A recent study recorded a 60 percent drop in the water supply of the Colorado River basin. Due to the scarcity of water in the last 12 years, in the regions involved there is talk of a “new normal”. This river crosses Argentina from the Andes mountain range to the sea, through five provinces, and is vital for the production of food and consumption of the populations.
The information was prepared by researchers from the National Water Institute (INA), the National Institute of Agricultural Technology (INTA) and the National Commission for Space Activities (CONAE) based on satellite images and in situ measurement stations. “The snow that accumulates during autumn and winter in the upper basin of the Colorado River is the source of water supply for this territory. shared by Mendoza, Neuquén, Río Negro, La Pampa and Buenos Aires”, explains Carolina Aumasanneof the Rural Extension Agency of INTA 25 de Mayo.
Knowing the hydrology of the basin is essential to plan the use that is given to the water along its route. Agriculture represents its main use: 98 percent of its consumption is for irrigated crops. The largest development is located in the Buenos Aires valley, with an area of 78,000 hectares, followed by the province of La Pampa, with 12,000 hectares.
“It is essential to generate qualified information to know how much it snows, when the thaw begins and what volume of water we will have during the year”, states Ana Paula Salcedoresearcher at the INA Andean Regional Center.
a new flow
The Colorado River has, according to the historical average, an annual spill (amount of water) of 4,400 cubic hectometers (Hm3). Nevertheless, in the last 12 years, spills below the average were recorded, between 1,600 and 3,600 Hm3. In the last time, it presented a decrease that oscillates between 40 and 60 percent. Added to the drop in water supply is the growth in agricultural production and population throughout the basin, which represents a greater demand for water.
INTA has been working on this issue since 2013, meeting the demands of the territory and with the aim of generating knowledge about hydrology throughout the basin. In 2021, the first lines of research were carried out in cooperation with the INA. “We are making progress in updating the precipitation and river flow databases, and we are evaluating their annual and interannual variations with information from meteorological and hydrological stations,” says Salcedo. And he adds: “Besides, We began to use optical and radar satellite data to estimate snow cover parameters in the upper basin of the River”.
Then they summoned CONAE to develop the lines of work with satellite information, interested in adding data provided by the radar of the Argentine SAOCOM satellites. Romina Solorza, a professional from CONAE’s Earth Observation Management, details: “We were able to reconstruct historical information scenarios, with very interesting results. For example, we find that since 2010 the Colorado River basin has a new flow rate lower than its historical average”. Knowing this situation makes it possible to plan the sustainable use of water from that new level.
more accurate information
Unlike measuring stations located on the ground, satellites obtain pixel-by-pixel information from the entire study area. “From INTA we had been working with satellite images from the MODIS sensor, which allowed us to know the state of the snow every eight days, with a pixel of 500 meters. The information provided by CONAE provides us with a much higher spatial and temporal resolution that generates objective and qualified information almost in real time.”, highlights Aumassanne.
The satellite information is corroborated with data from meteorological, flow and snow stations, located at more than 2,500 meters above sea level. However, the advantage of satellites is that, while each station provides data from a specific site (there are only four snow stations distributed in a 13,900 km2 basin), the SAOCOM radar image allows to cover the entire area and determine where the snow melting process begins.
“The SAOCOM data provide us with information about the moisture content in the snow pack in the spring months to know the date on which the melting process begins and, based on these data, infer the moment in which the water will be available in the rivers”, says Salcedo.
Currently, Work is focused on the design of mathematical models and machine learning technologies to integrate the information provided by satellites and stations in order to estimate flows. For this they have the collaboration of the School of Geosciences of the University of Edinburgh, Scotland. To future, They also plan to incorporate the study of climate change scenarios and the impact on regional hydrology.