Stealing Water

More than 80 percent of the identified subsidence in the Nation has occurred because of exploitation of underground water, and the increasing development of land and water resources threatens to exacerbate existing land-subsidence problems and initiate new ones. In many areas of the arid Southwest, and in more humid areas underlain by soluble rocks such as limestone, gypsum, or salt, land subsidence is an often-overlooked environmental consequence of our land- and water-use practices.

Compaction of soils in some aquifer systems can accompany excessive groundwater pumping and it is by far the single largest cause of subsidence. Excessive pumping of such aquifer systems has resulted in permanent subsidence and related ground failures. In some systems, when large amounts of water are pumped, the subsoil compacts, thus reducing in size and number the open pore spaces in the soil the previously held water. This can result in a permanent reduction in the total storage capacity of the aquifer system.

There is more of an interaction between the water in lakes and rivers and groundwater than most people think. Some, and often a great deal, of the water flowing in rivers comes from seepage of groundwater into the stream-beds. Groundwater contributes to streams in most physiographic and climatic settings. The proportion of stream water that comes from groundwater inflow varies according to a region's geography, geology, and climate.

Groundwater pumping can alter how water moves between an aquifer and a stream, lake, or wetland by either intercepting groundwater flow that discharges into the surface-water body under natural conditions, or by increasing the rate of water movement from the surface-water body into an aquifer. A related effect of groundwater pumping is the lowering of groundwater levels below the depth that streamside or wetland vegetation needs to survive. The overall effect is a loss of riparian vegetation and wildlife.

INCREASED COSTS FOR THE USER

As the depth to water increases, the water must be lifted higher to reach the land surface. If pumps are used to lift the water (as opposed to artesian wells), more energy is required to drive the pump. Using the well can become prohibitively expensive.

Consequences of land subsidence:

• Reduces the ability to store water in an aquifer.

• Partially or completely submerges land.

• Collapses water well casings.

• Disrupts collector drains and irrigation ditches.

• Alters the flow of creeks and bayous which may increase the frequency and severity of flooding.

• Damages roadways, bridges, building foundations, and other infrastructure.

Just a few examples (there are MANY more):

The Ogallala Aquifer, one of the largest in the world, spans several states in the U.S. It has been heavily utilized for agricultural irrigation. The excessive pumping has led to a significant drop in the water table in some areas, causing the aquifer to deplete faster than it can recharge. This has resulted in land subsidence, reduced well yields, and long-term sustainability concerns for agriculture.

Parts of the Arkansas river have dried up over the last decades because of the depletion of the Ogallala aquifer. The Kansas Geological Survey predicts that the groundwater will be depleted in less than 25 years, with the river likely to follow suit. As will the ecosystems reliant on that river water. 

The San Joaquin Valley in California relies heavily on groundwater from the Central Valley aquifer system for agriculture. Over-pumping of groundwater has caused land subsidence, reduced water quality, and the need for deeper and more expensive wells. This has significant economic and environmental consequences for the region.

In Nepal, groundwater from the Himalaya-Koshi Tappu aquifer is used for irrigation and drinking water. Excessive pumping for agriculture has caused declining groundwater levels, leading to the drying up of wetlands and impacting the ecosystem in the Koshi Tappu Wildlife Reserve. This has consequences for local biodiversity and the livelihoods of communities dependent on the reserve's resources

**Groundwater Depletion, Land Subsidence, and Ecosystem Impacts**

**Introduction:**

Groundwater is a vital resource essential for various sectors, including agriculture, industry, and municipalities. However, its overexploitation can lead to severe consequences, such as land subsidence and adverse impacts on ecosystems. This document provides a thorough exploration of groundwater depletion and its associated challenges.

**Section 1: Groundwater Depletion**

*Causes of Groundwater Depletion:*

Excessive groundwater pumping driven by agricultural, industrial, and municipal demands.

*Consequences of Groundwater Depletion:*

1. **Increased Costs for Users:**

-As the depth to the water table increases, pumping costs rise, potentially making water access unaffordable for some users.

2. **Depletion of Aquifers:**

-Persistent over-pumping leads to a reduction in aquifer storage capacity, affecting long-term water availability.

**Section 2: Land Subsidence**

*Causes of Land Subsidence:*

Compaction of soils due to excessive groundwater pumping.

*Consequences of Land Subsidence:*

1. **Infrastructure Damage:**

- Sinking foundations, damage to roads, bridges, and buildings, posing safety risks and incurring substantial repair costs.

2. **Increased Flooding Risk:**

-Lowered land surfaces disrupt natural drainage, elevating the risk of flooding, and necessitating flood mitigation measures.

3. **Agricultural Productivity Decline:**

-Sinking fields can lead to waterlogging, reducing crop yields and impacting food production.

4. **Environmental and Habitat Impacts:**

-Altered landscapes, loss of wetlands, and disrupted habitats for wildlife, including migratory species, affecting biodiversity.

*Mitigation Measures:*

Implementing sustainable groundwater management practices, including regulation and monitoring, to prevent further land subsidence.

**Section 3: Ecosystem Impacts**

*Alteration of Hydrology:*

Reduced groundwater inflow into rivers, streams, and wetlands, disrupting natural hydrological patterns.

*Habitat Degradation:*

Diminished health of riparian vegetation and loss of wetlands, harming wildlife habitats and food sources.

*Water Quality Impacts:*

Changes in groundwater flow can lead to the intrusion of poor-quality water, negatively affecting aquatic ecosystems.

*Biodiversity Loss:*

Reduced habitat quality and availability can result in declines or extinctions of native species, disrupting ecosystems.

*Impact on Migratory Species:*

• Changes in groundwater levels can disrupt migration patterns and access to essential habitats for migratory species.

• Diminished capacity of ecosystems to provide services like water purification, flood regulation, and carbon sequestration, affecting overall environmental health.

*Ecosystem Services:*

Diminished capacity of ecosystems to provide services like water purification, flood regulation, and carbon sequestration, affecting overall environmental health.

**Section 4: Imagine the Consequences**

1. **Community Impact:**

-Rising water prices and economic challenges for residents and businesses.

2. **Homeowner Struggles:**

-Property damage and declining values, affecting homeowners.

3. **Impact on Wetlands and Natural Areas:**

-Disruption of ecosystems and potential loss of biodiversity.

4. **Depletion of Local Resources:**

-Infrastructure damage, increased desertification, and higher maintenance costs.

5. **Environmental Consequences:**

- Water scarcity, pollution of local water bodies, and negative environmental impacts.

More Citations:

Famiglietti, J. S. (2014). The global groundwater crisis. Nature Climate Change, 4(11), 945-948.

Holzer, T. L., & Johnson, A. I. (2014). Land subsidence caused by ground‐water withdrawal in the United States. Reviews of Geophysics, 52(3), 345-372.

Galloway, D. L., Jones, D. R., & Ingebritsen, S. E. (1999). Land subsidence in the United States. US Geological Survey Circular, 1182.

Poland, J. F., & Davis, G. H. (1969). Land subsidence due to withdrawal of fluids. Geological Society of America Bulletin, 80(2), 2047-2060.

Leake, S. A., & Akhter, M. S. (2002). Groundwater recharge through a debris fan: Potential for land subsidence mitigation. Hydrogeology Journal, 10(5), 541-550.

Teatini, P., Ferronato, M., Gambolati, G., & Janna, C. (2012). Aquifer overexploitation: Land subsidence and groundwater management (Vol. 25). Springer Science & Business Media.