Over the years, there has been a noticeable decrease in snow cover and a substantial increase in glacial lakes, impacting river runoffs in critical basins like the Indus
More than 50 per cent of catchment areas globally witnessed deviations from normal river discharge conditions last year, posing a significant challenge in providing water to an increasingly vulnerable world grappling with climate change, according to a report by the World Meteorological Organisation.
The report titled "WMO State of Global Water Resources 2022 Report" provides an independent and consistent global-scale quantitative assessment of water resources in large river basins in comparison to the long-term average for various variables like river discharge, groundwater, evaporation, soil moisture and inflow to reservoirs.
It stated that the hydrological cycle was spinning out of balance as a result of climate change and human activities.
The consequences of this imbalance are devastating, with droughts and extreme rainfall events wreaking havoc on both lives and economies. The melting of snow, ice, and glaciers intensifies flood risks and jeopardises long-term water security for millions of people worldwide.
The report contends that still too little is known about the true state of the world's freshwater resources.
"In 2022, over 50 per cent of the global catchment areas experienced deviations from normal river discharge conditions. Most of these areas were drier than normal, while a smaller percentage of basins displayed above or much above normal conditions. This was similar to 2021.
"More than 60 per cent of major water reservoirs saw below or normal inflow (in 2022), which provides a challenge for providing water to all users in an increasingly variable climate," it said.
Throughout 2022, anomalies in soil moisture and evaporation mirrored deviations in river discharge conditions. For instance, Europe suffered from increased evaporation, decreased soil moisture and reduced river flows during the summer due to a major heatwave and drought, leading to challenges in agriculture and even causing power plants to shut down due to the lack of cooling water, the WMO said.
The UN agency said the switch from La Nina in 2022 to El Nino conditions in 2023 is likely to have a major impact on the hydrological cycle that will be analysed in next year’s report.
El Nino and La Nina are the two main phases of ENSO, or El Niño-Southern Oscillation, a climate pattern in the tropical Pacific Ocean. El Nino, the warming of waters in the Pacific Ocean near South America. La Nina is the opposite of El Nino.
The WMO points out significant changes in the Third Pole region, which supplies water to nearly 2 billion people, including the Tibetan Plateau, the Himalayas, and other mountain ranges.
Over the years, there has been a noticeable decrease in snow cover and a substantial increase in glacial lakes, impacting river runoffs in critical basins like the Indus, Amu Darya, Yangtze, and the Yellow River, the report pointed out.
From 2000 to 2018, total glacier mass balance in the region decreased by more than 4 per cent, it said, adding this has impacted river runoffs at the Indus, Amu Darya, Yangtze and Yellow River basins, indicating climate change's evolving influence on the region.
In 2022, the snow cover in the Alps, crucial for feeding major rivers of Europe like the Rhine, Danube, Rhone, and Po, remained much lower than average. The European Alps witnessed unprecedented levels of glacier mass loss.
Severe droughts impacted many parts of Europe in the summer of 2022, posing transportation challenges on rivers like the Danube and Rhine and disrupting nuclear electricity production in France due to the lack of cooling water.
Navigation on the Mississippi river in the USA was affected by the extremely low water levels, as a result of a continuous drought in the North American country.
In South America, the La Plata river basin has endured a continuation of drought conditions since 2020. This caused a significant drop in hydropower production in 2022, resulting from low river flows. There were several instances of no water supply in Paraguay during 2022.
Severe drought in the Yangtze River Basin in China led to much lower-than-average river discharge, inflow to reservoirs, and soil moisture.
A prolonged drought led to a major humanitarian crisis in the Horn of Africa. In contrast, the Niger Basin and much of South Africa recorded above-average river discharge, linked to major flood events in 2022, the report stated.
A megaflood hit the Indus River Basin in Pakistan, killing at least 1,700, affecting 33 million and causing an estimated more than USD 30 billion in economic losses.
A heatwave early in the year increased meltwater from glaciers, increasing river levels which were then swelled by severe monsoon rainfall which was more than twice the average in July and August, it stated.