гребень перемычки
crest of dyke
https://www.google.com/search?q=structure+of+dam&rlz=1C1GCEU_enKZ879KZ879&tbm=isch&source=iu&ictx=1&fir=mRVS3eNo5bXMFM%253A%252ChFHfj8mzVR7GcM%252C_&vet=1&usg=AI4_-kSgaDsZH5ofCNx6z58V_B1Aj63m4A&sa=X&ved=2ahUKEwjWsNOWlrzmAhVP06YKHSpXBmoQ9QEwAXoECAoQBg#imgrc=9wvFCRZKWpJ_2M