trend in the amount of rainfall over Sahibi Basin (Table 12.2). Similarly, most of the
stations have shown significant rising trends in the amount of rainfall, except
Thanagaji and Tapukara stations in June. In July, all the stations have shown
decreasing trends except Kotkasim, whereas Thanagaji and Tapukara stations have
shown significant declining trends. In August, Tapukara, Tijara, and Kotputli stations have shown significant decreasing trends. Similar results have been observed
by Meena et al. (2019) for western Rajasthan. In May, Behrod, Kotkasim, and
Kotputli stations have shown significant increasing trends. However, no significant
rising or declining trend has been observed over different stations during other
months.
Spatial Variations in Rainfall
Annual Variations
The spatial pattern of mean annual rainfall over Sahibi Basin is demonstrated in
Fig. 12.6a. An increase in rainfall from northeastern and western parts to the
southeast has been observed. This increase in rainfall southeastward may be attributed to the existence of the Aravalli Mountains. The northeastern and western parts
have received less rainfall. The maximum mean amount of rainfall has occurred over
Thanagaji station (about 708 mm) in the south, whereas the least occurred over
Tapukara station (about 575 mm) in the north (Table 12.4). This difference in the
magnitude of rainfall is high for such a small basin. Further, CV values have shown
an opposite pattern to the mean annual rainfall (Fig. 12.6b). The rainfall variability is
relatively less over the stations receiving higher rainfall and vice versa. High rainfall
variability can be seen over the northern parts, whereas less variability has been
witnessed over the southern parts. The minimum annual CV value has been observed
over Thanagaji station (about 34%) in the south, whereas the maximum occurred
over Tapukara station (about 51%) in the north (Table 12.4).
The pattern of percent change in amount of rainfall has not shown any unique
pattern over Sahibi Basin (Fig. 12.6c). In the northeast, Tapukara and Tijara have
shown a negative change in mean annual rainfall. Exceptionally, the Kotkasim
station located near Tapukara and Tijara stations has shown a positive change
following an increasing trend in rainfall (Fig. 12.6d). Bairath and Kotputli stations
have shown positive change as these two stations have shown nonsignificant
increasing trends. The remaining stations have not shown any significant change
in the amount of rainfall over Sahibi Basin.
Seasonal Variations
The spatial pattern of mean seasonal rainfall is shown in Fig. 12.7. The mean amount
of rainfall during the winter season is much less (between 20 and 26 mm) over all
12 Trends and Pattern of Rainfall over Semiarid Sahibi Basin in Rajasthan, India
289
stations have shown significant rising trends in the amount of rainfall, except
Thanagaji and Tapukara stations in June. In July, all the stations have shown
decreasing trends except Kotkasim, whereas Thanagaji and Tapukara stations have
shown significant declining trends. In August, Tapukara, Tijara, and Kotputli stations have shown significant decreasing trends. Similar results have been observed
by Meena et al. (2019) for western Rajasthan. In May, Behrod, Kotkasim, and
Kotputli stations have shown significant increasing trends. However, no significant
rising or declining trend has been observed over different stations during other
months.
Spatial Variations in Rainfall
Annual Variations
The spatial pattern of mean annual rainfall over Sahibi Basin is demonstrated in
Fig. 12.6a. An increase in rainfall from northeastern and western parts to the
southeast has been observed. This increase in rainfall southeastward may be attributed to the existence of the Aravalli Mountains. The northeastern and western parts
have received less rainfall. The maximum mean amount of rainfall has occurred over
Thanagaji station (about 708 mm) in the south, whereas the least occurred over
Tapukara station (about 575 mm) in the north (Table 12.4). This difference in the
magnitude of rainfall is high for such a small basin. Further, CV values have shown
an opposite pattern to the mean annual rainfall (Fig. 12.6b). The rainfall variability is
relatively less over the stations receiving higher rainfall and vice versa. High rainfall
variability can be seen over the northern parts, whereas less variability has been
witnessed over the southern parts. The minimum annual CV value has been observed
over Thanagaji station (about 34%) in the south, whereas the maximum occurred
over Tapukara station (about 51%) in the north (Table 12.4).
The pattern of percent change in amount of rainfall has not shown any unique
pattern over Sahibi Basin (Fig. 12.6c). In the northeast, Tapukara and Tijara have
shown a negative change in mean annual rainfall. Exceptionally, the Kotkasim
station located near Tapukara and Tijara stations has shown a positive change
following an increasing trend in rainfall (Fig. 12.6d). Bairath and Kotputli stations
have shown positive change as these two stations have shown nonsignificant
increasing trends. The remaining stations have not shown any significant change
in the amount of rainfall over Sahibi Basin.
Seasonal Variations
The spatial pattern of mean seasonal rainfall is shown in Fig. 12.7. The mean amount
of rainfall during the winter season is much less (between 20 and 26 mm) over all
12 Trends and Pattern of Rainfall over Semiarid Sahibi Basin in Rajasthan, India
289