Excavated pond. or "dug pond". They are harder to build because of earth removal. They are more resistant to collapse by erosion - no dam.
underground aquifers
groundwater
A shield volcano - a huge, flat shape, kind of like a giant contact lens made of rock and filled with magma, pressed against the earth's surface
Groundwater pollution.
its clay
In hydrology, snowmelt is surface runoff produced from melting snow. It can also be used to describe the period or season during which such runoff is produced. Water produced by snowmelt is an important part of the annual water cycle in many parts of the world, in some cases contributing high fractions of the annual runoff in a watershed. Predicting snowmelt runoff from a drainage basin may be a part of designing water control projects. Rapid snowmelt can cause flooding. If the snowmelt is then frozen, very dangerous conditions and accidents can occur, introducing the need for salt to melt the ice
Groundwater, freshwater, and melted water
Cenotes would be very important sources of groundwater in arid or semi-arid landscapes where surface water is scarce. Regions with porous limestone bedrock, such as the Yucatan Peninsula in Mexico, are particularly reliant on cenotes for freshwater due to the lack of surface rivers and lakes.
runoff im in the sixth grade
Soil erosion.
It means it's filled with silver. It's kind of implied.
Clay is the answer you're looking for.