vcmi/config/rivers.json

{
	"waterRiver":
	{
		"index": 1,
		"text" : "Water river",
		"shortIdentifier": "rw", //must be 2 characters
		"tilesFilename": "clrrvr",
		"delta": "clrdelt",
		"paletteAnimation" : [
			{ "start" : 183, "length" : 12 },
			{ "start" : 195, "length" : 6 }
		]
	},
	"iceRiver":
	{
		"index": 2,
		"text" : "Ice river",
		"shortIdentifier": "ri",
		"tilesFilename": "icyrvr",
		"delta": "icedelt"
	},
	"mudRiver":
	{
		"index": 3,
		"text" : "Mud river",
		"shortIdentifier": "rm",
		"tilesFilename": "mudrvr",
		"delta": "muddelt",
		"paletteAnimation" : [
			{ "start" : 228, "length" : 12 },
			{ "start" : 183, "length" : 6 },
			{ "start" : 240, "length" : 6 }
		]
	},
	"lavaRiver":
	{
		"index": 4,
		"text" : "Lava river",
		"shortIdentifier": "rl",
		"tilesFilename": "lavrvr",
		"delta": "lavdelt",
		"paletteAnimation" : [
			{ "start" : 240, "length" : 9 }
		]
	}
}