diff --git a/binaries/data/mods/public/maps/random/aegean_sea.js b/binaries/data/mods/public/maps/random/aegean_sea.js
index e2014e9db0..268e0b0ff2 100644
--- a/binaries/data/mods/public/maps/random/aegean_sea.js
+++ b/binaries/data/mods/public/maps/random/aegean_sea.js
@@ -154,46 +154,25 @@ for (var i = 0; i < numPlayers; i++)
 
 	placeDefaultDecoratives(fx, fz, aBush1, clBaseResource, radius);
 }
-
 RMS.SetProgress(30);
 
-const WATER_WIDTH = 0.35;
+paintRiver({
+	"horizontal": false,
+	"parallel": false,
+	"position": 0.5,
+	"width": 0.35,
+	"fadeDist": 0.025,
+	"deviation": 0,
+	"waterHeight": -3,
+	"landHeight": 2,
+	"meanderShort": 20,
+	"meanderLong": 0,
+	"waterFunc": (ix, iz, height) => {
 
-log("Creating the sea");
-var theta = randFloat(0, 1);
-var theta2 = randFloat(0, 1);
-var seed = randFloat(2,3);
-var seed2 = randFloat(2,3);
-for (var ix = 0; ix < mapSize; ix++)
-{
-	for (var iz = 0; iz < mapSize; iz++)
-	{
-		var x = ix / (mapSize + 1.0);
-		var z = iz / (mapSize + 1.0);
-
-		// add the rough shape of the water
-		var km = 20/scaleByMapSize(35, 160);
-		var cu = km*rndRiver(theta+z*0.5*(mapSize/64),seed);
-		var cu2 = km*rndRiver(theta2+z*0.5*(mapSize/64),seed2);
-
-		var fadeDist = 0.05;
-
-		if ((x > cu + 0.5 - WATER_WIDTH/2) && (x < cu2 + 0.5 + WATER_WIDTH/2))
-		{
-			var h;
-			if (x < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-				h = 2 - 5.0 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - x)/fadeDist);
-			else if (x > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-				h = 2 - 5.0 * (1 - (x - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-			else
-				h = -3.0;
-
-			setHeight(ix, iz, h);
-			if (h < 0.7)
-				addToClass(ix, iz, clWater);
-		}
+		if (height < 0.7)
+			addToClass(ix, iz, clWater);
 	}
-}
+});
 
 paintTerrainBasedOnHeight(-20, 1, 0, tWater);
 paintTerrainBasedOnHeight(1, 2, 0, tShore);
diff --git a/binaries/data/mods/public/maps/random/danubius.js b/binaries/data/mods/public/maps/random/danubius.js
index 4c4ad4bab5..79afb31f03 100644
--- a/binaries/data/mods/public/maps/random/danubius.js
+++ b/binaries/data/mods/public/maps/random/danubius.js
@@ -408,49 +408,36 @@ for (let i = 0; i < numPlayers; ++i)
 RMS.SetProgress(20);
 
 log("Creating the river");
-var theta = randFloat(0, 0.8);
-var theta2 = randFloat(0, 1.2);
-var seed = randFloat(3, 5);
-var seed2 = randFloat(2, 6);
-var fadeDist = 0.05;
+paintRiver({
+	"horizontal": false,
+	"parallel": true,
+	"position": 0.5,
+	"width": waterWidth,
+	"fadeDist": 0.025,
+	"deviation": 0,
+	"waterHeight": -3,
+	"landHeight": 2,
+	"meanderShort": 30,
+	"meanderLong": 0,
+	"waterFunc": (ix, iz, height) => {
 
-for (let ix = 0; ix < mapSize; ++ix)
-	for (let iz = 0; iz < mapSize; ++iz)
-	{
-		let x = ix / (mapSize + 1);
-		let z = iz / (mapSize + 1);
-
-		// Add the rough shape of the water
-		let km = 30 / scaleByMapSize(35, 100);
-		let cu = km * rndRiver(theta + z * mapSize / 128, seed);
-		let cu2 = km * rndRiver(theta2 + z * mapSize / 128, seed2);
-
-		if (x < cu + 0.5 - waterWidth / 2)
-		{
-			addToClass(ix, iz, clLand[0]);
-			continue;
-		}
-
-		if (x > cu2 + 0.5 + waterWidth / 2)
-		{
-			addToClass(ix, iz, clLand[1]);
-			continue;
-		}
-
-		let height = -3;
-		if (x < cu + 0.5 + fadeDist - waterWidth / 2)
-			height = 2 - 5 * (1 - ((cu + 0.5 + fadeDist - waterWidth / 2) - x) / fadeDist);
-		else if (x > (cu2 + 0.5 - fadeDist + waterWidth / 2))
-			height = 2 - 5 * (1 - (x - (cu2 + 0.5 - fadeDist + waterWidth / 2)) / fadeDist);
-
-		setHeight(ix, iz, height);
 		if (height < 0.7)
 			addToClass(ix, iz, clWater);
 
 		// Distinguish left and right shoreline
 		if (0 < height && height < 1 && iz > ShorelineDistance && iz < mapSize - ShorelineDistance)
 			addToClass(ix, iz, clShore[ix < mapSize / 2 ? 0 : 1]);
+	},
+	"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+
+		if (shoreDist1 > 0)
+			addToClass(ix, iz, clLand[0]);
+
+		if (shoreDist2 < 0)
+			addToClass(ix, iz, clLand[1]);
 	}
+});
+
 RMS.SetProgress(30);
 
 log("Creating shores...");
diff --git a/binaries/data/mods/public/maps/random/english_channel.js b/binaries/data/mods/public/maps/random/english_channel.js
index 662f031037..9d3d0e0806 100644
--- a/binaries/data/mods/public/maps/random/english_channel.js
+++ b/binaries/data/mods/public/maps/random/english_channel.js
@@ -43,8 +43,6 @@ const aLillies = "actor|props/flora/water_lillies.xml";
 const pForestD = [tGrassDForest + TERRAIN_SEPARATOR + oBeech, tGrassDForest];
 const pForestP = [tGrassPForest + TERRAIN_SEPARATOR + oOak, tGrassPForest];
 
