Land-use change has a stronger impact on streamflow than climate change in arid regions

Why It Matters

This insight highlights the critical need for designers and engineers to consider the complex interplay of environmental factors in their design projects. Understanding which factors exert the most influence allows for more targeted and effective design strategies, particularly in resource-sensitive regions.

Key Finding

While climate change is predicted to boost water flow in the Tarim River basin, the expansion of farmland and reduction of grasslands will lead to a greater overall decrease in streamflow.

Key Findings

• Projected increases in precipitation and temperature under climate change scenarios are expected to increase streamflow.
• Projected land-use changes (decreased grassland, increased farmland) are expected to decrease streamflow.
• The overall impact of land-use change on streamflow is greater than that of climate change.
• Combined effects predict a net decrease in streamflow, with land-use change being the dominant driver.

Research Evidence

Aim: To assess the individual and combined impacts of future climate and land-use changes on streamflow in the upper Tarim River basin.

Method: Integrated hydrological modelling

Procedure: Future climate scenarios from three General Circulation Models under different Shared Socioeconomic Pathways were used. Future land-use changes were predicted using a Cellular Automata–Markov model under three scenarios. The MIKE SHE model was then used to simulate streamflow under these combined scenarios for the period 2021-2050.

Context: Arid river basin hydrology and environmental planning

Design Principle

Environmental impact assessments must consider the relative influence of multiple drivers, prioritizing the dominant factor in design decisions.

How to Apply

When developing water management strategies or agricultural development plans in arid or semi-arid regions, use integrated modelling to quantify the relative impacts of climate change and land-use change on water availability.

Limitations

Model uncertainties, specific regional characteristics not fully captured, and the accuracy of future socio-economic pathway predictions.

Student Guide (IB Design Technology)

Simple Explanation: Even though warmer weather might bring more rain, changing how we use the land (like turning forests into farms) can actually reduce the amount of water flowing in rivers more.

Why This Matters: This research shows that when planning projects that affect water resources, you need to look at more than just the weather; how land is used is also super important and can have a bigger effect.

Critical Thinking: How might the socio-economic drivers behind the projected land-use changes (e.g., food security demands) be integrated into a design solution that mitigates negative impacts on streamflow?

IA-Ready Paragraph: This research by Han et al. (2023) demonstrates that in arid river basins, land-use change can exert a more significant influence on streamflow reduction than climate change. Their modelling of the Tarim River basin indicated that while climate change was projected to increase streamflow, the expansion of agricultural land at the expense of grasslands led to a net decrease, underscoring the critical role of land-use planning in water resource management.

Project Tips

• When modelling environmental systems, clearly define and justify the scenarios used for both climate and land-use changes.
• Use sensitivity analysis to understand how changes in different input parameters affect the model's output.

How to Use in IA

• Reference this study when discussing the impact of land-use change on hydrological systems in your design project's background research.
• Use the findings to justify the importance of considering land-use scenarios in your own modelling or impact assessment.

Examiner Tips

• Ensure that the chosen modelling software is appropriate for the scale and complexity of the problem being investigated.
• Clearly articulate the assumptions made during the modelling process and their potential impact on the results.

Independent Variable: ["Future climate scenarios (precipitation, temperature)","Future land-use scenarios (grassland area, farmland area)"]

Dependent Variable: Streamflow

Controlled Variables: ["Model parameters (MIKE SHE)","Time period (2021-2050)","Geographic area (Upper Tarim River basin)"]

Strengths

• Utilized multiple GCMs and SSPs for robust climate projections.
• Employed a well-established hydrological model (MIKE SHE) and a recognized land-use change model (CA-Markov).

Critical Questions

• To what extent do the chosen SSPs accurately reflect potential future socio-economic developments in the region?
• How sensitive are the streamflow predictions to variations in the parameters used in the MIKE SHE model?

Extended Essay Application

• Investigate the impact of different agricultural practices on water runoff in a specific region using hydrological modelling.
• Explore how urban development scenarios affect groundwater recharge and surface water availability in a watershed.

Source

Assessing the Impacts of Future Climate and Land-Use Changes on Streamflow under Multiple Scenarios: A Case Study of the Upper Reaches of the Tarim River in Northwest China · Water · 2023 · 10.3390/w16010100