Title
Streams, sewage, and shallow groundwater: stream-aquifer interactions in the Kathmandu Valley, Nepal
Author
Prajapati, Rajaram (Center of Research for Environment, Energy and Water, Kathmandu; Smartphones For Water Nepal (S4W-Nepal))
Overkamp, Nick N. (Student TU Delft)
Moesker, Niek (Student TU Delft)
Happee, K. (TU Delft Ship Design, Production and Operations)
van Bentem, R. (TU Delft Geo-engineering)
Danegulu, Anusha (Pulchowk Campus, Lalitpur)
Manandhar, Bikesh (Pulchowk Campus, Lalitpur)
Thapa, Amber Bahadur (Smartphones For Water Nepal (S4W-Nepal))
Davids, J.C. (TU Delft Water Resources; SmartPhones4Water; California State University, Chico)
Date
2021
Abstract
The Kathmandu Valley in Nepal is facing a water quantity and quality crisis due to rapid urbanization and haphazard water and wastewater planning and management. Annually, groundwater extractions in the Kathmandu Valley exceed capture, resulting in groundwater table declines. Streams are often important sources of recharge to (or destination of discharges from) aquifers. However, stream-aquifer interactions in the Kathmandu Valley are poorly understood. To improve this understanding, we performed topographic surveys of water levels, and measured water quality, in streams and adjacent hand-dug wells (shallow aquifer). In pre-monsoon, 12% (2018) and 44% (2019) of wells had water levels higher than adjacent streams, indicating mostly a loss of stream water to the aquifer. However, in post-monsoon, 69% (2018) and 70% (2019) of wells had water levels higher than adjacent streams, indicating that monsoon rainfall contributes to shallow aquifer recharge which, at least temporarily, causes streams to transition from losing to gaining. Concentrations of all water quality parameters (electrical conductivity, ammonia, alkalinity, and hardness) were higher in the pre-monsoon compared to post-monsoon in both streams and wells. There was no recurring trend in water level difference longitudinally from upstream to downstream. However, water quality in streams and wells depleted from upstream to downstream. While we clearly observed seasonal refilling of the shallow aquifer, the role of the deep aquifer in seasonal storage processes deserve future research attention.
Subject
Groundwater
Kathmandu Valley
Stream-aquifer interactions
Water management
Water quality
To reference this document use:
http://resolver.tudelft.nl/uuid:e04a0f51-827a-4adf-bd8e-78b9904d6c9b
DOI
https://doi.org/10.1007/s40899-021-00542-8
ISSN
2363-5037
Source
Sustainable Water Resources Management, 7 (5)
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2021 Rajaram Prajapati, Nick N. Overkamp, Niek Moesker, K. Happee, R. van Bentem, Anusha Danegulu, Bikesh Manandhar, Amber Bahadur Thapa, J.C. Davids, More Authors