-const WATER_WIDTH = 0.25;
-
 InitMap();
 
 const numPlayers = getNumPlayers();
@@ -157,49 +155,25 @@ for (var i = 0; i < numPlayers; i++)
 }
 RMS.SetProgress(10);
 
-log("Creating sea");
-
-var theta = randFloat(0, 1);
-var theta2 = randFloat(0, 1);
-
-var seed = randFloat(2,3);
-var seed2 = randFloat(2,3);
-
-for (var ix = 0; ix < mapSize; ix++)
-	for (var iz = 0; iz < mapSize; iz++)
-	{
-		var x = ix / (mapSize + 1.0);
-		var z = iz / (mapSize + 1.0);
-
-		// add the rough shape of the water
-		var km = 20/scaleByMapSize(35, 160);
-
-		var fadeDist = 0.02;
-
-		var cu = km*rndRiver(theta+x*0.5*(mapSize/64),seed);
-		var cu2 = km*rndRiver(theta2+x*0.5*(mapSize/64),seed2);
-
-		if (z > cu  + 0.5 - WATER_WIDTH/2 &&
-		    z < cu2 + 0.5 + WATER_WIDTH/2)
-		{
-			var h;
-			if (z < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-				h = 3 - 7 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - z)/fadeDist);
-			else if (z > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-				h = 3 - 7 * (1 - (z - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-			else
-				h = -4.0;
-
-			if (h < -1.5)
-				placeTerrain(ix, iz, tWater);
-			else
-				placeTerrain(ix, iz, tShore);
-
-			setHeight(ix, iz, h);
-		}
-		else
-			setHeight(ix, iz, 3.1);
+paintRiver({
+	"horizontal": true,
+	"parallel": false,
+	"position": 0.5,
+	"width": 0.25,
+	"fadeDist": 0.01,
+	"deviation": 0,
+	"waterHeight": -4,
+	"landHeight": 3,
+	"meanderShort": 20,
+	"meanderLong": 0,
+	"waterFunc": (ix, iz, height) => {
+		placeTerrain(ix, iz, height < -1.5 ? tWater : tShore);
+	},
+	"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+		setHeight(ix, iz, 3.1);
 	}
+});
+
 RMS.SetProgress(20);
 
 log("Creating rivers");
diff --git a/binaries/data/mods/public/maps/random/guadalquivir_river.js b/binaries/data/mods/public/maps/random/guadalquivir_river.js
index 2e2f3bf40b..2340368ef1 100644
--- a/binaries/data/mods/public/maps/random/guadalquivir_river.js
+++ b/binaries/data/mods/public/maps/random/guadalquivir_river.js
@@ -1,6 +1,6 @@
 RMS.LoadLibrary("rmgen");
 
-const tGrass = ["medit_grass_field_a", "medit_grass_field_b"];;
+const tGrass = ["medit_grass_field_a", "medit_grass_field_b"];
 const tForestFloorC = "medit_plants_dirt";
 const tForestFloorP = "medit_grass_shrubs";
 const tCliff = ["medit_cliff_grass", "medit_cliff_greek", "medit_cliff_greek_2", "medit_cliff_aegean", "medit_cliff_italia", "medit_cliff_italia_grass"];
@@ -36,8 +36,6 @@ const aRockMedium = "actor|geology/stone_granite_med.xml";
 const aBushMedium = "actor|props/flora/bush_medit_me.xml";
 const aBushSmall = "actor|props/flora/bush_medit_sm.xml";
 
-// terrain + entity (for painting)
-
 const pForestP = [tForestFloorP + TERRAIN_SEPARATOR + oPoplar, tForestFloorP];
 const pForestC = [tForestFloorC + TERRAIN_SEPARATOR + oCarob, tForestFloorC];
 
@@ -57,39 +55,26 @@ var clFood = createTileClass();
 var clBaseResource = createTileClass();
 var clSettlement = createTileClass();
 var clLand = createTileClass();
-var clUpperLand = createTileClass();
 var clRiver = createTileClass();
 var clShallow = createTileClass();
 
-//Create the continent body
-var fx = fractionToTiles(0.5);
-var fz = fractionToTiles(0.7);
-var ix = round(fx);
-var iz = round(fz);
-
-var placer = new RectPlacer(0, floor(mapSize * 0.70), mapSize - 1, mapSize - 1);
-var terrainPainter = new LayeredPainter(
-	[tWater, tShore, tGrass],		// terrains
-	[4, 2]		// widths
-);
-var elevationPainter = new SmoothElevationPainter(
-	ELEVATION_SET,			// type
-	3,				// elevation
-	4				// blend radius
-);
-createArea(placer, [terrainPainter, elevationPainter, paintClass(clUpperLand)], null);
-
-var placer = new ChainPlacer(2, floor(scaleByMapSize(5, 12)), floor(scaleByMapSize(60, 700)), 1, ix, iz, 0, [floor(mapSize * 0.49)]);
-var terrainPainter = new LayeredPainter(
-	[tGrass, tGrass, tGrass],		// terrains
-	[4, 2]		// widths
-);
-var elevationPainter = new SmoothElevationPainter(
-	ELEVATION_SET,			// type
-	3,				// elevation
-	4				// blend radius
-);
-createArea(placer, [terrainPainter, elevationPainter, paintClass(clLand)], null);
+log("Create the continent body");
+createArea(
+	new ChainPlacer(
+		2,
+		Math.floor(scaleByMapSize(5, 12)),
+		Math.floor(scaleByMapSize(60, 700)),
+		1,
+		Math.floor(fractionToTiles(0.5)),
+		Math.floor(fractionToTiles(0.7)),
+		0,
+		[Math.floor(mapSize * 0.49)]),
+	[
+		new LayeredPainter([tGrass, tGrass, tGrass], [4, 2]),
+		new SmoothElevationPainter(ELEVATION_SET, 3, 4),
+		paintClass(clLand)
+	],
+	null);
 
 var playerIDs = primeSortAllPlayers();
 
