Groundwater-Dependent Ecosystems are ecosystems that rely upon groundwater for their continued existence. Groundwater is water that has seeped down beneath Earth's surface and has come to reside within the pore spaces in soil and fractures in rock, this process can create water tables and aquifers, which are large storehouses for groundwater. An ecosystem is a community of living organisms interacting with the nonliving aspects of their environment. With a few exceptions, the interaction between various ecosystems and their respective groundwater is a vital yet poorly understood relationship, and their management is not nearly as advanced as in-stream ecosystems.
Methods of identification
Isotopes
Examining the composition of stable isotopes in the water found in soil, rivers, groundwater, and xylem of vegetation, using mass spectroscopy, which measures and sort the masses in a sample, along with data on the changes in groundwater depth coupled with the time and vegetative rooting patterns, shows spatial changes over time in the use of groundwater by the vegetation in its respective ecosystem.
Plants
A groundwater-dependent ecosystem can also be inferred through plant water use and growth. In areas with high rainfall groundwater reliance can be seen by monitoring the water use made by the plants of the ecosystem in relation to the water storage in the soil of the area. If the use of water in the vegetation exceeds that of the water being stored in the soil it is a strong indication of groundwater utilization. In areas of prolonged drought the continuation of water flow and plant growth are highly indicative of a groundwater reliant area.
is the scanning of Earth by satellite or aircraft to obtain information. GIS is a system designed to capture, store, analyze and manage geographic data. Together the data collected can very accurately predict where groundwater-dependent ecosystems are, how extensive they are, and can guide field expeditions to the right areas for further confirmation and data collection on the GDEs.
Classification
Due to the high variety of ecosystems and their individual fluctuation in dependency on groundwater there is some uncertainty when it comes to defining an ecosystem strictly as groundwater-dependent or merely groundwater-using. Each ecosystem expresses a varying degree of dependency. An ecosystem can be directly or indirectly dependent, as well as have a variation in groundwater use throughout the seasons. There are a variety of methods for classifying types of groundwater-dependent ecosystems either by their geomorphological setting and/or by their respective groundwater flow mechanism.
to humid terrestrial environments with no standing water but deeply rooted vegetation relies upon groundwater to support the producers of their ecosystem. The deeply rooted vegetation requires the groundwater to maintain a consistent or semi-consistent level to allow for their continued health and survival.
Aquatic
Springs
Springs, arguably, rely the most heavily on the continued contribution of groundwater because they are a natural discharge from relatively deep groundwater flows rising to the surface. Springs are often in association with uniquely adapted plants and animals.
Wetlands
s require a shallow discharge of groundwater, it flows as a seepage into depressions in the land surface, in some instances wetlands feed off of perched groundwater which is groundwater separated from the regular water table by an layer. Marshes are a type of wetland and though not directly reliant on groundwater they use it as an area of recharge. Bogs, are also a type of wetland that is not directly reliant on groundwater but uses the presence of groundwater to provide the area with recharge as well as buoyancy.
Rivers
s collect groundwater discharge from aquifers. This can happen seasonally, intermittently or constantly, and can keep an area's water needs stable during a dry season.
The extraction of groundwater in both large and smaller amounts lowers the areas water table, and in too large of quantities can even collapse parts of the aquifer and permanently damage the quantity of water the aquifer can store.
