hydro erosion problems

hey so ime making some random terrain and ime trying to do hydro erosion on it but i just cant seem to get it working how i want. so would anyone be kind enough to look through this code and see if they know where the problem is. not sure if its my method or just the variable quantities

public float[,] Water; //amount of water

 public Vector2[,] Velocity;        //velocity of water

 public float[,] Sed;            //sediment contained within water
 
 public int ErosionIts = 100;     //iterations of the erosion algorythem
 public float Rain = 5f;        //amount of rain
 public float ErosionRate = 0.001f;    //rate at wich rock is tuned to sediment
 public float EvapRate = 0.1f;    //rate at wich water evapirates
 
 public void Erode (){
     for (int i = 0; i < ErosionIts; i++){
         
         Water = new float[MapSize,MapSize];
         Velocity = new Vector2[MapSize,MapSize];
         Sed = new float[MapSize,MapSize];
         
         for (int x = 0; x < MapSize; x++){
             for (int y = 0; y < MapSize; y++){
                 Water [x,y] += Random.value*Rain;//add rain to each square
                 
                 Velocity[x,y] = new Vector2(0,0);//reset value
                 
                 
                 //find the largest drop and asighn it as a velocity in the given directtion
                 float RelativeHeight = 0;
                 
                 if (x < MapSize-1){
                     RelativeHeight = HeightMap[x,y]+Water[x,y]-HeightMap[x+1,y]-Water[x+1,y];
                     if (RelativeHeight > Velocity[x,y].magnitude){
                         if (RelativeHeight > 0){
                             Velocity[x,y] = new Vector2(RelativeHeight, 0);
                         }
                     }
                 }
                 
                 if (x > 0){
                     RelativeHeight = HeightMap[x,y]+Water[x,y]-HeightMap[x-1,y]-Water[x-1,y];
                     if (RelativeHeight > Velocity[x,y].magnitude){
                         if (RelativeHeight > 0){
                             Velocity[x,y] = new Vector2(-RelativeHeight, 0);
                         }
                     }
                 }
                 
                 if (y < MapSize-1){
                     RelativeHeight = HeightMap[x,y]+Water[x,y]-HeightMap[x,y+1]-Water[x,y+1];
                     if(RelativeHeight > Velocity[x,y].magnitude){
                         if (RelativeHeight > 0){
                             Velocity[x,y] = new Vector2(0, RelativeHeight);
                         }
                     }
                 }
                 
                 if (y > 0){
                     RelativeHeight = HeightMap[x,y]+Water[x,y]-HeightMap[x,y-1]-Water[x,y-1];
                     if (RelativeHeight > Velocity[x,y].magnitude){
                         if (RelativeHeight > 0){
                             Velocity[x,y] = new Vector2(0, -RelativeHeight);
                         }
                     }
                 }
                     
                 //erode or deposit soil based upon velocity and amount of watter 
                 float PreviusSed = Sed[x,y];
                 Sed[x,y] = Velocity[x,y].magnitude * Water[x,y] * ErosionRate;
                 HeightMap[x,y] -= Sed[x,y] - PreviusSed;
                 
                 //move the water and its contained sediment
                 float w1 = Water[x,y];        //initial water level of this tile
                 float w2;                    //initial water level of target tile
                 float w3;                    //final water level of this tile
                 float w4;                    //final water level of target tile
                 
                 float s1 = Sed[x,y];        //initial sediment level of this tile
                 float s2;                    //initial sediment level of target tile
                 float s3;                    //final sediment level of this tile
                 float s4;                    //final sediment level of target tile
                 
                 float h1 = HeightMap[x,y];    //height of this tile
                 float h2;                    //height of target tile
                 
                 //calcuate and apply final levels 
                 if ((x < MapSize-1) && (Velocity[x,y].x > 0)){
                     w2 = Water[x+1,y];
                     s2 = Sed[x+1,y];
                     h2 = HeightMap[x+1,y];
                     
                     w3 = (w1+w2+h2-h1)/2;
                     w4 = w1+w2-w3;
                     s3 = ((s1*(w1-w3))/w1)+s1;
                     s4 = s1+s2-s3;
                     
                     Water[x,y] = w3;
                     Sed[x,y] = s3;    
                     Water[x+1,y] = w4;
                     Sed[x+1,y] = s4;
                 }
                 if ((x > 0) && (Velocity[x,y].x < 0)){
                     w2 = Water[x-1,y];
                     s2 = Sed[x-1,y];
                     h2 = HeightMap[x-1,y];
                     
                     w3 = (w1+w2+h2-h1)/2;
                     w4 = w1+w2-w3;
                     s3 = ((s1*(w1-w3))/w1)+s1;
                     s4 = s1+s2-s3;
                     
                     Water[x,y] = w3;
                     Sed[x,y] = s3;                        
                     Water[x-1,y] = w4;
                     Sed[x-1,y] = s4;
                 }
                 if ((y < MapSize-1) && (Velocity[x,y].y > 0)){
                     w2 = Water[x,y+1];
                     s2 = Sed[x,y+1];
                     h2 = HeightMap[x,y+1];
                     
                     w3 = (w1+w2+h2-h1)/2;
                     w4 = w1+w2-w3;
                     s3 = ((s1*(w1-w3))/w1)+s1;
                     s4 = s1+s2-s3;
                     
                     Water[x,y] = w3;
                     Sed[x,y] = s3;                        
                     Water[x,y+1] = w4;
                     Sed[x,y+1] = s4;
                 }
                 if ((y > 0) && (Velocity[x,y].y < 0)){
                     w2 = Water[x,y-1];
                     s2 = Sed[x,y-1];
                     h2 = HeightMap[x,y-1];
                     
                     w3 = (w1+w2+h2-h1)/2;
                     w4 = w1+w2-w3;
                     s3 = ((s1*(w1-w3))/w1)+s1;
                     s4 = s1+s2-s3;
                     
                     Water[x,y] = w3;
                     Sed[x,y] = s3;            
                     Water[x,y-1] = w4;
                     Sed[x,y-1] = s4;
                 }
                 
                 
                 Water[x,y] *= EvapRate;// evaperate some water
                 
                 
             }
         }
     }`

Thanks