| Climate |
| The climate at the basin level generally remains dry except for monsoon months. There is a considerable variation in the mean daily maximum and minimum temperatures across the catchment. The mean daily maximum temperature ranges from 19.5 to 33.7O C, whereas the mean daily minimum varies from 9.1 to 25.2O C. Maximum temperature in the western areas, having high relief, such as Mercara is in the month of March (28.5 OC). Wind in the area is linked with the monsoons and so mainly blows from the directions between the south-west and north-west during the south-west monsoons. Clouds are also associated with the monsoon activity with the skies being generally overcast during the monsoons.
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| Evapotranspiration: |
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| Precipitation varies considerably across the basin. While, the western side of the catchment mainly experiences the south-west monsoon from June to September; north-east monsoon from October to December falls on the eastern side. The rainfall during the rest of the period is insignificant.
The maps below show the level of precipitation in the basin in four different months. Maximum rainfall happens in the month of August and even this month shows considerable variation across the basin with the western margin getting the bounties. Rainfall in the months of October and November is of comparable level; except for the fact that the maxima in the month of October is in the western part of the basin, whereas for the month of November, the highest rainfall region shifts to eastern margin.
Quantifying the total rainfall in the basin across the year; about 50% is received during the south-west monsoon, about 33 % in the northeast monsoon, roughly 10% in the pre monsoons and the rest in the winter months. The total number of rainy days is more than 100 per year in the western part of the basin and 40 to 50 elsewhere in the region.
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