In Conversation With: Erika Zarate Torres from Good Stuff International

In Conversation With: Erika Zarate Torres from Good Stuff International

The Water Network team had the pleasure to interview Erika Zarate Torres from Good Stuff International.

Erika Zarate holds a PhD in Environmental Sciences for EPF-Lausanne. She has several years of experience as project coordinator and consultant in water sustainability and policy at the watershed level. She specialises in WaterData4Action, a framework that uses available data so that they are translated into information for action.

She works at the interface between research and application, transferring complex water-related information to the language of stakeholders in order to increase their potential of decision-making.

Erika Zarate Torres is the Switzerland Regional Director of Good Stuff International.


Q1: We appreciate you taking the time to talk to us Erika. Would you please tell us about Good Stuff International?

Good Stuff International (GSI) is a global company that supports people and organisations to become sustainable water users. We operate from five different offices in three different continents, and have a societal mission: to explore and promote ways for people to live the best possible life on Earth while caring for the natural environment and other people. You can read more about our expertise and projects at

Q2: Could you tell our readers, who may be not acquainted with the topic, what the water footprint is and why is it important to measure it?

The water footprint is an indicator of water consumption and pollution that can be calculated for a crop, a farm, a company, a consumer, an entire sector, or for a site, a catchment or a country. It is a geographically explicit indicator that measures consumption of water stored in the soil as soil moisture (green water footprint), from surface and groundwater sources (blue water footprint) and polluted water (grey water footprint).

It is important to measure the water footprint in order to get an integrated picture of water consumption and therefore understand better how sustainable this consumption is for this specific location, and what can be done about it.

Q3: What are the unexpected and not too obvious things which contribute to the water footprint?

Water use is often only assessed from the point of view of water withdrawals, that is, surface and groundwater abstractions. Moreover, green water is neglected (because any way rain is naturally falling on my field so why should I account it).

In the case of agriculture, a great potential of improvement lays in comparing the consumptive component of blue water use (blue water footprint) with water abstractions, therefore estimating blue water losses at a daily basis, in relation to actual crop water needs.

Also, measuring green water consumption is fundamental for optimizing rainwater use, planning an efficient irrigation and ultimately having the highest possible yields with the smallest possible irrigation, therefore becoming more water sustainable.

Q4: How is the water footprint calculated?

In the case of agriculture, the water footprint is equivalent to the amount of water evapotranspired by the crop throughout the entire growing season. This is water needed by the crop in order to grow well. Depending on what you want to analyse, the water footprint can be expressed in different units.

For example, if you want to know the water footprint of your farm, you can express the water footprint in cubic metres per hectare, whereas if you want to know the water footprint of your crop product, you can express the water footprint in cubic metres per ton of product, using the yields of your farm. For assessing the amount of water evapotranspired by the crop, a soil water balance is needed, taking into account all in and outflows of water to the soil.


Q5: Can you please tell us about the Geographical Agricultural Water Footprint Calculator?

The Geographic Agricultural Water Footprint Calculator (GAWFC) is a software tool for calculating the water footprint of a crop. It does so by conducting a daily soil water balance for the entire growing season. It uses five georeferenced input files: precipitation, reference evapotranspiration, soil data, crop data and irrigation information. It is based in the FAO theory and equations to calculate crop Evapotranspiration.

We validated GAWFC against the FAO Cropwat model with a very good fit (r2 = 0.93). One of the best things about GAWFC is that costs and time investments are reduced, since many crops and many locations (for example farms) can be assessed at the same time. 

Q6: What inspired you to make the GAWFC?

We needed to assess the water footprint of 102 farms producing organic banana in Dominican Republic. This was a very interesting project as it aimed at improving the water use efficiency and increasing sustainability for bananas produced by small farmers, with the ultimate goal of making them fitter for the European market. The resources in the project were limited.

We made an agreement with Mesfin Mekonnen, a scientist from the University of Nebraska (formerly from University of Twente, The Netherlands), who produced the first version of the code to calculate the water footprint of crops globally, with academic purposes. We developed further the code to apply it for the 102 banana farms and discovered the enormous potential of applying this software tool in very practical and local situations, to support sustainable water use in agriculture. 

