– Professor Dr. Narendra Man Shakya
Water Resources Engineering
Institute of Engineering,
Tribhuvan University, Nepal
-continued from last issue:
Groundwater and its Utilization:
Available information shows that a good potential for groundwater extraction exists, specially in the southern plains (Terai) and inner valleys of the hills and mountainous regions.
Much of the Terai physiographic region and some parts of Siwalik valleys are underlain by shallow or deep aquifers, many of which are suitable for exploitation as sources of irrigation and drinking waters.
The annual recharge estimates range from 124 to 685 mm. The corresponding volume of water available for groundwater abstractions is estimated to be between 5.8 BCM and 12 BCM. However, based on the measurements of the seasonal fluctuations of the water table in shallow tube wells, the groundwater reserve is reported to be about 8.8 BCM annually.
Hydro Power Development:
Energy sources in Nepal can be divided into two categories: (i) traditional biomass related energy sources (fuel wood, agricultural residues, cow dung, etc.) and (ii) commercial energy sources (fossil fuel, hydroelectricity, coal, etc.).
Currently, hydropower contributes only 2% of the total energy usage.
The bulk of the energy need is met by fuel wood (78%), agricultural waste (4%), animal dung (6%) and imported coal and petroleum products (10%) (WECS, 2010).
At present, the power system in Nepal doesn’t have enough electricity even to meet low demand in the high production period of the year, causing a year round load shedding.
Hydropower contributes to meeting both water and energy needs, including water for irrigation and drinking water.
It usually works with a wider group of disciplines to maximise hydropower’s contribution to sustainable development.
And there will be no issue with the market, because currently only 40% of the population has access to electricity through the grid and off-grid systems, and demand is increasing.
Estimates of electricity income and price elasticity show that Nepal, for a long period of time, does not have to arrange demand management.
It further implies that higher generation will create its own demand.
Nepal will need to put more effort into increasing electricity supply investments as a national strategy towards advanced development in the long run.
According to the estimations of NEA, energy demand will grow in the next 17 years, with an average annual rate of 8.34%.
The National Energy Strategy 2010 projected energy demand on the assumption that the country’s economic growth will remain at 5.6% on average till 2030.
It has been aimed on the report to meet the growing demand of electricity by building more hydroelectric plants and reduce the dependence on bio mass and fossil fuels.
This shows that there is a huge potential for export of power without compromising domestic demands for the long term.
Without entering into the export market, the benefits from hydro-generation cannot be maximized, because for the near future the domestic electricity market of Nepal is limited.
Drinking Water and Water Security:
Fresh water is a key resource for human health, prosperity, and biodiversity.
Water is likely to be a constraint on economic growth.
The cost of global water insecurity is estimated to be $500 billion annually and is likely to be a drag on the world economy by 1% or more of gross domestic product (GDP).
The United Nations (UN) General Assembly has set the global agenda to achieve universal and equitable access to safe and affordable drinking water for all by the year 2030 as one of its sustainable development goals (SDG) for the water sector.
To achieve and measure those targets, water security has emerged as a prominent issue among water and development communities globally.
A national-level analysis of water security by the Asian Development Bank (ADB) in 2016 shows that South Asia had the lowest overall water security index in 2014 in the Asia-Pacific region.
Nepal positions itself 43rd out of 48 Asian and Pacific countries and fourth among six South Asian countries with a national water security (NWS) index of 2 out of 5.
For the five dimensions of water security considered in the ADB (2016) study, out of a possible score of 20, Nepal got 5.3 for households, 11.3 for the economy, 6.0 for urban, 10.7 for the environment, and 4.0 for resilience.
This reflects water insecurity in all aspects.
Hence, to achieve water security and enhance/sustain economic development, investment in water infrastructure and institutions in developing member countries is crucial.
To achieve the sustainable development goal (SDG) target for the water sector, the government of Nepal (GON) is investing in several water related infrastructure developments across the country.
The development of infrastructure and institutions is overcoming urban water insecurity in large cities.
One of the largest projects in the water sector since the year 2000 has been an inter-basin water transfer project called Melamchi Water Supply Project (MWSP), which aims to bring water to the Kathmandu Valley from water sources outside the valley.
MWSP plans to supply 510 million liters a day (MLD) of water in two phases: 170 MLD in the first phase by the year 2018, and an additional 340 MLD in the second phase by the year 2023.
Whether or not this mega project can contribute to achieving the SDG target in Nepal remains to be seen.
Water Security Index (WSI), is a ratio of supply to demand for domestic water use for basic human water requirements (50L per capita per day (Ipcd)) and economic growth (135 lpcd).
Results show a severe water insecurity condition in the year 2017 in all the Kathmandu Upatyaka Khanepani Limited (Kathmandu Valley Drinking Water Ltd. or KUKL for short) service areas (SAs), which is likely to improve after the completion of the MWSP.
A supply deficit of 102 million liters per day (MLD) will remain after the completion of the first phase of the Melamchi Water Supply Project.
If the MWSP is completed within the specified timeframe, and sufficient treatment and distribution infrastructure is developed, then there would be no water deficit by 2023-2025.
This indicates that the MWSP will make a significant contribution to the valley’s water security.
However, emphasis must be given to utilizing all of the water available from the MWSP by developing sufficient water treatment and distribution infrastructure.
Alternate mitigation options, such as planning land use for potential recharge, introducing micro- to macro-level rainwater harvesting structures, conjunctive use of surface and groundwater resources, and water demand-side management, would also be helpful.
The Kathmandu Upatyaka Khanepani Limited is the only body that supplies drinking water to the residents of Kathmandu Valley.
It has tapped almost all possible sources of water for Kathmandu.
Yet, it has been able to meet just one fourth of the water demand compelling the large fraction of population to be dependent on ground water.
According to the study (Metacalf and Eddy, 2000), pumping water levels has dropped from 9m to 68m. As the groundwater level declines, it will induce cascading effects through terrestrial and aquatic ecosystems (Palmer, 2003) increasing the drilling cost, pumping cost and causing land subsidence.
An estimation of sustainable withdrawal rate with adequate management measures can be key components in using the groundwater resources efficiently.
A pumping sensitive analysis of groundwater system in Kathmandu valley shows that the areas near Dharmasthali, Dhapasi, Maharajganj Sankhu and Gokarna have a decline of 0.02 to 0.12 m in head with per unit increase in pumping (m3/s) whereas the areas near Balaju, Samakhusi and Shwoyambu showed more decline of up to 0.12m to 0.23 m.
The proposed extraction rate map prepared through this analysis also indicates that the northern part of the ground water basin has more volume of water available per unit decline in head per year and the value of the extraction rate is decreasing as we move from northern part of groundwater basin to the southern part.
#Text courtesy: Association of Former Career Ambassadors of Nepal ( AFCAN) journal on “Strategies for the Development of nepal’s Water Resources” edited by Dr. Khaga Naath Adhikari.
Published with the permission of the AFCAN President Ambassador Dr. Ram Bhakta Thakur: Ed. Upadhyaya.
Thanks the distinguished author and AFCAN.
Our contact email address is” editor.telegraphnepal@gmail.com