Lake Urmia: A harsh learning lesson or a view of the future?

In this blog, I will explore the freshwater planetary boundary and its relationship with agriculture and consumption. I use Lake Urmia as a case study to demonstrate the problems associated with unsustainable freshwater use for agriculture as well as possible solutions.

Defining water scarcity and the freshwater planetary boundary

Water scarcity can occur due to a lack of sufficient water or not having access to safe water supplies. Global freshwater is increasing but 4 billion people still experience water scarcity for at least 1 month a year, as it is not the amount of global freshwater that is the problem but the uneven spatial and temporal distribution. Water scarcity is continuing to increase globally with the main drivers being population growth, changing consumption patterns, the expansion of irrigated agriculture and climate change.

At the moment we are using 2600 km cubed/yr of freshwater globally which is below the maximum global blue water use. However, this does not take into account regional water scarcity. Therefore, environmental water flow defined as the minimum blue water that must be retained in a river basin is used to measure the regional freshwater boundary. Figure 1 shows parts of Australia, South-West USA, North and South Africa, the Middle East and South America are experiencing water scarcity all year round.

Figure 1: The number of months per year where blue water consumption exceeds water availability

Agriculture and freshwater use

Agriculture accounts for 70% of global freshwater withdrawals and about one-third of this is used for irrigating crops for livestock feed. As a result, eating a plant-based diet could lower your water footprint by up to 30%. However, as mentioned last week achieving a sustainable freshwater footprint is more complicated than simply switching to a vegan diet. Considering the virtual water in products, which is the volume of water required to produce a commodity or a service is important.

Use the calculator below to calculate your water footprint:

Figure 2: Water footprint calculator

I also thought this was a great website explaining virtual water in food and it includes some tips on how you can save water at home.

Figure 3: The water we eat

Lake Urmia: A case study

You might be asking yourself, so what if I eat a beef burger every day (equivalent to spending two and a half hours in the shower)? In this section, I’m going to tell you why that’s a problem using the case study of Lake Urmia.

Lake Urmia is a saline lake situated in an endorheic region in northwest Iran. Between 1995 and 2013 Lake Urmia lost more than 90% of its volume, crossing into the zone of uncertainty for the regional freshwater boundary (figure 4). This resulted in an increase in salinity (8x saltier than the ocean), the decline of Artemia Urmiana (brine shrimp) and migratory birds, the collapse of the tourism industry and salt storms impacting respiratory health.

Figure 4: Interactive Google Earth Engine timelapse showing Lake Urmia’s decline

There is a debate around the reasons for Lake Urmia’s decline, with extraction for agriculture or climatic changes being the main cause. Endorheic basins have no outflows to the oceans and are losing more water yearly than exorheic regions (which do have ocean outflows). Wang et al. 2018 found little correlation between the El Niño–Southern Oscillation (ENSO) climate phenomenon and endorheic terrestrial water storage (TWS). This implies that endorheic regions are less influenced by climate and therefore humans are playing a bigger role in causing TWS variations. In contrast, studies by Shadkam et al. 2016, Delju et al. 2013 and Arkian et al. 2018 concluded that climatic factors including reduced precipitation and increased temperatures were leading causes of Lake Urmia’s decline. These studies made these assumptions based on the similarities between climate trends and lake inflows. The 2016 study concludes that Lake Urmia’s annual inflow dropped by 48% between 1960–2010 with three-fifths of this change being caused by climate. In contrast, studies by Hassanzadeh et al. 2012, Ghale et al. 2018 and Chaudhari et al. 2018 found that the decline was predominantly due to agricultural expansion and increased irrigation. For example, using a hydrological model, Chaudhari et al. 2018 found that 86% of the lake’s decline between 1995–2010 could be explained by human activities, which complements the results of Ghale et al. 2018.

However, regardless of whether climate or agricultural water extraction was the main reason for lake Urmia’s decline, Schulz et al. 2020 state that agricultural water extraction still has substantial influence on the resilience of the lake. Therefore, agricultural water savings would help keep the lake volume above the ecological water requirement and alleviate pressure off a dryer climate.

Agricultural solutions and restoration

It is not all doom and gloom and there are many academic reports and policies helping restore Lake Urmia to its former glory.

1. The ‘Aral Sea solution’ aims to preserve Lake Urmia by reducing the evaporative surface using dykes and dams to match the decreased discharge. However, a 2012 report mentioned that using Lake Urmia’s existing transportation causeway would be a cheaper way of doing this.

2. Estimate the minimum water needed to preserve the lake and implement water conservation and transfers schemes to achieve this. To do this, Lake Urmia’s inflows would have to increase by 83%, depriving users and ecosystems in the donor basin of much-needed water. A possible way to overcome this is to change cropping pattern to replace those with high water needs. A 2015 study found that replacing onions, sugar beets, and alfalfa (an important forage crop) with wheat, barley, and canola, would save 990.9 million cubic meters of water annually.