@@ -116,10 +101,10 @@ for (var i = 0; i < numPlayers; i++)
 	var elevation = 20;
 
 	// get the x and z in tiles
-	fx = fractionToTiles(playerX[i]);
-	fz = fractionToTiles(playerZ[i]);
-	ix = round(fx);
-	iz = round(fz);
+	let fx = fractionToTiles(playerX[i]);
+	let fz = fractionToTiles(playerZ[i]);
+	let ix = Math.round(fx);
+	let iz = Math.round(fz);
 	addToClass(ix, iz, clPlayer);
 	addToClass(ix+5, iz, clPlayer);
 	addToClass(ix, iz+5, clPlayer);
@@ -128,7 +113,7 @@ for (var i = 0; i < numPlayers; i++)
 
 	// create the city patch
 	var cityRadius = radius/3;
-	placer = new ClumpPlacer(PI*cityRadius*cityRadius, 0.6, 0.3, 10, ix, iz);
+	var placer = new ClumpPlacer(PI*cityRadius*cityRadius, 0.6, 0.3, 10, ix, iz);
 	var painter = new LayeredPainter([tRoadWild, tRoad], [1]);
 	createArea(placer, painter, null);
 
@@ -189,69 +174,35 @@ for (var i = 0; i < numPlayers; i++)
 
 RMS.SetProgress(20);
 
-const WATER_WIDTH = 0.07;
+var shallowHeight = -1.5;
+paintRiver({
+	"horizontal": false,
+	"parallel": true,
+	"constraint": stayClasses(clLand, 0),
+	"position": 0.5,
+	"width": 0.07,
+	"fadeDist": 0.025,
+	"deviation": 0.005,
+	"waterHeight": -3,
+	"landHeight": 2,
+	"meanderShort": 12,
+	"meanderLong": 0,
+	"waterFunc": (ix, iz, height) => {
+		addToClass(ix, iz, clRiver);
+		placeTerrain(ix, iz, tWater);
 
-log("Creating river");
+		let z = iz / (mapSize + 1.0);
 
-var theta = randFloat(0, 1);
-var seed = randFloat(2,3);
-
-for (var ix = 0; ix < mapSize; ix++)
-	for (var iz = 0; iz < mapSize; iz++)
-	{
-		var x = ix / (mapSize + 1.0);
-		var z = iz / (mapSize + 1.0);
-
-		var h = 0;
-		var distToWater = 0;
-
-		h = 32 * (z - 0.5);
-
-		// add the rough shape of the water
-		var km = 12/scaleByMapSize(35, 160);
-		var cu = km*rndRiver(theta+z*0.5*(mapSize/64),seed);
-		var zk = z*randFloat(0.995,1.005);
-		var xk = x*randFloat(0.995,1.005);
-		if (-3.0 < getHeight(ix, iz)){
-		if ((xk > cu+((1.0-WATER_WIDTH)/2))&&(xk < cu+((1.0+WATER_WIDTH)/2)))
+		if (height < shallowHeight && (
+				z > 0.3 && z < 0.4 ||
+				z > 0.5 && z < 0.6 ||
+				z > 0.7 && z < 0.8))
 		{
-			if (xk < cu+((1.05-WATER_WIDTH)/2))
-			{
-				h = -3 + 200.0* abs(cu+((1.05-WATER_WIDTH)/2-xk));
-				if ((((zk>0.3)&&(zk<0.4))||((zk>0.5)&&(zk<0.6))||((zk>0.7)&&(zk<0.8)))&&(h<-1.5))
-				{
-					h=-1.5;
-					addToClass(ix, iz, clShallow);
-				}
-
-			}
-			else if (xk > (cu+(0.95+WATER_WIDTH)/2))
-			{
-				h = -3 + 200.0*(xk-(cu+((0.95+WATER_WIDTH)/2)));
-				if ((((zk>0.3)&&(zk<0.4))||((zk>0.5)&&(zk<0.6))||((zk>0.7)&&(zk<0.8)))&&(h<-1.5))
-				{
-					h=-1.5;
-					addToClass(ix, iz, clShallow);
-				}
-			}
-			else
-			{
-				if (((zk>0.3)&&(zk<0.4))||((zk>0.5)&&(zk<0.6))||((zk>0.7)&&(zk<0.8))){
-					h = -1.5;
-					addToClass(ix, iz, clShallow);
-				}
-				else
-				{
-					h = -3.0;
-				}
-			}
-			setHeight(ix, iz, h);
-			addToClass(ix, iz, clRiver);
-			placeTerrain(ix, iz, tWater);
-		}
+			setHeight(ix, iz, shallowHeight);
+			addToClass(ix, iz, clShallow);
 		}
 	}
-}
+});
 
 paintTerrainBasedOnHeight(1, 3, 0, tShore);
 paintTerrainBasedOnHeight(-8, 1, 2, tWater);
@@ -320,7 +271,7 @@ createDecoration
  [avoidClasses(clHill, 1, clPlayer, 1, clDirt, 1, clRiver, 1), stayClasses(clLand, 6)]
 );
 