Q7: What exactly does it measure and how does it acquire and process data?

GAWFC conducts a daily water balance in the soil taking into account all water in- and outflows. It ultimately calculates the daily blue and green crop Evapotranspiration, using daily precipitation and irrigation data for a given location, a given crop and a given soil texture.

It is based on the theory presented by the FAO irrigation and drainage paper 56 on crop evapotranspiration. The best of it is that the outputs include the daily soil water balance for your sites. So you can really explore determine the efficiency of your irrigation and evaluate different scenarios.

Q8: What are the various applications of GAWFC?

We foresee a lot of potential for GAWFC:

Q9: Could you please tell us a bit about you project “Water Footprint Assessment of 316 watersheds in Colombia”?

This project was done under the umbrella of the National Water Study, the official document on the state of national water resources issued by IDEAM, the Colombian governmental institution on hydrology, meteorology and environment. In addition to the traditional indicators on blue water abstractions and pressure on blue water resources, the water footprint per economic sector and per watershed was included. Also, as part of the water footprint assessment, blue and green water scarcities per watershed were included.

One of the main outcomes of the study is that there is a strong competition for green water resources in some of the Colombian watersheds, which translates into green water scarcity and landuse conflicts, namely between agriculture and the environment. This is very interesting, because being Colombia a relatively well-endowed country with water, you wouldn’t expect that there is strong competition for green water resources. But there is!

Q10: And “Water Footprint of banana production by small-scale producers in Ecuador and Peru”?

We conducted a water footprint assessment for a sample of banana producers in the South of Ecuador (El Oro province) and for the North of Peru (Piura region). We included the crop and packaging phases in the assessment. We found out that the packaging phase contributes with less than 1% of the water footprint of the bananas assessed.

We also found out that for some farms, irrigation happens in a system of turns that makes farmers irrigate the crop for hours at once, but not so frequently, with important water losses and inefficiencies. However, the crop suffers water stress because the frequency of irrigation is too low. The water footprint can be decreased by managing water more smartly, for example by applying less water more frequently, and therefore increasing productivities.

Q11: How is the water footprint related to carrying capacity?

The water footprint at a given catchment or watershed can be analysed in the context of how much water is available in that watershed, taking into account environmental flow requirements. Ideally, the water footprint should not exceed the water designated as available for human use (once environmental flow requirements have been assigned).

Therefore, the importance of analyzing the water footprint in the context of the catchment or watershed where it is located and in relation to other water users in the same catchment or watershed.

Q12: Do people realize the importance of reducing the ecological and water footprint?

During the last 5-10 years, people have gained awareness with respect to the water footprint of food. Many people now understand that their domestic water consumption is only a small portion of their entire water consumption, which mostly happens in a “hidden” way, through the water that was needed to produce the food we eat and the products we consume.

However, it still remains intangible for people to grasp the problems in the watersheds where their products and goods were produced. It is even intangible for big producers/traders or big retailers such as supermarkets.

But slowly, this idea of having impacts on far-away watersheds has permeated the minds of many consumers and producers. Many big producers and some supermarkets have started taking an active role towards water sustainability in the critical watersheds where they source their products.

Q13: Finally, do you have a take-home message about the water footprint and water management?

The take home message is to start thinking in terms of watersheds and catchments. Become aware of the catchment where you live and how water is allocated there, even if it is a big city. Also, become aware of the fact that 70% of the water is used for agriculture, and that small-holder farmers produce 70% of the world’s food, usually with great water inefficiencies.

So we are literally speaking about a huge potential to increase water use efficiency globally while increasing yields and decreasing other agricultural inputs.

The entire water footprint science strongly supports moving towards this direction, and the Geographic Agricultural Water Footprint Calculator was conceived aiming at supporting and accelerating this work. 

Read More Interviews from the 'In Conversation With' Series
by The Water Network