‘Human activity around lakes depletes groundwater more than climate change’


The findings point to a need for improved governance of water resource sustainability which remains a critical challenge, particularly in semi-arid regions where despite an increase or no change in rainfall, there is a steady decline in the streamflow of catchments.

“We observed that nearly 50% of the water harvested by hydrological structures helps to increase groundwater recharge. However, crop area expansion using groundwater for irrigation has depleted streamflow and groundwater storage in Himayatsagar catchment. The annual groundwater recharge in the catchment is able to fully meet the irrigation requirement during high rainfall years, 50% during dry years and 30% during normal years,” said Dr. Rajesh Nune, hydrologist, ICRISAT Development Center (IDC).

Researchers at the IDC studied historical data on climate, land use, watershed structures, and groundwater levels available with the Telangana government organisations and conducted field surveys to gather data on groundwater utilisation for different cropping systems during the rainy (kharif) and post-rainy (rabi) seasons.

The data was analysed using an integrated hydrological model called Modified Soil and Water Assessment Tool (SWAT).’The approach combines SWAT’s rainfall-runoff model with a groundwater model for each of the 19 sub-catchments in Himayatsagar. The model is structured to capture dynamic changes in climate variability, land use, and watershed development structures in the catchment.

Climate variability

The ICRISAT-led study also explored the future impact of potential climate and catchment changes on streamflow and groundwater storage in the Himayatsagar catchment.

The model explored factors such as expanding groundwater irrigated areas, watershed structures, and rejuvenation of existing tanks under the Telangana government’s ‘Mission Kakatiya’ in future.

Notably, the State of Telangana is expected to witness the highest rainfall in September, instead of August by the end of this century, in light of rising temperatures (0.6 0 – 0.9 0 C every 30 years) and climate change.

ICRISAT’s findings reveal that despite the increase in average rainfall, a decline in streamflow is expected, considering variations in seasonal rainfall in the months of May and November.

Critically, the study observed that catchment changes would have a more significant impact than climate change (rainfall and temperature) in future.

Under the Mission Kakatiya programme, village tanks were desilted, rejuvenated, and interlinked with the drainage network. According to model predictions, this mitigation strategy captures excess runoff, enhances groundwater recharge for upstream users, and helps control flood damage to downstream users during high-intensity rainfall.

“It is also necessary to have a better water resource governing policy for the administration of village tanks, especially during the dry years, for the benefit of downstream users,” said Dr Rajesh Nune.

“The analytical framework ICRISAT has employed will help policymakers to take appropriate measures to monitor the cultivation of water-intensive crops (paddy, sugarcane, maize etc.) and guide farmers to diversify their crops while ensuring efficient use of water resources,” said Dr Rajesh Nune.

Leave a Comment