-// create water decoration in the shallow parts
+log("Create water decoration in the shallow parts");
 createDecoration
 (
  [[new SimpleObject(aReeds, 1,3, 0,1)],
diff --git a/binaries/data/mods/public/maps/random/hyrcanian_shores.js b/binaries/data/mods/public/maps/random/hyrcanian_shores.js
index 5d1fb4f2de..fe8c23e677 100644
--- a/binaries/data/mods/public/maps/random/hyrcanian_shores.js
+++ b/binaries/data/mods/public/maps/random/hyrcanian_shores.js
@@ -40,8 +40,6 @@ const aBushSmall = "actor|props/flora/bush_medit_sm_lush.xml";
 const pForestD = [tGrassDForest + TERRAIN_SEPARATOR + oPoplar, tGrassDForest];
 const pForestP = [tGrassPForest + TERRAIN_SEPARATOR + oOak, tGrassPForest];
 
-const WATER_WIDTH = 0.25;
-
 InitMap();
 
 const numPlayers = getNumPlayers();
@@ -146,42 +144,32 @@ for (var i = 0; i < numPlayers; i++)
 }
 RMS.SetProgress(10);
 
-log("Creating sea and northern hills...");
-var theta = randFloat(0, 1);
-var seed = randFloat(2,3);
-for (var ix = 0; ix < mapSize; ix++)
-	for (var iz = 0; iz < mapSize; iz++)
-	{
-		var x = ix / (mapSize + 1.0);
-		var z = iz / (mapSize + 1.0);
+paintRiver({
+	"horizontal": true,
+	"parallel": true,
+	"position": 1,
+	"width": 0.5,
+	"fadeDist": 0.05,
+	"deviation": 0,
+	"waterHeight": -3,
+	"landHeight": 1,
+	"meanderShort": 20,
+	"meanderLong": 0,
+	"waterFunc": (ix, iz, height) => {
 
-		// add the rough shape of the water
-		var km = 20/scaleByMapSize(35, 160);
-		var cu = km*rndRiver(theta+x*0.5*(mapSize/64),seed);
+		if (height < 0)
+			addToClass(ix, iz, clWater);
 
-		var fadeDist = 0.05;
-
-		if (z < 0.25)
-			addToClass(ix, iz, clHighlands);
-
-		if (z > cu + 0.75)
-		{
-			var h;
-			if ((z < (cu + 0.75 + fadeDist))&&(z > (cu + 0.75)))
-				h = 1 - 4.0 * (1 - ((cu + 0.75 + fadeDist) - z)/fadeDist);
-			else
-				h = -3.0;
-
-			if (h < -1.5)
-				placeTerrain(ix, iz, tWater);
-			else
-				placeTerrain(ix, iz, tShore);
-
-			setHeight(ix, iz, h);
-			if (h < 0)
-				addToClass(ix, iz, clWater);
-		}
+		if (height < -1.5)
+			placeTerrain(ix, iz, tWater);
+		else
+			placeTerrain(ix, iz, tShore);
+	},
+	"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+		addToClass(ix, iz, clHighlands);
 	}
+});
+
 RMS.SetProgress(20);
 
 log("Creating fish...");
diff --git a/binaries/data/mods/public/maps/random/kerala.js b/binaries/data/mods/public/maps/random/kerala.js
index b99a5a3433..d1e78ec572 100644
--- a/binaries/data/mods/public/maps/random/kerala.js
+++ b/binaries/data/mods/public/maps/random/kerala.js
@@ -141,31 +141,28 @@ for (var i = 0; i < numPlayers; i++)
 
 RMS.SetProgress(15);
 
-// create western sea
-var fadedistance = 8;
+const waterPos = 0.31;
+const mountainPos = 0.69;
 
-for (var ix = 0; ix < mapSize; ix++)
-{
-	for (var iz = 0; iz < mapSize; iz++)
-	{
-		if (ix < 0.31 * mapSize)
-		{
-			if (ix > 0.31 * mapSize - fadedistance)
-			{
-				setHeight(ix, iz, 3 - 8 * (0.31 * mapSize - ix) / fadedistance);
-				if (ix, iz, 3 - 8 * (0.31 * mapSize - ix) / fadedistance < 0.5)
-					addToClass(ix, iz, clWater);
-			}
-			else
-			{
-				setHeight(ix, iz, -5);
-				addToClass(ix, iz, clWater);
-			}
-		}
-		else if (ix > 0.69 * mapSize)
-			addToClass(ix, iz, clMountains);
+paintRiver({
+	"horizontal": false,
+	"parallel": false,
+	"position": 0,
+	"width": 2 * waterPos,
+	"fadeDist": 0.025,
+	"deviation": 0,
+	"waterHeight": -5,
+	"landHeight": 3,
+	"meanderShort": 20,
+	"meanderLong": 0,
+	"waterFunc": (ix, iz, height) => {
+		addToClass(ix, iz, clWater);
+	},
+	"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+		if (ix > mountainPos * mapSize)
+			addToClass(ix, iz, clMountains)
 	}
-}
+});
 
 log("Creating shores...");
 for (var i = 0; i < scaleByMapSize(20,120); i++)
diff --git a/binaries/data/mods/public/maps/random/phoenician_levant.js b/binaries/data/mods/public/maps/random/phoenician_levant.js
index f1d17b3f3e..b0f84fb6f8 100644
--- a/binaries/data/mods/public/maps/random/phoenician_levant.js
+++ b/binaries/data/mods/public/maps/random/phoenician_levant.js
@@ -145,40 +145,28 @@ for (var i = 0; i < numPlayers; i++)
 
 RMS.SetProgress(30);
 
-log("Creating sea");
+paintRiver({
+	"horizontal": false,
+	"parallel": true,
+	"position": 0,
+	"width": 1,
+	"fadeDist": 0.05,
+	"deviation": 0,
+	"waterHeight": -3,
+	"landHeight": 1,
+	"meanderShort": 20,
+	"meanderLong": 0,
+	"waterFunc": (ix, iz, height) => {
 
-var theta = randFloat(0, 1);
-var seed = randFloat(2,3);
-for (var ix = 0; ix < mapSize; ix++)
-	for (var iz = 0; iz < mapSize; iz++)
-	{
-		var x = ix / (mapSize + 1.0);
-		var z = iz / (mapSize + 1.0);
+		if (height < 0)
+			addToClass(ix, iz, clWater);
 
