The coal resources in western China are mainly Jurassic coal fields. and the Jurassic coal measure strata are generally affected by roof composite water. so the water-rich evaluation of roof sandstone aquifer is the premise of safe mining. Taking Longde Coal Mine as the research object. https://www.bekindtopets.com/special-offer-Sticker-Skywhalepapa-Missy-Minzy-mega-find/