Showing posts with label groundwater. Show all posts
Showing posts with label groundwater. Show all posts

Thursday, March 14, 2024

What is an aquifer? Where groundwater can move rapidly,

What is an aquifer? Where groundwater can move rapidly, such as through gravel and sandy deposits, an aquifer can form. In an aquifer, there is enough groundwater that it can be pumped to the surface and used for drinking water, irrigation, industry, or other uses. For water to move through underground rock, pores or fractures in the rock must be connected. If rocks have good connections between pores or fractures and water can move freely through them, we say that the rock is permeable. Permeability refers to how well a material transmits water. If the pores or fractures are not connected, the rock material cannot produce water and is therefore not considered an aquifer. The amount of water an aquifer can hold depends on the volume of the underground rock materials and the size and number of pores and fractures that can fill with water. An aquifer may be a few feet to several thousand feet thick, and less than a square mile or hundreds of thousands of square miles in area. For example, the High Plains Aquifer underlies about 280,000 square miles in 8 states— Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Aquifer, Underground water, Ground water, rain, ice, snow, rivers, streams, lakes, ponds, wetlands, saturated zone, unsaturated zone, aquifer, aquifers, confined aquifer, unconfined aquifer, Edwards aquifer, aquifer recharge, Edwards aquifer authority, open aquifer, aquifer types, difference between confined and unconfined aquifer, how aquifers, closed aquifer, basalt aquifer, aquifer ka matlb, types of aquifer, light aquifers, Floridan aquifer, Biscayne aquifer, tertiary aquifer, Adelaide aquifer, sandstone aquifer, limestone aquifer, carbonate aquifer.

How does water fill an aquifer? Aquifers get water from precipitation (rain and snow) that filters through the unsaturated zone. Aquifers can also receive water from surface waters like lakes and rivers. When the aquifer is full, and the water table meets the surface of the ground, water stored in the aquifer can appear at the land surface as a spring or seep. Recharge areas are where aquifers take in water; discharge areas are where groundwater flows to the land surface. Water moves from higher-elevation areas of recharge to lower-elevation areas of discharge through the saturated zone.

How does water circulate? Surface water and groundwater are part of the hydrologic cycle, the constant movement of water above, on, and below the earth’s surface (Diagram 2). The cycle has no beginning and no end, but you can understand it best by tracing it from precipitation. Precipitation occurs in several forms, including rain, snow, and hail. Rain, for example, wets the ground surface. As more rain falls, water begins to filter into the ground. How fast water soaks into, or infiltrates the soil depends on soil type, land use, and the intensity and length of the storm. Water infiltrates faster into soils that are mostly sand than into those that are mostly clay or silt. Almost no water filters into paved areas. Rain that cannot be absorbed into the ground collects on the surface, forming runoff streams. When the soil is completely saturated, additional water moves slowly down through the unsaturated zone to the saturated zone, replenishing or recharging the groundwater. Water then moves through the saturated zone to groundwater discharge areas. Evaporation occurs when water from such surfaces as oceans, rivers, and ice is converted to vapor. Evaporation, together with transpiration from plants, rises above the Earth’s surface, condenses, and forms clouds. Water from both runoff and from groundwater discharge moves toward streams and rivers and may eventually reach the ocean. Oceans are the largest surface water bodies that contribute to evaporation. What affects groundwater contamination? Many processes can affect how contamination spreads and what happens to it in the groundwater, potentially making the contaminant more or less harmful, or toxic. Some of the most important processes affecting hazardous substances in groundwater are advection, sorption, and biological degradation. Advection occurs when contaminants move with the groundwater. This is the main form of contaminant migration in groundwater. Sorption occurs when contaminants attach themselves to soil particles. Sorption slows the movement of contaminants in groundwater, but also makes it harder to clean up contamination. Biological degradation happens when microorganisms, such as bacteria and fungi, use hazardous substances as a food and energy source. In the process, contaminants break down and hazardous substances often become less harmful.