A large glass container has a rectangular base that measures $60\text{cm}$ by $40\text{cm}$ and has a height of $50\text{cm}$. It is filled with water to a height of $30\text{cm}$. Two identical metal blocks are carefully placed into the container. Each block has a rectangular base measuring $15\text{cm}$ by $10\text{cm}$ and a height of $8\text{cm}$. By how many centimeters does the water rise?