How to add erosion to terrain on runtime

Hello, I have a script that generates random terrain, but I can not get the terrain to have erosion. Can someone show me how to achieve erosion like looks on a terrain.

Here is the code (It is not mine).

 private NoiseModule m_mountainNoise = new PerlinNoise(1);
     private NoiseModule m_plainsNoise = new PerlinNoise(1);
     private NoiseModule m_mountainNoiseRidged = new RidgedNoise(1);
 
     public TerrainPatch(int globTileX_i, int globTileZ_i, Terrain terrain_i, int h0_i, int h1_i, Vector3 pos_i)
     {
         globalTileX = globTileX_i;
         globalTileZ = globTileZ_i;
         terrain = terrain_i;
         h0 = h0_i;
         h1 = h1_i;
         pos = pos_i;
     }
 
     private int globalTileX, globalTileZ, h0, h1;
     private Vector3 pos;
     private Terrain terrain;
 
     public void ExecutePatch()
     {
         FillTerrainPatch();
         if (h1 == InfiniteTerrain.m_heightMapSize)
         {
             terrain.terrainData.SetHeights(0, 0, InfiniteTerrain.m_terrainHeights);  //SetHeights calculates terrain collider
             terrain.transform.position = pos;
         }
     }
      
     private void FillTerrainPatch()
     {
         int hRes = InfiniteTerrain.m_heightMapSize;
         float ratio = (float)InfiniteTerrain.m_landScapeSize / (float)hRes;
 
         float z0 = (InfiniteLandscape.initialGlobalIndex * (InfiniteTerrain.m_heightMapSize - 1)) * ratio;
         float z1 = (InfiniteLandscape.initialGlobalIndex * (InfiniteTerrain.m_heightMapSize - 1)) * ratio + hRes * ratio;
         float y0 = 0.0f;
         float y1 = 1.0f;
 
         for (int z = h0; z < h1; z++)
         {
             float worldPosZ = (z + globalTileZ * (InfiniteTerrain.m_heightMapSize - 1)) * ratio;
             float hx = Mathf.Clamp((y1 - y0) / (z1 - z0) * (worldPosZ - z0) + y1, -4, 8);
 
             for (int x = 0; x < hRes; x++)
             {
                 float worldPosX = (x + globalTileX * (InfiniteTerrain.m_heightMapSize - 1)) * ratio;
                 float mountainsPerlin = m_mountainNoise.FractalNoise2D(worldPosX, worldPosZ, 4, 3000, 0.4f);
                 float mountainsRidged = m_mountainNoiseRidged.FractalNoise2D(worldPosX, worldPosZ, 4, 3000, 0.2f);
                 float height = (mountainsRidged + mountainsPerlin) + 0.03f * hx;
                 InfiniteTerrain.m_terrainHeights[z, x] = height;
             }
         }
     }

What do I need to change to add in erosion?