space between under my deck and my house.

Hello. I have a 3 inch gap between my house and yard, which runs along the width of the house, under my deck. Under my deck is a lot of gravel and dirt. I noticed there was previous water damage from the previous owners time and it seems to be the location in the basement of efflorescence. Is there something i can pour in the gap to stop the rain and water from snow melting continuously getting down there. Many Thanks. JW

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