Month Rain gauge station Thung Chang Pou Ta Wang Pa Maung  Nan Viang Sa Agriculture Na Noi Jan 20 12 15 8 9 6 7 Feb 12 11 18 20 21 19 15 Mar 95 57 60 21 54 52 22 Apr 443 236 315 367 362 291 227 May 851 617 915 945 772 837 647 Jun 1051 715 998 633 653 643 391 Jul 1676 1003 1160 1080 984 854 496 Aug 2227 1299 1697 1261 1270 1142 692 Sept 1085 878 692 980 971 799 745 Oct 254 134 241 249 319 334 233 Nov 62 27 41 51 32 28 16 Dec 12 3 6 5 6 6 4 Annual 7786 4995 6158 5618 5453 5010 3494

Table 2: Monthly rainfall erosivity for 7 continuous graphical records rain gauge stations in the Upper Nan watershed in northern Thailand (units are MJ mm ha-1 h-1 month-1 and MJ mm ha-1 h-1 yr-1).