-		// add the rough shape of the water
-		var km = 20/scaleByMapSize(35, 160);
-		var cu = km*rndRiver(theta+z*0.5*(mapSize/64),seed);
-
-		var fadeDist = 0.05;
-
-		if (x < cu + 0.5)
-		{
-			var h;
-			if (x < (cu + 0.5 + fadeDist))
-				h = 1 + 4.0 * (1 - ((cu + 0.5 + fadeDist) - x)/fadeDist);
-			else
-				h = -3.0;
-
-			if (h < -1.5)
-				placeTerrain(ix, iz, tWater);
-			else
-				placeTerrain(ix, iz, tShore);
-
-			setHeight(ix, iz, h);
-			if (h < 0)
-				addToClass(ix, iz, clWater);
-		}
+		if (height < -1.5)
+			placeTerrain(ix, iz, tWater);
+		else
+			placeTerrain(ix, iz, tShore);
 	}
+});
 
 RMS.SetProgress(40);
 
diff --git a/binaries/data/mods/public/maps/random/rmgen/misc.js b/binaries/data/mods/public/maps/random/rmgen/misc.js
index 37148d375c..4bd7547604 100644
--- a/binaries/data/mods/public/maps/random/rmgen/misc.js
+++ b/binaries/data/mods/public/maps/random/rmgen/misc.js
@@ -128,6 +128,85 @@ function rndRiver(f, seed)
 	return rndRa;
 }
 
+/**
+ * Creates a meandering river at the given location and width.
+ * Optionally calls a function on the affected tiles.
+ *
+ * @property horizontal - Whether the river is horizontal or vertical
+ * @property parallel - Whether the shorelines should be parallel or meander separately.
+ * @property position - Location of the river. Number between 0 and 1.
+ * @property width - Size between the two shorelines. Number between 0 and 1.
+ * @property fadeDist - Size of the shoreline.
+ * @property deviation - Fuzz effect on the shoreline if greater than 0.
+ * @property waterHeight - Ground height of the riverbed.
+ * @proeprty landHeight - Ground height of the end of the shoreline.
+ * @property meanderShort - Strength of frequent meanders.
+ * @property meanderLong - Strength of less frequent meanders.
+ * @property waterFunc - Optional function called on water tiles, providing ix, iz, height.
+ * @property landFunc - Optional function called on land tiles, providing ix, iz, shoreDist1, shoreDist2.
+ */
+function paintRiver(args)
+{
+	log("Creating the river");
+
+	let theta1 = randFloat(0, 1);
+	let theta2 = randFloat(0, 1);
+
+	let seed1 = randFloat(2, 3);
+	let seed2 = randFloat(2, 3);
+
+	let meanderShort = args.meanderShort / scaleByMapSize(35, 160);
+	let meanderLong = args.meanderLong / scaleByMapSize(35, 100);
+
+	let mapSize = g_Map.size;
+
+	for (let ix = 0; ix < mapSize; ++ix)
+		for (let iz = 0; iz < mapSize; ++iz)
+		{
+			if (args.constraint && !args.constraint.allows(ix, iz))
+				continue;
+
+			let x = ix / (mapSize + 1.0);
+			let z = iz / (mapSize + 1.0);
+
+			let coord1 = args.horizontal ? z : x;
+			let coord2 = args.horizontal ? x : z;
+
+			// River curve at this place
+			let cu1 = meanderShort * rndRiver(theta1 + coord2 * mapSize / 128, seed1);
+			let cu2 = meanderShort * rndRiver(theta2 + coord2 * mapSize / 128, seed2);
+
+			cu1 += meanderLong * rndRiver(theta2 + coord2 * mapSize / 256, seed2);
+			cu2 += meanderLong * rndRiver(theta2 + coord2 * mapSize / 256, seed2);
+			if (args.parallel)
+				cu2 = cu1;
+
+			// Fuzz the river border
+			let devCoord1 = coord1 * randFloat(1 - args.deviation, 1 + args.deviation);
+			let devCoord2 = coord2 * randFloat(1 - args.deviation, 1 + args.deviation);
+
+			let shoreDist1 = -devCoord1 + cu1 + args.position - args.width / 2;
+			let shoreDist2 = -devCoord1 + cu2 + args.position + args.width / 2;
+
+			if (shoreDist1 < 0 && shoreDist2 > 0)
+			{
+				let height = args.waterHeight;
+
+				if (shoreDist1 > -args.fadeDist)
+					height += (args.landHeight - args.waterHeight) * (1 + shoreDist1 / args.fadeDist);
+				else if (shoreDist2 < args.fadeDist)
+					height += (args.landHeight - args.waterHeight) * (1 - shoreDist2 / args.fadeDist);
+
+				setHeight(ix, iz, height);
+
+				if (args.waterFunc)
+					args.waterFunc(ix, iz, height);
+			}
+			else if (args.landFunc)
+				args.landFunc(ix, iz, shoreDist1, shoreDist2);
+		}
+}
+
 /////////////////////////////////////////////////////////////////////////////////////////
 // createStartingPlayerEntities
 //
diff --git a/binaries/data/mods/public/maps/random/the_nile.js b/binaries/data/mods/public/maps/random/the_nile.js
index 444d408c14..2810288803 100644
--- a/binaries/data/mods/public/maps/random/the_nile.js
+++ b/binaries/data/mods/public/maps/random/the_nile.js
@@ -160,90 +160,71 @@ for (var i = 0; i < numPlayers; i++)
 
 RMS.SetProgress(30);
 
