Installation of Meteorological Stations – Along the North-South transect of the catchment, we have established several monitoring stations, making significant strides in data collection. As of now, three weather stations have been installed, each equipped to measure 12 weather variables. The data is stored directly in the cloud for real-time access and analysis, ensuring that researchers can monitor climatic trends seamlessly. Additionally, two rain gauges, complemented by soil moisture sensors are also deployed.

Figure 1: Soil moisture sensors at different depth in the soil

Figure 2: Weather station at 2980 m altitude

Water Sampling Campaign – In October 2023, we initiated a comprehensive water sampling campaign that will continue through autumn 2024. We’re collecting samples from multiple sources, including rivers, rainfall, and springs across different locations in the basin. The key goal is to conduct isotope analysis (primarily of water itself) on these samples to determine the contributions of different water sources to streamflow, which can validate our hydrological model results. If successful, this field campaign will help us better understand the hydrological processes.

So far, we’ve established five sites for river water collection and three for rainfall sampling. Springwater samples have also been gathered to broaden the scope of our analysis. Additionally, we plan to incorporate snow samples into our upcoming fieldwork, enhancing our understanding of water sources in the region.

Figure 3:  Setup for collection of rainwater in the Karnali catchment

Figure 4: Collected samples from Karnali during spring 2024 ready to be analyzed in the lab

Hydrological modelling – The hydrological model for the Karnali catchement has been calibrated and validated, and we’re currently analyzing historical data to uncover long-term hydrometeorological trends and patterns. Using satellite data for the model, we’ve mapped the basin’s water balance components, which are precipitation, evapotranspiration, and four runoff components (rain, baseflow, glacier melt, and snow melt).

Preliminary results indicate a consistent spatial distribution of hydrological patterns across the basin, though the intensity of these components varies regionally. The data reveals that the highest precipitation and evapotranspiration occur in July, with the majority of rainfall concentrated at elevations between 1,000 and 2,000 meters above sea level. This period coincides with peak temperatures, driving higher evaporation rates.

Given the Karnali catchment’s vulnerability to extreme weather events, our model will focus on analyzing and forecasting these critical occurrences, providing valuable insights for both conservation efforts and local communities. Looking ahead, our research will delve deeper into forecasting extreme hydrological events in the Karnali catchment using a large ensemble dataset.