New Approaches to Source Water Protection
The drying up of water sources across Bhutan is one of the major challenges to achieving Bhutan’s national goal of ensuring “24/7 access to safe drinking water” by 2023.
Access to drinking water is closely linked to other national objectives of public health and hygiene and environmental management. A survey conducted by the Department of Forestry and Parks Services (DoFPS) as part of the Climate Resilience Strategic Program Preparatory Project in 2019 found that 35% of the 6,555 water sources surveyed are drying up while 2% (147) were reported as ‘completely dried’. Similarly, a recent national survey in 2021 by the DoFPS again reported that 25.1% (1,856) of 7,399 water sources have already dried up, while 69 (0.9%) were reported as “in drying up”.
A recent book published by the Tarayana Foundation titled “Springshed: Identifying
Recharge areas of drying springs and lakes with water quality in the southwest
Bhutan’ authored by Jambay and Karma Uden further offers insight into the protection of Bhutan’s critical drinking water sources. Through this article, the authors and a group of independent water researchers offer new ideas for improving the management of dewatering water sources.
Drinking water sources in Bhutan are mainly springs (35%) and river systems. A common strategy under current water source protection strategies in Bhutan includes fencing and improving the vegetation cover at the outfall – the place where water begins to flow. Recently, interventions such as trenching upstream of the discharge point to increase groundwater recharge have also been implemented in a few places like Trashigang and Pemagatshel. To enhance the effectiveness of such interventions, we offer the following recommendations based on our field experiences and the latest scientific research.
Shift interventions from discharge areas to recharge areas – The area of intervention for water resources management should start with effective management of recharge areas. A recharge zone refers to a geographic area where rainwater seeps through the ground to reach a groundwater reservoir. Management strategies should be targeted to maintain adequate water levels in these underground water reservoirs to ensure continued flow of streams and springs.
Integration of protection of public drinking water supply areas – Critical water supply basins could be delineated as critical public drinking water supply areas with a protection status similar to national parks, in order to limit development activities impacting the watershed. However, such a demarcation should be based on adequate hydrogeological observations. Boundary demarcations of these public drinking water supply areas could then be made available to the public during development and planning. For example, an environmental permit for any development could use such a database with an online portal to protect water sources against all sorts of risks.
Use of adequate, site-specific hydrogeological data – Tree planting cannot be considered a one-size-fits-all solution to reviving drying water sources in different watersheds due to the wide variability in groundwater hydrogeology in mountainous regions like ours. Thus, the relationship between vegetation cover and shallow groundwater reservoirs needs to be thoroughly investigated. In general, young vegetation can absorb more water than recharge, but mature vegetation would improve water recharge. However, there are many site-specific hydrogeological and other physical environmental factors that significantly influence the dynamics of the relationship between vegetation and underground water reservoirs. It is therefore essential to start collecting relevant data to calculate water balances at the national level. Such data collection could be integrated with the national forest inventory data collection which is carried out every few years. Otherwise, a one-time data collection at a few selected sites along the main river or stream channel, such as that conducted by the National Environment Commission (National Water Resources Inventory 2018), is less useful. .
Reduced Source Disturbance – Minimal disturbance to the water catchment site is essential. Any heavy civil works such as building water reservoirs or cutting and planting trees closer to water sources could sometimes be counterproductive to reviving water sources that are drying up. Large-scale disturbance near springs could potentially alter the orientation of the lithology. As a result, water flow paths can be altered, causing springs and lakes to dry up.
Creation of a repository of data and knowledge – The strategy for collecting long-term data on hydrology and geotechnical information is essential to make an informed decision. A simple start could be to have a national repository of drill logs of all groundwater explorations carried out in many places in Bhutan. If these drill logs were generated according to standard scientific procedures, they should contain detailed soil and hydrogeology information for every meter of the hole drilled in that area used for groundwater extraction. Analysis of borehole log data in the coming years is expected to be essential in the exploration and management of drinking water sources in similar hydrogeological locations across Bhutan.
Application of the concept of “spring basin” management – The majority of previous scientific research in Bhutan in the field of water resources management has applied the concept of watershed or river basin management to meet specific objectives.
However, in the case of exploring interventions to stop the drying up of water sources, we recommend the application of the principles of management of “source basins”. In addition, this new approach to spring basin management provides a better understanding of water flow pathways, as the geological formations of aquifers and springs are given equal importance. We believe that the concept of spring basin management is particularly relevant for dealing with dewatering springs in Bhutan, as inclined rocks generally guide water flow instead of horizontal rock formations.
The article is published based on personal experiences and observations of a group of water researchers from Bhutan. The group can be contacted at [email protected]