-const WATER_WIDTH = 0.1;
-
-log("Creating river");
-var theta = randFloat(0, 1);
-var seed = randFloat(2,3);
-var theta2 = randFloat(0, 1);
-var seed2 = randFloat(2,3);
-var rifp = 0;
-var rifp2 = 0;
-
-for (var ix = 0; ix < mapSize; ix++)
-	for (var iz = 0; iz < mapSize; iz++)
+const riverTextures = [
 	{
-		var x = ix / (mapSize + 1.0);
-		var z = iz / (mapSize + 1.0);
+		"left": 0,
+		"right": 0.04,
+		"tileClass": tLush
+	},
+	{
+		"left": 0.04,
+		"right": 0.06,
+		"tileClass": tSLush
+	},
+	{
+		"left": 0.06,
+		"right": 0.09,
+		"tileClass": tSDry
+	}
+];
 
-		var h = 0;
-		var distToWater = 0;
+const plantFrequency = 2;
 
-		h = 32 * (z - 0.5);
-		if ((x < 0.25)||(x > 0.75))
+var plantID = 0;
+
+paintRiver({
+	"horizontal": false,
+	"parallel": true,
+	"position": 0.5,
+	"width": 0.1,
+	"fadeDist": 0.025,
+	"deviation": 0.005,
+	"waterHeight": -3,
+	"landHeight": 2,
+	"meanderShort": 12,
+	"meanderLong": 50,
+	"waterFunc": (ix, iz, height) => {
+
+		addToClass(ix, iz, clWater);
+		placeTerrain(ix, iz, tShore);
+
+		// Place river bushes
+		if (height <= -0.2 || height >= 0.1)
+			return;
+
+		if (plantID % plantFrequency == 0)
+		{
+			plantID = 0;
+			placeObject(ix, iz, aPlants, 0, randFloat(0, TWO_PI));
+		}
+		++plantID;
+	},
+	"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+
+		let x = ix / (mapSize + 1.0);
+		if (x < 0.25 || x > 0.75)
 			addToClass(ix, iz, clDesert);
 
-		// add the rough shape of the water
-		var km = 12/scaleByMapSize(35, 160);
-		var cu = km*rndRiver(theta+z*0.5*(mapSize/64),seed)+(50/scaleByMapSize(35, 100))*rndRiver(theta2+z*0.5*(mapSize/128),seed2);
-		var zk = z*randFloat(0.995,1.005);
-		var xk = x*randFloat(0.995,1.005);
-
-		if (-3.0 >= getHeight(ix, iz))
-			continue;
-
-		if ((xk > cu+((1.0-WATER_WIDTH)/2))&&(xk < cu+((1.0+WATER_WIDTH)/2)))
-		{
-			if (xk < cu+((1.05-WATER_WIDTH)/2))
+		for (let riv of riverTextures)
+			if (-shoreDist1 > -riv.right && -shoreDist1 < -riv.left ||
+				-shoreDist2 > riv.left && -shoreDist2 < riv.right)
 			{
-				h = -3 + 200.0* abs(cu+((1.05-WATER_WIDTH)/2-xk));
-				if ((h < 0.1)&&(h>-0.2))
-				{
-					if (rifp%2 == 0)
-					{
-						rifp = 0;
-						placeObject(ix, iz, aPlants, 0, randFloat(0,TWO_PI));
-					}
-					++rifp;
-				}
+				placeTerrain(ix, iz, riv.tileClass);
+				addToClass(ix, iz, clShore);
 			}
-			else if (xk > (cu+(0.95+WATER_WIDTH)/2))
-			{
-				h = -3 + 200.0*(xk-(cu+((0.95+WATER_WIDTH)/2)));
-				if ((h < 0.1)&&(h>-0.2))
-				{
-					if (rifp2%2 == 0)
-					{
-						rifp2 = 0;
-						placeObject(ix, iz, aPlants, 0, randFloat(0,TWO_PI));
-					}
-					++rifp2;
-				}
-			}
-			else
-				h = -3.0;
-
-			setHeight(ix, iz, h);
-			addToClass(ix, iz, clWater);
-			placeTerrain(ix, iz, tShore);
-		}
-
-		if (((xk > cu+((1.0-WATER_WIDTH)/2)-0.04)&&(xk < cu+((1.0-WATER_WIDTH)/2)))||((xk > cu+((1.0+WATER_WIDTH)/2))&&(xk < cu+((1.0+WATER_WIDTH)/2) + 0.04)))
-		{
-			placeTerrain(ix, iz, tLush);
-			addToClass(ix, iz, clShore);
-		}
-		else if (((xk > cu+((1.0-WATER_WIDTH)/2)-0.06)&&(xk < cu+((1.0-WATER_WIDTH)/2)-0.04))||((xk > cu+((1.0+WATER_WIDTH)/2)+0.04)&&(xk < cu+((1.0+WATER_WIDTH)/2) + 0.06)))
-		{
-			placeTerrain(ix, iz, tSLush);
-			addToClass(ix, iz, clShore);
-		}
-		else if (((xk > cu+((1.0-WATER_WIDTH)/2)-0.09)&&(xk < cu+((1.0-WATER_WIDTH)/2)-0.06))||((xk > cu+((1.0+WATER_WIDTH)/2)+0.06)&&(xk < cu+((1.0+WATER_WIDTH)/2) + 0.09)))
-		{
-			placeTerrain(ix, iz, tSDry);
-			addToClass(ix, iz, clShore);
-		}
 	}
+});
+
 RMS.SetProgress(40);
 
 log("Creating bumps...");
diff --git a/binaries/data/mods/public/maps/random/unknown.js b/binaries/data/mods/public/maps/random/unknown.js
index 88345fb4d5..28447ecc40 100644
--- a/binaries/data/mods/public/maps/random/unknown.js
+++ b/binaries/data/mods/public/maps/random/unknown.js
@@ -303,108 +303,27 @@ else if (md == 3) //central sea
 			playerX[i] = playerPos[i];
 		}
 
