can come from the south for short periods and with high velocities reaching 50km/h. This wind is cold and causes a decrease in temperature in the region. This event is locally known as ‘surazo’ and can cause drought or drizzle. The latter benefits the crops cultivated during that period.
In the Vallegrande region there are six main climatic hazards that affect the production systems including: winds, snow (once a year in the Municipality of Pucara), frosts, hail, drought and flooding (Municipal Development Plan Mancommunity Vallegrande 2002). The municipalities in high elevation areas such as Moro Moro have a cold climate influenced by the high altitude, soil type, and the scarce vegetation cover. In the municipality of Vallegrande the climate is temperate, while in the municipality of Saipina the climate is dry. The lower humidity in the valley plains cause a reduction in the vegetation growth rate and density, resulting in low levels of organic matter in the soil. The slow vegetation growth is exacerbated by the temperature differences between day and night. Given the physiographic and climatic characteristics of the region, the production systems in the region are highly vulnerable to climatic variability and extremes.
Drought is considered to be the most significant by the local farmers. The soil is prepared for cultivation between March and June in Saipina and October and December in Moro Moro and Vallegrande. If the soils are not humid by then, the organic matter that contributes towards soil fertilization will not be sufficiently decomposed thus negatively affecting productivity. Moreover, if the soils are dry during sowing, the seeds will dry and germination will also be negatively affected. If drought affects the first development stage of the crops, this will reduce the resilience of crops to cope with frosts or plagues. If water is not ensured for crops at least until the flowering and grain building stages, then production is highly vulnerable and the probability of a good harvest is very low.
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