Aquifers: The groundwater in Colorado’s wells and how it gets there – Colorado Public Radio

Report on Groundwater Resources and Sustainable Development

Introduction: Groundwater’s Role in Achieving SDG 6

The sustainable management of groundwater is a critical component in achieving the United Nations Sustainable Development Goals (SDGs), particularly SDG 6 (Clean Water and Sanitation). As surface water resources face increasing pressure from drought and demand, understanding subterranean aquifer systems is fundamental to ensuring the availability and sustainable management of water for all. This report analyzes the hydrogeological characteristics of aquifers and their connection to broader sustainable development challenges, including climate action and ecosystem preservation.

1. Aquifer Systems and Water Security

An accurate understanding of aquifer composition is foundational for effective water resource management, a key target of SDG 6. Contrary to common misconceptions of underground lakes, aquifers are complex geological formations.

• Formation: Aquifers consist of water held within the pores and fractures of subterranean sediments (gravel, sand, silt) and rock layers.
• Recharge Process: They are replenished by surface precipitation, such as rain and snow, which infiltrates the ground and percolates downwards.
• The Water Table: The point at which the ground becomes fully saturated with water is known as the water table, marking the upper boundary of an unconfined aquifer.

Protecting these systems is essential for providing safe drinking water and supporting sanitation, directly contributing to the targets of SDG 6 and enhancing community resilience as outlined in SDG 11 (Sustainable Cities and Communities).

2. Aquifer Recharge Dynamics and Water Quality

The rate of aquifer recharge has significant implications for water availability and quality, impacting progress towards SDG 6, Target 6.3 (Improve water quality) and Target 6.4 (Substantially increase water-use efficiency).

1. Rapid Recharge: In highly porous, shallow systems, recharge can occur over days, weeks, or months, providing a renewable source of fresh water.
2. Prolonged Recharge: In deeper, less permeable formations, water may take decades or even millennia to percolate. This “fossil water” is a finite resource, and its quality may be lower than that of younger water.

Sustainable withdrawal strategies must account for these varying recharge rates to prevent depletion and ensure long-term water security.

3. Interconnection of Surface and Groundwater Systems

The hydrological connection between surface water and groundwater is a critical factor for integrated water resources management, as called for in SDG 6, Target 6.5. This linkage also underpins the health of terrestrial and aquatic ecosystems, a core objective of SDG 15 (Life on Land).

• Tributary Systems: Alluvial aquifers, composed of sediment deposited by rivers, are directly connected to adjacent streams. They provide a consistent baseflow that sustains river ecosystems, especially during dry periods.
• Bedrock Contributions: Deeper bedrock aquifers can also intersect with and discharge into rivers, contributing to surface water flows.
• Regulatory Frameworks: Legal definitions, such as Colorado’s distinction between “tributary” and “non-tributary” water, are governance tools designed to manage these interconnected systems sustainably, balancing human consumption with environmental needs.

4. Climate Change Impacts and Aquifer Resilience

Drought, exacerbated by climate change, poses a significant threat to groundwater resources, challenging the objectives of SDG 13 (Climate Action). The impact of drought varies depending on the type of aquifer.

1. Shallow Alluvial Aquifers: These systems are highly vulnerable to drought. A lack of precipitation leads to reduced recharge and a rapid decline in the water table, especially when combined with heavy pumping for agriculture (SDG 2: Zero Hunger) and municipal use (SDG 11).
2. Deep Bedrock Aquifers: While more insulated from short-term droughts, these aquifers are not immune. Prolonged, multi-decade droughts can affect their recharge, and they remain vulnerable to depletion from over-extraction.

Therefore, the prudent management of groundwater is a critical climate adaptation strategy, essential for building resilient water systems capable of withstanding the impacts of a changing climate.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

• SDG 6: Clean Water and Sanitation

  The entire article is dedicated to understanding groundwater resources (aquifers), which are a critical source of fresh water. It discusses their function, recharge process, and the impact of demand and drought, all of which are central to ensuring the availability and sustainable management of water.

• SDG 13: Climate Action

  The article explicitly mentions “drought” as a primary factor affecting water resources. It explains how drought reduces the recharge of aquifers (“when there’s a drought, there’s less water going in”). This directly links the discussion to the impacts of climate-related hazards and the need for adaptation and resilience in water management.

• SDG 15: Life on Land

  The connection between groundwater and surface water is a key theme. The article states that “surface water and groundwater are connected” and that “water from those aquifers are continually coming into the streams.” This highlights the importance of healthy aquifers for sustaining river ecosystems, which are a crucial part of terrestrial and inland freshwater ecosystems.

2. What specific targets under those SDGs can be identified based on the article’s content?

• Target 6.4: By 2030, substantially increase water-use efficiency across all sectors and ensure sustainable withdrawals and supply of freshwater to address water scarcity.

  The article addresses this target by discussing the consequences of unsustainable withdrawals. It notes that when an aquifer is “heavily pump[ed],” its water table “will go down pretty fast,” especially during a drought. This points directly to the challenge of ensuring sustainable withdrawals to prevent water scarcity.

• Target 6.5: By 2030, implement integrated water resources management at all levels.

  The article itself is an effort to improve public understanding of groundwater as part of the “bigger water resource picture.” It explains the complex relationship between precipitation, surface water, and groundwater (“all surface water is connected to groundwater and vice versa”). This foundational knowledge is essential for implementing an integrated approach to water management that considers all parts of the water cycle.

• Target 6.6: By 2020, protect and restore water-related ecosystems, including mountains, forests, wetlands, rivers, aquifers and lakes.

  The focus on understanding and managing aquifers is directly related to their protection. The article describes aquifers as vital water-related ecosystems and discusses their connection to rivers, implying that the health of one is dependent on the other. Protecting aquifers from over-extraction is a key step in protecting the broader water-related ecosystem.

• Target 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.

  The article discusses how aquifers are affected by drought, a major climate-related hazard. By explaining the different response times of shallow and deep aquifers to drought, it provides knowledge that is critical for building resilience and developing adaptive water management strategies to cope with prolonged dry periods.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

• Indicator 6.4.2: Level of water stress: freshwater withdrawal as a proportion of available freshwater resources.

  This indicator is implied through the discussion of the “groundwater table declining” as a result of “drought and demand” and “heavily pumping.” Monitoring the level of the water table is a direct measurement of the stress being placed on the aquifer (the freshwater resource) by withdrawals.

• Indicator 6.5.1: Degree of integrated water resources management implementation.

  The article implies this through its focus on education and the existence of specialized bodies like the “Colorado Geological Survey” and the “Colorado’s Division of Water Resources.” The work of these institutions in studying and managing groundwater, including establishing legal definitions for “non-tributary water,” is an indicator of an implemented management framework.

• Indicator 6.6.1: Change in the extent of water-related ecosystems over time.

  The article implies this indicator by describing how the “groundwater table will start declining.” The volume and saturated extent of an aquifer are key characteristics of this ecosystem. Measuring changes in the water table over time provides data on the changing extent and health of the aquifer itself.

SDGs, Targets, and Indicators Summary

Source: cpr.org