-	var WATER_WIDTH = randFloat(0.22,0.3)+scaleByMapSize(1,4)/20;
-	log("Creating sea");
-	var theta = randFloat(0, 1);
-	var theta2 = randFloat(0, 1);
-	var seed = randFloat(2,3);
-	var seed2 = randFloat(2,3);
-	for (var ix = 0; ix < mapSize; ix++)
-	{
-		for (var iz = 0; iz < mapSize; iz++)
-		{
-			var x = ix / (mapSize + 1.0);
-			var z = iz / (mapSize + 1.0);
-
-			// add the rough shape of the water
-			var km = 20/scaleByMapSize(35, 160);
-
-			var fadeDist = 0.05;
-
-			if (mdd1 == 1) //vertical
-			{
-				var cu = km*rndRiver(theta+z*0.5*(mapSize/64),seed);
-				var cu2 = km*rndRiver(theta2+z*0.5*(mapSize/64),seed2);
-
-				if ((x > cu + 0.5 - WATER_WIDTH/2) && (x < cu2 + 0.5 + WATER_WIDTH/2))
-				{
-					var h;
-					if (x < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - x)/fadeDist);
-					}
-					else if (x > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - (x - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-					}
-					else
-					{
-						h = -3.0;
-					}
-
-					if (h < -1.5)
-					{
-						placeTerrain(ix, iz, tWater);
-					}
-					else
-					{
-						placeTerrain(ix, iz, tShore);
-					}
-
-					setHeight(ix, iz, h);
-					if (h < 0){
-						addToClass(ix, iz, clWater);
-					}
-				}
-				else
-				{
-					setHeight(ix, iz, 3.1);
-					addToClass(ix, iz, clLand);
-				}
-			}
-			else //horizontal
-			{
-				var cu = km*rndRiver(theta+x*0.5*(mapSize/64),seed);
-				var cu2 = km*rndRiver(theta2+x*0.5*(mapSize/64),seed2);
-
-				if ((z > cu + 0.5 - WATER_WIDTH/2) && (z < cu2 + 0.5 + WATER_WIDTH/2))
-				{
-					var h;
-					if (z < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - z)/fadeDist);
-					}
-					else if (z > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - (z - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-					}
-					else
-					{
-						h = -3.0;
-					}
-
-					if (h < -1.5)
-					{
-						placeTerrain(ix, iz, tWater);
-					}
-					else
-					{
-						placeTerrain(ix, iz, tShore);
-					}
-
-					setHeight(ix, iz, h);
-					if (h < 0){
-						addToClass(ix, iz, clWater);
-					}
-				}
-				else
-				{
-					setHeight(ix, iz, 3.1);
-					addToClass(ix, iz, clLand);
-				}
-			}
+	paintRiver({
+		"horizontal": mdd1 != 1,
+		"parallel": false,
+		"position": 0.5,
+		"width": randFloat(0.22, 0.3) + scaleByMapSize(1, 4) / 20,
+		"fadeDist": 0.025,
+		"deviation": 0,
+		"waterHeight": -3,
+		"landHeight": 3,
+		"meanderShort": 20,
+		"meanderLong": 0,
+		"waterFunc": (ix, iz, height) => {
+			placeTerrain(ix, iz, height < -1.5 ? tWater : tShore);
+			if (height < 0)
+				addToClass(ix, iz, clWater);
+		},
+		"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+			setHeight(ix, iz, 3.1);
+			addToClass(ix, iz, clLand);
 		}
-	}
+	});
 
 	if (randBool(1/3))
 	{
diff --git a/binaries/data/mods/public/maps/random/unknown_land.js b/binaries/data/mods/public/maps/random/unknown_land.js
index 260ce1e6cc..07bf6b325e 100644
--- a/binaries/data/mods/public/maps/random/unknown_land.js
+++ b/binaries/data/mods/public/maps/random/unknown_land.js
@@ -168,108 +168,27 @@ else if (md == 3) //central sea
 			playerX[i] = playerPos[i];
 		}
 
-	var WATER_WIDTH = randFloat(0.22,0.3)+scaleByMapSize(1,4)/20;
-	log("Creating sea");
-	var theta = randFloat(0, 1);
-	var theta2 = randFloat(0, 1);
-	var seed = randFloat(2,3);
-	var seed2 = randFloat(2,3);
-	for (var ix = 0; ix < mapSize; ix++)
-	{
-		for (var iz = 0; iz < mapSize; iz++)
-		{
-			var x = ix / (mapSize + 1.0);
-			var z = iz / (mapSize + 1.0);
-
-			// add the rough shape of the water
-			var km = 20/scaleByMapSize(35, 160);
-
-			var fadeDist = 0.05;
-
-			if (mdd1 == 1) //vertical
-			{
-				var cu = km*rndRiver(theta+z*0.5*(mapSize/64),seed);
-				var cu2 = km*rndRiver(theta2+z*0.5*(mapSize/64),seed2);
-
-				if ((x > cu + 0.5 - WATER_WIDTH/2) && (x < cu2 + 0.5 + WATER_WIDTH/2))
-				{
-					var h;
-					if (x < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - x)/fadeDist);
-					}
-					else if (x > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - (x - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-					}
-					else
-					{
-						h = -3.0;
-					}
-
-					if (h < -1.5)
-					{
-						placeTerrain(ix, iz, tWater);
-					}
-					else
-					{
-						placeTerrain(ix, iz, tShore);
-					}
-
-					setHeight(ix, iz, h);
-					if (h < 0){
-						addToClass(ix, iz, clWater);
-					}
-				}
-				else
-				{
-					setHeight(ix, iz, 3.1);
-					addToClass(ix, iz, clLand);
-				}
-			}
-			else //horizontal
-			{
-				var cu = km*rndRiver(theta+x*0.5*(mapSize/64),seed);
-				var cu2 = km*rndRiver(theta2+x*0.5*(mapSize/64),seed2);
-
-				if ((z > cu + 0.5 - WATER_WIDTH/2) && (z < cu2 + 0.5 + WATER_WIDTH/2))
-				{
-					var h;
-					if (z < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - z)/fadeDist);
-					}
-					else if (z > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - (z - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-					}
-					else
-					{
-						h = -3.0;
-					}
-
-					if (h < -1.5)
-					{
-						placeTerrain(ix, iz, tWater);
-					}
-					else
-					{
-						placeTerrain(ix, iz, tShore);
-					}
-
-					setHeight(ix, iz, h);
-					if (h < 0){
-						addToClass(ix, iz, clWater);
-					}
-				}
-				else
-				{
-					setHeight(ix, iz, 3.1);
-					addToClass(ix, iz, clLand);
-				}
-			}
+	paintRiver({
+		"horizontal": mdd1 != 1,
+		"parallel": false,
+		"position": 0.5,
+		"width": randFloat(0.22, 0.3) + scaleByMapSize(1, 4) / 20,
+		"fadeDist": 0.025,
+		"deviation": 0,
+		"waterHeight": -3,
+		"landHeight": 3,
+		"meanderShort": 20,
+		"meanderLong": 0,
+		"waterFunc": (ix, iz, height) => {
+			placeTerrain(ix, iz, height < -1.5 ? tWater : tShore);
+			if (height < 0)
+				addToClass(ix, iz, clWater);
+		},
+		"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+			setHeight(ix, iz, 3.1);
+			addToClass(ix, iz, clLand);
 		}
-	}
+	});
 
