**4. Results and discussion**

The descriptive statistics of 31-year monthly and seasonal streamflow data are shown in **Table 1** and **2**, respectively.

## **4.1 Statistical analysis of streamflow**

To understand the hydrological characteristics of the Kosi river watershed, the overall behavior of streamflow and rainfall of the watershed, mean monthly rainfall, and mean monthly streamflow were analyzed over the periods from 1986 to 2016 (**Figure 2**). The mean monthly streamflow varies from 9.31 m<sup>3</sup> /sec (May) to 92.37 m<sup>3</sup> /sec (August). The month of high streamflow generally matches with the monsoon season, which clearly demarcates that streamflow in this area is largely dependent on rainfall. The maximum mean monthly streamflow occurs in August,


### **Table 1.**

*Mean monthly streamflow dynamics for the period from 1986 to 2016.*


*@MAM = March, April, and May; JJAS = June, July, August, and September; ON = October, November; DJF = December, January, and February*

### **Table 2.**

*Mean seasonal streamflow dynamics for the period from 1986 to 2016.*

*Trend Analysis of Streamflow and Rainfall in the Kosi River Basin of Mid-Himalaya... DOI: http://dx.doi.org/10.5772/intechopen.107920*

**Figure 2.** *Mean monthly streamflow and mean monthly rainfall of Kosi watershed from 1986–2016 at Ramnagar gauging station.*

while the maximum mean monthly rainfall of the catchment occurs in August in most of the years. This concludes that most of the rainfall occurring in August may be the majority contributing to streamflow.
