Climate change has brought changes to the characteristics of the rain, wherein the rainy season duration is short; however, the dry season is getting longer. This study aims to detect the climate change presence or absence, identify the relationship of climate change to the nature of rainfall, and the relationship of climate change to rainy, humid and dry months. This research was conducted in the Mepanga Watershed, Parigi Moutong Regency, Central Sulawesi, Indonesia. The Makesens method is used for climate change detection. The rainfall characteristics use standard deviation statistical methods; furthermore, the Oldman method is used for dry, humid, and wet months. The data used is rainfall data for 30 years (1990-2019) from Kayu Agung Station. The results show that there has been a climate change in the Mepanga watershed. Marked by a Z ≠ zero value, where there is a positive trend (Z> 0) and a negative trend (Z <0). The increase in rainfall and conversely indicates the positive trend; otherwise, a decrease in rainfall indicates a negative trend. There is an effect of climate change on the nature of rain, wet, humid and dry months but not significant.

This study aims to grasp and analyze the water availability in Sausu Watershed and the need of water in Lower Sausu Irrigation Scheme. The research begins with data collection and hydro-climatological analysis to determine whether the water is enough or not enough to be used during a hydrological period. To obtain the comparison between the needs and availability of water, a hydro-climatological analysis and calculation of water need are carried out. Methods that used namely the Penman Modification method and the F.J Mock method. Penman modification method is used to calculate monthly evapotranspiration (ETo) by taking into account climatological factors such as air temperature, wind speed, solar radiation and relative humidity. By applying the F.J.Mock method for calculating the water availability, the amount of water flow from the rain, characteristics of the drainage area and evapotranspiration can be calculated. Based on the results of data analysis for Sausu watershed area of 568.64 km², it shows that the average value of water availability in the lower intake for 1 year is app. 30.19 m³/sec with the maximum value of app. 48.149 m3/sec and the minimum is app. 4.134 m3/sec. Whereas the maximum water demand in the Lower Sausu irrigation scheme is app. 1.77 m³/sec with the minimum of 0.04 m3 /sec and the average is app. 0.49 m3/sec. It can be concluded that the water availability in the Sausu River Basin is sufficient to meet the water needs of the Lower Sausu Irrigation Scheme throughout the year, or there is a continuous surplus.