# Assessment of Drought Severity and Vulnerability in the Lam Phaniang River Basin, Thailand
## 3 Results and Discussion
### Comprehensive Analysis of Drought Risk Assessment  
To accurately identify the distribution of drought risk, maps of drought risk in the Lam Phaniang River Basin were produced based on the combination of representative indicators of drought vulnerability and hazard. The raster grids of the two aforementioned indicators were calculated by the layer operation function of ArcGIS, in which the drought risk index layer with four risk levels (low, moderate, high, and very high) using the Jenks  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{ \begin{tabular}{c} **Water Balance** \\ **Components** \\ \end{tabular}  } & \multirow{2}{*}{**Period**} & \multirow{2}{*}{**RCP**} & \multicolumn{8}{c}{Value (Million m\({}^{3}\))} \\ \cline{3-17}  & & & **Jan** & & **Feb** & & **Mar** & & **Apr** & **May** & **Jun** & **Jal** & **Aug** & **Sep** & **Oct** & **Nov** & **Dec** & **Total** \\ \hline \multirow{2}{*}{Rcnoff} & 2000-2017 & - & 1.54 & 3.39 & 6.86 & 20.09 & 31.18 & 16.26 & 58.81 & 101.86 & 168.60 & 41.93 & 3.99 & 3.14 & **457.65** \\ \cline{2-17}  & & & & & & & & & & & & & & & & \\ \hline \multirow{6}{*}{} & 2021-2040 & 4.5 & 0.18 & 1.49 & 20.00 & 33.61 & 16.19 & 23.46 & 40.29 & 155.92 & 215.91 & 0.71 & 0.00 & 0.00 & **507.77** \\  & & 8.5 & 0.06 & 2.64 & 12.36 & 23.64 & 11.07 & 20.95 & 45.89 & 18.12 & 236.11 & 0.76 & 0.00 & 0.00 & **503.75** \\ \cline{2-17}  & & & & & & & & & & & & & & & & \\ \hline \multirow{6}{*}{} & 2041-2060 & 4.5 & 0.08 & 1.90 & 19.32 & 45.06 & 18.30 & 24.28 & 32.84 & 193.29 & 194.21 & 0.27 & 0.00 & 0.00 & **529.85** \\  & & 8.5 & 0.12 & 1.72 & 15.69 & 36.0 & 15.80 & 37.25 & 67.16 & 16.75 & 23.71 & 0.24 & 0.00 & 0.00 & **538.71** \\ \hline \multirow{6}{*}{} & 2061-2080 & 4.5 & 0.24 & 3.18 & 19.27 & 41.24 & 12.99 & 18.03 & 41.23 & 140.08 & 154.83 & 0.50 & 0.00 & 0.01 & **431.61** \\  & & 8.5 & 0.23 & 3.06 & 21.46 & 43.10 & 14.07 & 19.73 & 40.28 & 194.13 & 193.71 & 0. Natural Breaks method was obtained. Thereafter, the relative risk grade division of drought based on 29 sub-district polygons within the Lam Phaniang River Basin for each period (2000-2017 and 2021-2100) was produced in the form of drought risk maps of 3-, 12-, and 24-month time scales for the Lam Phaniang River Basin. The red color in the maps in Figures 7 and 8 showed the most dangerous risk within a particular time scale and period, while the dark green color shows the area least affected. In this study, short-term drought was represented by a 3-month time scale, which reflects the soil moisture available from germination until maturity of the crop, and also provides a thorough evaluation of seasonal rainfall during different stages of plant development. However, as emphasized by [PERSON] et al. [40] and UNDRR [41], the 3-month short-term scale is not able to detect predominantly severe conditions at the drought peak, since the previous quarter rainfall was close to normal. Therefore, intermediate- and long-term droughts (12-month and 24-month) were considered to reflect inter-seasonal and long-term rainfall patterns, which would potentially show the lack of rainfall during the previous one and two years, respectively, and is likely to lead to changing of streamflow, groundwater, and reservoir levels [42; 43; 44; 45]. When considering the average drought risk in sub-districts in the Lam Phaniang River Basin, during 2000-2017 at a 3-month time scale, the dark green polygons located in the western part covering some parts of the Sap Phaiwan Sub-district (Sd-18), Erawan District, Loei Province, central part covering Thep Khiri Sub-district (Sd-10), Na Wang District, Nong Bua Lamphu Province, eastern part covering some parts of Nong Phai Sun (Sd-14), Lam Phu (Sd-15), Pho Chai (Sd-17), and Nong Sawan (Sd-19) Sub-districts, Mueang District, Nong Bua Lamphu Province, and southern part covering Khok Muang Sub-district (Sd-27), Non Sang District and Nong Bua Tai Sub-district (Sd-29), Si Bun Rueang District, Nong Bua Lamphu Province, showed a homogenized low drought risk zone.