getting confused with pointer to a pointer - 2d array

crashes at

Code:

unsigned int **save = new unsigned int *[rows+1];//increases the rows by 1

and I don't know why.

Code:

    properTime = 0;
    rows = 1;
    obstacles = new unsigned int *[rows];
    unsigned int i = 0;
    //memory allocated for  elements of each column.
    
    for(unsigned int i = 0 ; i < rows ; i++)
        obstacles[i] = new unsigned int[COLUMNS];
    unsigned int timeOfCaging = whenCaged();
    while(properTime < SECONDS_WORKED)
    {
        std::cout<<"no problem here"<<std::endl;
        timeOfCaging = Drib::whenCaged();
        obstacles[i][0] = timeOfCaging;
        obstacles[i][1] = Drib::GetRandomNumber(0, TREE_HEIGHT-1);
        std::cout<<"or here"<<std::endl;
        //resize
       
        unsigned int **save = new unsigned int *[rows+1];//increases the rows by 1
        std::cout<<"right here"<<std::endl;
        for(unsigned int j = 0; j < rows; j++){
            for(unsigned int k = 0; k < COLUMNS; k++){//columns is equal to 2
                std::cout<<"this"<<std::endl;
                save[j][k] = obstacles[j][k];
                std::cout<<"j: "<<j<<" k: "<<k<<" save[j][k]: "<<save[j][k]<<std::endl;
            }
        }
        rows++;
        delete [] obstacles;
        obstacles = save;
        
        properTime += whenCaged();
        i++;
        std::cout<<"at end of while loop"<<std::endl;
    }
    std::cout<<"exit here"<<std::endl;