 	// linked
 	if (mdd1 == 1) //vertical
diff --git a/binaries/data/mods/public/maps/random/unknown_nomad.js b/binaries/data/mods/public/maps/random/unknown_nomad.js
index c3580acf15..ad26bfcb43 100644
--- a/binaries/data/mods/public/maps/random/unknown_nomad.js
+++ b/binaries/data/mods/public/maps/random/unknown_nomad.js
@@ -216,108 +216,27 @@ else if (md == 3) //central sea
 {
 	var playerIDs = primeSortAllPlayers();
 
-	var WATER_WIDTH = randFloat(0.22,0.3)+scaleByMapSize(1,4)/20;
-	log("Creating sea");
-	var theta = randFloat(0, 1);
-	var theta2 = randFloat(0, 1);
-	var seed = randFloat(2,3);
-	var seed2 = randFloat(2,3);
-	for (var ix = 0; ix < mapSize; ix++)
-	{
-		for (var iz = 0; iz < mapSize; iz++)
-		{
-			var x = ix / (mapSize + 1.0);
-			var z = iz / (mapSize + 1.0);
-
-			// add the rough shape of the water
-			var km = 20/scaleByMapSize(35, 160);
-
-			var fadeDist = 0.05;
-
-			if (mdd1 == 1) //vertical
-			{
-				var cu = km*rndRiver(theta+z*0.5*(mapSize/64),seed);
-				var cu2 = km*rndRiver(theta2+z*0.5*(mapSize/64),seed2);
-
-				if ((x > cu + 0.5 - WATER_WIDTH/2) && (x < cu + 0.5 + WATER_WIDTH/2))
-				{
-					var h;
-					if (x < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - x)/fadeDist);
-					}
-					else if (x > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - (x - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-					}
-					else
-					{
-						h = -3.0;
-					}
-
-					if (h < -1.5)
-					{
-						placeTerrain(ix, iz, tWater);
-					}
-					else
-					{
-						placeTerrain(ix, iz, tShore);
-					}
-
-					setHeight(ix, iz, h);
-					if (h < 0){
-						addToClass(ix, iz, clWater);
-					}
-				}
-				else
-				{
-					setHeight(ix, iz, 3.1);
-					addToClass(ix, iz, clLand);
-				}
-			}
-			else //horizontal
-			{
-				var cu = km*rndRiver(theta+x*0.5*(mapSize/64),seed);
-				var cu2 = km*rndRiver(theta2+x*0.5*(mapSize/64),seed2);
-
-				if ((z > cu + 0.5 - WATER_WIDTH/2) && (z < cu + 0.5 + WATER_WIDTH/2))
-				{
-					var h;
-					if (z < (cu + 0.5 + fadeDist - WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - ((cu + 0.5 + fadeDist - WATER_WIDTH/2) - z)/fadeDist);
-					}
-					else if (z > (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))
-					{
-						h = 3 - 6 * (1 - (z - (cu2 + 0.5 - fadeDist + WATER_WIDTH/2))/fadeDist);
-					}
-					else
-					{
-						h = -3.0;
-					}
-
-					if (h < -1.5)
-					{
-						placeTerrain(ix, iz, tWater);
-					}
-					else
-					{
-						placeTerrain(ix, iz, tShore);
-					}
-
-					setHeight(ix, iz, h);
-					if (h < 0){
-						addToClass(ix, iz, clWater);
-					}
-				}
-				else
-				{
-					setHeight(ix, iz, 3.1);
-					addToClass(ix, iz, clLand);
-				}
-			}
+	paintRiver({
+		"horizontal": mdd1 != 1,
+		"parallel": false,
+		"position": 0.5,
+		"width": randFloat(0.22, 0.3) + scaleByMapSize(1, 4) / 20,
+		"fadeDist": 0.025,
+		"deviation": 0,
+		"waterHeight": -3,
+		"landHeight": 3,
+		"meanderShort": 20,
+		"meanderLong": 0,
+		"waterFunc": (ix, iz, height) => {
+			placeTerrain(ix, iz, height < -1.5 ? tWater : tShore);
+			if (height < 0)
+				addToClass(ix, iz, clWater);
+		},
+		"landFunc": (ix, iz, shoreDist1, shoreDist2) => {
+			setHeight(ix, iz, 3.1);
+			addToClass(ix, iz, clLand);
 		}
-	}
+	});
 
 	if (randBool(1/3))
 	{