Stopping 3rd Person Controller When It Hits Raised Terrtain

Hello!

I am working on a top down RTS game. I have created a click to move script for my 3rd person character and I've come up against a problem.

The character you control is stuck in a big crater and he's not supposed to be able to leave this crater. Currently I am using raycasting to pick a point on the terrain with a mouse click and the character turns and moves there.

However, when I click somewhere outside the terrain, my character moves through it. If I add a rigidbody it does stop when it hits the wall --- but it bounces off randomly and uncontrollably.

Is there a way to have my character just stop moving if he his the terrain wall? Here is my code:

 using UnityEngine;
 using System.Collections;

public class ClickCharacterController : MonoBehaviour

{

 bool canMove = false;
 public int speed = 5;
 RaycastHit hit; //Create an object to store all the raycast data
 Vector3 groundedHitPoint;


 void Start()
 {}
 
 
 void OnCollisionEnter ( Collision c )
 {
     //Debug.Log("Hitting");
     if ( c.gameObject.tag == "Ground" )
     {
       // Debug.Log("Terrain Collision");
        canMove = false;
     }
     else Debug.Log("Sorry Charlie.");
    
 }


 void Update() 
 {
     if(Input.GetMouseButton(1))
         {  
          //create a new ray from the source point from the camera to the mouse position
          Ray ray = (Camera.main.ScreenPointToRay(Input.mousePosition));
 
 
          //ray is the origin and vector, and out hit is a vector, passing by reference so it needs out keyword
             if (Physics.Raycast(ray, out hit)) 
          {
                 //Debug.Log("Hit: " + hit.transform.name);
               if (hit.transform.name == "Ground")
                  {
                    Debug.DrawLine(Camera.main.transform.position, hit.point);
                  }
           //have the cube turn to face the point
 
           groundedHitPoint = hit.point;
           groundedHitPoint.y = 1;
           transform.LookAt(groundedHitPoint);
           //Debug.Log("groundedhitpoint is : " + groundedHitPoint);
           canMove = true;
            }
 
        }
     if (canMove)
     {
        //OnCollisionEnter();
        //this moves an object
        transform.Translate(Vector3.forward*Time.deltaTime*speed);
        //Debug.Log ("Vector3.forward is: " + Vector3.forward);
        //GameObject.FindWithTag("ScavengerSprite").transform.position.y.Equals(1000);
 
        float  distance = Vector3.Distance(transform.position, groundedHitPoint);
        if (distance <= 0.1F)
        {
          canMove = false;
        }
     }
 
 }
 
 
 

}